Coadministration of Kaletra and tenofovir (300 mg once daily) increased tenofovir AUC and Cmin by 32% and 51% respectively, but had no effect on Cmax. Higher tenofovir concentrations could potentiate tenofovir associated adverse events, including renal disorders. No dose adjustment necessary.
Kaletra Summary of Product Characteristics, AbbVie Ltd, January 2021.

Coadministration of tenofovir (300 mg once daily) and lopinavir/ritonavir (400/100 mg twice daily) to 24 HIV- volunteers resulted in no change in tenofovir Cmax, but increases of 32% and 51% in tenofovir AUC and Cmin respectively. Patients receiving Kaletra and tenofovir should be monitored for adverse reactions associated with tenofovir.
Kaletra Prescribing Information, AbbVie Ltd, October 2020.

When tenofovir disoproxil fumarate (300 mg once daily) was administered with lopinavir/ritonavir (400/100 mg twice daily), there was no significant effect on lopinavir/ritonavir PK parameters. Tenofovir AUC increased by 32%, Cmin increased by 51%, and there was no change in Cmax. No dose adjustment is recommended. The increased exposure of tenofovir could potentiate tenofovir associated adverse events, including renal disorders. A higher risk of renal impairment has been reported in patients receiving tenofovir disoproxil fumarate in combination with a ritonavir or cobicistat boosted protease inhibitor. A close monitoring of renal function is required in these patients. In patients with renal risk factors, the co-administration of tenofovir disoproxil fumarate with a boosted protease inhibitor should be carefully evaluated.
Viread Summary of Product Characteristics, Gilead Sciences Ltd, September 2016.

Coadministration of lopinavir/ritonavir (400/100 mg twice times daily for 14 days) and tenofovir-DF (300 mg once daily) was investigated in 24 healthy volunteers. There was no change in tenofovir Cmax; AUC and Cmin increased by 32% and 51% respectively. There was no change in Cmax, AUC or Cmin for lopinavir or ritonavir. Patients receiving tenofovir-DF concomitantly with lopinavir/ritonavir should be monitored for tenofovir-associated adverse reactions. Tenofovir-DF should be discontinued in patients who develop tenofovir-associated adverse reactions.
Viread Prescribing Information, Gilead Sciences Inc, February 2016.

Plasma concentrations of tenofovir (300 mg once daily) with lopinavir/ritonavir (400/100 mg twice daily, n=14) or nevirapine (400 mg once daily, n=13) were determined in HIV positive patients. Tenofovir AUC, Cmax and Ctrough were 50%, 33% and 72% higher, respectively, in the presence of lopinavir/ritonavir when compared to nevirapine. The authors suggest that observed increase in tenofovir exposure may involve intestinal P-gp inhibition by lopinavir and/or ritonavir.
Pilot pharmacokinetic study of Human Immunodeficiency Virus-infected patients receiving tenofovir disoproxil fumarate (TDF): Investigation of systemic and intracellular interactions between TDF and abacavir, lamivudine, or lopinavir-ritonavir. Pruvost A, Negredo E, Théodoro F, et al. Antimicrob Agents Chemother, 2009, 53(5): 1937-1943.

The pharmacokinetic interaction between tenofovir (300 mg once daily) and lopinavir (400/100 mg twice daily) was determined in 27 HIV-negative subjects. Coadministration of lopinavir/ritonavir increase tenofovir AUC (32%), Cmax (15%) and Cmin (51%). Lopinavir and ritonavir pharmacokinetics were unaffected by tenofovir (n=24). Clinical estimates of renal function were unaffected by administration of tenofovir alone or with lopinavir/ritonavir. The increase in tenofovir exposure is not believed to be clinically relevant based on the safety and efficacy of this combination in HIV-infected patients in long-term controlled clinical trials.
Pharmacokinetics and safety of tenofovir disoproxil fumarate on coadministration with lopinavir/ritonavir. Kearney BP, Mathias A, Mittan A, et al. J Acquir Immune Defic Syndr, 2006, 43: 278-283.

The effect of lopinavir/ritonavir (400/100 mg twice daily) on the renal clearance of tenofovir was investigated in HIV-infected subjects receiving tenofovir (300 mg once daily) alone or in combination with LPV/r. Tenofovir clearance was 16% lower in subjects receiving LPV/r, consistent with a renal interaction between tenofovir and LPV/r. There was no difference in tenofovir-diphosphate concentrations when tenofovir was given alone or in combination.
Effect of lopinavir/ritonavir on the renal clearance of tenofovir in HIV-infected patients. Kiser J, et al. 13th Conference on Opportunistic Infections and Retroviruses, Denver, February 2006, abstract 570.

Significant increases in TDF plasma exposure have been reported when coadministered with Kaletra. This study looked at the interaction at the intracellular level by investigating the effect of LPV/RTV (400/100 once daily) on TDF-DP concentrations in HIV+ patients taking TDF (300 mg once daily). There was a trend to higher TDF-DP concentrations when used in combination with LPV/r. However, due to interpatient variability, this did not reach statistical significance. Mean ± SD TDF-DP concentrations were 181.4 ± 80.1 and 280.3 ± 181.8 fmol/106 cells, alone and in combination with LPV/RTV respectively. Since target concentrations have yet to be defined for TDF-DP, the possible consequences of this increase remain unknown.
Possible interaction between tenofovir and boosted lopinavir; analysis at the intracellular level in HIV infected patients. Benech, H et al. 6th International Workshop on Clinical Pharmacology of HIV Therapy, Quebec, April 2005, abstract 34.

The effect of tenofovir on the pharmacokinetics of lopinavir and ritonavir was investigated in 18 treatment experienced HIV+ patients. Lopinavir concentrations decreased in the presence of tenofovir (Cmin from 4.61 to 3.06 µg/ml; Cmax from 10.68 to 9.65 µg/ml). Decreases in ritonavir concentrations were also observed (Cmin from 0.63 to 0.35 µg/ml; Cmax from 1.02 to 0.72 µg/ml). Therapeutic drug monitoring of lopinavir when coadministered with tenofovir may be useful to indicate if individual dose modification of lopinavir and/or ritonavir is required.
Pharmacokinetic drug interaction of lopinavir/ritonavir in combination with tenofovir in experienced HIV+ patients. Breilh D, Rouzes A, Djabarouti S, et al. 44th Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, October/November 2004, abstract A-445.

Lopinavir trough concentrations were obtained from 14 HIV+ patients receiving lopinavir with tenofovir and from 15 patients without tenofovir. Lopinavir Ctroughs were 5.6 µg/ml in the tenofovir group and 7.0 µg/ml without tenofovir.
Comparison of lopinavir/r plasma levels with and without tenofovir as part of HAART in HIV-1 infected patients. Scarsi K, Postelnick M, Murphy R. 5th International Workshop on Clinical Pharmacology of HIV Therapy, Rome, April 2004, abstract 26.