Phenotyping of South African black tuberculosis patients for inactivation of isoniazid.

Studies of isoniazid inactivation rates in black tuberculosis patients from South Africa and Birmingham, Alabama, showed a higher frequency of fast inactivation than those of North American Caucasian patients. After an oral test dose of 10 mg/kg isoniazid the percentage of fast inactivators in black patients of South Africa and Alabama was close to 60% while in North American white participants (Canadian and Birmingham Caucasians), the frequency of fast inactivation was approximately 40%.