There were no clinically significant pharmacokinetic interactions when tenofovir disoproxil fumarate was coadministered with ribavirin.
Viread Summary of Product Characteristics, Gilead Sciences Ltd, September 2016.

No clinically significant drug interactions have been observed between tenofovir-DF and ribavirin.
Viread Prescribing Information, Gilead Sciences International Inc, February 2016.

The effects of multiple doses of tenofovir (300 mg once daily) on a single dose of ribavirin (600 mg) were evaluated in 22 HIV-negative subjects. Pharmacokinetics of ribavirin were not affected by tenofovir with 90% CI for Cmax (0.89 to 1.01) and AUC (1.06 to 1.17 lying within the equivalence bounds (0.80 to 1.25). Tenofovir pharmacokinetics after ribavirin coadministration were similar to those observed in previous studies.
Absence of clinically relevant pharmacokinetic interaction between ribavirin and tenofovir in healthy subjects. Ramanathan S, et al. J Clin Pharmacol, 2006, 46:559-566.

The pharmacokinetics of ribavirin were evaluated in 22 subjects following administration of single doses of ribavirin alone and with multiple doses of tenofovir. Ribavirin exposure met the definition of pharmacokinetic equivalence (90% CI for the geometric mean ratio of 80% to 125%) when dosed with or without tenofovir. Mean differences in Cmax and AUC were 12% or less.
Tenofovir pharmacokinetics in hepatic impairment and drug interaction potential with agents used to treat viral hepatitis. Kearney BP, et al. 11th Conference on Retroviruses and Opportunistic Infections, San Francisco, February 2004, abstract 600.