Rosiglitazone is extensively metabolized or broken down by a group of liver enzymes known as CYP2C8. Gemfibrozil (Lopid), a known inhibitor of CYP2C8 may increase blood levels of rosiglitazone and consequently increase the risk of side effects. Concomitant use of agents that also inhibit CYP2C8 requires a reduction in the dose of rosiglitazone.
Rifampin (Rimactane or Rifadin), a known inducer of CYP2C8, increases the breakdown of rosiglitazone. Therefore, concomitant use of agents that induce CYP2C8 may decrease the effectiveness of rosiglitazone.
Drugs which cause blood glucose levels to increase may diminish the effectiveness of Avandamet therapy. These drugs include
- other diuretics,
- thyroid medications,
- birth control pills,
- phenytoin (Dilantin),
- nicotinic acid,
- calcium channel blockers (CCBs), and
- isoniazid (Nydrazid).
PREGNANCY: Avandamet has not been adequately evaluated in pregnant women. Due to the lack of conclusive safety data, Avandamet should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. Avandamet is classified as FDA pregnancy risk category C.
NURSING MOTHERS: It is not known if Avandamet is excreted in breast milk. Due to the lack of safety data, Avandamet is not recommended for use in nursing mothers.
REFERENCE: FDA Prescribing Information
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