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49. Postexposure Prophylaxis in HIV
ARV drugs are in use since the last three decades for postexposure prophylaxis following occupational exposure to HIV, but more recently, the same has been extended to accidental exposure like unprotected intercourse, sexual assault, needle prick injuries, IV drug users, etc. Use of ART for postexposure prophylaxis is supported by animal studies [1], a case control study [2], and systematic reviews which have demonstrated reduced risk of acquiring chronic infection and cost-effectiveness in high-risk groups [3, 4]. That ARV drugs are effective in postexposure prophylaxis is further supported by their role in preexposure prophylaxis and in preventing mother-to-child transmission.
Postexposure prophylaxis cannot be considered 100% effective because its effectiveness depends upon a number of factors like timing of initiation, adherence to treatment, completion of course, drug resistance, viral load, etc. Postexposure prophylaxis should form a part of wider strategy to prevent acquiring HIV infection, HBV, HCV, and other blood-borne viruses [5, 6].
- 1.
Parenteral or mucous membrane exposure (sexual exposure and splashes to the eye, nose, or oral cavity)
- 2.
Body fluids like blood, blood-stained saliva, CSF, breast milk, genital secretions, and pleural, pericardial, synovial, rectal, and peritoneal fluids.
- 3.
With high background prevalence of HIV infection, all exposures can be considered.
- 1.
When the source is known to be HIV negative, etc.
- 2.
When the exposed individual is known to be HIV positive
- 3.
Exposure to body fluids that do not pose a significant risk like tears, sweat, urine, non-blood-stained saliva, etc.
Percutaneous needle stick injury has a risk of 23 in 10,000 exposures to an infected source [7].
- 1.
HIV testing of exposed person and source if possible.
- 2.
First aid in case of a broken skin or wound.
- 3.
Counseling if postexposure prophylaxis is to be prescribed:
- (a)
Risks and benefits
- (b)
Side effects
- (c)
Risk of HIV
- (d)
Consent
- (a)
- 4.
Postexposure prophylaxis should be started as early as possible preferably within 72 h of exposure.
- 5.
28-day prescription.
- 6.
Assessment of underlying comorbidities and drug-drug interactions.
- 7.
Retesting at 3 months.
- 8.
Preventive measures.
According to ART guidance, postexposure prophylaxis can be dispensed by trained nurses, midwives, and nonphysicians [3].
- 1.
Simplified prescribing.
- 2.
Availability of
- (a)
Better tolerated
- (b)
Less toxic drugs
- (c)
Difficulty in assessing drug interactions
- (a)
- 3.
Completion rates are similar compared to two drug regimes.
Tenofovir (TDF) | 300 mg once daily |
Lamivudine (3TC) | 150 mg twice daily or 300 mg once daily |
Emtricitabine (FTC) | 200 mg once daily |
Lopinavir/ritonavir | 400 mg/100 mg twice daily or 800mg/(LPV/r) |
200 mg once daily | |
Atazanavir/ritonavir (ATV/r) | 300 mg + 100 mg once daily |
Raltegravir (RAL) | 400 mg twice daily |
Darunavir + ritonavir (DRV/r) | 800 mg + 100 mg once daily or 600 mg + 100 mg twice daily |
Efavirenz (EFV) | 600 mg once daily |
Tenofovir and lamivudine are the combination of choice for HIV postexposure prophylaxis (strong recommendation, low-quality evidence).
Lopinavir/ritonavir or atazanavir/ritonavir is the preferred third drug (conditional recommendation, very low-quality evidence). These are widely available in low- and middle-income group countries.
RAL, DRV/r, and EFV can be considered if available, with limited availability owing to higher cost.
Indirect comparisons have been made between zidovudine + lamivudine [8–19] and tenofovir + lamivudine [20–22] in several studies. Completion rates were 78% in the latter group compared to 59% in the former. Discontinuation rate was higher in the former group in comparison to the latter (3.2 vs. 0.3%) due to some adverse event.
Newer drugs, dolutegravir (high potency and tolerability), rilpivirine (high tolerability), and elvitegravir (high tolerability and convenient coformulation), have promise, but there are no current recommendations for their use.
Efavirenz is also recommended as an alternative third-line drug for postexposure prophylaxis. It is well tolerated but has limited acceptability in HIV-negative individuals (nervous system and mental events).
LPV/r | ATV/r | RAL | DRV/r | EFV | NVP | |
|---|---|---|---|---|---|---|
Discontinuation rate in postexposure prophylaxis | Low (use for preventing mother-to-child transmission of HIV) | No data | Low (use for preventing mother-to-child transmission of HIV) | |||
Daily dosing | Twice daily | One tablet once daily | Twice daily | Once or twice daily | Once daily | Twice daily |
Availability of heat-stable age-appropriate formulation | Yes | No | Yes | No | Yes | Yes |
Accessibility in country (registration status) | High | Low | Low | Low | High (>3 years) | High (all ages) |
Accessibility by health providers | High | High | High | High | High | High |
Availability of WHO prequalified generic formulation | Yes | Yes | No | No | Yes | Yes |
Age indication | >14 years | >3 months | >2 weeks | >3 years | >3 months | <2 years |
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