If glimepiride is taken simultaneously with certain other medicinal products, both undesired increases and decreases in the hypoglycaemic action of glimepiride can occur. For this reason, other medicinal products should only be taken with the knowledge (or at the prescription) of the doctor. Glimepiride is metabolized by cytochrome P450 2C9 (CYP2C9). Its metabolism is known to be influenced by concomitant administration of CYP2C9 inducers (e.g. rifampicin) or inhibitors (e.g. fluconazole). Results from an in vivo interaction study reported in literature show that glimepiride AUC is increased approximately 2-fold by fluconazole, one of the most potent CYP2C9 inhibitors. Based on the experience with glimepiride and with other sulfonylureas the following interactions have to be mentioned.
Potentiation of the blood-glucose-lowering effect and thus in some instances hypoglycaemia may occur when one of the following medicinal products is taken, for example: Phenylbutazone, azapropazone and oxyfenbutazone; Insulin and oral antidiabetic products such as metformin; Salicylates and p-amino-salicylic acid; Anabolic steroids and male sex hormones; Chloramphenicol, certain long acting sulfonamides, tetracyclines, quinolone antibiotics and clarithromycin; Coumarin anticoagulants; Fenfluramine; Fibrates; ACE inhibitors; Fluoxetine, MAO-inhibitors; Allopurinol, probenecid, sulfinpyrazone; Sympatholytics; Cyclophosphamide, trophosphamide and iphosphamides; Miconazole, fluconazole; Pentoxifylline (high dose parenteral); Tritoqualine.
Weakening of the blood-glucose-lowering effect and thus raised blood glucose levels may occur when one of the following medicinal products is taken, for example: Oestrogens and progestogens; Saluretics, thiazide diuretics; Thyroid stimulating agents, glucocorticoids; Phenothiazine derivatives, chlorpromazine; Adrenaline and sympathicomimetics; Nicotinic acid (high dosages) and nicotinic acid derivatives; Laxatives (long term use); Phenytoin, diazoxide; Glucagon, barbiturates and rifampicin; Acetazolamide.
H2 antagonists, betablockers, clonidine and reserpine may lead to either potentiation or weakening of the blood glucose lowering effect. Under the influence of sympatholytic medicinal products such as betablockers, clonidine, guanethidine and reserpine, the signs of adrenergic counterregulation to hypoglycaemia may be reduced or absent. Alcohol intake may potentiate or weaken the hypoglycaemic action of glimepiride in an unpredictable fashion. Glimepiride may either potentiate or weaken the effects of coumarin derivatives.