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phentolamine (Regitine, OraVerse)

Tradename: Regitine. Indications: - used in diagnosis of pheochromocytoma & associated hypertension - prevention of dermal necrosis due to extravasation of vasoconstrictors - reversal of soft-tissue anesthesia - erectile dysfunction [4] Dosage: 1) pheochromocytoma: a) diagnosis: 5 mg IV; 1 mg if child b) 5 mg increments IV; 1 mg if child c) 5-10 mg IV every 1-2 hours PRN 2) extravasation: a) 5-10 mg in 10 mL normal saline in & around the site of extravasation b) best if given immediately, but may be effective if given within 12 hours Injection: 5 mg/mL (1 mL), OraVerse may be different Pharmacokinetics: 1) response to IV administration is within 2 minutes 2) duration of action 15-30 minutes Adverse effects: 1) common (> 10%) - orthostatic hypotension, abdominal pain, nausea, reflex tachycardia, anginal pain, diarrhea 2) less common (1-10%) - weakness, fainting, flushing of face, nasal congestion 3) uncommon (< 1%) - myocardial infarction, severe headache, exacerbation of peptic ulcer 4) other - dyspepsia - angina - dizziness - cerebrovascular spasm Mechanism of action: 1) competitively blocks alpha adrenergic receptors 2) decreases peripheral resistance 3) induces peripheral vasodilation 4) stimulates beta adrenergic receptors a) positive inotropic effects b) positive chronotropic effects c) increases cardiac output 5) dilates bronchial smooth muscle

Interactions

drug interactions drug adverse effects of antihypertensive agents

General

alpha adrenergic receptor antagonist imidazole; glyoxaline; 1,3-diazole; iminazole

Properties

MISC-INFO: elimination route PLASMA pregnancy-category C safety in lactation ?

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  3. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. Deprecated Reference