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DONEPEZIL

Classification   |    Detailed evidence-based information

Therapeutic Toxic Class

    A) Donepezil is a centrally active, reversible, specific acetylcholinesterase inhibitor, approved for treatment of dementia of Alzheimer's disease. It is a piperidine derivative. It is highly specific for the CNS. Overdoses may be expected to consist of enhanced muscarinic effects.

Specific Substances

    1) 2,3-dihydro-5,6-dimethoxy-2-((1-(phenylmethyl)-4-piperidinyl)methyl)-1H-inden-1-one hydrochloride
    2) Donepezil hydrochloride
    3) E2020
    4) Molecular Formula: C24-H29-NO3-HCl
    5) E-2020
    6) 120014-06-4 (donepezil)
    7) 142057-79-2 (donepezil)
    8) 120011-70-3 (donepezil hydrochloride)
    9) 142057-77-0 (donepezil hydrochloride)

Available Forms Sources

    A) FORMS
    1) Donepezil is available as 5 mg, 10 mg, and 23 mg oral tablets and 5 mg and 10 mg oral disintegrating tablets (Prod Info ARICEPT(R) oral tablets, 2015).
    B) USES
    1) Donepezil is used for the treatment of Alzheimer's type dementia (Prod Info ARICEPT(R) oral tablets, 2015).

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) WITH THERAPEUTIC USE
    1) The most common adverse reactions following administration of donepezil include diarrhea, loss of appetite, nausea, vomiting, muscle cramps, insomnia and fatigue.
    B) WITH POISONING/EXPOSURE
    1) Overdose information is limited. Based on its cholinergic effects, typical findings might include muscarinic actions consisting of: miosis, flushing, bradycardia, bronchospasm, increased bronchial secretions, involuntary urination and/or defecation, sweating, lacrimation, hypotension, and/or seizures.
    2) Because of its high degree of selectivity for AChE in the CNS and less peripheral selectivity, overdoses would be expected to exhibit more CNS-related symptomatology, including extrapyramidal effects.
    0.2.3) VITAL SIGNS
    A) WITH POISONING/EXPOSURE
    1) Blood pressure and pulse may be decreased following an overdose.
    0.2.4) HEENT
    A) WITH THERAPEUTIC USE
    1) Miosis, salivation, and lacrimation are common systemic effects of cholinergic agonists and may occur with donepezil in therapeutic amounts.
    B) WITH POISONING/EXPOSURE
    1) Miosis, salivation, and lacrimation are common systemic effects of cholinergic agonists and may occur with donepezil in overdose.
    0.2.5) CARDIOVASCULAR
    A) WITH THERAPEUTIC USE
    1) Hypotension and bradycardia may occur at high doses. Decreased cardiac contractility, shock, cardiac arrest, atrial fibrillation, and heart block may occur as a result of cholinergic crisis.
    0.2.6) RESPIRATORY
    A) WITH THERAPEUTIC USE
    1) Dyspnea, bronchospasm, tachypnea, increased pulmonary secretions, and pulmonary edema may occur, especially in asthmatic patients.
    0.2.7) NEUROLOGIC
    A) WITH THERAPEUTIC USE
    1) Extrapyramidal effects may be seen with donepezil therapy.
    B) WITH POISONING/EXPOSURE
    1) Seizures, vertigo, tremors, agitation, lethargy, and coma may occur.
    0.2.8) GASTROINTESTINAL
    A) WITH THERAPEUTIC USE
    1) Nausea, vomiting, abdominal pain, diarrhea and salivation may occur following therapeutic doses.
    B) WITH POISONING/EXPOSURE
    1) Nausea, vomiting, abdominal pain, diarrhea and salivation may occur in overdoses.
    0.2.10) GENITOURINARY
    A) WITH THERAPEUTIC USE
    1) Increased micturition may occur due to cholinergic effects of donepezil.
    B) WITH POISONING/EXPOSURE
    1) Increased micturition may occur due to cholinergic effects of donepezil.
    0.2.12) FLUID-ELECTROLYTE
    A) WITH POISONING/EXPOSURE
    1) Fluid depletion may occur through bronchorrhea, vomiting and diarrhea, polyuria, and sweating.
    0.2.13) HEMATOLOGIC
    A) WITH THERAPEUTIC USE
    1) Hematological effects are rare, but have included anemia, thrombocytopenia, and eosinophilia.
    0.2.14) DERMATOLOGIC
    A) WITH POISONING/EXPOSURE
    1) Diaphoresis may occur in donepezil overdose.
    0.2.15) MUSCULOSKELETAL
    A) WITH POISONING/EXPOSURE
    1) Tremors and fasciculations may occur following overdoses. Muscle weakness is expected following substantial acute overdoses, and may result in respiratory depression.
    0.2.20) REPRODUCTIVE
    A) Donepezil and the combination product donepezil/memantine are classified as FDA pregnancy category C.
    0.2.21) CARCINOGENICITY
    A) At the time of this review, no studies were found on the possible carcinogenic activity of donepezil in humans.
    0.2.22) OTHER
    A) WITH THERAPEUTIC USE
    1) Drugs that may interact with donepezil include: bethanechol, cimetidine, succinylcholine, and theophylline.

Laboratory Monitoring

    A) Signs and symptoms of cholinesterase inhibitor poisoning should be monitored. Cholinesterase activity may be depressed and should be monitored in plasma (pseudocholinesterase) and red blood cells.
    B) Monitor ECG following significant exposures. Overdoses may be associated with bradycardia.
    C) Monitor pulse oximetry and/or arterial blood gases and obtain a chest radiograph in patients with pulmonary symptoms.

Treatment Overview

    0.4.2) ORAL/PARENTERAL EXPOSURE
    A) EMESIS/NOT RECOMMENDED -
    1) EMESIS: Ipecac-induced emesis is not recommended because of the potential for CNS depression and seizures.
    B) ACTIVATED CHARCOAL -
    1) Administer as aqueous slurry. Cathartics should not be used as they will contribute to nausea and diarrhea. (Dose: Usual dose is 50 to 100 g in adults and 15 to 30 g in children).
    C) LAVAGE -
    1) For substantial overdose gastric lavage preceded by endotracheal intubation may be necessary.
    D) ATROPINE SULFATE -
    1) Atropine sulfate is the drug of choice to treat cholinergic effects such as bradycardia, bronchorrhea and bronchospasm. For significant muscarinic symptoms administer:
    a) ADULTS - initial dose of 1 to 2 mg IV repeated every 3 to 60 min as needed to control muscarinic symptoms, then as needed for 24 to 48 hours. As much as 50 mg of atropine sulfate may be required in the first 24 hours.
    b) CHILD - Initial dose 0.05 mg/kg up to 4 mg (usual dose 1 mg), IM or IV every 10 to 30 min until muscarinic signs and symptoms subside, and repeat if they reappear.
    E) ATROPINE ALTERNATIVE -
    1) Glycopyrrolate and methscopolamine bromide have been suggested as alternatives to atropine in treating the peripheral cholinergic symptoms induced by physostigmine and may be of benefit in donepezil overdoses.
    F) BRONCHOSPASM -
    1) ALBUTEROL: 0.25 to 0.5 milliliter in 2 to 4.5 milliliters of normal saline delivered every 4 to 6 hours per nebulizer. Children: 100 to 200 micrograms 3 to 6 times a day.
    2) Epinephrine may assist in overcoming severe cardiovascular or bronchoconstrictor responses (DOSE: 0.1 to 1.0 mg SC).
    G) ACUTE LUNG INJURY: Maintain ventilation and oxygenation and evaluate with frequent arterial blood gases and/or pulse oximetry monitoring. Early use of PEEP and mechanical ventilation may be needed.
    H) SEIZURES: Administer a benzodiazepine; DIAZEPAM (ADULT: 5 to 10 mg IV initially; repeat every 5 to 20 minutes as needed. CHILD: 0.1 to 0.5 mg/kg IV over 2 to 5 minutes; up to a maximum of 10 mg/dose. May repeat dose every 5 to 10 minutes as needed) or LORAZEPAM (ADULT: 2 to 4 mg IV initially; repeat every 5 to 10 minutes as needed, if seizures persist. CHILD: 0.05 to 0.1 mg/kg IV over 2 to 5 minutes, up to a maximum of 4 mg/dose; may repeat in 5 to 15 minutes as needed, if seizures continue).
    1) Consider phenobarbital or propofol if seizures recur after diazepam 30 mg (adults) or 10 mg (children greater than 5 years).
    2) Monitor for hypotension, dysrhythmias, respiratory depression, and need for endotracheal intubation. Evaluate for hypoglycemia, electrolyte disturbances, and hypoxia.
    I) HYPOTENSION: Infuse 10 to 20 mL/kg isotonic fluid. If hypotension persists, administer dopamine (5 to 20 mcg/kg/min) or norepinephrine (ADULT: begin infusion at 0.5 to 1 mcg/min; CHILD: begin infusion at 0.1 mcg/kg/min); titrate to desired response.

Range Of Toxicity

    A) TOXICITY: Overdoses of 45 mg and 50 mg resulted in nausea, vomiting, and diarrhea in two elderly adults, one of these patients developed persistent bradycardia (ie, heart rate in the 40's); both recovered uneventfully.
    B) THERAPEUTIC DOSE: ADULT: Mild to moderate Alzheimer's Disease: 5 mg to 10 mg orally once daily; MAX daily dose is 10 mg. Moderate to severe Alzheimer's Disease: 5 mg to 23 mg orally once daily; MAX daily dose is 23 mg. CHILDREN: Safety and effectiveness not established.

Summary Of Exposure

    A) WITH THERAPEUTIC USE
    1) The most common adverse reactions following administration of donepezil include diarrhea, loss of appetite, nausea, vomiting, muscle cramps, insomnia and fatigue.
    B) WITH POISONING/EXPOSURE
    1) Overdose information is limited. Based on its cholinergic effects, typical findings might include muscarinic actions consisting of: miosis, flushing, bradycardia, bronchospasm, increased bronchial secretions, involuntary urination and/or defecation, sweating, lacrimation, hypotension, and/or seizures.
    2) Because of its high degree of selectivity for AChE in the CNS and less peripheral selectivity, overdoses would be expected to exhibit more CNS-related symptomatology, including extrapyramidal effects.

Vital Signs

    3.3.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Blood pressure and pulse may be decreased following an overdose.
    3.3.4) BLOOD PRESSURE
    A) WITH POISONING/EXPOSURE
    1) Hypotension and syncope may occur in an overdose due to muscarinic cholinergic effects of donepezil (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006; Suleyman et al, 2006).
    3.3.5) PULSE
    A) WITH POISONING/EXPOSURE
    1) Decreased pulse rate may occur due to vagotonic cholinergic effects of donepezil (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Heent

    3.4.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Miosis, salivation, and lacrimation are common systemic effects of cholinergic agonists and may occur with donepezil in therapeutic amounts.
    B) WITH POISONING/EXPOSURE
    1) Miosis, salivation, and lacrimation are common systemic effects of cholinergic agonists and may occur with donepezil in overdose.
    3.4.3) EYES
    A) WITH POISONING/EXPOSURE
    1) MIOSIS
    a) Miosis may occur with systemic poisoning as a result of cholinergic agonist effects.
    3.4.6) THROAT
    A) WITH POISONING/EXPOSURE
    1) SALIVA INCREASED
    a) Salivation may occur with systemic poisonings (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Cardiovascular

    3.5.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Hypotension and bradycardia may occur at high doses. Decreased cardiac contractility, shock, cardiac arrest, atrial fibrillation, and heart block may occur as a result of cholinergic crisis.
    3.5.2) CLINICAL EFFECTS
    A) HYPOTENSIVE EPISODE
    1) WITH THERAPEUTIC USE
    a) Therapeutic doses may also result in a hypotensive episode as a result of cholinergic muscarinic effects (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    2) WITH POISONING/EXPOSURE
    a) Hypotension, accompanied by reflex tachycardia, may initially occur as a sign of cholinergic crisis. Hypotension following overdose could be severe, leading to cardiovascular collapse or shock (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    B) BRADYCARDIA
    1) WITH THERAPEUTIC USE
    a) BRADYCARDIA has been observed with therapeutic use of donepezil (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    2) WITH POISONING/EXPOSURE
    a) Overdose may cause a cholinergic crisis which may be characterized by bradycardia as well as hypotension (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006; Shepherd et al, 1998).
    b) CASE REPORT - Persistent bradycardia (heart rate in the 40's) was reported in a 79-year-old female who was inadvertently given 50 mg donepezil instead of 5 mg. Atropine, 0.2 mg PRN bradycardia, was given to a total dose of 3 mg over 18 hours to control bradycardia. Her heart rate was kept in the 60's for 0.5 to 2 hours after each atropine dose. By day 2 the patient returned to baseline (Shepherd et al, 1998; Shepherd et al, 1999).
    C) HEART BLOCK
    1) WITH THERAPEUTIC USE
    a) HEART BLOCK has been infrequently observed with therapeutic use of donepezil (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    b) CASE REPORT - An 82-year-old man who had been taking 10 mg/day of donepezil for one month, developed complete atrioventricular block and non-sustained runs of ventricular tachycardia. The patient had no previous history of cardiac abnormalities. He reported no other medication use. Upon presentation to the emergency department he complained of dizziness and syncope. His blood pressure was 100/60 mm Hg with a heart rate of 35 beats per minute. An ECG revealed complete AV block with non-sustained ventricular beats. A temporary ventricular pacing catheter was placed, Rhythm returned to normal on hospital day 4. The pacemaker was removed and the patient was discharged on day 6 (Suleyman et al, 2006).
    2) WITH POISONING/EXPOSURE
    a) Various dysrhythmias, primarily heart block, may theoretically occur because of its cholinergic effects.

Respiratory

    3.6.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Dyspnea, bronchospasm, tachypnea, increased pulmonary secretions, and pulmonary edema may occur, especially in asthmatic patients.
    3.6.2) CLINICAL EFFECTS
    A) BRONCHOSPASM
    1) WITH THERAPEUTIC USE
    a) Dyspnea and bronchoconstriction may be noted and is more pronounced in asthmatic patients. Cholinomimetics may cause increase in asthma or obstructive pulmonary disease symptoms (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006). Bronchospasm may be life-threatening.
    B) SPUTUM ABNORMAL - AMOUNT
    1) WITH THERAPEUTIC USE
    a) Bronchial secretions may be increased secondary to cholinergic effects and bouts of coughing may occur.
    C) APNEA
    1) WITH POISONING/EXPOSURE
    a) Cholinergic crisis may result in muscle weakness which may cause a respiratory paralysis leading to apnea (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    3.6.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) HYPOVENTILATION
    a) Acute toxicity studies in animals resulted in depressed spontaneous respirations (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Neurologic

    3.7.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Extrapyramidal effects may be seen with donepezil therapy.
    B) WITH POISONING/EXPOSURE
    1) Seizures, vertigo, tremors, agitation, lethargy, and coma may occur.
    3.7.2) CLINICAL EFFECTS
    A) SEIZURE
    1) WITH POISONING/EXPOSURE
    a) Overdose may result in seizures, tremor, and vertigo from a cholinergic toxicity to the CNS (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006; Dunn et al, 2000).
    B) COMA
    1) WITH POISONING/EXPOSURE
    a) Drowsiness and coma are uncommon events, but are effects that may occur on occasion with cholinergic drug overdoses (Prod Info Aricept(R), 2003).
    b) CASE REPORT - Following an inadvertent overdose of 45 mg, a 74-year-old woman slept for 4 to 5 hours, but was arousable. Recovery was uneventful (Greene et al, 1999).
    C) PSYCHOMOTOR AGITATION
    1) WITH THERAPEUTIC USE
    a) Agitation, headache, dizziness, fatigue, insomnia and drowsiness have been reported in 10% or less of patients treated with donepezil. Agitation may be attributed to cholinergic toxicity (Prod Info Aricept(R), 2003). In a large pharmacovigilance study (1762 donepezil patients), aggression, agitation and abnormal dreams were uncommonly associated with donepezil therapy (Dunn et al, 2000).
    D) EXTRAPYRAMIDAL DISEASE
    1) WITH THERAPEUTIC USE
    a) An exacerbation of Parkinsonism may occur following therapeutic doses of donepezil for Alzheimer's disease. This is presumed to be due to an excess of cholinergic activity in the striatum of Parkinson patients, which is then aggravated by the cholinergic effects of tacrine.
    1) Approximately 0.1% to 1% of patients in clinical trials exhibited extrapyramidal effects, hyperkinesia, movement disorders, and abnormal reflexes following therapeutic donepezil doses (Prod Info Aricept(R), 2003).
    b) CASE REPORT - Worsening Parkinson's disease symptoms (unsteady balance and falls) were reported in an 80-year-old woman after donepezil 5 mg/day was added to her therapy in place of tacrine for Alzheimer disease. Shuffling gait, bradykinesia, stiffness and marked tremor slowly improved following discontinuation of the donepezil (Bourke & Druckenbrod, 1998).
    2) WITH POISONING/EXPOSURE
    a) CASE REPORT - A 73-year-old woman was inadvertently given five tablets of 5 mg donepezil (total dose was 25 mg) in one day (prescribed dose was a total of 5 mg/day) and developed worsening Parkinson's symptoms within 24 hours of exposure (eg, camptocormia became so severe that the patient's chest was almost at a 90 degree angle with her hips). Symptoms were noticeably improved within 5 days (approximate half-life of donepezil is 70 hours) of drug withdrawal and continued improvement was observed over the next month (Onofrj & Thomas, 2003).
    E) DYSTONIA
    1) WITH THERAPEUTIC USE
    a) CASE REPORT - Pisa syndrome (abnormal posturing with body and head flexion to one side and slight axial rotation of the trunk) has been reported as an adverse effect after 16 weeks of therapy with donepezil and risperidone. Following discontinuation of these drugs, the patient's dystonia improved. Upon re-challenge with another cholinesterase inhibitor (rivastigmine) the symptoms returned. The authors speculated that cholinergic excess may have been a factor in Pisa syndrome (Kwak et al, 2000).
    F) DISTURBANCE IN SPEECH
    1) WITH THERAPEUTIC USE
    a) CASE REPORT - Mumbling and stuttering, as well as abnormal lower limb movements, were reported as an adverse effect of donepezil in a 72-year-old man after 7 months of therapy. All symptoms improved following discontinuation of donepezil. A positive re-challenge was reported one month later (Amouyal-Barkate et al, 2000).
    3.7.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) SEIZURES
    a) ANIMAL STUDIES - Acute toxicity in animal studies resulted in clonic seizures, decreased spontaneous movement, muscle fasciculations, tremors, staggering gait, and depressed respiration (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Gastrointestinal

    3.8.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Nausea, vomiting, abdominal pain, diarrhea and salivation may occur following therapeutic doses.
    B) WITH POISONING/EXPOSURE
    1) Nausea, vomiting, abdominal pain, diarrhea and salivation may occur in overdoses.
    3.8.2) CLINICAL EFFECTS
    A) GASTROENTERITIS
    1) WITH POISONING/EXPOSURE
    a) Overdose may result in cholinergic signs and symptoms of gastroenteritis, including severe nausea and vomiting, abdominal pain, diarrhea, and increased salivation as a result of increased gastrointestinal motility (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006; Anon, 1996; Rogers et al, 1996; Greene et al, 1999; Shepherd et al, 1999; Dunn et al, 2000).
    b) CASE REPORT - A 79-year-old female presented to the ED with nausea, vomiting and bradycardia following an inadvertent overdose of 50 mg (Shepherd et al, 1998; Shepherd et al, 1999).
    c) CASE REPORT - A 74-year-old female developed nausea and vomiting about 2 hours after an accidental overdose of 45 mg donepezil. An episode of diarrhea occurred about 9 hours after the overdose. An uneventful recovery ensued (Greene et al, 1999).

Hepatic

    3.9.2) CLINICAL EFFECTS
    A) TOXIC HEPATITIS
    1) WITH THERAPEUTIC USE
    a) Fulminant chemical hepatitis possibly associated with donepezil and sertraline therapy has been reported. The role of donepezil in this reaction has not been clarified (Verrico et al, 2000).
    b) CASE REPORT - A 90-year-old man with multiple health conditions and an established medication regimen began treatment with donepezil for Alzheimer's disease. Two weeks after treatment initiation, he complained of abdominal pain with nausea and vomiting; jaundice followed and liver enzymes were elevated. Donepezil was discontinued one week later due to worsening liver function. Liver enzymes peak values were: AST 304 Units/L; ALT 363 Units/L; total bilirubin 22.6 mg/dL. Liver biopsy revealed probable drug-induced hepatitis with cholestasis. Following discontinuation of donepezil, the patient improved clinically and liver function tests normalized within 13 weeks (Dierckx & Vandewoude, 2008).
    B) LACK OF EFFECT
    1) WITH THERAPEUTIC USE
    a) Donepezil lacks the dose-limiting hepatic toxicity of the acridine-based Alzheimer's drug, tacrine (Prod Info Aricept(R), 2003; Rogers et al, 1996).

Genitourinary

    3.10.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Increased micturition may occur due to cholinergic effects of donepezil.
    B) WITH POISONING/EXPOSURE
    1) Increased micturition may occur due to cholinergic effects of donepezil.
    3.10.2) CLINICAL EFFECTS
    A) INCREASED FREQUENCY OF URINATION
    1) WITH THERAPEUTIC USE
    a) Urinary frequency, stimulation of ureters and urinary bladder may occur, with resultant involuntary urination as a result of cholinergic effects of donepezil, especially at higher doses or overdoses (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    b) Urinary incontinence, a peripheral cholinergic side effect, has been reported following therapy with donepezil (5 mg/day) in a series of 7 patients (Hashimoto et al, 2000).
    2) WITH POISONING/EXPOSURE
    a) Urinary frequency, stimulation of ureters and urinary bladder may occur, with resultant involuntary urination as a result of cholinergic effects of donepezil, especially at higher doses or overdoses (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Hematologic

    3.13.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Hematological effects are rare, but have included anemia, thrombocytopenia, and eosinophilia.
    3.13.2) CLINICAL EFFECTS
    A) MYELOSUPPRESSION
    1) WITH THERAPEUTIC USE
    a) Although uncommon, anemia, thrombocytopenia, and eosinophilia have been reported during donepezil therapy (Prod Info Aricept(R), 2003). A causal relationship has not been established.

Dermatologic

    3.14.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Diaphoresis may occur in donepezil overdose.
    3.14.2) CLINICAL EFFECTS
    A) EXCESSIVE SWEATING
    1) WITH THERAPEUTIC USE
    a) Diaphoresis occurred in greater than 1% of treated patients (Prod Info Aricept(R), 2003).
    2) WITH POISONING/EXPOSURE
    a) Overdosage may result in a cholinergic crisis which can cause increased sweating and flushing (Greene et al, 1999; Shepherd et al, 1999).
    B) ERUPTION
    1) WITH THERAPEUTIC USE
    a) Purpuric rash has been reported with donepezil treatment (Bryant et al, 1998).

Musculoskeletal

    3.15.1) SUMMARY
    A) WITH POISONING/EXPOSURE
    1) Tremors and fasciculations may occur following overdoses. Muscle weakness is expected following substantial acute overdoses, and may result in respiratory depression.
    3.15.2) CLINICAL EFFECTS
    A) TREMOR
    1) WITH THERAPEUTIC USE
    a) In therapeutic trials, 0.1% to 1% of patients experienced muscle fasciculations (Prod Info Aricept(R), 2003).
    2) WITH POISONING/EXPOSURE
    a) Tremors and fasciculations may occur following cholinergic stimulation in overdoses of donepezil.
    B) MUSCLE WEAKNESS
    1) WITH POISONING/EXPOSURE
    a) Substantial overdoses are expected to result in muscle weakness. In severe cases, muscle weakness leading to respiratory depression may occur as a result of cholinergic crisis (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    3.15.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) TWITCHING
    a) ANIMAL STUDIES - Acute toxicity in animals resulted in tremors, muscle fasciculations, reduced respirations, staggering gait, and clonic seizures (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Reproductive

    3.20.1) SUMMARY
    A) Donepezil and the combination product donepezil/memantine are classified as FDA pregnancy category C.
    3.20.2) TERATOGENICITY
    A) LACK OF INFORMATION
    1) At the time of this review, no data were available to assess the teratogenic potential of this agent (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).
    B) ANIMAL STUDIES
    1) RATS, RABBITS: Teratogenic effects were not observed in rats and rabbits administered oral donepezil up to 16 mg/kg/day (approximately 6 times the maximum recommended human dose of 23 mg/kg/day) during organogenesis. Administration of oral donepezil 1, 3, or 10 mg/kg/day in rats during late gestation and throughout lactation resulted in an increased incidence of stillbirths as well as reduced offspring survival through postpartum day 4 at doses of 10 mg/kg/day (approximately 7 times the maximum recommended human dose of 23 mg/kg/day) (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).
    3.20.3) EFFECTS IN PREGNANCY
    A) LACK OF INFORMATION
    1) At the time of this review, no data were available to assess the potential effects of exposure to this agent during pregnancy in humans (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012)
    B) PREGNANCY CATEGORY
    1) Donepezil is classified as FDA pregnancy category C (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).
    2) Donepezil/memantine is classified as FDA pregnancy category C (Prod Info NAMZARIC oral capsules, 2014).
    3.20.4) EFFECTS DURING BREAST-FEEDING
    A) LACK OF INFORMATION
    1) At the time of this review, no data were available to assess the potential effects of exposure to this agent during lactation in humans (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).
    3.20.5) FERTILITY
    A) ANIMAL STUDIES
    1) RATS: Oral doses of donepezil up to 10 mg/kg/day had no effect on fertility in male and female rats prior to and during mating and throughout implantation (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).

Carcinogenicity

    3.21.2) SUMMARY/HUMAN
    A) At the time of this review, no studies were found on the possible carcinogenic activity of donepezil in humans.
    3.21.4) ANIMAL STUDIES
    A) LACK OF EFFECT
    1) There was no evidence of a carcinogenic potential when CD-1 mice were given donepezil hydrochloride at doses up to 180 mg/kg/day (approximately 40 times the maximum recommended human dose on a mg/m(2) basis) for 88 weeks. There was no evidence of a carcinogenic potential when rats were given donepezil hydrochloride at doses up to 30 mg/kg/day (approximately 13 times the maximum recommended human dose on a mg/m(2) basis) for 104 weeks (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).

Genotoxicity

    A) There was no evidence of genotoxicity in the following tests: in vitro bacterial reverse mutation, in vitro mouse lymphoma tk, in vitro chromosomal aberration, and in vivo mouse micronucleus (Prod Info ARICEPT(R) oral tablets, oral disintegrating tablets, 2012).

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) Signs and symptoms of cholinesterase inhibitor poisoning should be monitored. Cholinesterase activity may be depressed and should be monitored in plasma (pseudocholinesterase) and red blood cells.
    B) Monitor ECG following significant exposures. Overdoses may be associated with bradycardia.
    C) Monitor pulse oximetry and/or arterial blood gases and obtain a chest radiograph in patients with pulmonary symptoms.
    4.1.2) SERUM/BLOOD
    A) BLOOD/SERUM CHEMISTRY
    1) Monitor serum electrolytes and serum renal function tests in severe exposures.
    B) ACID/BASE
    1) Monitor blood gases in comatose patients and those in whom aspiration of vomitus is suspected.
    4.1.4) OTHER
    A) OTHER
    1) ECG
    a) ECG should be monitored for signs of cholinesterase inhibitor toxicity, such as bradycardia.
    2) PULMONARY FUNCTION TESTS
    a) Pulmonary function testing and chest x-ray may be indicated in patients with dyspnea or bronchospasm.

Methods

    A) CHROMATOGRAPHY
    1) High-performance liquid chromatography (HPLC) has been used for quantification of donepezil and its metabolites in plasma (Ohnishi et al, 1993).

Life Support

    A) Support respiratory and cardiovascular function.

Monitoring

    A) Signs and symptoms of cholinesterase inhibitor poisoning should be monitored. Cholinesterase activity may be depressed and should be monitored in plasma (pseudocholinesterase) and red blood cells.
    B) Monitor ECG following significant exposures. Overdoses may be associated with bradycardia.
    C) Monitor pulse oximetry and/or arterial blood gases and obtain a chest radiograph in patients with pulmonary symptoms.

Oral Exposure

    6.5.1) PREVENTION OF ABSORPTION/PREHOSPITAL
    A) EMESIS/NOT RECOMMENDED -
    1) EMESIS: Ipecac-induced emesis is not recommended because of the potential for CNS depression and seizures.
    B) ACTIVATED CHARCOAL -
    1) PREHOSPITAL ACTIVATED CHARCOAL ADMINISTRATION
    a) Consider prehospital administration of activated charcoal as an aqueous slurry in patients with a potentially toxic ingestion who are awake and able to protect their airway. Activated charcoal is most effective when administered within one hour of ingestion. Administration in the prehospital setting has the potential to significantly decrease the time from toxin ingestion to activated charcoal administration, although it has not been shown to affect outcome (Alaspaa et al, 2005; Thakore & Murphy, 2002; Spiller & Rogers, 2002).
    1) In patients who are at risk for the abrupt onset of seizures or mental status depression, activated charcoal should not be administered in the prehospital setting, due to the risk of aspiration in the event of spontaneous emesis.
    2) The addition of flavoring agents (cola drinks, chocolate milk, cherry syrup) to activated charcoal improves the palatability for children and may facilitate successful administration (Guenther Skokan et al, 2001; Dagnone et al, 2002).
    2) CHARCOAL DOSE
    a) Use a minimum of 240 milliliters of water per 30 grams charcoal (FDA, 1985). Optimum dose not established; usual dose is 25 to 100 grams in adults and adolescents; 25 to 50 grams in children aged 1 to 12 years (or 0.5 to 1 gram/kilogram body weight) ; and 0.5 to 1 gram/kilogram in infants up to 1 year old (Chyka et al, 2005).
    1) Routine use of a cathartic with activated charcoal is NOT recommended as there is no evidence that cathartics reduce drug absorption and cathartics are known to cause adverse effects such as nausea, vomiting, abdominal cramps, electrolyte imbalances and occasionally hypotension (None Listed, 2004).
    b) ADVERSE EFFECTS/CONTRAINDICATIONS
    1) Complications: emesis, aspiration (Chyka et al, 2005). Aspiration may be complicated by acute respiratory failure, ARDS, bronchiolitis obliterans or chronic lung disease (Golej et al, 2001; Graff et al, 2002; Pollack et al, 1981; Harris & Filandrinos, 1993; Elliot et al, 1989; Rau et al, 1988; Golej et al, 2001; Graff et al, 2002). Refer to the ACTIVATED CHARCOAL/TREATMENT management for further information.
    2) Contraindications: unprotected airway (increases risk/severity of aspiration) , nonfunctioning gastrointestinal tract, uncontrolled vomiting, and ingestion of most hydrocarbons (Chyka et al, 2005).
    6.5.2) PREVENTION OF ABSORPTION
    A) ACTIVATED CHARCOAL
    1) Administer as aqueous slurry. Cathartics should not be used as they will contribute to nausea and diarrhea.
    2) CHARCOAL ADMINISTRATION
    a) Consider administration of activated charcoal after a potentially toxic ingestion (Chyka et al, 2005). Administer charcoal as an aqueous slurry; most effective when administered within one hour of ingestion.
    3) CHARCOAL DOSE
    a) Use a minimum of 240 milliliters of water per 30 grams charcoal (FDA, 1985). Optimum dose not established; usual dose is 25 to 100 grams in adults and adolescents; 25 to 50 grams in children aged 1 to 12 years (or 0.5 to 1 gram/kilogram body weight) ; and 0.5 to 1 gram/kilogram in infants up to 1 year old (Chyka et al, 2005).
    1) Routine use of a cathartic with activated charcoal is NOT recommended as there is no evidence that cathartics reduce drug absorption and cathartics are known to cause adverse effects such as nausea, vomiting, abdominal cramps, electrolyte imbalances and occasionally hypotension (None Listed, 2004).
    b) ADVERSE EFFECTS/CONTRAINDICATIONS
    1) Complications: emesis, aspiration (Chyka et al, 2005). Aspiration may be complicated by acute respiratory failure, ARDS, bronchiolitis obliterans or chronic lung disease (Golej et al, 2001; Graff et al, 2002; Pollack et al, 1981; Harris & Filandrinos, 1993; Elliot et al, 1989; Rau et al, 1988; Golej et al, 2001; Graff et al, 2002). Refer to the ACTIVATED CHARCOAL/TREATMENT management for further information.
    2) Contraindications: unprotected airway (increases risk/severity of aspiration) , nonfunctioning gastrointestinal tract, uncontrolled vomiting, and ingestion of most hydrocarbons (Chyka et al, 2005).
    B) GASTRIC LAVAGE
    1) INDICATIONS: Consider gastric lavage with a large-bore orogastric tube (ADULT: 36 to 40 French or 30 English gauge tube {external diameter 12 to 13.3 mm}; CHILD: 24 to 28 French {diameter 7.8 to 9.3 mm}) after a potentially life threatening ingestion if it can be performed soon after ingestion (generally within 60 minutes).
    a) Consider lavage more than 60 minutes after ingestion of sustained-release formulations and substances known to form bezoars or concretions.
    2) PRECAUTIONS:
    a) SEIZURE CONTROL: Is mandatory prior to gastric lavage.
    b) AIRWAY PROTECTION: Place patients in the head down left lateral decubitus position, with suction available. Patients with depressed mental status should be intubated with a cuffed endotracheal tube prior to lavage.
    3) LAVAGE FLUID:
    a) Use small aliquots of liquid. Lavage with 200 to 300 milliliters warm tap water (preferably 38 degrees Celsius) or saline per wash (in older children or adults) and 10 milliliters/kilogram body weight of normal saline in young children(Vale et al, 2004) and repeat until lavage return is clear.
    b) The volume of lavage return should approximate amount of fluid given to avoid fluid-electrolyte imbalance.
    c) CAUTION: Water should be avoided in young children because of the risk of electrolyte imbalance and water intoxication. Warm fluids avoid the risk of hypothermia in very young children and the elderly.
    4) COMPLICATIONS:
    a) Complications of gastric lavage have included: aspiration pneumonia, hypoxia, hypercapnia, mechanical injury to the throat, esophagus, or stomach, fluid and electrolyte imbalance (Vale, 1997). Combative patients may be at greater risk for complications (Caravati et al, 2001).
    b) Gastric lavage can cause significant morbidity; it should NOT be performed routinely in all poisoned patients (Vale, 1997).
    5) CONTRAINDICATIONS:
    a) Loss of airway protective reflexes or decreased level of consciousness if patient is not intubated, following ingestion of corrosive substances, hydrocarbons (high aspiration potential), patients at risk of hemorrhage or gastrointestinal perforation, or trivial or non-toxic ingestion.
    6.5.3) TREATMENT
    A) MONITORING OF PATIENT
    1) Monitor and support respiratory and cardiovascular function.
    B) ATROPINE
    1) ATROPINE sulfate is recommended and will reverse actions at muscarinic receptors (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    2) DOSE: ADULTS - initial dose of 1 to 2 milligrams intravenously repeated every 3 to 60 minutes as needed to control muscarinic symptoms, then as needed for 24 to 48 hours. As much as 50 milligrams of atropine sulfate may be required in the first 24 hours.
    3) CHILD - Initial dose 0.05 milligram/kilogram up to 4 milligrams (usual dose 1 milligram), intramuscularly or intravenously every 10 to 30 minutes until muscarinic signs and symptoms subside, and repeat if they reappear.
    C) DRUG THERAPY
    1) ATROPINE ALTERNATIVE -
    a) Glycopyrrolate and methscopolamine bromide have been suggested as alternatives to atropine in treating the peripheral cholinergic symptoms induced by cholinergic, muscarinic agonists (Granacher et al, 1976).
    b) These agents should not contribute to the initial anticholinergic delirium, as they do not easily cross the blood brain barrier.
    c) Administration of glycopyrrolate with other cholinomimetics have resulted in atypical responses with blood pressure and heart rate (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).
    d) Controversy exists on the effectiveness of glycopyrrolate to reverse cholinergic effects of tacrine, a drug related to donepezil.
    1) Wilcock et al (1988) and Summers et al (1986) found glycopyrrolate effective in reversing mild side effects (Wilcock et al, 1988; Summers et al, 1986).
    2) Levy (1988) found glycopyrrolate to aggravate the adverse effects of tacrine.
    3) Summers et al (1986) suggest glycopyrrolate to be effective only where peripheral muscarinic toxicity is noted. These agents should be used cautiously, as atypical increases in blood pressure and heart rate have been reported (Summers et al, 1986; Prod Info Cognex(R), tacrine hydrochloride, 1995).
    D) BRONCHOSPASM
    1) ALBUTEROL - 0.25 to 0.5 milliliter in 2 to 4.5 milliliters of normal saline delivered every 4 to 6 hours per nebulizer. Children: 100 to 200 micrograms 3 to 6 times a day.
    2) Epinephrine may assist in overcoming severe cardiovascular or bronchoconstrictor responses (DOSE: 0.1 to 1 milligram subcutaneously).
    E) ACUTE LUNG INJURY
    1) ONSET: Onset of acute lung injury after toxic exposure may be delayed up to 24 to 72 hours after exposure in some cases.
    2) NON-PHARMACOLOGIC TREATMENT: The treatment of acute lung injury is primarily supportive (Cataletto, 2012). Maintain adequate ventilation and oxygenation with frequent monitoring of arterial blood gases and/or pulse oximetry. If a high FIO2 is required to maintain adequate oxygenation, mechanical ventilation and positive-end-expiratory pressure (PEEP) may be required; ventilation with small tidal volumes (6 mL/kg) is preferred if ARDS develops (Haas, 2011; Stolbach & Hoffman, 2011).
    a) To minimize barotrauma and other complications, use the lowest amount of PEEP possible while maintaining adequate oxygenation. Use of smaller tidal volumes (6 mL/kg) and lower plateau pressures (30 cm water or less) has been associated with decreased mortality and more rapid weaning from mechanical ventilation in patients with ARDS (Brower et al, 2000). More treatment information may be obtained from ARDS Clinical Network website, NIH NHLBI ARDS Clinical Network Mechanical Ventilation Protocol Summary, http://www.ardsnet.org/node/77791 (NHLBI ARDS Network, 2008)
    3) FLUIDS: Crystalloid solutions must be administered judiciously. Pulmonary artery monitoring may help. In general the pulmonary artery wedge pressure should be kept relatively low while still maintaining adequate cardiac output, blood pressure and urine output (Stolbach & Hoffman, 2011).
    4) ANTIBIOTICS: Indicated only when there is evidence of infection (Artigas et al, 1998).
    5) EXPERIMENTAL THERAPY: Partial liquid ventilation has shown promise in preliminary studies (Kollef & Schuster, 1995).
    6) CALFACTANT: In a multicenter, randomized, blinded trial, endotracheal instillation of 2 doses of 80 mL/m(2) calfactant (35 mg/mL of phospholipid suspension in saline) in infants, children, and adolescents with acute lung injury resulted in acute improvement in oxygenation and lower mortality; however, no significant decrease in the course of respiratory failure measured by duration of ventilator therapy, intensive care unit, or hospital stay was noted. Adverse effects (transient hypoxia and hypotension) were more frequent in calfactant patients, but these effects were mild and did not require withdrawal from the study (Wilson et al, 2005).
    7) However, in a multicenter, randomized, controlled, and masked trial, endotracheal instillation of up to 3 doses of calfactant (30 mg) in adults only with acute lung injury/ARDS due to direct lung injury was not associated with improved oxygenation and longer term benefits compared to the placebo group. It was also associated with significant increases in hypoxia and hypotension (Willson et al, 2015).
    F) SEIZURE
    1) SUMMARY
    a) Attempt initial control with a benzodiazepine (eg, diazepam, lorazepam). If seizures persist or recur, administer phenobarbital or propofol.
    b) Monitor for respiratory depression, hypotension, and dysrhythmias. Endotracheal intubation should be performed in patients with persistent seizures.
    c) Evaluate for hypoxia, electrolyte disturbances, and hypoglycemia (or, if immediate bedside glucose testing is not available, treat with intravenous dextrose).
    2) DIAZEPAM
    a) ADULT DOSE: Initially 5 to 10 mg IV, OR 0.15 mg/kg IV up to 10 mg per dose up to a rate of 5 mg/minute; may be repeated every 5 to 20 minutes as needed (Brophy et al, 2012; Prod Info diazepam IM, IV injection, 2008; Manno, 2003).
    b) PEDIATRIC DOSE: 0.1 to 0.5 mg/kg IV over 2 to 5 minutes; up to a maximum of 10 mg/dose. May repeat dose every 5 to 10 minutes as needed (Loddenkemper & Goodkin, 2011; Hegenbarth & American Academy of Pediatrics Committee on Drugs, 2008).
    c) Monitor for hypotension, respiratory depression, and the need for endotracheal intubation. Consider a second agent if seizures persist or recur after repeated doses of diazepam .
    3) NO INTRAVENOUS ACCESS
    a) DIAZEPAM may be given rectally or intramuscularly (Manno, 2003). RECTAL DOSE: CHILD: Greater than 12 years: 0.2 mg/kg; 6 to 11 years: 0.3 mg/kg; 2 to 5 years: 0.5 mg/kg (Brophy et al, 2012).
    b) MIDAZOLAM has been used intramuscularly and intranasally, particularly in children when intravenous access has not been established. ADULT DOSE: 0.2 mg/kg IM, up to a maximum dose of 10 mg (Brophy et al, 2012). PEDIATRIC DOSE: INTRAMUSCULAR: 0.2 mg/kg IM, up to a maximum dose of 7 mg (Chamberlain et al, 1997) OR 10 mg IM (weight greater than 40 kg); 5 mg IM (weight 13 to 40 kg); INTRANASAL: 0.2 to 0.5 mg/kg up to a maximum of 10 mg/dose (Loddenkemper & Goodkin, 2011; Brophy et al, 2012). BUCCAL midazolam, 10 mg, has been used in adolescents and older children (5-years-old or more) to control seizures when intravenous access was not established (Scott et al, 1999).
    4) LORAZEPAM
    a) MAXIMUM RATE: The rate of intravenous administration of lorazepam should not exceed 2 mg/min (Brophy et al, 2012; Prod Info lorazepam IM, IV injection, 2008).
    b) ADULT DOSE: 2 to 4 mg IV initially; repeat every 5 to 10 minutes as needed, if seizures persist (Manno, 2003; Brophy et al, 2012).
    c) PEDIATRIC DOSE: 0.05 to 0.1 mg/kg IV over 2 to 5 minutes, up to a maximum of 4 mg/dose; may repeat in 5 to 15 minutes as needed, if seizures continue (Brophy et al, 2012; Loddenkemper & Goodkin, 2011; Hegenbarth & American Academy of Pediatrics Committee on Drugs, 2008; Sreenath et al, 2010; Chin et al, 2008).
    5) PHENOBARBITAL
    a) ADULT LOADING DOSE: 20 mg/kg IV at an infusion rate of 50 to 100 mg/minute IV. An additional 5 to 10 mg/kg dose may be given 10 minutes after loading infusion if seizures persist or recur (Brophy et al, 2012).
    b) Patients receiving high doses will require endotracheal intubation and may require vasopressor support (Brophy et al, 2012).
    c) PEDIATRIC LOADING DOSE: 20 mg/kg may be given as single or divided application (2 mg/kg/minute in children weighing less than 40 kg up to 100 mg/min in children weighing greater than 40 kg). A plasma concentration of about 20 mg/L will be achieved by this dose (Loddenkemper & Goodkin, 2011).
    d) REPEAT PEDIATRIC DOSE: Repeat doses of 5 to 20 mg/kg may be given every 15 to 20 minutes if seizures persist, with cardiorespiratory monitoring (Loddenkemper & Goodkin, 2011).
    e) MONITOR: For hypotension, respiratory depression, and the need for endotracheal intubation (Loddenkemper & Goodkin, 2011; Manno, 2003).
    f) SERUM CONCENTRATION MONITORING: Monitor serum concentrations over the next 12 to 24 hours. Therapeutic serum concentrations of phenobarbital range from 10 to 40 mcg/mL, although the optimal plasma concentration for some individuals may vary outside this range (Hvidberg & Dam, 1976; Choonara & Rane, 1990; AMA Department of Drugs, 1992).
    6) OTHER AGENTS
    a) If seizures persist after phenobarbital, propofol or pentobarbital infusion, or neuromuscular paralysis with general anesthesia (isoflurane) and continuous EEG monitoring should be considered (Manno, 2003). Other anticonvulsants can be considered (eg, valproate sodium, levetiracetam, lacosamide, topiramate) if seizures persist or recur; however, there is very little data regarding their use in toxin induced seizures, controlled trials are not available to define the optimal dosage ranges for these agents in status epilepticus (Brophy et al, 2012):
    1) VALPROATE SODIUM: ADULT DOSE: An initial dose of 20 to 40 mg/kg IV, at a rate of 3 to 6 mg/kg/minute; may give an additional dose of 20 mg/kg 10 minutes after loading infusion. PEDIATRIC DOSE: 1.5 to 3 mg/kg/minute (Brophy et al, 2012).
    2) LEVETIRACETAM: ADULT DOSE: 1000 to 3000 mg IV, at a rate of 2 to 5 mg/kg/min IV. PEDIATRIC DOSE: 20 to 60 mg/kg IV (Brophy et al, 2012; Loddenkemper & Goodkin, 2011).
    3) LACOSAMIDE: ADULT DOSE: 200 to 400 mg IV; 200 mg IV over 15 minutes (Brophy et al, 2012). PEDIATRIC DOSE: In one study, median starting doses of 1.3 mg/kg/day and maintenance doses of 4.7 mg/kg/day were used in children 8 years and older (Loddenkemper & Goodkin, 2011).
    4) TOPIRAMATE: ADULT DOSE: 200 to 400 mg nasogastric/orally OR 300 to 1600 mg/day orally divided in 2 to 4 times daily (Brophy et al, 2012).
    G) HYPOTENSIVE EPISODE
    1) SUMMARY
    a) Infuse 10 to 20 milliliters/kilogram of isotonic fluid and keep the patient supine. If hypotension persists, administer dopamine or norepinephrine. Consider central venous pressure monitoring to guide further fluid therapy.
    2) DOPAMINE
    a) DOSE: Begin at 5 micrograms per kilogram per minute progressing in 5 micrograms per kilogram per minute increments as needed (Prod Info dopamine hcl, 5% dextrose IV injection, 2004). If hypotension persists, dopamine may need to be discontinued and a more potent vasoconstrictor (eg, norepinephrine) should be considered (Prod Info dopamine hcl, 5% dextrose IV injection, 2004).
    b) CAUTION: If ventricular dysrhythmias occur, decrease rate of administration (Prod Info dopamine hcl, 5% dextrose IV injection, 2004). Extravasation may cause local tissue necrosis, administration through a central venous catheter is preferred (Prod Info dopamine hcl, 5% dextrose IV injection, 2004).
    3) NOREPINEPHRINE
    a) PREPARATION: 4 milligrams (1 amp) added to 1000 milliliters of diluent provides a concentration of 4 micrograms/milliliter of norepinephrine base. Norepinephrine bitartrate should be mixed in dextrose solutions (dextrose 5% in water, dextrose 5% in saline) since dextrose-containing solutions protect against excessive oxidation and subsequent potency loss. Administration in saline alone is not recommended (Prod Info norepinephrine bitartrate injection, 2005).
    b) DOSE
    1) ADULT: Dose range: 0.1 to 0.5 microgram/kilogram/minute (eg, 70 kg adult 7 to 35 mcg/min); titrate to maintain adequate blood pressure (Peberdy et al, 2010).
    2) CHILD: Dose range: 0.1 to 2 micrograms/kilogram/minute; titrate to maintain adequate blood pressure (Kleinman et al, 2010).
    3) CAUTION: Extravasation may cause local tissue ischemia, administration by central venous catheter is advised (Peberdy et al, 2010).
    H) BRADYCARDIA
    1) ATROPINE/DOSE
    a) ADULT BRADYCARDIA: BOLUS: Give 0.5 milligram IV, repeat every 3 to 5 minutes, if bradycardia persists. Maximum: 3 milligrams (0.04 milligram/kilogram) intravenously is a fully vagolytic dose in most adults. Doses less than 0.5 milligram may cause paradoxical bradycardia in adults (Neumar et al, 2010).
    b) PEDIATRIC DOSE: As premedication for emergency intubation in specific situations (eg, giving succinylchoine to facilitate intubation), give 0.02 milligram/kilogram intravenously or intraosseously (0.04 to 0.06 mg/kg via endotracheal tube followed by several positive pressure breaths) repeat once, if needed (de Caen et al, 2015; Kleinman et al, 2010). MAXIMUM SINGLE DOSE: Children: 0.5 milligram; adolescent: 1 mg.
    1) There is no minimum dose (de Caen et al, 2015).
    2) MAXIMUM TOTAL DOSE: Children: 1 milligram; adolescents: 2 milligrams (Kleinman et al, 2010).

Enhanced Elimination

    A) HEMODIALYSIS
    1) Because of donepezil's large volume of distribution and high degree of protein binding (94% to 96%), hemodialysis is not expected to be of benefit. It is not known whether donepezil or its metabolites can be removed by hemodialysis, peritoneal, or hemofiltration (Prod Info ARICEPT(R) oral tablets, ARICEPT(R) ODT orally-disintegrating tablets, 2006).

Summary

    A) TOXICITY: Overdoses of 45 mg and 50 mg resulted in nausea, vomiting, and diarrhea in two elderly adults, one of these patients developed persistent bradycardia (ie, heart rate in the 40's); both recovered uneventfully.
    B) THERAPEUTIC DOSE: ADULT: Mild to moderate Alzheimer's Disease: 5 mg to 10 mg orally once daily; MAX daily dose is 10 mg. Moderate to severe Alzheimer's Disease: 5 mg to 23 mg orally once daily; MAX daily dose is 23 mg. CHILDREN: Safety and effectiveness not established.

Therapeutic Dose

    7.2.1) ADULT
    A) DONEPEZIL
    1) MILD TO MODERATE ALZHEIMER'S DISEASE: Initially, 5 mg orally once daily at bedtime. After 4 to 6 weeks, may increase to a MAX dose of 10 mg orally once daily (Prod Info ARICEPT(R) oral tablets, 2015).
    a) Orally disintegrating tablets should be dissolved on the tongue and followed with water (Prod Info ARICEPT(R) oral tablets, 2015).
    2) MODERATE TO SEVERE ALZHEIMER'S DISEASE: Initially, 5 mg orally once daily at bedtime. May titrate up to 10 mg orally once daily after 4 to 6 weeks; if necessary, after 3 months, the dose can be increased to a MAX dose of 23 mg orally once daily (Prod Info ARICEPT(R) oral tablets, 2015).
    a) Orally disintegrating tablets should be dissolved on the tongue and followed with water (Prod Info ARICEPT(R) oral tablets, 2015).
    B) MEMANTINE AND DONEPEZIL
    1) EXTENDED RELEASE: The recommended dose is 28 mg memantine hydrochloride/10 mg donepezil hydrochloride orally once daily. The capsules may be swallowed whole, or opened and the contents sprinkled on applesauce and swallowed without chewing. The capsules should not be chewed, crushed, or divided (Prod Info NAMZARIC(R) oral extended-release capsules, 2016).
    7.2.2) PEDIATRIC
    A) Safety and efficacy of donepezil in the pediatric or adolescent population have not been established (Prod Info ARICEPT(R) oral tablets, 2015; Prod Info NAMZARIC(R) oral extended-release capsules, 2016).

Maximum Tolerated Exposure

    A) ADULT
    1) Overdoses of 45 and 50 mg, respectively, in a 74-year-old and a 79-year-old resulted in gastrointestinal effects (ie, nausea, vomiting, and diarrhea) with complete recovery (Greene et al, 1999; Shepherd et al, 1998; Shepherd et al, 1999). One patient also experienced lethargy for several hours following the overdose (Greene et al, 1999). The other patient experienced persistent bradycardia (ie, heart rate in the 40's) for 2 days (Shepherd et al, 1999).

Pharmacologic Mechanism

    A) Donepezil is a reversible and noncompetitive inhibitor of centrally-active acetylcholinesterase. Increased concentrations of acetylcholine are expected to be available for synaptic transmission (Mihara et al, 1993; Rogers et al, 1991; Rogers et al, 1996). This drug is highly specific for neural acetylcholinesterases (AChE) and preferentially binds AChE by more than 3 orders of magnitude over butyrylcholinesterases. Peripheral adverse effects are minimized at therapeutic doses due to this specificity (Shepherd et al, 1998).
    1) Alzheimer's disease is characterized by cholinergic deficiency in the cortex and basal forebrain, which contributes to cognitive deficits (Rogers et al, 1996).

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