Name of the medicinal product
Dimercaprol 50 mg/ml Injection BP
Dimercaprol 100 mg/ml Injection BP
Qualitative and quantitative composition
Each 1 ml ampoule contains 50 mg of the active substance dimercaprol.
Each 2 ml ampoule contains 100 mg of the active substance dimercaprol.
Excipients with known effect:
|Arachis oil (peanut oil)||(1595.00 mg/2 ml)|
|Benzyl benzoate||(200.00 mg/2 ml)|
For the full list of excipients, see section 6.1.
A clear, bright pale yellow solution for injection.
4.1 Therapeutic indications
Dimercaprol Injection is indicated in adults and children for 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.
4.2 Posology and method of administration
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.
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.
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.
Method of administration
For intramuscular injection.
Hypersensitivity to dimercaprol or to any of the excipients listed in section 6.1.
Poisoning by iron, cadmium, or selenium.
Impaired hepatic function unless due to arsenic poisoning.
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.
A reaction apparently peculiar to children is fever which may persist during therapy (see section 4.8). It occurs in approximately 30% of children.
A transient reduction of the percentage of polymorphonuclear leukocytes may also be observed (see section 4.8).
Dimercaprol has been reported to induce hemolysis (which may be severe) in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Therefore, high-risk individuals should be screened for G6PD deficiency, and susceptible patients should be monitored for hemolysis during therapy with dimercaprol.
Dimecaprol Injection contains Arachis oil (peanut oil)
Dimercaprol Injection should not be given to 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 Injection.
Dimercaprol Injection contains benzyl benzoate
May increase the risk of jaundice in newborn babies.
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 Fertility, 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:
Blood and lymphatic system disorders
Haemolysis, transient reductions in leukocyte count have also been reported (see section 4.4).
Nervous system disorders
Headache, tingling of the hands and other extremities, tremor. High doses have produced hypertensive encephalopathy with convulsions and coma.
Burning sensation of the eyes, lacrimation, conjunctivitis, blepharospasm
Elevation of blood pressure accompanied by tachycardia
Respiratory, thoracic and mediastinal disorders
Rhinorrhoea, a feeling of constriction in the chest and throat
Nausea and possibly vomiting, salivation, abdominal pain, burning sensation of the lips, mouth and throat
Skin and subcutaneous tissue disorders
Sweating of the forehead and hands
Musculoskeletal and connective tissue disorders
Muscle pain and spasm, pain in jaw
Renal and urinary disorders
Reproductive system and breast disorders
Burning sensation in the penis
General disorders and administration site conditions
Local pain may occur at the site of injection and gluteal abscess has occasionally been encountered. Pyrexia.
Activated partial thromboplastin time prolonged, blood zinc decreased
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.
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 the Yellow Card Scheme (website: www.mhra.gov.uk/yellowcard).
Symptoms of over dosage 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.
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Antidote
ATC code: V03AB
Dimercaprol is a chelating agent used in the treatment of acute poisoning by heavy metals.
Mechanism of action
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 widely distributed to all body tissues, with the highest concentrations found in the kidneys and liver.
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
6.1 List of excipients
Benzyl benzoate, arachis oil, 5N alcoholic ammonia, nitrogen.
6.3 Shelf life
6.4 Special precautions for storage
Store at 2º – 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.