Phenylephrine Injection BP 10 mg/ml

Phenylephrine hydrochloride Ph Eur 1.0% w/v

Sterile solution

For the treatment of hypotensive states, e.g. circulatory failure, during spinal anaesthesia or drug-induced hypotension.

For subcutaneous, intramuscular, slow intravenous injection or intravenous infusion.

Adults

Phenylephrine injection may be administered subcutaneously or intramuscularly in a dosage of 2 to 5 mg with further doses of 1 to 10 mg if necessary according to response, or in a dose of 100 to 500 micrograms by slow intravenous injection as a 0.1% solution, repeated as necessary after at least 15 minutes.

Alternatively, 10 mg in 500 ml of glucose 5% injection or sodium chloride 0.9% injection may be infused intravenously, initially at a rate of up to 180 micrograms per minute, reduced according to response to 30-60 micrograms per minute.

Children

100 mcg/kg bodyweight subcutaneously or intramuscularly.

Elderly

There is no need for dosage reduction in the elderly.

Patients taking monoamine oxidase inhibitors, or within 14 days of ceasing such treatment. Severe hypertension and hyperthyroidism.

Great care should be exercised in administering Phenylephrine Injection to patients with pre-existing cardiovascular disease such as ischaemic heart disease, arrhythmias, occlusive vascular disease including arteriosclerosis, hypertension or aneurysms. Anginal pain may be precipitated in patients with angina pectoris.

Care is also required when given to patients with diabetes mellitus or closed-angle glaucoma.

Keep all medicines out of the reach of children.

Phenylephrine may interact with cyclopropane and halothane and other halogenated inhalational anaesthetics, to induce ventricular fibrillation. An increased risk of arrhythmias may also occur if phenylephrine injection is given to patients receiving cardiac glycosides, quinidine or tricyclic antidepressants.

Phenylephrine may increase blood pressure and consequently reverse the action of many antihypertensive agents. Interactions of phenylephrine with alpha and beta receptor blocking drugs may be complex.

¹ Drugs which have an effect on α₁ adrenoreceptors could potentiate (such as ganisetron) or inhibit (such as doxazosin or buspirone) the vasopressive action of phenylephrine.

¹PL 06464/0902-0013; 17/04/09

The safety of phenylephrine during pregnancy and lactation has not been established. Administration of phenylephrine in late pregnancy or labour may cause foetal hypoxia and bradycardia. Excretion of phenylephrine in breast milk appears to be minimal.

No adverse effects known.

Extravasation of Phenylephrine Injection may cause tissue necrosis. Phenylephrine will cause a rise in blood pressure with headache and vomiting and this may produce cerebral haemorrhage and pulmonary oedema. There may also be a reflex bradycardia or tachycardia, other cardiac arrhythmias, anginal pain, palpitations and cardiac arrest, hypotension with dizziness, and fainting and flushing may occur. Phenylephrine may induce difficulty in micturition and urinary retention, ²mydriasis, dyspnoea, altered metabolism including disturbances of glucose metabolism, sweating, hypersalivation, transient tingling and coolness of the skin and temporary fullness of the head. Phenylephrine is without significant stimulating effects on the central nervous system at usual doses.

²PL 06464/0902-0014; 11/05/2009

Symptoms of overdosage include headache, vomiting, hypertension and reflex bradycardia and other cardiac arrhythmias.

Treatment should consist of symptomatic and supportive measures. The hypertensive effects may be treated with an alpha-adrenoceptor blocking drug, such as phentolamine, 5 to 60 mg i.v. over 10-30 minutes, repeated as necessary.

Phenylephrine hydrochloride is a sympathomimetic agent with mainly direct effects on adrenergic receptors. It has predominantly alpha-adrenergic activity and is without significant stimulating effects on the central nervous system at usual doses. After injection it produces peripheral vasoconstriction and increased arterial pressure. It also causes reflex bradycardia.

When injected subcutaneously or intramuscularly, phenylephrine takes 10 to 15 minutes to act. Subcutaneous and intramuscular injections are effective for up to about one and up to two hours respectively. Intravenous injections are effective for up to about 20 minutes. Phenylephrine is metabolised in the liver by monoamine oxidase. The metabolites, their route and rate of excretion have not been identified.

³Phenylephrine has been used to induce cardiac myocyte hypertrophy in cultures of rat neonatal mycocytes at doses of 100 µM and 10 µM. To the best of our knowledge there have been no human studies associating therapeutic phenylephrine use with the development of cardiac myocyte hypertrophy.

³PL 06464/0902-0015; 17/12/2008

N/1 Sodium Hydroxide for SP

N/1 Hydrochloric Acid for SP

Water for Injections Ph Eur

Sterile N/1 Sodium Hydroxide for SP

Sterile N/1 Hydrochloric Acid for SP

Phenylephrine Injection has been stated to be incompatible with alkalis, ferric salts, phenytoin sodium and oxidising agents.

24 months.

Store at 2-25°C. Protect from light.

1 ml neutral glass ampoule with ceramic breakring.

Pack size: 6, 10 ampoules

Not applicable.

Waymade Plc

Sovereign Medical

Sovereign House

Miles Gray Road

Basildon

Essex SS14 3FR

United Kingdom

PL 06464/0902

17 November 1999

May 2009