Antacids: The effects of simultaneous administration of antacid with azithromycin no effect on overall bioavailability.
Cetirizine: No pharmacokinetic interaction and no significant changes in the QT Interval.
Didanosine (Dideoxyinosine): No pharmacokinetic interaction.
Digoxin: Some of the macrolide antibiotics have been reported to impair the microbial metabolism of digoxin in the gut in some patients.
In patients receiving concomitant azithromycin, a related azalide antibiotic, and digoxin the possibility of raised digoxin levels should be borne in mind.
Zidovudine: Single 1000 mg doses and multiple 1200 mg or 600 mg doses of azithromycin had little effect on the plasma pharmacokinetics or urinary excretion of zidovudine or its glucuronide metabolite.
Ergot: Due to the theoretical possibility of ergotism, the concurrent use of azithromycin with ergot derivatives is not recommended.
Pharmacokinetic between azithromycin and the following drugs known to undergo significant cytochrome P450 mediated metabolism: Atorvastatin: Coadministration of atorvastatin (10 mg daily) and azithromycin (500 mg daily) did not alter the plasma concentrations of atorvastatin.
Carbamazepine: No significant effect was observed on the plasma levels of carbamazepine or its active metabolite in subject receiving concomitant azithromycin.
Cimetidine: The effects of a single dose of cimetidine, given 2 hours before azithromycin, on the pharmacokinetics of azithromycin, no alteration of azithromycin pharmacokinetics was seen.
Coumarin-Type Oral Anticoagulants: Azithromycin did not alter the anticoagulant effect of a single 15-mg dose of warfarin. There have been post-marketing reports of potentiated anticoagulation subsequent to coadministration of azithromycin and coumarin-type oral anticoagulants. Prothrombin time should be carefully monitored when azithromycin is used in patients receiving coumarin-type oral anticoagulants.
Cyclosporin: Consequently, caution should be exercised before considering concurrent administration of these drugs. If coadministration of these drugs is necessary, cyclosporin levels should be monitored and the dose adjusted accordingly.
Efavirenz: No pharmacokinetic interaction.
Fluconazole: No pharmacokinetic interaction.
Indinavir: No pharmacokinetic interaction.
Methylprednisolone: No pharmacokinetic interaction.
Midazolam: No pharmacokinetic interaction.
Nelfinavir: No pharmacokinetic interaction.
Rifabutin: Coadministration of azithromycin and rifabutin did not affect the serum concentrations of either drug. Neutropenia was observed in subjects receiving concomitant treatment of azithromycin and rifabutin. Although neutropenia has been associated with the use of rifabutin, a causal relationship to combination with azithromycin has not been established.
Sildenafil: There was no evidence of an effect of azithromycin (500 mg daily for 3 days) on the AUC and Cmax of sildenafil or its major circulating metabolite.
Terfenadine: There have been rare cases reported where the possibility of such an interaction when azithromycin and terfenadine are coadministered.
Theophylline: No significant effect on any of the pharmacokinetic interaction when azithromycin and theophylline are coadministered.
Triazolam: No significant effect on any of the pharmacokinetic interaction when azithromycin and triazolam are coadministered.
Trimethoprim/sulfamethoxazole: Co-administration of trimethoprim/sulfamethoxazole DS (160 mg/800 mg) for 7 days with azithromycin 1200 mg on the Day 7 had no significant effect on peak concentration, total exposure to urinary excretion of either trimethoprim or sulfamethoxazole.