Setting: The absorption of rifampicin, isoniazid and pyrazinamide was tested after administration of each drug in free combinations and in a fixed-dose combination of the three drugs, known as Trifazid.
Objective: To examine the relative bioavailability of rifampicin, isoniazid and pyrazinamide after oral administration of the drugs given alone in comparison to that of the same drugs after administration of Trifazid.
Design: An open, randomized, cross-over study comprising 16 healthy volunteers.
Results: The pattern of absorption, plasma concentrations and pharmacokinetic parameters were very similar after administration of the drugs in free and fixed combinations.
Conclusion: The triple combination of antituberculosis drugs could replace the separate drugs in the treatment of tuberculosis.