Thai national guidelines for the use of antiretroviral therapy in pediatric HIV infection in 2010

"I want to be healthy and move on": A qualitative study of barriers and facilitators to antiretroviral treatment adherence among young adult survivors with perinatal HIV in Thailand

We know that HIV treatment outcome depends on antiretroviral treatment (ART) adherence. Young adults with perinatal HIV (YPHIV) who survived have endured various adherence challenges in their adolescent years. While some of them could maintain perfect adherence with sustainable virologic suppression, many experienced one or more episodes of virologic failure. We explored factors affecting ART adherence from real-life experiences of YPHIV. A qualitative study was conducted between June and November 2022. Twenty YPHIV aged 21-29 years with a history of virologic failure and resumed virologic suppression during adolescent years were invited to share their experiences through individual in-depth interviews. Audio records were transcribed verbatim and analyzed using deductive thematic analysis. We divided excerpts into two themes: barriers and facilitators to ART adherence. The socio-ecological model was used to frame subthemes at personal, societal, and healthcare system levels. Most barriers to adherence were concentrated at the personal level, including work/study-related conditions, personal entertainment, medication issues, mental health problems, thought, and belief. At the societal level, social activities and fear of HIV disclosure were frequently mentioned as barriers. Medical care cost was the only identified barrier at the healthcare system level. The facilitators to adherence at the personal level included perceiving health deterioration, being afraid of hospitalization and medical procedures, and wishing to be healthy and move on. At the same time, perceived family support and determination to complete family without HIV transmission were identified as facilitators at the societal level. Service behaviors of healthcare providers were mentioned as facilitators to adherence at the healthcare system level. From this study, most factors associated with non-adherence in adolescents were at the personal level, and the fear of HIV disclosure was critical at the societal level. The key facilitator to adherence was the determination to be healthy and have a promising future. Our findings reinforce the importance of establishing youth-friendly services in the existing HIV care setting. More time allocation for tailored individual counseling, using other novel approaches like mHealth, online media, and involvement of social support from different sectors might be beneficial to maximize adherence self-efficacy during the transitional period of YPHIV.

Outcomes of etravirine-based antiretroviral treatment in treatment-experienced children and adolescents living with HIV in Europe and Thailand

BACKGROUND

Etravirine (ETR) is approved as a component of second or third-line antiretroviral treatment (ART) for children living with HIV. We assessed the outcomes of ETR-based ART in children in routine care in Europe and Thailand.

METHODS

Data on children aged <18 years at ETR start were pooled from 17 observational cohorts. Characteristics at ETR start, immunological and virological outcomes at 12 months, discontinuations, adverse events (AEs) and serious adverse events (SAEs) were described. Follow-up was censored at ETR discontinuation, death or last visit.

RESULTS

177 children ever received ETR. At ETR start, median [IQR] age was 15 [12,16] years, CD4 count 480 [287, 713] cells/mm³, 70% had exposure to ≥3 ART classes and 20% had viral load (VL) <50 copies/mL. 95% received ETR in combination with ≥1 potent drug class, mostly protease inhibitor-based regimens. Median time on ETR was 24 [7, 48] months. Amongst those on ETR at 12 months (n=141), 69% had VL<50 copies/mL. Median CD4 increase since ETR start (n=83) was 147 [16, 267] cells/mm³. Overall, 81 (46%) discontinued ETR by last follow-up. Median time to discontinuation was 23 [8, 47] months. Common reasons for discontinuation were treatment simplification (19%), treatment failure (16%) and toxicity (12%). Eight children (5%) had AEs causally associated with ETR, all dermatological/hypersensitivity reactions. Two were SAEs, both Stevens-Johnson Syndrome in children on regimens containing ETR and darunavir and were causally related to either drugs; both resolved following ART discontinuation.

CONCLUSION

Children receiving ETR were predominantly highly treatment-experienced, over two-thirds were virally suppressed at 12 months.

Rapid antiretroviral initiation among Thai youth living with HIV in the National AIDS programme in the era of treatment at any CD4 cell count: a national registry database study

INTRODUCTION

The process indicators of ending the HIV epidemic include 90% of people living with HIV receiving antiretroviral therapy (ART). The population of youth, however, has less access to healthcare. We assessed ART initiation and attrition outcomes of the HIV continuum from HIV diagnosis to ART initiation in youth living with HIV (YLHIV) and factors associated with ART initiation.

METHODS

We studied YLHIV aged 15 to 24 years who were registered on the National AIDS Program (NAP) from January 2008 to May 2019. The study period was divided into 2008 to 2013 (initiated ART by CD4-guided criteria) and 2014 to 2018 (initiate ART at any CD4). Date of registration was used as a surrogate for the diagnosis date and defined as the baseline. The database included ART prescription and laboratory results, and the vital status was linked daily with the National Death Registry. Competing risk methods were used to assess factors associated with accessing ART, with loss to follow-up (LTFU) and death considered as competing events. Logistic regression was used to assess factors associated with rapid ART initiation, defined as initiation ≤1 month after registration.

RESULTS

Overall, 51,607 youth registered on the NAP (42% between 2008 and 2013). Median age was 21 (IQR 20 to 23) years; 64% were male. Overall ART initiation was 80% in the first period and 83% in the second. The ART initiation rate was higher among YLHIV aged 15 to 19 years (86%) than 20 to 24 years (82%) (p < 0.001) in the second period. The proportion of youth starting rapid ART increased significantly from 27% to 52% between the two periods (p < 0.001). Factors associated with ART initiation were age 15 to 19 years (aSHR 1.09, 95% CI 1.06 to 1.11), female (aSHR 1.26, 95% CI 1.23 to 1.29) and registration year 2014 to 2018 (aSHR 1.73, 95% CI 1.69 to 1.76). The cumulative incidence of LTFU/death prior to ART initiation at 12 months was 3.8% (95% CI 3.6% to 4.1%) in the first period and 1.9% (95% CI 1.8% to 2.1%) in the second period.

CONCLUSIONS

In the era of universal treatment of all at any CD4 level, 83% of YLHIV registered on the Thai National AIDS Program initiated ART. The majority initiated within one month of registration.

Behavioral problems in perinatally HIV-infected young children with early antiretroviral therapy and HIV-exposed uninfected young children: prevalence and associated factors

Although behavioral problems have been observed in children and adolescents with perinatally-acquired HIV infection (PHIV), behavioral information regarding younger PHIV children are scarce. This study aims to identify behavioral problems in PHIV and HIV-exposed uninfected (HEU) children and to evaluate factors associated with such problems. A prospective study of PHIV and HEU young children was conducted. Behavioral problems were assessed with the Child Behavior Checklist (CBCL) at baseline and 12 months later among children aged 18-60 months old. The Patient Health Questionnaire-9 and the Parenting Styles & Dimensions Questionnaire identified primary caregivers' symptoms of depression and parenting styles, respectively, at both visits. Chi-squared analyses were used to compare the prevalence of behavioral problems between groups. Factors associated with behavioral problems were analyzed by logistic regression. From 2016 to 2017, 121 children (41 PHIV and 80 HEU) were assessed with no significant differences in prevalence of Total, Internalizing, Externalizing, and Syndrome scales problems between PHIV and HEU at both visits (p > 0.5). Primary caregivers' depression and lower education in addition to authoritarian and permissive parenting styles were significantly related to child behavioral problems. Family-centered care for families affected by HIV, including positive parenting promotion, mental health care, and education are warranted.

Low risk of neurodevelopmental impairment among perinatally acquired HIV-infected preschool children who received early antiretroviral treatment in Thailand

INTRODUCTION

Antiretroviral therapy (ART) is recommended in perinatally HIV-infected (PHIV) infants immediately upon diagnosis. We aimed to compare neurodevelopmental outcomes between PHIV children who initiated ART within 12 months of life and perinatally HIV-exposed uninfected (PHEU) children and to assess neurodevelopmental outcomes by timing of ART.

METHODS

This prospective cohort study included Thai children aged 12 to 56 months who were assessed with the Mullen Scales of Early Learning (MSEL) at enrolment and at 48 weeks. Global Developmental Impairment (GDI) was defined as Early Learning Composite (ELC) ≤ 70 on the MSEL; typical developmental pattern was defined as ELC > 70 at both visits. Logistic regression was used to compare prevalence of any GDI. Predictors of changing ELC scores were analysed with generalized estimating equations linear regression model.

RESULTS

From 2016 to 2017, 50 PHIV (twenty-seven early ART within three months and twenty-three standard ART within three to twelve months) and 100 PHEU children were enrolled. Median (IQR) age at first assessment was 28 (19 to 41) months. PHIV children had lower age-relevant Z scores for weight, height and head circumference compared to the PHEU group (p < 0.05). The prevalence of overall GDI was 18% (95% CI 11 to 27) and 32% (95% CI 20 to 47) in PHEU and PHIV children respectively (p = 0.06). In subgroup analysis, 22% (95% CI 9 to 42) of early ART PHIV children and 44% (95% CI 23 to 66) of standard ART PHIV children had overall GDI. There was a higher rate of GDI in standard ART PHIV children (p = 0.01), but not in the early ART group (p = 0.62) when compared with PHEU children. The standard ART PHIV group demonstrated lower typical developmental pattern than both the early ART PHIV group and the PHEU group (57% vs. 77% vs. 82% respectively). Non-attendance at nursery school was associated with changes in ELC score during study participation (adjusted coefficient -3.8; 95% CI -6.1 to -1.6, p = 0.001).

CONCLUSIONS

Preschool children with HIV who initiated ART in the first three months of life had a similar rate of GDI as PHEU children. Lack of nursery school attendance predicted poor developmental trajectory outcomes among PHIV children.

Prevalence of Persistent Renal Dysfunction in Perinatally HIV-infected Thai Adolescents

BACKGROUND

Persistent renal dysfunction (PRD) has been reported in up to 22% of perinatally HIV-infected adolescents (PHAs) in the United States and Europe. There are limited data available on PRD among PHAs in resource-limited settings regarding access to antiretroviral therapy (ART) at more advanced HIV stages.

METHODS

We retrospectively described the prevalence of PRD and associated factors in a Thai PHA cohort. Inclusion criteria were current age ≥10 years old and at least 2 serum creatinine (Cr) measurements after ART initiation. Cr and urine examination were performed every 6-12 months. PRD was defined as having ≥2 measurements of low estimated glomerular filtration rate (eGFR); either <60 mL/min/1.73 m2 or elevated Cr for age and eGFR 60-89 mL/min/1.73 m2, or proteinuria (dipstick proteinuria ≥1+). Factors associated with PRD were analyzed using a multivariate logistic regression analysis.

RESULTS

This study included 255 PHAs with median (interquartile range) age of 16.7 (14.5-18.8) and ART duration of 10.3 (7.1-12.4) years. Fifty-six percentage used boosted protease inhibitor (bPI)-based regimens, and 63% used tenofovir disoproxil fumarate (TDF). The overall PRD prevalence was 14.1% [95% confidence interval (CI): 10.1-19.0]; low eGFR 6.7%, proteinuria 3.5% and both 3.9%. Among 109 users of TDF with bPI, 22.9% had PRD and 2.8% discontinued/adjusted dosing of TDF because of nephrotoxicity. Factors associated with PRD were age 10-15 years old (adjusted odd ratio (aOR): 10.1, 95% CI: 4.1-25.2), male (aOR: 3.2, 95% CI: 1.4-7.7), CD4 nadir <150 cells/mm (aOR: 2.6, 95% CI: 1.1-6.1) and use of TDF with bPI (aOR: 9.6, 95% CI: 3.2-28.9).

CONCLUSIONS

PRD is common among PHAs. Almost one-fifth of adolescents using TDF with bPI had PRD. These adolescents should be a priority group for renal monitoring.

Attrition and Mortality of Children Receiving Antiretroviral Treatment through the Universal Coverage Health Program in Thailand

OBJECTIVE

To assess mortality and loss to follow-up of children with HIV infection who started antiretroviral therapy (ART) through the Universal Coverage Health Program (UC) in Thailand.

STUDY DESIGN

Children with HIV infection who initiated ART at age <15 years through the UC between 2008 and 2013 were included in the analysis. Death was ascertained through linkage with the National Death Registry. A competing-risks method was used to calculate subdistribution hazard ratios (SHRs) of predictors for loss to follow-up. Death was considered a competing risk. Cox proportional hazards models were used to assess predictors of mortality.

RESULTS

A total of 4618 children from 497 hospitals in Thailand were included in the study. Median age at ART initiation was 9 years (IQR, 6-12 years), and the median duration of tracking was 4.1 years (a total of 18 817 person-years). Three hundred and ninety-five children (9%) died, for a mortality rate of 2.1 (95% CI, 1.9-2.3) per 100 person-years, and 525 children (11%) were lost to follow-up, for a lost to follow-up rate of 2.9 (95% CI, 2.7-3.2) per 100 person-years. The cumulative incidence of loss to follow-up increased from 4% at 1 year to 8.8% at 3 years. Children who started ART at age ≥12 years were at the greatest risk of loss to follow-up. The probability of death was 3.2% at 6 months and 6.4% at 3 years. Age ≥12 years at ART initiation, lower baseline CD4%, advanced HIV staging, and loss to follow-up were associated with mortality.

CONCLUSION

The Thai national HIV treatment program has been very effective in treating children with HIV infection, with low mortality and modest rates of loss to follow-up.

First-Line Antiretroviral Treatment Outcomes and Durability in HIV-Infected Children Treated Through the Universal Coverage Health Program in Thailand

BACKGROUND

We assessed the treatment outcomes on first-line antiretroviral therapy (ART), and factors associated with switching regimen in HIV-infected children treated through the universal coverage health program (UC) in Thailand.

METHODS

Children aged <15 years at ART initiation who had been receiving ART for at least 6 months between 2008 and 2014 through UC were included in the analysis. The Kaplan-Meier method was used to estimate immunological recovery (IMR), immunological failure, and virological failure (VF). Cox models were used to assess predictors of IMR and VF. Competing risk models were used to assess factors associated with switching to a second-line regimen, with death considered as a competing risk.

RESULTS

A total of 4120 children initiated ART at a median (interquartile range) age of 9.3 (5.8-12.0) years. The median duration of ART was 3.7 years with 17,950 person-years of follow-up. Two thousand eight hundred five children achieved IMR, and the probability of IMR increased to 76% by 3 years after ART initiation. Among 1054 children switched to second-line regimens, 84% had VF and 19% had immunological failure. The cumulative rate of switching regimen increased from 4% to 20% from 1 to 3 years after treatment. Children aged ≥12 years at ART initiation, starting with nonnucleoside reverse-transcriptase inhibitors, and baseline CD4% <10% had an increased risk of switching to second-line regimens.

CONCLUSIONS

Children receiving ART through UC had good treatment outcomes, although a fifth required switching regimen by 3 years. Earlier treatment initiation and avoiding nonnucleoside reverse-transcriptase inhibitor first-line regimens in high-risk children may prevent treatment failure.

Comparison of in-house HIV-1 genotypic drug resistant test with commercial HIV-1 genotypic test kit

Background: The use of combination antiretroviral therapy (cART) has become a standard of care in the treatment of HIV infection. However, antiretroviral drug resistance occurs in a substantial number of patients. In resource-limited settings, genotypic resistance assay using a commercial kit is costly.

Objective: Focus on the validation of an in-house HIV-1 specific genotypic drug resistance assay in Thai patients failing cART.

Materials and methods: Results of HIV-1 genotypic drug resistance assay was evaluated by comparing an inhouse method to a commercial test. The TRUGENE HIV-1 genotyping kit was used in 79 plasma specimens (49 from HIV patients failing cART therapy and 30 from proficiency testing panels).

Results: The results from the in-house assay were comparable to those obtained from the TRUGENE HIV-1 genotyping kit with >99.0% codon-to-codon agreement. The lower limit of detection by the in-house assay was approximately 100 copies/mL of HIV-1 RNA. In addition, this in-house assay would allow testing of samples from patients infected with HIV-1 subtype other than B.

Conclusion: The in-house HIV-1 genotypic drug resistance assay may be used as an alternative to commercial kits, particularly in resource limited settings.

Early infant HIV diagnosis and entry to HIV care cascade in Thailand: an observational study

BACKGROUND

Early infant diagnosis of HIV is crucial for timely initiation of antiretroviral therapy (ART) in infected children who are at high risk of mortality. Early infant diagnosis with dried blood spot testing was provided by the National AIDS Programme in Thailand from 2007. We report ART initiation and vital status in children with HIV after 7 years of rollout in Thailand.

METHODS

Dried blood spot samples were collected from HIV-exposed children in hospitals in Thailand and mailed to the Faculty of Associated Medical Sciences, Chiang Mai University, where HIV DNA was assessed with real-time PCR to establish HIV infection. We linked data from children with an HIV infection to the National AIDS Programme database to ascertain ART and vital status.

FINDINGS

Between April 5, 2007, and Oct 1, 2014, 16 046 dried blood spot samples were sent from 8859 children in 364 hospitals in Thailand. Median age at first dried blood spot test was 2·1 (IQR 1·8-2·5) months. Of 7174 (81%) children with two or more samples, 223 (3%) were HIV positive (including five unconfirmed). Of 1685 (19%) children with one sample, 70 (4%) were unconfirmed positive. Of 293 (3%) children who were HIV positive, 220 (75%) registered for HIV care and 170 (58%) initiated ART. Median age at ART initiation decreased from 14·2 months (IQR 10·2-25·6) in 2007 to 6·1 months (4·2-9·2) in 2013, and the number of children initiating ART aged younger than 1 year increased from five (33%) of 15 children initiating ART in 2007 to ten (83%) of 12 initiating ART in 2013. 15 (9%) of 170 children who initiated ART died and 16 (32%) of 50 who had no ART record died.

INTERPRETATION

Early infant diagnosis with dried blood spot testing had high uptake in primary care settings. Further improvement of linkage to HIV care is needed to ensure timely treatment of all children with an HIV infection.

FUNDING

None.

Risk of first-line antiretroviral therapy failure in HIV-infected Thai children and adolescents

BACKGROUND

Adolescence may affect adherence and response to highly active antiretroviral therapy (HAART). Limited data are available regarding the long-term treatment outcomes of perinatal HIV-infected adolescents.

METHODS

Data from perinatally acquired HIV-infected Thai children who started first-line nonnucleoside analog-based HAART before 18 years of age and treated for ≥24 weeks were analyzed. Children were categorized by age at HAART initiation; age<3 years, 3-9 years, early adolescence (10-13 years) and middle adolescence (14-16 years). CD4 and HIV-RNA were monitored every 6-12 months. Virologic failure (VF) was defined as HIV-RNA≥1000 copies/mL after ≥24 weeks of HAART.

RESULTS

Of 840 children, 68% were in pre-adolescence. Median baseline CD4% was 7.9%. Use of nevirapine versus efavirenz was 77:23%. Median duration of nonnucleoside reverse transcriptase inhibitor-based HAART was 5.6 years. No differences between groups were observed for rate of HIV-RNA<50 copies/mL (68%, P=0.18) and rate of VF (28%, P=0.82), median time to VF (22 months, P=0.13). Incidence of VF per 100 child-year in children age<3 years, 3-9 years, early adolescence and middle adolescence were 7.9, 4.7, 7.4 and 10.8, respectively (P=0.012). Median adherence by pill count was 97.3% (P=0.23). By multivariate analysis, predictors for VF were age at HAART initiation of <3 years (HR: 1.73, 95% CI: 1.18-2.55), age 10-16 years (HR: 1.47, 95% CI: 1.09-1.97), and nevirapine use (HR: 1.63, 95% CI: 1.14-2.32).

CONCLUSIONS

VF rates were observed in one-third of long-term treated Thai children on first-line HAART. Age 3-9 years at HAART initiation was associated with less VF compared with those younger or older, whereas children who used nevirapine had higher VF.

Factors associated with high rates of antiretroviral medication adherence among youth living with perinatal HIV in Thailand

Antiretroviral medication adherence behaviour among Thai youth with perinatal HIV in Thailand has received growing attention. However, few studies have examined individual predictors of antiretroviral adherence using multiple self-reports. A convenience sample of 89 Thai youth (interquartile range 14-16 years) with perinatal HIV at three paediatric programmes in Chiang Mai completed a structured questionnaire and reported their antiretroviral adherence in the past one, seven and 30 days using count-based recall and a visual analog scale. Mean self-reported adherence rates ranged from 83.5% (past 30 days) to 99.8% (yesterday) of the time. One-inflated beta regression models were used to examine the associations between antiretroviral adherence outcomes, treatment self-efficacy, depression, anxiety, social support and beliefs/attitudes about medications. Higher percentage of medications taken in the past 30 days was independently associated with higher treatment self-efficacy and fewer symptoms of depression. Adherence monitoring would benefit from focal assessment of youth depression and perceived capacity to follow their antiretroviral regimen.

Cost-effectiveness of early infant HIV diagnosis of HIV-exposed infants and immediate antiretroviral therapy in HIV-infected children under 24 months in Thailand

Background

HIV-infected infants have high risk of death in the first two years of life if untreated. WHO guidelines recommend early infant HIV diagnosis (EID) of all HIV-exposed infants and immediate antiretroviral therapy (ART) in HIV-infected children under 24-months. We assessed the cost-effectiveness of this strategy in HIV-exposed non-breastfed children in Thailand.

Methods

A decision analytic model of HIV diagnosis and disease progression compared: EID using DNA PCR with immediate ART (Early-Early); or EID with deferred ART based on immune/clinical criteria (Early-Late); vs. clinical/serology based diagnosis and deferred ART (Reference). The model was populated with survival and cost data from a Thai observational cohort and the literature. Incremental cost-effectiveness ratio per life-year gained (LYG) was compared against the Reference strategy. Costs and outcomes were discounted at 3%.

Results

Mean discounted life expectancy of HIV-infected children increased from 13.3 years in the Reference strategy to 14.3 in the Early-Late and 17.8 years in Early-Early strategies. The mean discounted lifetime cost was $17,335, $22,583 and $29,108, respectively. The cost-effectiveness ratio of Early-Late and Early-Early strategies was $5,149 and $2,615 per LYG, respectively as compared to the Reference strategy. The Early-Early strategy was most cost-effective at approximately half the domestic product per capita per LYG ($4,420 in Thailand 2011). The results were robust in deterministic and probabilistic sensitivity analyses including varying perinatal transmission rates.

Conclusion

In Thailand, EID and immediate ART would lead to major survival benefits and is cost- effective. These findings strongly support the adoption of WHO recommendations as routine care.

Five-year trends in antiretroviral usage and drug costs in HIV-infected children in Thailand

BACKGROUND

As antiretroviral treatment (ART) programs mature, data on drug utilization and costs are needed to assess durability of treatments and inform program planning.

METHODS

Children initiating ART were followed up in an observational cohort in Thailand. Treatment histories from 1999 to 2009 were reviewed. Treatment changes were categorized as: drug substitution (within class), switch across drug class (non nucleoside reverse-transcriptase inhibitors (NNRTI) to/from protease inhibitor (PI)), and to salvage therapy (dual PI or PI and NNRTI). Antiretroviral drug costs were calculated in 6-month cycles (US$ 2009 prices). Predictors of high drug cost including characteristics at start of ART (baseline), initial regimen, treatment change, and duration on ART were assessed using mixed-effects regression models.

RESULTS

Five hundred seven children initiated ART with a median 54 (interquartile range, 36-72) months of follow-up. Fifty-two percent had a drug substitution, 21% switched across class, and 2% to salvage therapy. When allowing for drug substitution, 78% remained on their initial regimen. Mean drug cost increased from $251 to $428 per child per year in the first and fifth year of therapy, respectively. PI-based and salvage regimens accounted for 16% and 2% of treatments prescribed and 33% and 5% of total costs, respectively. Predictors of high cost include baseline age ≥ 8 years, non nevirapine-based initial regimen, switch across drug class, and to salvage regimen (P < 0.005).

CONCLUSIONS

At 5 years, 21% of children switched across drug class and 2% received salvage therapy. The mean drug cost increased by 70%. Access to affordable second- and third-line drugs is essential for the sustainability of treatment programs.

Pharmacokinetics and safety of a new paediatric fixed-dose combination of zidovudine/lamivudine/nevirapine in HIV-infected children

BACKGROUND

Alternatives to the available stavudine-containing paediatric fixed-dose combination (FDC) tablets are rapidly needed due to concerns regarding the cumulative toxicity of long-term stavudine exposure. We report the bioavailability and short-term safety of a novel paediatric FDC tablet of zidovudine (ZDV)/lamivudine (3TC)/nevirapine (NVP; 30/15/28 mg) in HIV-infected children.

METHODS

In this Phase I/II open-label pharmacokinetic study, 42 children weighing 6-30 kg treated with NVP-based HAART for ≥4 weeks were randomized to receive the FDC tablets (GPO-VIR Z30) or the liquid formulations. Dosing was weight-based. Intensive 12-h blood sampling was performed after 2 weeks; subjects then crossed-over to the alternate formulation at equal doses and sampling repeated 2 weeks later. Pharmacokinetic parameters were determined by non-compartmental analysis. Buccal-swab samples were collected for cytochrome P450 (CYP)2B6 polymorphism analysis.

RESULTS

With the FDC tablet, the geometric mean (90% CI) area under the curve (AUC) for ZDV, 3TC and NVP was 1.58 (1.49-1.68), 7.78 (7.38-8.19) and 68.88 (62.13-76.36) μg•h/ml, respectively. Rules for NVP therapeutic inadequacy were defined a priori, and despite lower NVP exposure with the tablet (P<0.001), the levels remained therapeutically adequate. ZDV AUC was similar between formulations. 3TC exposure was significantly higher with the tablet but comparable to historical data in adults and children taking branded tablets. While receiving the tablet, NVP AUC in children with CYP2B 516 GG (45%), GT (45%) and TT (10%) genotypes were 67.0, 74.5 and 106.4 μg•h/ml, respectively (P=0.04).

CONCLUSIONS

Disparities in drug exposure between formulations were observed; however, the FDC tablet delivered therapeutically adequate exposures of each drug and could well play an important role in simplifying antiretroviral treatment for children.