This information is intended for use by health professionals
Dibenyline 10mg Capsules.
Phenoxybenzamine 10mg Capsules
Each capsule contains 10 mg Phenoxybenzamine hydrochloride BP.
Size no. three hard gelatin capsule with opaque body and a clear red cap, both printed with 'P10' in grey. The capsules are filled with a white powder.
Hypertensive episodes associated with Phaeochromocytoma.
Method of Administration
: The usual starting dose is 10 mg daily. This may be increased by 10 mg daily until control of hypertensive episodes is achieved, or postural hypotension occurs. Usually the dosage required is 1-2 mg/kg body weight daily in two doses. Concomitant beta-adrenergic blockade may be necessary to control tachycardia and arrythmias notably when tumours are secreting an appreciable amount of adrenaline as well as noradrenaline.
Elderly: Use with caution: 10mg daily dose should be sufficient (see Contra-Indications and Cautions below).
Children: There is little experience in children but, doses of 1 to 2 mg/kg daily have been used successfully.
Do not use 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 in whom a fall in blood pressure and/or tachycardia may be undesirable, such as the elderly or those with severe heart disease, congestive heart failure, cerebrovascular disease or renal damage. The mode of action should be borne in mind, if used concurrently with α-sympatho-mimetics or myocardial depressants.
Phenoxybenzamine is carcinogenic in the rat and has shown mutagenic activity in the bacterial Ames test and mouse lymphoma assay. It should only be used after very careful consideration of the risks, in patients in which alternative treatment is inappropriate.
See under Special Precautions and Warnings.
There is little evidence of safety of Dibenyline in pregnancy and it should not be used in pregnancy unless essential.
Side effects are generally mild and transient, but may include postural hypotension with dizziness and compensatory tachycardia, nasal congestion, inhibition of ejaculation, miosis and lassitude. Gastro-intestinal upset has also been reported.
The main effect of overdosage is profound hypotension, which may last several hours, tachycardia and collapse. Treatment consists of the induction of vomiting and/or gastric lavage together with appropriate symptomatic and supportive measures.
Treat hypotension with plasma expanders and the 'head down' position.
Noradrenaline is of little value when α-adrenergic receptors are blocked.
Adrenaline should not be used since stimulation of β-adrenergic receptors will further increase blood pressure.
Phenoxybenzamine is a non competitive long acting ☐-adrenergic receptor antagonist.
Phenoxybenzamine is incompletely absorbed from the gastrointestinal tract. The maximum effect is attained in about 1 hour after an intravenous dose. Following oral administration the onset of action is gradual over several hours and persists for 3-4 days following a single dose. The plasma half-life is about 24 hours. Phenoxybenzamine is metabolised in the liver and excreted in the urine and bile but small amounts remain in the body for several days. It has prolonged action probably owing to stable covalent bonding.
No further information of relevance.
Hard Gelatin Capsules:
Titanium Dioxide E171
Edible grey ink.
Store in a dry place and protect from light.
Polypropylene securitainers, amber glass bottles, polythene containers and blisters. (PVC/PVDC/Aluminium foil). In packs of 30 and 100.
Mercury Pharmaceuticals Ltd,
85 King William Street,
London EC4N 7BL, UK