Hypertensive episodes associated with Phaeochromocytoma.

Posology

Adults: 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).

Paediatric population: There is little experience in children but, doses of 1 to 2 mg/kg daily have been used successfully.

Method of Administration

Oral

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

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.

Excipients

Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose galactose malabsorption should not take this medicine.

See under Special Precautions and Warnings.

Pregnancy

There is little evidence of safety of Dibenyline in pregnancy and it should not be used in pregnancy unless essential.

Breast-feeding

No data available

Fertility

No data available

None known.

Side effects are generally mild and transient but may include the following adverse reactions:

Not known (cannot be estimated from the available data)

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via Yellow Card Scheme, Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store

Symptoms

The main effect of overdosage is profound hypotension, which may last several hours, tachycardia and collapse.

Management

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 alpha-adrenergic receptor antagonist, ATC code: C04AX02

Absorption

Phenoxybenzamine is incompletely absorbed from the gastrointestinal tract.

Distribution

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.

Biotransformation

Phenoxybenzamine is metabolized in the liver.

Elimination

It is 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.

Lactose

Talc

Hard Gelatin Capsules:

Titanium Dioxide E171

Indigotin E132

Erythrosine E127

Edible grey ink.

None known.

2 years.

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.

Not all pack sizes may be marketed.

No special requirements for disposal.