Emtricitabine with tenofovir disoproxil

How it works

Both agents are phosphorylated within cells and incorporated by reverse transcriptase into viral DNA, terminating the growing chain and preventing viral replication.

Prescribing in practice

• Tenofovir disoproxil can cause renal tubular dysfunction and reduced bone mineral density, so assess renal function before and during use and avoid concurrent nephrotoxic drugs.
• Hepatitis B status must be checked, as discontinuation can precipitate severe acute exacerbation of hepatitis B in co-infected patients.
• When used for prophylaxis, HIV-negative status must be confirmed first and it forms only one part of combined HIV prevention.

Monitoring

Monitor HIV status, renal function (including markers of tubular function) and hepatitis B markers during use.

Counselling the patient

• Take once daily and do not stop without advice, particularly if you have hepatitis B.
• For prevention, keep testing regularly for HIV and continue using condoms against other infections.
• Report any bone pain or symptoms suggesting kidney problems.

Evidence & guidelines

This combination is the long-established backbone for HIV pre-exposure prophylaxis, supported by the PROUD trial and NICE guidance.