What is the least expensive medication regimen for post-exposure prophylaxis (PEP)?

Least Expensive Medication Regimen for HIV Post-Exposure Prophylaxis (PEP)

The least expensive medication regimen for HIV post-exposure prophylaxis (PEP) is the basic regimen of generic tenofovir disoproxil fumarate (TDF) plus lamivudine (3TC), which provides effective prophylaxis while minimizing cost.

Understanding PEP Medication Options

Basic Regimens

1. Traditional Basic Regimen (Historical)

   • Zidovudine (ZDV) + Lamivudine (3TC) (available as Combivir)
   • ZDV: 600 mg per day in two or three divided doses
   • 3TC: 150 mg twice daily 1
   • While historically recommended, this regimen has largely been replaced due to side effect profile

2. Current Preferred Basic Regimen

   • Tenofovir disoproxil fumarate (TDF) + lamivudine (3TC)
   • Less expensive than newer formulations while maintaining efficacy
   • Generic versions available, substantially reducing cost 1

Alternative Regimens (More Expensive)

1. Tenofovir-based coformulations

   • TDF/emtricitabine (FTC) with integrase inhibitors (bictegravir, dolutegravir)
   • Better tolerability but significantly more expensive 2

2. Single tablet regimens

   • TDF/FTC/rilpivirine (RPV) - once daily dosing 3
   • BIC/FTC/TAF - newer formulation with better tolerability 4
   • Higher cost but improved adherence rates

Cost-Effectiveness Considerations

Generic Medication Impact

• Generic antiretrovirals have substantially reduced the cost of HIV treatment globally 1
• Using generic TDF+3TC instead of branded coformulations can provide significant cost savings
• Modeling studies have found that partially generic regimens are highly cost-effective 1

Cost vs. Adherence Trade-offs

• While single-tablet regimens may improve adherence (90% completion with BIC/FTC/TAF 4), they come at significantly higher cost
• TDF+3TC provides similar efficacy at lower cost when adherence is maintained
• The basic regimen remains effective for preventing HIV seroconversion when completed as prescribed 1

Implementation Guidelines

Dosing and Duration

• PEP should be initiated as soon as possible after exposure, ideally within 72 hours
• Complete a full 28-day course regardless of regimen chosen 2
• Follow-up evaluations and monitoring at baseline, 6 weeks, 3 months, and 6 months

Monitoring for Side Effects

• Common side effects with TDF-based regimens:
  • Gastrointestinal issues (nausea, diarrhea)
  • Fatigue
  • Mild elevations in liver enzymes
• Monitor renal function as TDF can cause mean eGFR decrease of 14 ml/min/1.73m² 5

Special Considerations

When to Consider More Expensive Alternatives

• Known source patient with antiretroviral resistance
• Patient with renal impairment (TDF contraindicated)
• Pregnancy (certain regimens contraindicated)
• History of poor medication adherence where single-tablet regimen might improve completion

Pitfalls to Avoid

• Don't sacrifice efficacy for cost when source patient has known resistance
• Don't delay initiation of PEP while waiting for "ideal" regimen
• Remember that completion of the full 28-day course is critical for effectiveness
• Consider drug interactions when selecting regimen

Conclusion

For most patients requiring HIV PEP, the basic regimen of generic TDF+3TC provides the optimal balance of cost-effectiveness and efficacy. While newer regimens may offer improved tolerability and convenience, the substantial cost difference makes the basic regimen the preferred choice when cost is a primary consideration.