Interventions for Tuberculosis Control and Elimination 2002

Table 8. Fixed-dose combinations (FDC) of antituberculosis drugs and dosages
of individual drugs as recommended by WHO. 454
FDC per tablet For daily use (mg drug) For three-times weekly
use (mg drug)
{TH} 150 T + 300 H
50 T + 100 H * –
{EH} 400 E + 150 H –
{RH} 300 R + 150 H –
150 R + 75 H 150 R + 150 H
60 R + 30 H * 60 R + 60 H
{RHZ} 150 R + 75 H + 400 Z 150 R + 150 H + 500 Z
60 R + 30 H + 150 Z * –
{RHZE} 150 R + 75 H + 400 Z + 275 E –
* For pediatric use
Abbreviations: T = thioacetazone; H = isoniazid; E = ethambutol; R = rifampicin; Z = pyrazinamide.
Fixed-dose combinations will guarantee that drugs cannot be taken separately.
They thus reduce the potential of acquisition of drug resistance.
However, prescription errors or selective use of the number of tablets by
the patient may lead to sub-inhibitory concentrations of all drugs. The
need for direct observation of drug intake is thus not obviated with their
introduction into national programs.
Principal prerequisites
for an efficacious anti-tuberculosis drug
It is general practice to define the action of antimicrobial agents as “bacteriostatic”
or “bactericidal”. This terminology might not be that useful in
describing the activity of anti-tuberculosis medications. Mitchison has proposed
the utility of defining three prerequisites for an anti-tuberculosis drug
(table 9): 456
• Early bactericidal activity;
• Sterilizing activity;
• Ability to prevent emergence of resistance to the companion drug.
50