Interventions for Tuberculosis Control and Elimination 2002

contraceptives and anti-retroviral medications, which preclude any such
combination.
• Pyrazinamide also has particular relapse-preventing properties that have
allowed the duration of required chemotherapy to be further reduced.
In the currently recommended dosages, it is also a very well tolerated
drug. Arthralgias are the most frequently reported adverse event that
can be alleviated by the administration of acetylic salicylic acid or
intermittent administration. There are no practically important interactions
with other medications.
• Ethambutol’s main purpose is to reduce the risk of emergence of resistance
to isoniazid. It is a very well tolerated drug, and optic neuritis,
its main adverse drug event, occurs infrequently with the currently recommended
dosages. It does not interact with any other drug, but its
absorption might be reduced if patients take certain antacids.
• Streptomycin might add bactericidal activity to a regimen in the intensive
phase and may add additional protection against the emergence of
drug resistance, particularly in patients receiving a re-treatment regimen.
It is reasonably well tolerated by young patients, but its vestibulocochlear
toxicity and hypersensitivity reactions make its prolonged use
an unpleasant experience for many patients. The only potentially important
interaction in daily practice is that its toxic effects are enhanced
by some diuretics.
• Thioacetazone’s main purpose is to reduce the risk of emergence of
drug resistance to isoniazid and to reduce the risk of failure and relapse
where there is resistance to the latter. More than any other drug it
has the potential of multi-system adverse drug events. Among human
immunodeficiency virus (HIV) infected patients, the most prominent is
a muco-cutaneous syndrome that may progress to toxic epidermal
necrolysis. This precludes its use in an increasing number of countries.
No important interactions with other medications are known.
The treatment of previously untreated tuberculosis patients begins with the
direct observation of intake of a four-drug regimen (isoniazid, rifampicin,
pyrazinamide, and ethambutol, preferably in a fixed-dose combination tablet)
during a two-month intensive phase. To facilitate the organization of
directly observed therapy, treatment may be given thrice-weekly after a
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