Ketoconazole Efavirenz

Drugs that may be affected by nevirapine include rifamycins, clarithromycin, oral contraceptives, efavirenz, ketoconazole, methadone, protease inhibitors, warfarin, zidovudine. 

Drugs that may affect atazanavir include the following antacids and buffered medications, clarithromycin, didanosine (buffered formulation only), efavirenz, H2-receptor antagonists, indinavir, itraconazole, ketoconazole, nevirapine, proton pump inhibitors, rifampin, ritonavir, St. John s wort, tenofovir, voriconazole. 

St. John s wort, rifamycins, and ritonavir. Drugs that may be affected by efavirenz include phenytoin, phenobarbital, carbamazepine, itraconazole, ketoconazole, methadone, ritonavir, amprenavir, benzodiazepines, clarithromycin, ethinyl estradiol, indinavir, nelfinavir, saquinavir, and warfarin. 

Others Acetaminophen, amiodarone, carbamazepine, delavirdine, efavirenz, nevirapine, quinidine, repaglinide, sildenafil, tadalafil, trazodone, vardenafil Amiodarone, amprenavir, atazanavir, ciprofloxacin, cisapride, clarithromycin, diltiozem, erythromycin, fluconazole, fluvoxamine, grapefruit juice (in high ingestion), indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, norfloxacin, ritonavir, telithromycin, troleandomycin, verapamil, voriconazole Carbamazepine, efavirenz, glucocorticoids, macrolide antibiotics, nevirapine, phenytoin, phenobarbital, rifabutin, rifapentine, rifampin, St. John s wort... 

Nevirapine is a moderate inducer of CYP3A metabolism, resulting in decreased levels of amprenavir, indinavir, lopinavir, saquinavir, efavirenz, and methadone (Table 49-4). Drugs that induce the CYP3A system, such as tipranavir, rifampin, rifabutin, and St. John s wort, can decrease levels of nevirapine, whereas those that inhibit CYP3A activity, such as fluconazole, ketoconazole, and clarithromycin, can increase nevirapine levels. 

Since indinavir is a substrate as well as an inhibitor of CYP3 A4, numerous and complex drug interactions can occur as described above. Indinavir levels decrease with concurrent use of rifabutin, fluconazole, St. John s wort, and rifampin. Caution is advised with other 3 A4 inducers also, including phenobarbital, phenytoin, carbamezepine, and dexamethasone. Dose reduction of indinavir should be considered if coadministered with delavirdine, ketoconazole, or itraconazole, while an increase in the dose of indinavir is indicated if the drug is coadministered with efavirenz or rifabutin. 

IFOSFAMIDE 1. ANTIBIOTICS -clarithromycin, erythromycin 2. ANTIFUNGALS -fluconazole, itraconazole, ketoconazole voriconazole 3. ANTIVIRALS-efavirenz, ritonavir 4. GRAPEFRUIT JUICE 5. H2 RECEPTOR BLOCKERS - cimetidine 1 plasma concentrations of 4-hydroxyifbsfamide, the active metabolite of ifosfamide, and risk of inadequate therapeutic response Due to inhibition of the isoenzymatic conversion to active metabolites Monitor the efficacy of ifosfamide clinically and t dose accordingly... 

Clinically important, potentially hazardous interactions with alcohol, aprepitant, clarithromycin, CNS depressants, delavirdine, digoxin, efavirenz, fluconazole, fluoxetine, fluvoxamine, grapefruit juice, indinavir, itraconazole, ivermectin, kava, ketoconazole, propoxyphene, ritonavir, saquinavir, St John s wort... 

Clinically important, potentially hazardous interactions with chlorpheniramine, clarithromycin, efavirenz, esomeprazole, imatinib, indinavir, ketoconazole, nelfinavir, nilutamide, ritonavir... 

Clinically important, potentially hazardous interactions with atazanavir, clarithromycin, darunavir, delavirdine, efavirenz, erythromycin, fosamprenavir, indinavir, itraconazole, ketoconazole, rifampin, ritonavir, telithromycin, tipranavir... 

IRINOTECAN 1. ANTIBIOTICS-clarithromycin, erythromycin 2. ANTICANCER AND IMMUNOMODULATING DRUGS - imatinib 3. ANTIFUNGALS -fluconazole, itraconazole, ketoconazole, voriconazole 4. ANTIVIRALS-efavirenz, ritonavir 5. GRAPEFRUIT JUICE 6. H2 RECEPTOR BLOCKERS - cimetidine t plasma concentrations of SN-38 (t AUC by 100%) and t toxicity of irinotecan, e.g. diarrhoea, acute cholinergic syndrome, interstitial pulmonary disease Due to inhibition of the metabolism of irinotecan by CYP3A4 isoenzymes by ketoconazole Peripheral blood counts should be checked before each course of treatment. Monitor lung function. Recommendation is to -L dose of irinotecan by 25%... 

Nevirapine markedly reduces the AUC of ketoconazole. In theory, efavirenz may interact similarly, whereas delavirdine may increase ketoconazole levels. The NNRTI plasma levels may be raised by ketoconazole. 

Ketoconazole is likely to inhibit the metabolism of the NNRTIs by the cytochrome P450 isoenzyme CYP3A4. Nevirapine induces the metabolism of ketoconazole by CYP3A4, and, in theory, efavirenz is likely to interact similarly, whereas delavirdine is likely to inhibit ketoconazole metabolism by CYP3A4 (see Table 21.2 , (p.773)). 

The manufacturer of nevirapine states that ketoconazole and nevirapine should not be used together, because of the likely reduced efficacy of ke-toconazole. Efavirenz might be expected to interact similarly although the manufacturer of efavirenz says that the potential for an interaction has not been studied. NNRTI levels might be raised by ketoconazole, which might increase adverse effects. Cautious monitoring of efficacy and adverse effects would be prudent if concurrent use is necessary. 

Drug-drug interactions Maraviroc is a substrate of P glycoprotein and CYP3A4, by which it is about 65% metabolized. Maraviroc should therefore be used with caution when inhibitors of CYP3A4 are used concomitantly. Potent CYP 3A4 inhibitors, such as ketoconazole and protease inhibitors, except tipranavir + ritonavir, increase maraviroc exposure dosage reduction can compensate [246 ]. Conversely, enzyme inducers, such as rifampicin and efavirenz, reduce exposure [247 ]. In contrast, drugs... 

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