Rifabutin Didanosine

Rifabutin 300 to 600 mg daily for 12 days did not significantly affect the pharmacokinetics of [buffered] didanosine 167 to 250 mg twice daily in 12 patients with AIDS. The steady-state pharmacokinetics of rifabutin were not affected by didanosine (buffered sachet preparation), which suggests that the buffer used in the didanosine preparation had no effect on rifabutin absorption. However, a case has been reported of a patient taking lopinavir/ritonavir, efavirenz, lamivudine and buffered didanosine who had impaired rifabutin absorption. When rifabutin was taken 30 minutes after didanosine, rifabutin levels were undetectable, but when rifabutin was taken 3 hours after didanosine, rifabutin levels were apparent. ... 

Drugs that may affect nelfinavir include anticonvulsants, azithromycin, azole antifungals, efavirenz, delavirdine, HMG-CoA reductase inhibitors, indinavir, interleukins, nevirapine, rifabutin, rifampin, ritonavir, saquinavir, St. John s wort. Drugs that may be affected by nelfinavir include amiodarone, antiarrhythmics (amiodarone, quinidine), azithromycin, benzodiazepines, efavirenz, ergot alkaloids, delavirdine, didanosine, fentanyl, indinavir, lamivudine methadone, nonsedating antihistamines, oral contraceptives, phenytoin, pimozide, quinidine, rifabutin, saquinavir, sildenafil, sirolimus, tacrolimus, zidovudine. 

Deravirdine (Rescnptor) [Antiretroviral/NNRTI] Uses HIV Infxn Action Nonnucleoside RT inhibitor Dose 400 mg PO tid Caution [C, ] CDC recommends HIV-infected mothers not to breast-feed (transmission risk) w/ renal/hepatic impair Contra Use w/ drugs dependent on CYP3A for clearance (Table VI-8) Disp Tabs SE Fat redistribution, immune reconstitution synd, HA, fatigue, rash, T transaminases, N/V/D Interactions T Effects W/ fluoxetine T effects OF benzodiazepines, cisapride, clarithromycin, dapsone, ergotamine, indinavir, lovastatin, midazolam, nifedipine, quinidine, ritonavir, simvastatin, terfena-dine, triazolam, warfarin effects W/ antacids, barbiturates, carbamazepine, cimetidine, famotidine, lansoprazole, nizatidine, phenobarbital, phenytoin, ranitidine, rifabutin, rifampin effects OF didanosine EMS Use of benzodiazepines and CCBs should be avoided may cause a widespread rash located on upper body and arms OD May cause an extension of nl SEs symptomatic and supportive Deferasirox (Exjade) [Iron Chelator] Uses Chronic iron overload d/t transfusion in pts >2 y Action Oral iron chelator Dose Initial 20 mg/kg... 

Lopinavir/Ritonavir (Kaletra) [Anrirelroviral/Protease Inhibitor] Uses HIV Infxn Action Protease inhibitor Dose Adults. Tx naive 2 tab PO daily or 1 tab PO bid Tx experiencedpt 1 tab PO bid (T dose if w/ amprenavir, efavirenz, fosamprenavir, nelfinavir, nevirapine) Peds. 7-15 kg 12/3 mg/kg PO bid 15-40 kg 10/2.5 mg/kg PO bid >40 kg Adult dose w/ food Caution [C, /-] Numerous interactions Contra w/drugs dependent on CYP3A/CYP2D6 (Table VI-8) Disp Tab, soln SE Avoid disulfiram (soln has EtOH), metronidazole GI upset, asthenia, T cholesterol/triglycerides, pancreatitis protease metabolic synd Interactions T Effects Wl clarithromycin, erythromycin T effects OF amiodarone, amprenavir, azole andfungals, bepridil, cisapride, cyclosporine, CCBs, ergot alkaloids, flecainide, flurazepam, HMG-CoA reductase inhibitors, indinavir, lidocaine, meperidine, midazolam, pimozide, propafenone, propoxyphene, quinidine, rifabutin, saquinavir, sildenafil, tacrolimus, terfenadine, triazolam, zolpidem 1 effects Wl barbiturates, carbamazepine, dexamethasone, didanosine, efavirenz, nevirapine, phenytoin, rifabutin, rifampin, St. John s wort 1 effects OF OCPs, warfarin EMS Use andarrhythmics and benzodiazepines... 

T effects OF amiodarone, astemizole, atorvastadn, barbiturates, bepridil, bupropion, cerivastatin, cisapride, clorazepate, clozapine, clarithromycin, desipramine, diazepam, encainide, ergot alkaloids, estazolam, flecainide, flurazepam, indinavir, ketoconazole, lovastatin, meperidine, midazolam, nelfinavir, phenytoin, pimozide, piroxicam, propafenone, propoxyphene, quinidine, rifabutin, saquinavir, sildenafil, simvastatin, SSRIs, TCAs, terfenadine, triazolam, troleandomycin, zolpidem X effects W/ barbiturates, carbamazepine, phenytoin, rifabutin, rifampin, St. John s wort, tobacco X effects OF didanosine, hypnotics, methadone, OCPs, sedatives, theophylline, warfarin EMS T Effects of amiodarone, diazepam, midazolam and BBs, may need X- doses concurrent use of Viagra-type drugs can lead to hypotension X- effects of warfarin concurrent EtOH use can T adverse effects T glucose ODs May cause an extension of adverse SEs symptomatic and supportive Rivasrigmine (Exelon) [Cholinesterase Inhibitor/Anri ... 

Abacavir Adinazolam 5-Aminosalicylic acid Atorvastatin Avitriptan Bromazepam Bumetanide Celecoxib CGP 43371 Clodronate Cyclosporin Danazol Didanosine Erythromycin Fexofenadine Furosemide Ganciclovir Halofantrine Inidnavir Itraconazole Levofloxacin Methotrexate Nifedipine Pravastatin Rifabutin Stavudine Tacrine... 

Clinically important, potentially hazardous interactions with chloroquine, didanosine, furazolidone, ganciclovir, hydroxychloroquine, methotrexate, pyrimethamine, rifabutin, rifampin, sulfonamides, ursodeoxycholic acid... 

Didanosine, stavudine and zalcitabine are not expected to interact with rifabutin, but rifabutin may modestly increase the clearance of zidovudine. An isolated case describes undetectable rifabutin levels in a patient taking antiretrovirals including buffered didanosine. 

The controlled study suggests that no special precautions are necessary if both drugs are given. However, the case report introduces an element of caution, especially if other drugs that may affect rifabutin pharmacokinetics are used. If indeed rifabutin absorption is affected by antacids (there appear to be no clinical data on this), then giving the drugs at least 2 hours apart, or using the enteric-coated didanosine preparation should avoid the interaction. ... 

Sahai J, Foss N, Li R, Narang PK, Cameron DW. Rifabutin and didanosine interaction in AIDS patients. Clin Pharmacol Ther (1993) 53, 197. 

Li RC, Narang PK, Sahai J, Cameron W, Bianchine JR. Rifabutin absorption in the gut unal tered by concomitant administtation of didanosine in AIDS patients. Antimicrob Agents Chemother( 991)4, 156 70. 

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