CLINICAL PHARMACOLOGY
Actions: The mechanism of action in
Dermatitis herpetiformis has not been established. By the kinetic method in
mice, Dapsone is bactericidal as well as bacteriostatic against Mycobacterium leprae.
Absorption and Excretion: Dapsone, when
given orally, is rapidly and almost completely absorbed. About 85 percent of the
daily intake is recoverable from the urine mainly in the form of water-soluble
metabolites. Excretion of the drug is slow and a constant blood level can be
maintained with the usual dosage.
Blood Levels: Detected a few minutes
after ingestion, the drug reaches peak concentration in 4-8 hours. Daily
administration for at least eight days is necessary to achieve a plateau level.
With doses of 200 mg daily, this level averaged 2.3 μg/ml with a range of
0.1-7.0 μg/ml. The half-life in the plasma in different individuals varies from
ten hours to fifty hours and averages twenty-eight hours. Repeat tests in the
same individual are constant. Daily administration (50 - 100 mg) in leprosy
patients will provide blood levels in excess of the usual minimum inhibitory
concentration even for patients with a short Dapsone half-life.
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