Date of report: 19 Feb 2020
Reported case interaction between
 Tenofovir-Af and Pemetrexed

FLS Science

Drugs suspected to be involved in the DDI

Drug A
Tenofovir-Af (Victim)
Daily Dose
10 (mg)
Dose adjustment performed
No
Administration Route
Oral
Start date
Oct. 15, 2018
End date
Ongoing
Drug B
Pemetrexed (Perpetrator)
Daily Dose
Unknown
Dose adjustment performed
No
Administration Route
Intravenous
Start date
Oct. 8, 2019
End date
Ongoing

Complete list of drugs taken by the patient

Antiretroviral treatment
Darunavir/Cobicistat/Emtricitabine/Tenofovir-AF
Complete list of all comedications taken by the patient, included that involved in the DDI
Pemetrexed, cotrimoxazole, citalopram, trazodone, mirabegron, esomeprazol, colecalciferol/calcium carbonate, olodaterol/tiotropium bromide.

Clinical case description

Gender
Female
Age
59
eGFR (mL/min)
>60
Liver function impairment
No
Description
HIV patient on antiretroviral treatment with DRV/c/FTC/TAF with good virological control. NSCLC diagnosed in Sept 2019, on treatment with pemetrexed without significant side effects. Despite combination of two potential nephrotoxic drugs, eGFR (CKD-EPI) remains stable and >90 ml/min.

Outcome

No unwanted outcome

Editorial Comment

Pemetrexed is primarily eliminated unchanged renally as a result of glomerular filtration and tubular secretion. Concomitant administration of nephrotoxic drugs could result in delayed clearance of Pemetrexed. Concomitant administration of substances that are also tubularly secreted (e.g., probenecid) could also potentially result in delayed clearance of pemetrexed. Despite lower risk for nephotoxicity of TAF than TDF, eGFR should be monitored if these two drus are to be co-administered.