Contraindicated the simultaneous use of clarithromycin with cisapride, pimozide, terfenadine, astemizole, as this leads to an increase in the concentration of these drugs in blood plasma by 2-3 times, which can cause lengthening of the interval QT, disturbance of the rhythm of the heart, including ventricular tachycardia, ventricular fibrillation.
At simultaneous reception clarithromycin increases the concentration in the blood of drugs metabolized in the liver with the help of cytochrome P450 enzymes: indirect anticoagulants, carbamazepine, theophylline, triazolam, midazolam, cyclosporine, vinblastine, disopyramide, phenytoin, rifabutin, simvastatin,lovastatin, digoxin, alprazolam, valproic acid, cilostazol, methylprednisolone, omeprazole, quinidine, ergot alkaloids, sildenafil, tacrolimus.
At simultaneous reception of clarithromycin and zidovudine in HIV-infected patients there was a decrease in the value of the equilibrium concentration of zidovudine (between the use of drugs, an interval of at least 4 hours is required).
With the simultaneous use of ritonavir (200 mg every 8 hours) and clarithromycin (500 mg every 12 hours), the metabolism of clarithromycin slows down (Cmax clarithromycin increased by 31%, Cmin - by 182%, AUC - on77%). There was a significant delay in the formation of 14-hydroxyclarithromycin. When taking ritonavir, do not simultaneously prescribe clarithromycin in a dose of more than 1 g per day. In this case, in patients without renal dysfunction, there is no need to correct the dose of clarithromycin. This is of great importance in the case of using this combination in patients with impaired renal function: for patients with creatinine clearance from 30 to 60 ml / min, the dose of clarithromycin is reduced by 50% (up to 500 mg once a day).
It is possible to develop cross-resistance between clarithromycin, lincomycin and clindamycin.