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phenoxybenzamine (Dibenzyline)
Tradename: Dibenzyline.
Indications:
1) prevention or control of paroxysmal hypertension & sweating in patients with pheochromocytoma
2) Raynaud's syndrome
3) micturition disorders
Contraindications: Caution:
1) renal insufficiency
2) coronary or cerebral atherosclerosis
3) severe congestive heart failure
Dosage:
1) adults:
a) start 10 mg PO BID
b) usual maintenance dose: 10-40 mg BID-TID
c) maximum dose: 120 mg/day
2) children:
a) 0.2 mg//kg (max 10 mg) QD
b) increase by 0.2 mg/kg increments
c) usual maintenance dose: 0.4-1.2 mg/kg/day divided TID
d) maximum single dose 10 mg
Tabs: 10 mg.
Pharmacokinetics:
1) well absorbed orally
2) onset of action within 2 hours
3) peak effect in 4-6 hours
4) alpha-adrenergic receptor blockade is complete & may last several days
5) highly lipid soluble; accumulates in fat tissue
6) elimination 1/2life is 24 hours
7) eliminated in bile & urine
Adverse effects:
1) common (> 10%)
- nasal congestion, miosis, postural hypotension, tachycardia, dizziness
2) less common (1-10%)
- confusion, dry mouth, headache, sexual dysfunction, tiredness, weakness, syncope, shock, lethargy, nausea/vomiting, diarrhea
3) other [2]
- drowsiness
- nasal congestion
- anorgasmia
Drug interactions:
1) alcohol in combination increases hypertension
2) alpha-adrenergic antagonists block effects of phenoxybenzamine
Mechanism of action:
1) non-competitive alpha adrenergic receptor antagonist
2) peripheral vasodilation
3) reflex tachycardia
4) blocks & reverses pressor effects of epinephrine
5) blocks, but does NOT reverse pressor effects of norepinephrine
Interactions
drug interactions
drug adverse effects (more general classes)
General
alkylating agent
alpha adrenergic receptor antagonist
amine
serotonin antagonist
Properties
MISC-INFO: pregnancy-category C
safety in lactation ?
Database Correlations
PUBCHEM correlations
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
Substructures
benzene
phenol