1) Monitor vital signs regularly. For mild/moderate hypertension without evidence of end organ damage, pharmacologic intervention is generally not necessary. Sedative agents such as benzodiazepines may be helpful in treating hypertension and tachycardia in agitated patients, especially if a sympathomimetic agent is involved in the poisoning.
2) For hypertensive emergencies (severe hypertension with evidence of end organ injury (CNS, cardiac, renal), or emergent need to lower mean arterial pressure 20% to 25% within one hour), sodium nitroprusside is preferred. Nitroglycerin and phentolamine are possible alternatives.
3) SODIUM NITROPRUSSIDE/INDICATIONS
a) Useful for emergent treatment of severe hypertension secondary to poisonings. Sodium nitroprusside has a rapid onset of action, a short duration of action and a half-life of about 2 minutes (Prod Info NITROPRESS(R) injection for IV infusion, 2007) that can allow accurate titration of blood pressure, as the hypertensive effects of drug overdoses are often short lived.
4) SODIUM NITROPRUSSIDE/DOSE
a) ADULT: Begin intravenous infusion at 0.1 microgram/kilogram/minute and titrate to desired effect; up to 10 micrograms/kilogram/minute may be required (American Heart Association, 2005). Frequent hemodynamic monitoring and administration by an infusion pump that ensures a precise flow rate is mandatory (Prod Info NITROPRESS(R) injection for IV infusion, 2007). PEDIATRIC: Initial: 0.5 to 1 microgram/kilogram/minute; titrate to effect up to 8 micrograms/kilogram/minute (Kleinman et al, 2010).
5) SODIUM NITROPRUSSIDE/SOLUTION PREPARATION
a) The reconstituted 50 mg solution must be further diluted in 250 to 1000 mL D5W to desired concentration (recommended 50 to 200 mcg/mL) (Prod Info NITROPRESS(R) injection, 2004). Prepare fresh every 24 hours; wrap in aluminum foil. Discard discolored solution (Prod Info NITROPRESS(R) injection for IV infusion, 2007).
6) SODIUM NITROPRUSSIDE/MAJOR ADVERSE REACTIONS
a) Severe hypotension; headaches, nausea, vomiting, abdominal cramps; thiocyanate or cyanide toxicity (generally from prolonged, high dose infusion); methemoglobinemia; lactic acidosis; chest pain or dysrhythmias (high doses) (Prod Info NITROPRESS(R) injection for IV infusion, 2007). The addition of 1 gram of sodium thiosulfate to each 100 milligrams of sodium nitroprusside for infusion may help to prevent cyanide toxicity in patients receiving prolonged or high dose infusions (Prod Info NITROPRESS(R) injection for IV infusion, 2007).
7) SODIUM NITROPRUSSIDE/MONITORING PARAMETERS
a) Monitor blood pressure every 30 to 60 seconds at onset of infusion; once stabilized, monitor every 5 minutes. Continuous blood pressure monitoring with an intra-arterial catheter is advised (Prod Info NITROPRESS(R) injection for IV infusion, 2007).
8) NITROGLYCERIN/INDICATIONS
a) May be used to control hypertension, and is particularly useful in patients with acute coronary syndromes or acute pulmonary edema (Rhoney & Peacock, 2009).
9) NITROGLYCERIN/ADULT DOSE
a) Begin infusion at 10 to 20 mcg/min and increase by 5 or 10 mcg/min every 5 to 10 minutes until the desired hemodynamic response is achieved (American Heart Association, 2005). Maximum rate 200 mcg/min (Rhoney & Peacock, 2009).
10) NITROGLYCERIN/PEDIATRIC DOSE
a) Usual Dose: 29 days or Older: 1 to 5 mcg/kg/min continuous IV infusion. Maximum 60 mcg/kg/min (Laitinen et al, 1997; Nam et al, 1989; Rasch & Lancaster, 1987; Ilbawi et al, 1985; Friedman & George, 1985).
11) PHENTOLAMINE/INDICATIONS
a) Useful for severe hypertension, particularly if caused by agents with alpha adrenergic agonist effects usually induced by catecholamine excess (Rhoney & Peacock, 2009).
12) PHENTOLAMINE/ADULT DOSE
a) BOLUS DOSE: 5 to 15 mg IV bolus repeated as needed (U.S. Departement of Health and Human Services, National Institutes of Health, and National Heart, Lung, and Blood Institute, 2004). Onset of action is 1 to 2 minutes with a duration of 10 to 30 minutes (Rhoney & Peacock, 2009).
b) CONTINUOUS INFUSION: 1 mg/hr, adjusted hourly to stabilize blood pressure. Prepared by adding 60 mg of phentolamine mesylate to 100 mL of 0.9% sodium chloride injection; continuous infusion ranging from 12 to 52 mg/hr over 4 days has been used in case reports (McMillian et al, 2011).
13) PHENTOLAMINE/PEDIATRIC DOSE
a) 0.05 to 0.1 mg/kg/dose (maximum of 5 mg per dose) intravenously every 5 minutes until hypertension is controlled, then every 2 to 4 hours as needed (Singh et al, 2012; Koch-Weser, 1974).
14) PHENTOLAMINE/ADVERSE EFFECTS
a) Adverse events can include orthostatic or prolonged hypotension, tachycardia, dysrhythmias, angina, flushing, headache, nasal congestion, nausea, vomiting, abdominal pain and diarrhea (Rhoney & Peacock, 2009; Prod Info Phentolamine Mesylate IM, IV injection Sandoz Standard, 2005).
15) CAUTION
a) Phentolamine should be used with caution in patients with coronary artery disease because it may induce angina or myocardial infarction (Rhoney & Peacock, 2009).
16) LABETALOL
a) INTRAVENOUS INDICATIONS
1) Consider if severe hypertension is unresponsive to short acting titratable agents such as sodium nitroprusside. Although labetalol has mixed alpha and beta adrenergic effects (Pearce & Wallin, 1994), it should be used cautiously if sympathomimetic agents are involved in the poisoning, as worsening hypertension may develop from alpha adrenergic effects.
b) ADULT DOSE
1) INTRAVENOUS BOLUS: Initial dose of 20 mg by slow IV injection over 2 minutes. Repeat with 40 to 80 mg at 10 minute intervals. Maximum total dose: 300 mg. Maximum effects on blood pressure usually occur within 5 minutes (Prod Info Trandate(R) IV injection, 2010).
2) INTRAVENOUS INFUSION: Administer infusion after initial bolus, until desired blood pressure is reached. Administer IV at 2 mg/min of diluted labetalol solution (1 mg/mL or 2 mg/3 mL concentrations); adjust as indicated and continue until adequate response is achieved; usual effective IV dose range is 50 to 200 mg total dose; maximum dose: 300 mg. Prepare 1 mg/mL concentration by adding 200 mg labetalol (40 mL) to 160 mL of a compatible solution and administered at a rate of 2 mL/min (2 mg/min); also can be mixed as an approximate 2 mg/3 mL concentration by adding 200 mg labetalol (40 mL) to 250 mL of solution and administered at a rate of 3 mL/min (2 mg/min) (Prod Info Trandate(R) IV injection, 2010). Use of an infusion pump is recommended (Prod Info Trandate(R) IV injection, 2010).
c) PEDIATRIC DOSE
1) INTRAVENOUS: LOADING DOSE: 0.2 to 1 mg/kg, may repeat every 5 to 10 minutes (Hari & Sinha, 2011; Flynn & Tullus, 2009; Temple & Nahata, 2000; Fivush et al, 1997; Fivush et al, 1997; Bunchman et al, 1992). Maximum dose: 40 mg/dose (Hari & Sinha, 2011; Flynn & Tullus, 2009). CONTINUOUS INFUSION: 0.25 to 3 mg/kg/hour IV (Hari & Sinha, 2011; Flynn & Tullus, 2009; Temple & Nahata, 2000; Fivush et al, 1997; Miller, 1994; Deal et al, 1992; Bunchman et al, 1992).
d) ADVERSE REACTIONS
1) Common adverse events include postural hypotension, dizziness; fatigue; nausea; vomiting, sweating, and flushing (Pearce & Wallin, 1994).
e) PRECAUTIONS
1) Contraindicated in patients with bronchial asthma, congestive heart failure, greater than first degree heart block, cardiogenic shock, or severe bradycardia or other conditions associated with prolonged or severe hypotension. In patients with pheochromocytoma, labetalol should be used with caution because it has produced a paradoxical hypertensive response in some patients with this tumor (Prod Info Trandate(R) IV injection, 2010).
2) Use caution in hepatic disease or intermittent claudication; effects of halothane may be enhanced by labetalol (Prod Info Trandate(R) IV injection, 2010). Labetalol should be stopped if there is laboratory evidence of liver injury or jaundice (Prod Info Trandate(R) IV injection, 2010).
f) MONITORING PARAMETER
1) Monitor blood pressure frequently during initial dosing and infusion (Prod Info Trandate(R) IV injection, 2010).