To compare the plasma pharmacokinetic (PK) parameters of q24h versus q12h dosing of abacavir in HIV-1-infected infants and children aged 3 months to 36 months

The secondary objectives of PENTA15 were:

To compare the plasma PK parameters of q24h versus q12h dosing of lamivudine in HIV-1-infected infants and children aged 3 months to 36 months who were receiving lamivudine in combination with abacavir

To compare age-related differences in the PK parameters of q24h versus q12h dosing of abacavir and lamivudine infants and children in 3 age groups (≥3 to <12 months, ≥12 to <24 months and ≥24 to <36 months)

To describe child and family acceptability of and adherence to q24h compared to q12h dosage regimens of abacavir and lamivudine

Inclusion Criteria:

• Infants and children with confirmed presence of HIV-1 infection

• Infants and children aged 3 to <36 months

• Parents/guardians able and willing to give written, informed consent

• Currently on combination ART including Abacavir (ABC) oral solution with or without Lamivudine (3TC) oral solution, for at least 12 weeks and expected to stay on this regimen for at least a further 12 weeks.

• HIV-1 RNA viral load either;

  • suppressed HIV-1 RNA viral load (i.e. <400 copies/ml)
  • non-suppressed, but low, HIV-1 RNA viral load (i.e. 400-20 000 copies/ml). The non-suppressed children should have had a stable or decreasing HIV-1 RNA viral load prior to study entry and should be considered to be still gaining benefit from the current regimen

• Stable or rising CD4+ cell percent prior to study entry and should not be expected to fall within the next 12 weeks.

Exclusion Criteria:

• Intercurrent illness
• Receiving concomitant therapy except prophylactic antibiotics
• Abnormal renal or liver function (grade 3 or above)