Effect of rifampicin on theophylline pharmacokinetics in human beings

Theophylline pharmacokinetics before and after rifampicin administration was studied in 10 healthy volunteers. It was seen that Rifampicin significantly increased the volume of distribution of theophylline by 23.41% (p < 0.01) and its metabolic clearance by 47.65% (P < 0.05). This has got clinical significance in the treatment of patients of pulmonary tuberculosis with chronic obstructive airways disease where both the drugs may have to be given concurrently.