Rifampicin and bioavailability in combination formulation

The drug rifampicin (R) is used as a first line antibiotic treatment for tuberculosis (TB), together with Isoniazide (H), Pyrazinamide (Z) and Ethambutol (E). According to recent statistics, there has been an increase in TB on a worldwide scale, with the main causes being: monotherapies, the appearance of resistant microorganisms, the lack of effective preventative programs, non-compliance to treatment and mistaken dosage schedules. The world health organisation (WHO) and the International Union Against Tuberculosis and Lung Diseases(IUTALD) declared a state of emergency with respect to the disease and established programs to increase compliance to therapy and to reduce the incidence of problems arising from such. Along these lines, a list of first line drug therapy treatments were established, which included R, Z, H & E combinations at fixed dosage combinations (FDC), permitting safe combined administrations of the drugs at correct dosage levels. These fixed dose combinations have been officially recommended by the WHO in the treatment of TB. However, as has been widely recognised in numerous scientific publications, in such formulations, there are factors that alter the bioavailability of R. The objective of this work has been to study the most relevant aspects concerning R bioavailability alterations and to consider possible solutions to the problem.