Amprenavir/fosamprenavir atazanavir, interaction

Clinically important, potentially hazardous interactions with amprenavir, aprepitant, atazanavir, carbamazepine, chlorpheniramine, cimetidine, clarithromycin, clorazepate, CNS depressants, darunavir, delavirdine, dexamethasone, efavirenz, erythromycin, esomeprazole, fluconazole, fluoxetine, fosamprenavir, grapefruit juice, griseofulvin, imatinib, indinavir, itraconazole, ivermectin, ketoconazole, lopinavir, nelfinavir, nevirapine, phenobarbital, phenytoin, primidone, rifabutin, rifampin, ritonavir, roxithromycin, saquinavir, St John s wort, telithromycin, tipranavir... 

Amprenavir and atazanavir, given alone increase the levels of ethinylestradiol and norethisterone. Ritonavir and nelfinavir, in contrast to the effect that would normally be expected decrease the levels of ethinylestradiol. Reduced ethinylestradiol and norethisterone levels occur with fosamprenavir, lopinavir and ti-pranavir given with ritonavir. Indinavir does not appear to interact. 

Although information is limited, the pharmacokinetic interaction between the ethinylestradiol component of combined hormonal contraceptives and nelfinavir or ritonavir appears to be established and is likely to be clinically important. Similar decreases in plasma levels of ethinylestradiol caused by other drugs have resulted in reduced efficacy and reliability of combined oral contraceptives, and one retrospective report suggests that this has occurred with nelfinavir. It seem likely that the reduced contraceptive levels seen with fosamprenavir, lopinavir and tipranavir were due to the concurrent use of ritonavir (as would be common in practice). Similarly, although no interaction was reported with saquinavir, and raised contraceptive steroid levels were reported with amprenavir and atazanavir, in practice these drugs would be given with ritonavir (as a pharmacokinetic enhancer), and so the levels of combined hormonal contraceptives can reasonably be expected to be reduced. The Faculty ofFamily Planning... 

Clinically important, potentially hazardous interactions with amisulpride, amprenavir, atazanavir, celiprolol, ciprofloxacin, enoxacin, epirubicin, fosamprenavir, gatifloxacin, lomefloxacin, lopinavir, mistletoe, moxifloxacin, nilotinib, norfloxacin, ofloxacin, quinolones, ritonavir, sparfloxacin, tipranavir... 

Clinically important, potentially hazardous interactions with amiodarone, amprenavir, anisindione, antacids, anticoagulants, aprepitant, atazanavir, atovaquone, beclomethasone, buprenorphine, corticosteroids, cortisone, cyclosporine, cyproterone, dabigatran, dapsone, darunavir, delavirdine, dexamethasone, dicumarol, digoxin, eszopiclone, flunisolide, fosamprenavir, gadoxetate, gestrinone, halothane, imatinib, isoniazid, itraconazole, ketoconazole, lapatinib, lorcainide, methylprednisolone, midazolam, nelfinavir, nifedipine, oral contraceptives, phenylbutazone, prednisone, protease inhibitors, pyrazinamide, ramelteon, ritonavir, saquinavir, solifenacin, sunitinib, tacrolimus, telithromycin, temsirolimus, tipranavir, tolvaptan, trabectedin, triamcinolone, triazolam, voriconazole, warfarin, zaleplon... 

Clinically important, potentially hazardous interactions with amprenavir, amyl nitrite, atazanavir, delavirdine, erythromycin, fosamprenavir, indinavir, isosorbide dinitrate, isosorbide mononitrate, itraconazole, ketoconazole, nelfinavir, nitrates, nitroglycerin, ritonavir, saquinavir... 

The decrease in atazanavir levels with tenofovir is not of clinical importance if ritonavir is also used, and this combination has been used successfully as part of antiretroviral therapy in clinical studies. Unboosted atazanavir should be used with caution or not given with tenofovir because of the potential for reduced etficacy and development of resistance. Ritonavir-boosted darunavir and lopinavir levels were not significantly affected by tenofovir, amprenavir levels were also unaffected following boosted fosamprenavir administration, and the increase in ritonavir-boosted saquinavir levels are not likely to be clinically relevant. The slight interaction between tenofovir and tipranavir/ritonavir is unlikely to be clinically relevant. There is no clinically relevant interaction between nelfinavir or indinavir and tenofovir. 

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