Dimercaprol Injection BP (Sovereign Medical)

1. Name Of The Medicinal Product

Dimercaprol Injection BP

2. Qualitative And Quantitative Composition

Active ingredient

Dimercaprol PhEur 5.0% w/v

3. Pharmaceutical Form

Solution for injection.

4. Clinical Particulars

4.1 Therapeutic Indications

Dimercaprol Injection is indicated in the treatment of acute poisoning by certain heavy metals, arsenic, mercury, gold, bismuth, antimony and possibly thallium. Although dimercaprol has not been successful in the treatment of lead poisoning when used alone, there is evidence that used in conjunction with sodium calcium edetate, it can be used successfully in the treatment of lead poisoning, particularly in children.

For intramuscular injection.

4.2 Posology And Method Of Administration

Adults

400 - 800 mg, in divided doses, on the first day.

200 - 400 mg, in divided doses, on the second and third days.

100-200 mg, in divided doses, on the subsequent days.

Within the above dose range, individual dosage should be calculated on a bodyweight basis and will depend upon the severity of symptoms and the causative agent. As a general guide, single doses should not exceed 3 mg per kg bodyweight. However, in severe acute poisoning, single doses up to 5 mg per kg bodyweight may be required initially.

Children

Dimercaprol Injection is well tolerated by children and the dosage should be calculated on the basis of bodyweight, using the same unit dose per kg of bodyweight as for an adult under similar clinical circumstances.

Elderly

There are no specific data on the use of dimercaprol in the elderly but since it is eliminated via the kidney, it should be used with caution in this age group.

4.3 Contraindications

Dimercaprol Injection is contra-indicated in poisoning by iron, cadmium or selenium, in the presence of impaired hepatic function unless due to arsenic poisoning and in patients hypersensitive to dimercaprol.

4.4 Special Warnings And Precautions For Use

Dimercaprol Injection should be used with care in patients with hypertension or impaired renal function. It should be discontinued or continued with extreme caution if acute renal insufficiency develops during therapy. Dimercaprol Injection may not be effective in cases of concomitant renal failure, e.g. in arsine poisoning and some cases of arsenic poisoning. Any abnormal reaction (e.g. pyrexia) occurring after the initial injection of dimercaprol should be assessed before continuing treatment. The use of Dimercaprol Injection does not eliminate the need for the general treatment of poisoning due to the particular heavy metal.

Dimercaprol contains Arachis oil (peanut oil) and should not be taken by patients known to be allergic to peanut. As there is a possible relationship between allergy to peanut and allergy to Soya, patients with Soya allergy should also avoid Dimercaprol.

4.5 Interaction With Other Medicinal Products And Other Forms Of Interaction

Iron supplements must not be taken during dimercaprol therapy as iron forms toxic complexes with it.

4.6 Pregnancy And Lactation

Dimercaprol Injection has been used in Wilson's disease with successful full-term pregnancies, but since there is no other experience of its use in pregnancy or lactation, it should be prescribed with caution during these periods.

4.7 Effects On Ability To Drive And Use Machines

No adverse effects known.

4.8 Undesirable Effects

Side effects are relatively frequent, but at the therapeutic dosage employed, are seldom severe enough to warrant cessation of treatment and are almost invariably reversible. There is some evidence to indicate that 30-60 mg of ephedrine sulphate by mouth, given half an hour before each injection of dimercaprol, will reduce these reactions. Also, a minimum interval of four hours between doses appears to reduce side effects. Dimercaprol may cause the following side effects, particularly at the higher dosage levels: elevation of blood pressure accompanied by tachycardia, nausea and possibly vomiting, burning sensation of the lips, mouth, throat and eyes, salivation and lacrimation, conjunctivitis, rhinorrhoea, muscle pain and spasm, abdominal pain, headache, tingling of the hands and other extremities, a feeling of constriction in the chest and throat, sweating of the forehead and hands. Local pain may occur at the site of injection and gluteal abscess has occasionally been encountered.

A side effect apparently peculiar to children is a fever which develops after the second or third injection, and persists until treatment with dimercaprol is terminated.

4.9 Overdose

Symptoms of overdosage include malaise, nausea, vomiting, lacrimation and salivation, burning sensation of lips, mouth, throat and eyes with headache. A sense of constriction of the throat and chest. Increased blood pressure maximal after 15-20 minutes. Transient effects lasting about four hours.

Treatment consists of the subcutaneous administration of diphenhydramine 50 mg or ephedrine 30 mg or ephedrine in a dosage of 30-60 mg orally if time permits.

5. Pharmacological Properties

5.1 Pharmacodynamic Properties

Dimercaprol is a chelating agent used in the treatment of acute poisoning by heavy metals. The sulphydryl groups of dimercaprol compete with endogenous sulphydryl groups on proteins such as enzymes to combine with these metals; chelation by dimercaprol therefore prevents or reverses any inhibition of the sulphydryl enzymes by the metal and the dimercaprol-metal complex formed is readily excreted by the kidney.

5.2 Pharmacokinetic Properties

After intramuscular injection, maximum plasma concentrations of dimercaprol may be attained within one hour. Dimercaprol is rapidly metabolised and the metabolites and dimercaprol-metal chelates are excreted in the urine and bile. Elimination is essentially complete within four hours of a single dose.

5.3 Preclinical Safety Data

None stated.

6. Pharmaceutical Particulars

6.1 List Of Excipients

Benzyl benzoate, arachis oil, 5N alcoholic ammonia, nitrogen.

6.2 Incompatibilities

None stated.

6.3 Shelf Life

3 years.

6.4 Special Precautions For Storage

Store at 2° - 25°C. Protect from light.

6.5 Nature And Contents Of Container

A 2 ml clear neutral glass ampoule with ceramic breakring. Pack sizes of 1 ampoule packed in a cardboard carton, or 10 ampoules packed in a polystyrene pack within a cardboard sleeve.

6.6 Special Precautions For Disposal And Other Handling

Special precautions for disposal: react with weak aqueous solution (up to 15% of calcium hypochlorite). Leave for 24 hours. Neutralise and discharge to drain with copious quantities of water.

Administrative Data

7. Marketing Authorisation Holder

Waymade PLC t/a Sovereign Medical

Sovereign House,

Miles Gray Road,

Basildon,

Essex,

SS14 3FR, UK

8. Marketing Authorisation Number(S)

PL 06464/0897

9. Date Of First Authorisation/Renewal Of The Authorisation

17 November 1999

10. Date Of Revision Of The Text

June 2003