[Adverse effects of interactions of antibiotics with other drugs].

Many drugs used in combination with antibiotics may show different interactions of clinical significance (for instance: an increase of toxicity of the drugs used). It is important especially among patients treated concurrently with antibiotics and other drugs in high doses for a long time. The most significant clinically are pharmacokinetic interactions of antibiotics that are inhibitors of microsomal enzymes (makrolide or quinolones antibiotics, metronidazole or imidazole antifungal agents). Clinical caution is indicated when these antibiotics are combined with drugs that have a narrow therapeutic index such as warfarin, theophylline, phenytoin or digitalis glicosides. Moreover toxic reactions may be observed among patients receiving simultaneously antibiotics and the agents blocking neuromuscular transmission, oral hypoglycaemics, loop diuretics or digoxin. Some antibiotics (rifampicin, ampicillin, tetracyclines, griseofulvin) may decrease the efficacy of hormonal oral contraceptives.