Aspects of chemotherapy and management need clarifying

EDITOR—We take issue with some of the comments made by Chan and Iseman in their clinical review of current medical treatment for tuberculosis.1 These points have already been covered in the evidence based guidelines on both the chemotherapy and management and the control and prevention of tuberculosis by the Joint Tuberculosis Committee of the British Thoracic Society, but we believe that they bear restatement. 2 3

Supplementation with pyridoxine (up to 50 mg/day) as routine—Peripheral neuropathy from isoniazid is very uncommon. Pyridoxine is appropriate for patients at increased risk of peripheral neuropathy.2 However, pyridoxine antagonises isoniazid on a milligram for milligram basis. Studies have shown that only 6 mg/day prevents peripheral neuropathy, so only 10 mg (the smallest tablet size available) should be used, if indicated.

Routine liver function monitoring—Detailed advice on liver function monitoring has been given and is incorporated in the 1998 code of practice, 2 4 but regular liver function measurements are not required in patients with normal pretreatment liver function, unless symptoms, in an informed patient, suggest hepatic upset.

Monthly visual acuity checks of patients taking ethambutol—Ocular toxicity is extremely rare in patients with normal visual acuity (Snellen chart) and renal function who are taking an ethambutol dose of 15 mg/kg, and there is no evidence that regular ocular checks prevent events.5 …