Diethylcarbamazine citrate (Hetrazan) is active against several microfilaria and adult filarial worms. It interferes with the metabolism of arachidonic acid and blocks the production of prostaglandins, resulting in capillary vasoconstriction and impairment of the passage of the microfilaria. Diethylcarbamazine also increases the adherence of microfilariae to the vascular wall, platelets, and granulocytes.
Diethylcarbamazine is absorbed from the gastrointestinal tract, and peak blood levels are obtained in 4 hours; the drug disappears from the blood within 48 hours. The intact drug and its metabolites are excreted in the urine.
Diethylcarbamazine is the drug of choice for certain filarial infections, such as Wuchereria bancrofti, Brugia malayi and Loa loa. Since diethylcarbamazine is not universally active against filarial infections, a specific diagnosis based on blood smears, biopsy samples, and a geographic history is important. Dosage should be adjusted in patients with renal impairment.
Caution is necessary when using this agent, particularly when treating onchocerciasis. The sudden death of the microfilariae can produce mild to severe reactions within hours of drug administration. These are manifested by fever, lymphadenopathy, cutaneous swelling, leukocytosis, and intensification of any preexisting eosinophilia, edema, rashes, tachycardia, and headache. If microfilariae are present in the eye, further ocular damage may result. Other side effects are relatively mild and range from malaise, headache, and arthralgias to gastrointestinal symptoms.
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