Azithromycin (Page 3 of 14)
Drug-Drug Interactions
Drug interaction studies were performed with azithromycin and other drugs likely to be coadministered. The effects of coadministration of azithromycin on the pharmacokinetics of other drugs are shown in Table 1 and the effect of other drugs on the pharmacokinetics of azithromycin are shown in Table 2.
Coadministration of azithromycin at therapeutic doses had a modest effect on the pharmacokinetics of the drugs listed in Table 1. No dosage adjustment of drugs listed in Table 1 is recommended when coadministered with azithromycin.
Coadministration of azithromycin with efavirenz or fluconazole had a modest effect on the pharmacokinetics of azithromycin. Nelfinavir significantly increased the Cmax and AUC of azithromycin. No dosage adjustment of azithromycin is recommended when administered with drugs listed in Table 2 (see PRECAUTIONS , Drug Interactions).
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Coadministered Drug | Dose of Coadministered Drug | Dose of Azithromycin | n | Ratio (With/Without Azithromycin) of Coadministered Drug Pharmacokinetic Parameters (90% CI); No Effect = 1 | |
Mean Cmax | Mean AUC | ||||
Atorvastatin | 10 mg/day x 8 days | 500 mg/day PO on days 6 to 8 | 12 | 0.83 (0.63 to 1.08) | 1.01 (0.81 to 1.25) |
Carbamazepine | 200 mg/day x 2 days, then 200 mg BID x 18 days | 500 mg/day PO for days 16 to 18 | 7 | 0.97 (0.88 to 1.06) | 0.96 (0.88 to 1.06) |
Cetirizine | 20 mg/day x 11 days | 500 mg PO on day 7, then 250 mg/day on days 8 to 11 | 14 | 1.03 (0.93 to 1.14) | 1.02 (0.92 to 1.13) |
Didanosine | 200 mg PO BID x 21 days | 1,200 mg/day PO on days 8 to 21 | 6 | 1.44 (0.85 to 2.43) | 1.14 (0.83 to 1.57) |
Efavirenz | 400 mg/day x 7 days | 600 mg PO on day 7 | 14 | 1.04* | 0.95* |
Fluconazole | 200 mg PO single dose | 1,200 mg PO single dose | 18 | 1.04 (0.98 to 1.11) | 1.01 (0.97 to 1.05) |
Indinavir | 800 mg TID x 5 days | 1,200 mg PO on day 5 | 18 | 0.96 (0.86 to 1.08) | 0.90 (0.81 to 1) |
Midazolam | 15 mg PO on day 3 | 500 mg/day PO x 3 days | 12 | 1.27 (0.89 to 1.81) | 1.26 (1.01 to 1.56) |
Nelfinavir | 750 mg TID x 11 days | 1,200 mg PO on day 9 | 14 | 0.9 (0.81 to 1.01) | 0.85 (0.78 to 0.93) |
Rifabutin | 300 mg/day x 10 days | 500 mg PO on day 1, then 250 mg/day on days 2 to 10 | 6 | See footnote below | NA |
Sildenafil | 100 mg on days 1 and 4 | 500 mg/day PO x 3 days | 12 | 1.16 (0.86 to 1.57) | 0.92 (0.75 to 1.12) |
Theophylline | 4 mg/kg IV on days 1, 11, 25 | 500 mg PO on day 7, 250 mg/day on days 8 to 11 | 10 | 1.19 (1.02 to 1.4) | 1.02 (0.86 to 1.22) |
Theophylline | 300 mg PO BID x 15 days | 500 mg PO on day 6, then 250 mg/day on days 7 to 10 | 8 | 1.09 (0.92 to 1.29) | 1.08 (0.89 to 1.31) |
Triazolam | 0.125 mg on day 2 | 500 mg PO on day 1, then 250 mg/day on day 2 | 12 | 1.06* | 1.02* |
Trimethoprim/ Sulfamethoxazole | 160 mg/800 mg/day PO x 7 days | 1,200 mg PO on day 7 | 12 | 0.85 (0.75 to 0.97)/0.9 (0.78 to 1.03) | 0.87 (0.8 to 0.95)/0.96 (0.88 to 1.03) |
Zidovudine | 500 mg/day PO x 21 days | 600 mg/day PO x 14 days | 5 | 1.12 (0.42 to 3.02) | 0.94 (0.52 to 1.7) |
Zidovudine | 500 mg/day PO x 21 days | 1,200 mg/day PO x 14 days | 4 | 1.31 (0.43 to 3.97) | 1.30 (0.69 to 2.43) |
NA – Not Available
Mean rifabutin concentrations one-half day after the last dose of rifabutin were 60 ng/mL when coadministered with azithromycin and 71 ng/mL when coadministered with placebo.
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Coadministered Drug | Dose of Coadministered Drug | Dose of Azithromycin | n | Ratio (With/Without Coadministered Drug) of Azithromycin Pharmacokinetic Parameters (90% CI); No Effect = 1 | |
Mean Cmax | Mean AUC | ||||
Efavirenz | 400 mg/day x 7 days | 600 mg PO on day 7 | 14 | 1.22 (1.04 to 1.42) | 0.92* |
Fluconazole | 200 mg PO single dose | 1,200 mg PO single dose | 18 | 0.82 (0.66 to 1.02) | 1.07 (0.94 to 1.22) |
Nelfinavir | 750 mg TID x 11 days | 1,200 mg PO on day 9 | 14 | 2.36 (1.77 to 3.15) | 2.12 (1.8 to 2.5) |
Rifabutin | 300 mg/day x 10 days | 500 mg PO on day 1, then 250 mg/day on days 2 to 10 | 6 | See footnote below | NA |
NA – Not Available
Mean azithromycin concentrations one day after the last dose were 53 ng/mL when coadministered with 300 mg daily rifabutin and 49 ng/mL when coadministered with placebo.
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