Efavirenz with emtricitabine and tenofovir disoproxil

How it works

Efavirenz directly inhibits reverse transcriptase by binding a non-catalytic site, while emtricitabine and tenofovir disoproxil are phosphorylated and incorporated into viral DNA by reverse transcriptase, terminating chain elongation.

Prescribing in practice

• Efavirenz commonly causes central nervous system effects including dizziness, abnormal dreams and mood disturbance, and has been associated with depression and suicidal ideation, so screen for psychiatric history.
• Tenofovir disoproxil can cause renal tubular dysfunction and reduced bone mineral density, requiring caution in renal impairment and avoidance with other nephrotoxic drugs.
• Efavirenz induces hepatic enzymes and can lower the efficacy of hormonal contraception and many co-medications.

Monitoring

Monitor HIV viral load and CD4 count, together with renal function, liver function and lipids during treatment.

Counselling the patient

• Take once daily, ideally at bedtime and on an empty stomach, to reduce nervous-system side effects.
• Tell your doctor about any low mood, anxiety or unusual dreams.
• Use additional or non-hormonal contraception, as this medicine can reduce the pill's effectiveness.

Evidence & guidelines

Efficacy of efavirenz-based fixed-dose therapy is well established, though current BHIVA guidance generally favours integrase-inhibitor regimens as first line.