Ricovir Drug Interactions

Interaction studies have only been performed in adults.
Based on the results of in vitro experiments and the known elimination pathway of tenofovir, the potential for CYP450 mediated interactions involving tenofovir with other medicinal products is low.
Tenofovir is excreted renally, both by filtration and active secretion via the anionic transporter (hOAT1). Co-administration of tenofovir disoproxil fumarate with other medicinal products that are also actively secreted via the anionic transporter (e.g. cidofovir) may result in increased concentrations of tenofovir or of the co-administered medicinal product.
Concomitant antiretroviral medicinal products: Emtricitabine, lamivudine, indinavir, efavirenz, nelfinavir, and saquinavir (ritonavir boosted): co-administration with tenofovir disoproxil fumarate did not result in any clinically relevant interaction.
When tenofovir disoproxil fumarate was administered with lopinavir/ritonavir, no changes were observed in the pharmacokinetics of lopinavir and ritonavir. Tenofovir AUC was increased by approximately 30% when tenofovir disoproxil fumarate was administered with lopinavir/ritonavir. Higher tenofovir concentrations could potentiate tenofovir associated adverse events, including renal disorders.
When didanosine gastro-resistant capsules were administered 2 hours prior to or concurrently with tenofovir disoproxil fumarate, the AUC for didanosine was on average increased by 48% and 60% respectively. The mean increase in the AUC of didanosine was 44% when the buffered tablets were administered 1 hour prior to tenofovir. In both cases the pharmacokinetic parameters for tenofovir administered with a light meal were unchanged. The co-administration of tenofovir disoproxil fumarate and didanosine is not recommended.
When tenofovir disoproxil fumarate was administered with atazanavir, a decrease in concentrations of atazanavir was observed (decrease of 25% and 40% of AUC and C_min respectively compared to atazanavir 400 mg). When ritonavir was added to atazanavir, the negative impact of tenofovir on atazanavir C_min was significantly reduced, whereas the decrease of AUC was of the same magnitude (decrease of 25% and 26% of AUC and C_min respectively compared to atazanavir/ritonavir 300/100 mg). The co-administration of atazanavir/ritonavir with tenofovir resulted in increased exposure to tenofovir. Higher tenofovir concentrations could potentiate tenofovir-associated adverse events, including renal disorders. The co-administration of atazanavir with ritonavir in combination with tenofovir has been substantiated in a clinical study.
Other interactions: Co-administration of tenofovir disoproxil fumarate, methadone, ribavirin, adefovir dipivoxil or the hormonal contraceptive norgestimate/ethinyl oestradiol did not result in any pharmacokinetic interaction.
Tenofovir disoproxil fumarate must be taken with food, as food enhances the bioavailability of tenofovir.