Interventions for Tuberculosis Control and Elimination 2002

depending on the technique of susceptibility testing and the origin of the
strain. 422 An observation made in a comparison of tubercle bacilli isolated
from India and in the United Kingdom showed that Indian strains were
considerably less susceptible to thioacetazone than strains from the United
Kingdom. 423 This geographic variation was subsequently confirmed. 424-427
The susceptibility of strains may vary even within the same country. 428
The correlation between in vitro and in vivo results is often very poor. 429
The mode of action of thioacetazone has not been elucidated, 430 although
it has been shown that thioacetazone forms copper complex salts and it has
been postulated that these might represent the effective compound. 431
There is partial cross-resistance between thioacetazone and ethionamide.
422
Pharmacokinetics. Thioacetazone is rapidly absorbed and maximum serum
concentrations are achieved about four hours (range two to six hours) after
ingestion, 432-434 and is eliminated from serum almost completely within 24
hours (figure 26). 434
Dosage. The currently recommended dosage of thioacetazone is 2.5 mg/kg
body weight per day. 13 Only daily treatment is recommended.
Adverse drug events (table 7). Thioacetazone frequently causes adverse
drug events, 435-438 which occur in up to 40% of patients. The most fre-
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Figure 26. Pharmacokinetics of thioacetazone in healthy volunteers. 434
46