Tolbutamide Irbesartan

SULPHONYLUREAS -TOLBUTAMIDE ANGIOTENSIN II RECEPTOR ANTAGONISTS-IRBESARTAN Possible t hypotensive effect of irbesartan Tolbutamide competitively inhibits CYP2C9-mediated metabolism of irbesartan Monitor BP at least weekly until stable. Warn patients to report symptoms of hypotension (light-headedness, dizziness on standing, etc.)... 

Acenocoumarol, amiodarone, celecoxib, coumadin, dexamethasone, diclofenac, etoposide, fluconazole, fluoxetine, fluvas-tatin, fluvoxamine, ghmepiride, ghpizide, glyburide, ibuprofen, irbesartan, isoniazid, losartan, midazolam, phenylbutazone, phenytoin, rifampin, teniposide, tenoxicam, thiotepa, tolbutamide, torsemide, vitamin D, warfarin... 

In vitro studies show significant inhibition of the formation of oxidized irbesartan metabolites with the known cytochrome CYP2C9 substrates/inhibitors, tolbutamide, and nifedipine. However, clinical consequences were negligible. 

Angiotensin blockers not Irbesartan Losartan Candesartan not Valsartan Celecoxib Flnvastatin Naproxen Phenytoin Sulfamethoxazole Tamoxifen Tolbutamide Torsemide Warfarin... 

Examples of therapeutic compounds metabolized by CYP2C9 include nonsteroidal antiinflammatory (NSAID) medications, irbesartan, naproxen, and fluvastatin (see Table 43-3). Proposed dose adjustments based on phenotype have been published for CYP2C9 drug substrates such as warfarin, glipizide, tolbutamide, and phenytoin. ... 

Glibenclamide (glyburide) causes a small reduction in valsartan plasma levels, but this is unlikely to be of any clinical significance. No clinically relevant pharmacokinetic interaction occurs between glibenclamide and candesartan or tehnisartan, or between tolbutamide and irbesartan. Eprosartan does not alter the efficacy of glibenclamide. Losartan and possibly eprosartan may reduce awareness of hypoglycaemic symptoms. 

A study in 18 healthy subjects given irbesartan 300 mg daily and tolbutamide 1 g daily, either alone or in eombination, found that no elinieally important pharmacokinetie interaetions oceurred. ... 

No special precautions would appear to be needed if eandesartan, eprosartan, telmisartan or valsartan are given with glibenelamide, or if irbesartan is given with tolbutamide. However, symptoms of hypoglyeaemia may be reduced by losartan and possibly other angiotensin II reeeptor antagonists. Further clinical study is needed, but note that this is similar to the effeet of ACE inhibitors , (p.471). 

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