Antiretroviral Therapy in Adolescents and Young Adults 

The number of cases of human immunodeficiency virus (HIV) infection among young adolescents has been increasing over the years. Adolescents and young adults acquire HIV through high-risk behaviors. Many of them are recently infected or unaware of their HIV infection status.^[1] Early intervention, including prevention strategies, counseling, and HIV testing, plays a key role in treating adolescents and young adults.

• For postpubertal adolescents, antiretroviral treatment guidelines for adults may be used; postpubertal youth who were perinatally infected may also use the adult antiretroviral treatment guidelines^[1]
• Puberty has a direct effect on how a drug is metabolized and on the drugs’ pharmacokinetic properties; therefore, dosage of medications for HIV infection should be based on the Tanner staging of puberty and not just on age alone^{[2, 3]}
• Adolescents in early puberty (ie, Tanner stages I and II) should be on pediatric dosing schedules, whereas those in late puberty (ie, Tanner stage V) should follow adult dosing schedules^[1]
• Adolescents who are undergoing their growth-spurt period (ie, Tanner stage III in females and Tanner stage IV in males) should follow the adult dosing guidelines
• Puberty may be delayed in children who were perinatally infected with HIV, adding to discrepancies between Tanner stage ̶ based dosing and age-based dosing^[4]
• Dosing of antiretroviral medications for adolescents can be unpredictable and is dependent on multiple factors, including body mass and composition and chronologic age^[1]

The definition of “adolescent” may differ depending on the regimen; for regimens with specific definitions of “adolescent,” the definition is provided in parentheses following the regimen.

Abacavir (ABC)

• ABC 300mg PO BID or 600mg PO once daily (adolescent, ≥16y)
• Trizivir: Combination formulation including ABC 300mg/lamivudine (3TC) 150mg/zidovudine (ZDV) 300mg; give 1 tablet PO BID (adolescent, ≥40 kg,)
• Epzicom: Combination formulation including ABC 600mg/3TC 300mg; give 1 tablet PO once daily (adolescent, >16y)

Didanosine (ddI)

• Adolescents < 60 kg: 250 mg PO once daily
• Adolescents ≥60 kg: 400 mg PO once daily
• Dosing recommendations for coadministration with tenofovir (TDF): no data on combination in children or adolescents < 18y; < 60 kg: 200mg PO once daily; ≥ 60 kg: 250 mg PO once daily

Emtricitabine (FTC)

• Oral solution: 240 mg (24 mL) PO once daily; capsules: 200 mg PO once daily (adolescent, ≥18y)
• Truvada: Combination formulation including FTC 200mg/tenofovir (TDF) 300mg; 1 tablet PO once daily (adult dose; not recommended for patients < 18y)
• Atripla: Combination formulation including FTC 200mg/efavirenz (EFV) 600mg/TDF 300mg; 1 tablet PO once daily (adult dose; not recommended for patients < 18y)

Lamivudine (3TC)

• If ≥50kg, give 150mg PO BID or 300mg PO once daily; if < 50 kg, give 4 mg/kg (up to 150mg) BID (adolescent, ≥16y)
• Combivir: Combination formulation including 3TC 150mg/ZDV 300mg; give 1 tablet PO BID (adolescent, ≥30 kg)
• Trizivir: Combination formulation including ABC 300mg/3TC 150mg/ZDV 300mg; give 1 tablet PO BID (adolescent, ≥ 40 kg)
• Epzicom: Combination formulation including ABC 600mg/3TC 300mg; give 1 tablet PO once daily (adolescent, ≥40 kg)

Stavudine (d4t)

• Adolescents 30kg to < 60 kg: 30mg PO BID
• Adolescents ≥60kg: 40 mg PO BID

Tenofovir disoproxil fumarate (TDF)

• 300 mg PO once daily (adolescent, ≥12y and >35 kg)
• Truvada: Combination formulation including 3TC 200mg/TDF 300mg; 1 tablet PO once daily
• Atripla: Combination formulation including EFV 600mg/FTC 200mg/TDF 300mg; 1 tablet PO once daily

Zidovudine (ZDV)

• 200mg PO TID or 300mg PO BID (adolescent, ≥18y)
• Combivir: Combination formulation including 3TC 150 mg/ZDV 300mg; give 1 tablet PO BID (adolescent, ≥30 kg)
• Trizivir: Combination formulation including ABC 300mg/3TC 150mg/ZDV 300mg; give 1 tablet PO BID (adolescent, ≥ 40 kg)

The definition of “adolescent” may differ depending on the regimen; for regimens with specific definitions of “adolescent,” the definition is provided in parentheses following the regimen.

Efavirenz (EFV)

• 600 mg PO once daily (adolescent, ≥40 kg)
• Atripla: Combination formulation including EFV 600mg/emtricitabine (FTC) 200mg/ tenofovir disoproxil fumarate (TDF) 300mg; 1 tablet PO once daily (drug combination should not be used in pediatric patients, < 40kg, in whom the EFV dose would be excessive)

Etravirine (ETR)

• General adult dosing: 200 mg (one 200mg tablet or two 100mg tablets) PO BID following a meal

Nevirapine (NVP)

• 200 mg PO BID; initiate therapy with 200mg given once daily for the first 14d; increase to 200mg administered BID if there is no rash and if no other adverse effects occur
• Dosing recommendations during coadministration with other antiretrovirals: NVP in combination with lopinavir/ritonavir (LPV/RTV) may require a higher dose of LPV/RTV

Rilpivirine (RPV)

• General adult dosing: 25 mg PO once daily

The definition of “adolescent” may differ depending on the regimen; for regimens with specific definitions of “adolescent,” the definition is provided in parentheses following the regimen.

Atazanavir (ATV)

• 16-21y: For antiretroviral-naive patients, give ATV 300mg PO plus  ritonavir (RTV) 100mg PO with food or ATV 400mg PO once daily with food
• Antiretroviral-experienced patients: ATV 300mg PO plus RTV 100mg PO, both once daily with food
• Dosing recommendations during coadministration with other antiretrovirals: ATV in combination with EFV in therapy-naive patients only (adult dose): ATV 400 mg plus  RTV 100 mg PO plus EFV 600mg PO, all once daily but at separate times (ATV + RTV with food, EFV without food)
• ATV in combination with TDF (adult dose): ATV 300mg PO plus  RTV 100mg PO plus TDF 300mg PO, all once daily with food
• Only RTV-boosted ATV should be used in combination with TDF, because TDF decreases ATV exposure

Darunavir (DRV)

• Treatment naïve: Adolescent (≥ 18y)/adult dose: DRV 800 mg PO plus RTV 100mg PO, both once daily with food
• Treatment experienced: Adolescent (≥ 18y)/adult dose: DRV 600mg PO plus RTV 100mg PO, both twice daily with food

Fosamprenavir (FPV)

• Antiretroviral-naive patients: Adolescent (>18y)/adult dose: For unboosted (without RTV) twice-daily regimen, give FPV 1,400mg PO BID; for boosted (with RTV) twice-daily regimen, give FPV 700mg PO plus ritonavir 100mg PO, both BID
• Boosted (with RTV) once-daily regimen: FPV 1400 mg PO plus  RTV 200mg PO, both once daily or  FPV 1400mg PO plus RTV 100mg PO, both once daily
• Protease inhibitor ̶ experienced patients: FPV 700mg PO plus RTV 100mg PO, both BID
• Once-daily administration of FPV plus RTV is not recommended in protease inhibitor ̶ experienced patients
• Only FPV boosted with RTV should be used in combination with EFV

Indinavir (IDV)

• Adolescents: 800mg PO q8h
• IDV in combination with RTV: IDV 800mg PO plus RTV 100mg or 200mg BID

Lopinavir/ritonavir (LPV/RTV)

• LPV 400mg/RTV 100mg per dose BID (adolescent, ≥ 40 kg)
• Pediatric dose (>6mo-18y): For individuals receiving concomitant nelfinavir (NFV), NVP, EFV, or FPV (these drugs induce LPV metabolism and reduce LPV plasma levels), increased LPV/RTV dosing is required with concomitant administration of these drugs and/or in treatment-experienced patients in whom reduced susceptibility to LPV is suspected (such as those with prior treatment with other protease inhibitors)
• Once-daily dosing is not recommended in adolescents

Nelfinavir (NFV)

• Adolescents: 1250mg (five 250mg tablets or two 625mg tablets) BID or 750mg (three 250mg tablets) TID
• Some adolescents require higher doses than adults to achieve equivalent drug exposures; monitor patients carefully to guide appropriate dosing

Ritonavir (RTV)

• RTV as a pharmacokinetic enhancer: Major use of RTV is as a pharmacokinetic enhancer of other protease inhibitors; dose of RTV recommended varies with the different protease inhibitors

Saquinavir (SQV)

• SQV 1000mg plus RTV 100mg, both BID; should be taken within 2h after a full meal; SQV should only be used in combination with RTV or LPV/RTV (never unboosted) (adolescents, ≥ 16y)

Tipranavir (TPV)

Pediatric dose (2-18y):

• Body-surface-area dosing: TPV 375mg/m²plus  RTV 150mg/m², both BID; maximum dose is TPV 500mg plus RTV 200mg, both BID
• Weight-based dosing: TPV 14mg/kg plus  RTV 6mg/kg, both BID; maximum dose is TPV 500mg plus RTV 200mg, both BID

Older than 18y:

• TPV 500mg plus RTV 200mg, both BID

Enfuvirtide (ENF)

• 90 mg (1 mL) injected SC BID into the upper arm, anterior thigh, or abdomen (adolescent defined as > 16y):

Maraviroc (MVC)

• Approved only for those >16y
• When given with potent CYP3A inhibitors (with or without CYP3A inducers), including protease inhibitors (except TPV/RTV): 150mg PO BID
• When given with nucleoside reverse transcriptase inhibitors, ENF, TPV/RTV, NVP, raltegravir (RAL), and drugs that are not potent CYP3A inhibitors or inducers: 300mg PO BID
• When given with potent CYP3A inducers, including EFV and ETR (without a strong CYP3A inhibitor): 600mg PO BID

Raltegravir (RAL)

• 400 mg PO BID (adolescents ≥ 16y)