Dacarbazine

Dacarbazine is indicated in the treatment of metastatic malignant melanoma. In addition, Dacarbazine is also indicated for Hodgkin's disease as a second-line therapy when used in combination with other effective agents.

Dacarbazine is a non-cell cycle specific antineoplastic agent. The exact mechanism of action by which it exerts cytotoxic effects is still unclear. However, three possible mechanisms have been postulated, including inhibition of DNA synthesis by acting as a purine analog, action as an alkylating agent, and interaction with sulfydryl group in the inhibition of bacterial cell growth.

Malignant Melanoma: The recommended dosage is 2 to 4.5 mg/kg/day for 10 days. Treatment may be repeated at 4 week intervals. An alternate recommended dosage is 250 mg/m²/day IV for 5 days. Treatment may be repeated every 3 weeks.

Hodgkin’s Disease: The recommended dosage of Dacarbazine in the treatment of Hodgkin’s disease is 150 mg/m²/day for 5 days, in combination with other effective drugs. Treatment may be repeated every 4 weeks. An alternative recommended dosage is 375 mg/m² on day 1, in combination with other effective drugs, to be repeated every 15 days.

Increased metabolism when used with enzyme inducers (e.g. barbiturates, rifampicin, phenytoin). May potentiate the effect of mercaptopurine, azathioprine, allopurinol. May impair immune response to vaccines. May enhance the effects of methoxsalen due to photosensitisation.

Dacarbazine is contraindicated in patients who  have demonstrated a hypersensitivity to it in the past.

Symptoms of anorexia, nausea and vomiting are the most frequently noted of all toxic reactions. Over 90% of patients are affected with the initial few doses. The vomiting lasts 1 to 12 hours and is incompletely and unpredictably palliated with phenobarbital and/or prochlorperazine. Rarely, intractable nausea and vomiting have necessitated discontinuance of therapy with Dacarbazine for Injection. Rarely, Dacarbazine for Injection has caused diarrhea. Some helpful suggestions include restricting the patient’s oral intake of food for 4 to 6 hours prior to treatment. The rapid toleration of these symptoms suggests that a central nervous system mechanism may be involved, and usually these symptoms subside after the first 1 or 2 days.

Pregnancy Category C. Dacarbazine for Injection has been shown to be teratogenic in rats when given in doses 20 times the human daily dose on day 12 of gestation. Dacarbazine when administered in 10 times the human daily dose to male rats (twice weekly for 9 weeks) did not affect the male libido, although female rats mated to male rats had higher incidence of resorptions than controls. In rabbits, dacarbazine daily dose 7 times the human daily dose given on Days 6 to 15 of gestation resulted in fetal skeletal anomalies. There are no adequate and well controlled studies in pregnant women. Dacarbazine for Injection should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for tumorigenicity shown for Dacarbazine for Injection in animal studies, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Hospitalization is not always necessary but adequate laboratory study capability must be available. Extravasation of the drug subcutaneously during intravenous administration may result in tissue damage and severe pain. Local pain, burning sensation and irritation at the site of injection may be relieved by locally applied hot packs. Carcinogenicity of dacarbazine was studied in rats and mice. Proliferative endocardial lesions, including fibrosarcomas and sarcomas were induced by dacarbazine in rats. In mice, administration of dacarbazine resulted in the induction of angiosarcomas of the spleen.

Give supportive treatment and monitor blood cell counts.

Cytotoxic Chemotherapy

Dacarbazine 200 mg/vial is reconstituted with 19.7 mL of Sterile Water for Injection. The resulting solution contains 10 mg/mL of dacarbazine having a pH of 3.0 to 4.0. The calculated dose of the resulting solution is drawn into a syringe and administered only intravenously. The reconstituted solution may be further diluted with 5% dextrose injection or sodium chloride injection and administered as an intravenous infusion. After reconstitution and prior to use, the solution in the vial may be stored at 4°C for up to 72 hours or at normal room conditions (temperature and light) for up to 8 hours. If the reconstituted solution is further diluted in 5% dextrose injection or sodium chloride injection, the resulting solution may be stored at 4°C for up to 24 hours or at normal room conditions for up to 8 hours. Procedures for proper handling and disposal of anticancer drugs should be considered. Several guidelines on this subject have been published. There is no general agreement that all the procedures recommended in the guidelines are necessary or appropriate.

Store in a refrigerator 2°C to 8°C