Phenoxybenzamine
Mechanism :
Phenoxybenzamine hydrochloride is a long-acting, adrenergic, alpha-receptor blocking agent. It increases blood flow to the skin, mucosa and abdominal viscera, and lowers both supine and erect blood pressures. It has no effect on the parasympathetic system.
Indication :
- Pheochromocytoma Hypertension (off-label)
Contraindications :
Contraindicated in conditions where a fall in blood pressure may be undesirable, in the presence of hypovolemia in patients with severe shock, in patients who have had a cerebrovascular accident or in the recovery period (usually 3-4 weeks) after acute myocardial infarction. Use with great caution in patients with severe heart disease, congestive heart failure, cerebrovascular disease or renal damage.
Dosing :
Oral:
0.25-1 mg/kg daily; gradually increase the dose to achieve effect;
Maximum dose: 10 mg/day.
IV infusion:
0.5-1 mg/kg over at least 2 hours.
May repeat every 12 hours with dose adjusted according to response.
Adverse Effect :
Postural hypotension, tachycardia, inhibition of ejaculation, nasal congestion, dry mouth, miosis, gastrointestinal irritation, dizziness, drowsiness, fatigue.
Interaction :
Epinephrine: Produce an exaggerated hypotensive response and tachycardia.
Levarterenol: Blocks hyperthermia production by levarterenol.
Reserpine: Blocks hypothermia production by reserpine.
Hepatic Dose :
No dose adjustment recommended.