Ribavirin Tenofovir

Didanosine (ddl) NRTT1 Tablets, 400 mg daily,3 adjusted for weight. 30 min before or 2 h after meals. Separate dosing from fluoroquinolones and tetracyclines by 2 h Peripheral neuropathy, pancreatitis, diarrhea, nausea, hyperuricemia. Possible increase in myocardial infarction Avoid concurrent neuropathic drugs (eg, stavudine, zalcitabine, isoniazid), ribavirin, and alcohol. Do not administer with tenofovir... 

Allopurinol increases didanosine plasma concentrations and their coadministration is not recommended. Ganciclovir, tenofovir and disoproxil also increase didanosine plasma concentrations, and dose reduction is recommended. Conversely, methadone decreases didanosine plasma concentrations, and appropriate doses for the combination have not been established. Didanosine should not be administered with drugs that cause pancreatic or neurotoxicity. Ribavirin increases its risk of toxicity and should not be coadministered. 

Tenofovir absorption is increased by high-fat food. Caution is recommended with drugs causing renal toxicity. Tenofovir did not alter the pharmacokinetics of ribavirin, and there was no clinically significant pharmacokinetic interaction with rifampicin (rifampin). 

Tenofovir disoproxil fumarate 300 mg daily did not alter the pharmacokinetics of a single 600-mg dose of ribavirin in 22 subjects, and the pharmacokinetics of tenofovir did not appear to be changed by ribavirin when compared with historical data. Note that, there is evidence that HIV-pos-itive patients co-infected with hepatitis C and treated with interferon alfa and ribavirin may be at increased risk of lactic acidosis and hepatic decompensation when receiving any NRTF, (p.805), including tenofovir, and increased monitoring is recommended. ... 

Ramanathan S, Chei A, Mittan A, Ebmhimi R, Kearney BP. Absence of clinically relevant pharmacokinetic intemction between ribavirin and tenofovir in healthy subjects. J Clin Pharmacol (2006) 46, 559-66. 

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