Melarsomine dihydrochloride

Chemical group: arsenical

Trade name: Immiticide

Mode of action: Unknown, presumably due to the arsenic’s effect on glycolysis.

Pharmacokinetics: Absorbed very rapidly from the injections site, some metabolites and the parent compound are eliminated in the bile and other metabolites are passed in the urine. The drug is rapidly cleared from the body.

Dose: 2.5 mg/kg (IM) twice, 24 hours apart. (Dogs with class 3 disease should receive one dose and allowed to recover for a few months before receiving the complete set of 2 doses.)

Toxicity: LD50 in rats (IM) was 24 to 33 mg/kg, some mortality seen in dogs given 7.5 mg/kg. Injection site reactions are common, as are lethargy, vomiting and anorexia. (A 10% death rate can be expected in dogs with class 3 disease when 2 doses are given initially.)   Doses between 2.5 mg/kg and 2.7 mg/kg were fatal to Heartworm infected river otters (Lontra canadensis) and red pandas (Ailurus fulgens fulgens) [Neiffer, et al., 2002, J. Zoo. Wildl. Med  33(3)242-248].

Parasite Targets: Heartworm adults

© University of Pennsylvania  2004

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