Bioavailability of rifampicin following concomitant administration of ethambutol or isoniazid or pyrazinamide or a combination of the three drugs.

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dc.contributor.authorImmanuel, Chandraen_US
dc.contributor.authorGurumurthy, Premaen_US
dc.contributor.authorRamachandran, Geethaen_US
dc.contributor.authorVenkatesan, Pen_US
dc.contributor.authorChandrasekaran, Ven_US
dc.contributor.authorPrabhakar, Ren_US
dc.date.accessioned2003-09-01en_US
dc.date.accessioned2009-05-27T07:23:43Z
dc.date.available2003-09-01en_US
dc.date.available2009-05-27T07:23:43Z
dc.date.issued2003-09-01en_US
dc.description.abstractBACKGROUND & OBJECTIVES: Poor bioavailability of rifampicin (R) in combination with other anti-tuberculosis drugs such as isoniazid (H), pyrazinamide (Z), and ethambutol (E) is a subject of much concern for the last few decades. This could be due to an interaction between R and other drugs. An investigation was therefore undertaken to examine the bioavailability of R in the presence of H, Z and E or a combination of the three drugs. METHODS: The study included eight healthy volunteers, each being investigated on four occasions at weekly intervals once with R alone and with three of the four combinations on the three remaining occasions. A partially balanced incomplete block design was employed and the allocation of R or the drug combinations was random. Plasma concentrations of R at intervals up to 12 h were determined by microbiological assay using Staphylococcus aureus as the test organism. The proportion (%) dose of R as R plus desacetyl R (DR) in urine excreted over the periods 0-8 and 8-12 h was also determined. Bioavailability was expressed as an index (BI) of area under time concentration curve (AUC) calculated from the plasma concentrations or proportion of dose of R excreted as R plus DR in urine with the combinations to that with R alone. RESULTS: The bioavailability indices based on AUC were 0.96 with RE, 0.76 with RH, 1.08 with RZ and 0.65 with REHZ. The indices based on urine estimations (0-8 h) were similar, the values being 0.94, 0.84, 0.94 and 0.75, respectively. A second investigation revealed that the decrease of bioavailability of R with H was not due to the excipients present in H tablets. INTERPRETATION & CONCLUSION: Isoniazid alone or in combination with E and Z reduces the bioavailability of R. Urinary excretion data offer a simple and non invasive method for the assessment of bioavailability of R.en_US
dc.description.affiliationTuberculosis Research Centre (ICMR), Chennai, India.en_US
dc.identifier.citationImmanuel C, Gurumurthy P, Ramachandran G, Venkatesan P, Chandrasekaran V, Prabhakar R. Bioavailability of rifampicin following concomitant administration of ethambutol or isoniazid or pyrazinamide or a combination of the three drugs. Indian Journal of Medical Research. 2003 Sep; 118(): 109-14en_US
dc.identifier.urihttps://imsear.searo.who.int/handle/123456789/20529
dc.language.isoengen_US
dc.source.urihttps://icmr.nic.in/ijmr/ijmr.htmen_US
dc.subject.meshAdolescenten_US
dc.subject.meshAdulten_US
dc.subject.meshAntibiotics, Antitubercular --pharmacokineticsen_US
dc.subject.meshArea Under Curveen_US
dc.subject.meshBody Weighten_US
dc.subject.meshEthambutol --pharmacologyen_US
dc.subject.meshHumansen_US
dc.subject.meshIsoniazid --pharmacologyen_US
dc.subject.meshMaleen_US
dc.subject.meshMiddle Ageden_US
dc.subject.meshPyrazinamide --pharmacologyen_US
dc.subject.meshRifampin --pharmacokineticsen_US
dc.subject.meshStaphylococcus aureus --metabolismen_US
dc.subject.meshTime Factorsen_US
dc.titleBioavailability of rifampicin following concomitant administration of ethambutol or isoniazid or pyrazinamide or a combination of the three drugs.en_US
dc.typeJournal Articleen_US
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