Repaglinide Rifampicin

Studies involving rifampicin and repaglinide have yielded conflicting results, perhaps because of timing and dosages. In one study rifampicin had no effect on the pharmacokinetics and pharmacodynamics of a single dose repaglinide... 

In a more recent study, 12 male volunteers took rifampicin 600 mg/day for 7 days followed by two doses of repaglinide 4 mg 24 hours apart the AUC for repaglinide was reduced by 50% on day 7, and by 80% on day 8 (67). Timing of the drugs may alter the clinical effects. 

Bidstrup TB, Stilling N, Damkier P, Scharling B, Thomsen MS, Brpsen K. Rifampicin seems to act as both an inducer and inhibitor of the metabolism of repaglinide. Eur J Clin Pharmacol 2004 60 109-14. 

Co-administration of rifampicin with repaglinide considerably lowers the concentration of repaglinide and alters its therapeutic effect in diabetes melUtns (126). In nine healthy volnnteers, the maximnm rednction in blood gln-cose after a single 0.5 mg dose of repaglinide fell from 1.6 to 1.0 mmol/1 after pretreatment with rifampicin for 5 days. This presnmably occurred by induction of CYP3A4. 

Deferasirox did not alter the pharmacokinetics of digoxin. Food increases the bioavailability of deferasirox, and it should be taken on an empty stomach. The use of deferasirox with aluminium antacids is not recommended. Rifampicin, phenobarbital and pheny-toin are predicted to increase the metabolism of deferasirox, and, until more is known, concurrent use should be monitored. Based on in vitro data, deferasirox might inhibit the metabolism of CYP2C8 substrates like paclitaxel and repaglinide. Hydroxycar-bamide does not alter deferasirox metabolism. 

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