Interventions for Tuberculosis Control and Elimination 2002

The patient is maintained on these two drugs until the acute symptoms
subside, which usually occurs within one or two weeks.
Isoniazid might then be added in a dosage of 50 mg per day. If there
is no clinical deterioration, the dose of isoniazid may then be increased to
100 mg on day 4, to 200 mg on day 7 and to the full dose on day 14. 642
Following the patient for another seven days, rifampicin might then be reintroduced,
and if well tolerated, pyrazinamide might finally be added if
rifampicin plus isoniazid has been well tolerated for seven days, and if it
has been given for less than two months prior to the onset of hepatitis.
This schedule can be expected to be successful in over 90% of cases. 642
Some clinicians prefer to re-introduce isoniazid at the full dose when
liver enzymes (where available) have normalized, or if liver enzyme tests
are not available after two weeks (Schraufnagel DE, personal written communication,
April 3, 2001; O’Brien RJ, personal written communication,
April 19, 2001).
The patient with gastrointestinal symptoms
Gastrointestinal symptoms such as nausea, pain and vomiting might be prodromal
symptoms of hepatitis, and close clinical observation is mandatory.
In addition to isoniazid, rifampicin, and pyrazinamide, thioacetazone frequently
causes gastrointestinal symptoms. In a patient on isoniazid and
thioacetazone, the latter is probably the cause. Such reactions can often
be dealt with easily by taking the medications with a meal or before going
to bed. Monitoring of the response is important. If the symptoms do not
subside, the isoniazid plus thioacetazone combination should be replaced
by isoniazid plus ethambutol. Should the symptoms persist despite the
change, isoniazid and the possibility of liver toxicity must be suspected and
the patient be placed on streptomycin plus ethambutol until symptoms subside.
Isoniazid might be re-introduced subsequently, as described above.
The patient with impaired vision
The most frequent drug-related cause of impaired vision among the medications
used for treating tuberculosis is ethambutol. Optic toxicity is not
detectable fundoscopically. If ethambutol is suspected, it must be withdrawn
immediately and never be given again. If the event occurs in the
intensive phase where ethambutol is given as a fourth companion drug, no
replacement is necessary (although streptomycin might be used if deemed
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