Fanconi Syndrome Induced by Concomitant HIV PrEP and Tacrolimus

Area of Science:

• Nephrology
• Pharmacology
• Infectious Diseases

Background:

• Fanconi syndrome (FS) is a severe proximal tubule toxicity often induced by drugs.
• Nucleoside reverse transcriptase inhibitors (NRTIs), specifically tenofovir disoproxil fumarate (TDF), are associated with FS.
• TDF is commonly used with emtricitabine (FTC) for HIV preexposure prophylaxis (PrEP).

Observation:

• This case report details a patient who developed FS after initiating TDF/FTC for PrEP.
• The patient had pre-existing chronic kidney disease (CKD).
• The patient was also receiving tacrolimus, a known nephrotoxic medication.

Findings:

• TDF/FTC-induced FS is linked to drug dosage, kidney function, proximal tubule drug absorption, and medication interactions.
• The patient's CKD and tacrolimus therapy likely contributed to the development of TDF/FTC-induced FS.
• This case illustrates a complex interaction leading to drug-induced kidney injury.

Implications:

• Healthcare providers should consider renal function and concomitant medications when prescribing TDF/FTC, especially in patients with CKD.
• Awareness of potential drug-drug interactions, like TDF/FTC with tacrolimus, is crucial for preventing FS.
• This case underscores the importance of monitoring kidney function in patients on PrEP, particularly those with underlying renal conditions or on nephrotoxic drugs.