Negative impact of a health insurer-mandated de-simplification from a single-tablet regimen to a two-tablet regimen.

OBJECTIVES: Antiretroviral therapy (ART) accounts for a considerable proportion of HIV care expenses. In June 2021, a Dutch healthcare insurer implemented a mandatory policy to de-simplify branded RPV/TDF/FTC (Eviplera®) into a two-tablet regimen containing rilpivirine (Edurant®) plus generic TDF/FTC as part of cost-saving measures. The objectives of this study were to evaluate (1) the acceptance of this policy, (2) the trends in antiretroviral therapy dispensation, and (3) cost developments. DESIGN: A retrospective database study. METHODS: In this study, medication dispensation data were obtained from the Dutch Foundation for Pharmaceutical Statistics (SFK). This database covers 98% of all medication dispensations from Dutch pharmacies including people with HIV who receive ART. We received pseudonymized data exclusively from individuals insured by the insurer for the years 2020-2022. Costs were calculated using Dutch drug prices for each year. RESULTS: In June 2021, 128 people with HIV were on branded RPV/TDF/FTC. Following the policy implementation, 59 (46%) had switched to RPV + generic TDF/FTC, but after 1.5 years, only 17/128 individuals (13%) used the proposed two-tablet regimen. The other 111/128 used RPV/TDF/FTC with prescriptions for 'medical necessity' (n = 29), switched to RPV/TAF/FTC (n = 51), or other ART (n = 31). Despite expectations of cost-savings, costs increased from €72,988 in May 2021 to €75,649 in May 2022. CONCLUSIONS: A mandatory switch from an STR to a TTR in people with HIV proved unsuccessful, marked by low acceptance, and increased costs after one year. This underscores the necessity of incorporating patient and prescriber involvement in changing medication policies.

Relative Bioavailability of Dolutegravir (DTG) and Emtricitabine/Tenofovir Alafenamide Fumarate (F/TAF) Administered as Paediatric Tablet Formulations in Healthy Volunteers.

BACKGROUND AND OBJECTIVE: Within the UNIVERSAL project (RIA2019PD-2882) we aim to develop a paediatric dolutegravir (DTG)/emtricitabine (FTC or F)/tenofovir alafenamide (TAF) fixed-dose combination. To inform dosing of this study, we undertook a relative bioavailability (RBA) study in healthy volunteers to investigate a potential pharmacokinetic effect when paediatric formulations of DTG and F/TAF are taken together. METHODS: Participants received all of the following treatments as paediatric formulations in randomised order: a single dose of 180/22.5 mg F/TAF; a single dose of 30 mg DTG; a single dose of 180/22.5 mg F/TAF plus 30 mg DTG. Blood concentrations of DTG, FTC, TAF, and tenofovir (TFV) were measured over 48 h post-dose. If the 90% confidence intervals (CIs) of the geometric least squares mean (GLSM) ratios of area under the curve (AUC) and maximum concentration (Cmax) of each compound were within 0.70-1.43, we considered this as no clinically relevant PK interaction. RESULTS: A total of 15 healthy volunteers were included. We did not observe a clinically relevant PK interaction between the paediatric DTG and F/TAF formulations for the compounds DTG, FTC, and TFV. For TAF, the lower boundaries of the 90% CIs of the GLSM ratios of the AUC0-∞ and Cmax fell outside our acceptance criteria of 0.70-1.43. CONCLUSIONS: Although TAF AUC and Cmax 90% CIs fell outside the pre-defined criteria (0.62-1.11 and 0.65-1.01, respectively), no consistent effect on TAF PK was observed, likely due to high inter-subject variability. Moreover, there are several reasons to rely on TFV exposure as being more clinically relevant than TAF exposure. Therefore, we found no clinically relevant interactions in this study.

Efficacy and Safety of Bariatric Surgery in Dutch People Living with HIV: a Retrospective Matched Cohort Analysis.

PURPOSE: Obesity is rising among people with HIV (PLWH), sparking interest in bariatric surgery (BS) for this group. Yet, large-scale comparative research on BS outcomes in PLWH is lacking. METHODS: We performed a retrospective, matched cohort analysis in PLWH and HIV uninfected controls. Subjects were retrieved from the Dutch Audit for Treatment of Obesity (DATO) registry. Matching (1:7 ratio) included age (± 5-years), sex, body-mass index (BMI) of ± 3 kg/m2, surgery type, and associated health problems (AHPs) at baseline. The primary endpoint was total weight loss percentage (%TWL) ≥ 20% achieved at 1-year post-BS. Secondary endpoints were cumulative %TWL achieved at 2-years post-BS, a reported remission or improvement in AHPs post-BS, and surgical complications, both at 1-year post-BS. Comparisons were performed using conditional logistic regression. RESULTS: Twenty-seven PLWH and 168 controls were included. At 1-year post-BS, 89% PLWH achieved ≥ 20%TWL, compared to 94% of controls (p = 0.4). Cumulative %TWL at 2-years post-BS were 82% and 92% in PLWH and controls, respectively (p = 0.2). Improvement rates in hypertension and type 2 diabetes mellitus were 50% and 86% in PLWH, versus 87% and 87% in controls. Full remission occurred in 20% and 71% of PLHIV, versus 49% and 44% of controls, respectively. No improvement or remission was observed for dyslipidaemia in PLHIV compared to 54% improvement and 29% remission in controls. Surgical complications were 0% in PLHIV and 13% (n = 21) in controls. CONCLUSION: Efficacy and safety outcomes of BS were similar between PLWH and controls except for the lack of improvement in dyslipidaemia in PLWH.

Availability and stock-outs of paediatric antiretroviral treatment formulations at health facilities in Kenya and Uganda.

INTRODUCTION: The large number of deaths among children with HIV is driven by poor antiretroviral treatment (ART) coverage among this cohort. The aim of the study was to assess the availability and stock-outs of paediatric and adult ART formulations in Kenya and Uganda across various regions and types of health facilities. METHODS: A survey on availability and stock-outs of paediatric ART at health facilities was adapted from the standardized Health Action International-WHO Medicine Availability Monitoring Tool. All preferred and limited-use formulations, and three phased-out formulations according to the 2021 WHO optimal formulary list were included in the survey, as well as a selection of adult ART formulations suitable for older children, adolescents, and adults. Availability data were collected in June-July 2022 and stock-out data were obtained over the previous year from randomly selected public and private-not-for-profit (PNFP) facilities registered to dispense paediatric ART across six districts per country. All data were analysed descriptively. RESULTS: In total, 144 health facilities were included (72 per country); 110 were public and 34 PNFP facilities. Overall availabilities of preferred paediatric ART formulations were 52.2% and 63.5% in Kenya and Uganda, respectively, with dolutegravir (DTG) 10 mg dispersible tablets being available in 70.2% and 77.4% of facilities, respectively, and abacavir/lamivudine dispersible tablets in 89.8% and 98.2% of facilities. Of note, availability of both formulations was low (37.5% and 62.5%, respectively) in Kenyan PNFP facilities. Overall availabilities of paediatric limited-use products were 1.1% in Kenya and 1.9% in Uganda. At least one stock-out of a preferred paediatric ART formulation was reported in 40.0% of Kenyan and 74.7% of Ugandan facilities. Nevirapine solution stock-outs were reported in 43.1% of Ugandan facilities, while alternative formulations for postnatal HIV prophylaxis were not available. CONCLUSIONS: Recommended DTG-based first-line ART for children across all ages was reasonably available at health facilities in Kenya and Uganda, with the exception of Kenyan PNFP facilities. Availability of paediatric ART formulations on the limited-use list was extremely low across both countries. Stock-outs were reported regularly, with the high number of reported stock-outs of neonatal ART formulations in Uganda being most concerning.

Twice-Daily Dosing of Dolutegravir in Infants on Rifampicin Treatment: A Pharmacokinetic Substudy of the EMPIRICAL Trial.

BACKGROUND: We evaluated dolutegravir pharmacokinetics in infants with human immunodeficiency virus (HIV) receiving dolutegravir twice daily (BID) with rifampicin-based tuberculosis (TB) treatment compared with once daily (OD) without rifampicin. METHODS: Infants with HIV aged 1-12 months, weighing ≥3 kg, and receiving dolutegravir BID with rifampicin or OD without rifampicin were eligible. Six blood samples were taken over 12 (BID) or 24 hours (OD). Dolutegravir pharmacokinetic parameters, HIV viral load (VL) data, and adverse events (AEs) were reported. RESULTS: Twenty-seven of 30 enrolled infants had evaluable pharmacokinetic curves. The median (interquartile range) age was 7.1 months (6.1-9.9), weight was 6.3 kg (5.6-7.2), 21 (78%) received rifampicin, and 11 (41%) were female. Geometric mean ratios comparing dolutegravir BID with rifampicin versus OD without rifampicin were area under curve (AUC)0-24h 0.91 (95% confidence interval, .59-1.42), Ctrough 0.95 (0.57-1.59), Cmax 0.87 (0.57-1.33). One infant (5%) receiving rifampicin versus none without rifampicin had dolutegravir Ctrough <0.32 mg/L, and none had Ctrough <0.064 mg/L. The dolutegravir metabolic ratio (dolutegravir-glucuronide AUC/dolutegravir AUC) was 2.3-fold higher in combination with rifampicin versus without rifampicin. Five of 82 reported AEs were possibly related to rifampicin or dolutegravir and resolved without treatment discontinuation. Upon TB treatment completion, HIV viral load was <1000 copies/mL in 76% and 100% of infants and undetectable in 35% and 20% of infants with and without rifampicin, respectively. CONCLUSIONS: Dolutegravir BID in infants receiving rifampicin resulted in adequate dolutegravir exposure, supporting this treatment approach for infants with HIV-TB coinfection.

The impact of obesity on doravirine exposure in people with HIV.

Obesity incidence is increasing among people with HIV. Doravirine is a recommended first-line antiretroviral drug in many countries with no data from people with obesity. This study investigates the exposure of doravirine 100 mg standard dose in obese versus normal weight patients using clinical data combined with physiologically based pharmacokinetic modelling. Results from both approaches showed an elevated doravirine exposure during obesity, yet within the safety range of doravirine with no need for dose modification.

First-Line Antituberculosis Drug Concentrations in Infants With HIV and a History of Recent Admission With Severe Pneumonia.

Optimal antituberculosis therapy is essential for favorable clinical outcomes. Peak plasma concentrations of first-line antituberculosis drugs in infants with living HIV receiving WHO-recommended dosing were low compared with reference values for adults, supporting studies on increased doses of first-line TB drugs in infants.

Outcomes of Bariatric Surgery in People With Human Immunodeficiency Virus: A Retrospective Analysis From the ATHENA Cohort.

BACKGROUND: The implications of bariatric surgery (BS) on virologic and metabolic outcomes in people with human immunodeficiency virus (HIV; PWH) on antiretroviral therapy (ART) are unknown. METHODS: Here, we report a retrospective analysis up to 18 months post-BS in PWH from the AIDS Therapy evaluation in The Netherlands (ATHENA) cohort with data from all dutch HIV treating Centers. Primary end points were a confirmed virologic failure (2 consecutive HIV-RNA measurements >200 copies/mL) and the percentage of patients who achieved >20% total body weight loss up to 18 months post-BS. Switches from baseline ART and trough plasma concentrations of antiretrovirals were also reported post-BS. Metabolic parameters and medication usage were compared pre- and post-BS. RESULTS: Fifty-one patients were included. One case of confirmed virologic failure and 3 cases with viral blips were detected in this cohort up to 18 months post-BS. Eighty-five percent of patients achieved >20% total body weight loss at 18 months post-BS, with a mean difference from baseline (95% confidence interval) of -33.5% (-37.7% to -29.3%). Trough plasma concentrations of measured antiretroviral agents were all above minimum effective concentrations, except for 1 sample of darunavir. Lipid profiles, but not serum creatinine and blood pressure, improved significantly (P < .01) post-BS. Total medications and obesity-related comedications declined from 203 to 103 and from 62 to 25, respectively, at 18 months post-BS. CONCLUSIONS: BS was an effective intervention for weight loss and lipid control in PWH using ART in this cohort with no clear link to poor virologic outcomes.

Pharmacokinetic Data of Dolutegravir in Second-line Treatment of Children With Human Immunodeficiency Virus: Results From the CHAPAS4 Trial.

BACKGROUND: Dolutegravir (DTG), combined with a backbone of 2 nucleoside reverse transcriptase inhibitors, is currently the preferred first-line treatment for human immunodeficiency virus (HIV) in childhood. CHAPAS4 is an ongoing randomized controlled trial investigating second-line treatment options for children with HIV. We did a nested pharmacokinetic (PK) substudy within CHAPAS4 to evaluate the DTG exposure in children with HIV taking DTG with food as part of their second-line treatment. METHODS: Additional consent was required for children on DTG enrolled in the CHAPAS4 trial to participate in this PK substudy. Children weighing 14-19.9 kg took 25 mg DTG as dispersible tablets and children ≥20 kg took 50 mg film-coated tablets. Steady-state 24-hour DTG plasma concentration-time PK profiling was done at t = 0 and 1, 2, 4, 6, 8, 12, and 24 hours after observed DTG intake with food. Reference adult PK data and pediatric data from the ODYSSEY trial were used primarily for comparison. The individual target trough concentration (Ctrough) was defined as 0.32 mg/L. RESULTS: Thirty-nine children on DTG were included in this PK substudy. The geometric mean (GM) area under the concentration-time curve over the dosing interval (AUC0-24h) was 57.1 hours × mg/L (coefficient of variation [CV%], 38.4%), which was approximately 8% below the average AUC0-24h in children in the ODYSSEY trial with comparable dosages, but above the adult reference. The GM (CV%) Ctrough was 0.82 mg/L (63.8%), which was comparable to ODYSSEY and adult reference values. CONCLUSIONS: This nested PK substudy shows that the exposure of DTG taken with food in children on second-line treatment is comparable with that of children in the ODYSSEY trial and adult references. Clinical Trials Registration.ISRCTN22964075.

First Pharmacokinetic Data of Tenofovir Alafenamide Fumarate and Tenofovir With Dolutegravir or Boosted Protease Inhibitors in African Children: A Substudy of the CHAPAS-4 Trial.

BACKGROUND: We evaluated the pharmacokinetics of tenofovir alafenamide fumarate (TAF) and tenofovir in a subset of African children enrolled in the CHAPAS-4 trial. METHODS: Children aged 3-15 years with human immunodeficiency virus infection failing first-line antiretroviral therapy were randomized to emtricitabine/TAF versus standard-of-care nucleoside reverse transcriptase inhibitor combination, plus dolutegravir, atazanavir/ritonavir, darunavir/ritonavir, or lopinavir/ritonavir. Daily emtricitabine/TAF was dosed according to World Health Organization (WHO)-recommended weight bands: 120/15 mg in children weighing 14 to <25 kg and 200/25 mg in those weighing ≥25 kg. At steady state, 8-9 blood samples were taken to construct pharmacokinetic curves. Geometric mean (GM) area under the concentration-time curve (AUC) and the maximum concentration (Cmax) were calculated for TAF and tenofovir and compared to reference exposures in adults. RESULTS: Pharmacokinetic results from 104 children taking TAF were analyzed. GM (coefficient of variation [CV%]) TAF AUClast when combined with dolutegravir (n = 18), darunavir/ritonavir (n = 34), or lopinavir/ritonavir (n = 20) were 284.5 (79), 232.0 (61), and 210.2 (98) ng*hour/mL, respectively, and were comparable to adult reference values. When combined with atazanavir/ritonavir (n = 32), TAF AUClast increased to 511.4 (68) ng*hour/mL. For each combination, tenofovir GM (CV%) AUCtau and Cmax remained below reference values in adults taking 25 mg TAF with a boosted protease inhibitors. CONCLUSIONS: In children, TAF combined with boosted PIs or dolutegravir and dosed according to WHO-recommended weight bands provides TAF and tenofovir concentrations previously demonstrated to be well tolerated and effective in adults. These data provide the first evidence for use of these combinations in African children. CLINICAL TRIALS REGISTRATION: ISRCTN22964075.

Lamivudine and Emtricitabine Dosing Proposal for Children with HIV and Chronic Kidney Disease, Supported by Physiologically Based Pharmacokinetic Modelling.

Dose recommendations for lamivudine or emtricitabine in children with HIV and chronic kidney disease (CKD) are absent or not supported by clinical data. Physiologically based pharmacokinetic (PBPK) models have the potential to facilitate dose selection for these drugs in this population. Existing lamivudine and emtricitabine compound models in Simcyp® (v21) were verified in adult populations with and without CKD and in non-CKD paediatric populations. We developed paediatric CKD population models reflecting subjects with a reduced glomerular filtration and tubular secretion, based on extrapolation from adult CKD population models. These models were verified using ganciclovir as a surrogate compound. Then, lamivudine and emtricitabine dosing strategies were simulated in virtual paediatric CKD populations. The compound and paediatric CKD population models were verified successfully (prediction error within 0.5- to 2-fold). The mean AUC ratios in children (GFR-adjusted dose in CKD population/standard dose in population with normal kidney function) were 1.15 and 1.23 for lamivudine, and 1.20 and 1.30 for emtricitabine, with grade-3- and -4-stage CKD, respectively. With the developed paediatric CKD population PBPK models, GFR-adjusted lamivudine and emtricitabine dosages in children with CKD resulted in adequate drug exposure, supporting paediatric GFR-adjusted dosing. Clinical studies are needed to confirm these findings.

Exploring the Breastfeeding Desires and Decision-Making of Women Living with HIV in the Netherlands: Implications for Perinatal HIV Management in Developed Countries.

Introduction: Guidelines in high-income countries recommend women living with human immunodeficiency virus (HIV) to formula feed their newborns, because the possibility of mother-to-child-transmission of HIV during breastfeeding cannot be ruled out. It is an ongoing debate if the possible transmission risk outweighs the medical, cultural, psychological, and social importance of breastfeeding in women stable on current first-line suppressive antiretroviral regimens. The study aim was to explore breastfeeding desires and decision-making of immigrant and nonimmigrant women living with HIV in the Netherlands. Method: A questionnaire was administered orally or online to 82 women living with HIV in the Netherlands. The breastfeeding desires of the participants were collected as categorical data, and breastfeeding decision-making and willingness to adhere to additional monitoring were collected on a 5-point Likert scale. Categorical data were presented as proportions, and Likert scale data were presented in Likert scale bar plots. Results: Seventy-one percent of the participants expressed a desire to breastfeed in the future. The most important factors influencing decision-making to breastfeed were the chance of transmission of HIV to the infant and the advice by the doctor or nurse practitioner. Of the participants, 42% expressed their interest in breastfeeding with a <1/100 transmission risk. More than half of the participants expressed their interest to breastfeed with additional monitoring. Conclusions: A substantial proportion of the women living with HIV in the Netherlands has a desire to breastfeed, of which the majority are willing to adhere to additional monitoring to do so.

Brief Report: Suboptimal Lopinavir Exposure in Infants on Rifampicin Treatment Receiving Double-dosed or Semisuperboosted Lopinavir/Ritonavir: Time for a Change.

BACKGROUND: Although super-boosted lopinavir/ritonavir (LPV/r; ratio 4:4 instead of 4:1) is recommended for infants living with HIV and receiving concomitant rifampicin, in clinical practice, many different LPV/r dosing strategies are applied due to poor availability of pediatric separate ritonavir formulations needed to superboost. We evaluated LPV pharmacokinetics in infants with HIV receiving LPV/r dosed according to local guidelines in various sub-Saharan African countries with or without rifampicin-based tuberculosis (TB) treatment. METHODS: This was a 2-arm pharmacokinetic substudy nested within the EMPIRICAL trial (#NCT03915366). Infants aged 1-12 months recruited into the main study were administered LPV/r according to local guidelines and drug availability either with or without rifampicin-based TB treatment; during rifampicin cotreatment, they received double-dosed (ratio 8:2) or semisuperboosted LPV/r (adding a ritonavir 100 mg crushed tablet to the evening LPV/r dose). Six blood samples were taken over 12 hours after intake of LPV/r. RESULTS: In total, 14/16 included infants had evaluable pharmacokinetic curves; 9/14 had rifampicin cotreatment (5 received double-dosed and 4 semisuperboosted LPV/r). The median (IQR) age was 6.4 months (5.4-9.8), weight 6.0 kg (5.2-6.8), and 10/14 were male. Of those receiving rifampicin, 6/9 infants (67%) had LPV Ctrough <1.0 mg/L compared with 1/5 (20%) in the control arm. LPV apparent oral clearance was 3.3-fold higher for infants receiving rifampicin. CONCLUSION: Double-dosed or semisuperboosted LPV/r for infants aged 1-12 months receiving rifampicin resulted in substantial proportions of subtherapeutic LPV levels. There is an urgent need for data on alternative antiretroviral regimens in infants with HIV/TB coinfection, including twice-daily dolutegravir.

Renal function-based versus standard dosing of pemetrexed: a randomized controlled trial.

PURPOSE: Pemetrexed is a chemotherapeutic drug in the treatment of non-small cell lung cancer and mesothelioma. Optimized dosing of pemetrexed based on renal function instead of body surface area (BSA) is hypothesized to reduce pharmacokinetic variability in systemic exposure and could therefore improve treatment outcomes. The aim of this study is to compare optimized dosing to standard BSA-based dosing. METHODS: A multicenter randomized (1:1) controlled trial was performed to assess superiority of optimized dosing versus BSA-based dosing in patients who were eligible for pemetrexed-based chemotherapy. The individual exposure to pemetrexed in terms of area under the concentration-time curve (AUC) was determined. The fraction of patients attaining to a predefined typical target AUC (164 mg × h/L ± 25%) was calculated. RESULTS: A total of 81 patients were included. Target attainment was not statistically significant different between both arms (89% vs. 84% (p = 0.505)). The AUC of pemetrexed was similar between the optimized dosing arm (n = 37) and the standard of care arm (n = 44) (155 mg × h/L vs 160 mg × h/L (p = 0.436). CONCLUSION: We could not show superiority of optimized dosing of pemetrexed in patients with an adequate renal function does not show added value on the attainment of a pharmacokinetic endpoint, safety, nor QoL compared to standard of care dosing. CLINICAL TRIAL NUMBER: Clinicaltrials.gov identifier: NCT03655821.

Proposal for individualized dosing of eculizumab in atypical haemolytic uraemic syndrome: patient friendly and cost-effective.

BACKGROUND: Eculizumab is a lifesaving yet expensive drug for atypical haemolytic uraemic syndrome (aHUS). Current guidelines advise a fixed-dosing schedule, which can be suboptimal and inflexible in the individual patient. METHODS: We evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) [classical pathway (CP) activity levels] of eculizumab in 48 patients, consisting of 849 time-concentration data and 569 CP activity levels. PK-PD modelling was performed with non-linear mixed-effects modelling. The final model was used to develop improved dosing strategies. RESULTS: A PK model with parallel linear and non-linear elimination rates best described the data with the parameter estimates clearance 0.163 L/day, volume of distribution 6.42 L, maximal rate 29.6 mg/day and concentration for 50% of maximum rate 37.9 mg/L. The PK-PD relation between eculizumab concentration and CP activity was described using an inhibitory Emax model with the parameter estimates baseline 101%, maximal inhibitory effect 95.9%, concentration for 50% inhibition 22.0 mg/L and  Hill coefficient 5.42. A weight-based loading dose, followed by PK-guided dosing was found to improve treatment. On day 7, we predict 99.95% of the patients to reach the efficacy target (CP activity <10%), compared with 94.75% with standard dosing. Comparable efficacy was predicted during the maintenance phase, while the dosing interval could be prolonged in ∼33% of the population by means of individualized dosing. With a fixed-dose 4-week dosing interval to allow for holidays, treatment costs will increase by 7.1% and we predict 91% of the patients will reach the efficacy target. CONCLUSIONS: A patient-friendly individualized dosing strategy of eculizumab has the potential to improve treatment response at reduced costs.

Interchangeability of generic drugs for subpopulations: Bioequivalence simulation from a nonparametric PK model of gabapentin generic drugs.

Patients are often switched between generic formulations of the same drug, but in some cases generic interchangeability is questioned. For generic drugs to be approved, bioequivalence with the innovator drug should be demonstrated, but evidence of bioequivalence is not required in the intended patient population or relative to other approved generics. AIM: We aim to identify pathophysiological pharmacokinetic subpopulations for whom there is a difference in comparative bioavailability compared to a healthy population. METHODS: We used simulated exposures from a nonparametric model of multiple generics and the originator gabapentin. Exposure was simulated for virtual populations with pharmacokinetic characteristics beyond those of healthy subjects with regard to rate of absorption, volume of distribution and reduced renal function. Virtual parallel design bioequivalence studies were performed using a random sample of 24 simulated subjects, with standard acceptance criteria. RESULTS: Results indicated increased pharmacokinetic variability for patient populations with a lower rate of absorption or a reduced renal function, but no change in the average comparable bioavailability ratio. This increased variability results in a reduced likelihood of demonstrating bioequivalence. Observations were similar for comparisons between all different formulations, as well as between subjects who received the identical formulation in a repeated fashion. No relevant effect was observed for simulations with increased volume of distribution. CONCLUSION: Our simulations indicate that the reduced likelihood of demonstrating bioequivalence for subjects with altered pharmacokinetics is not influenced by a formulation switch, nor does the average comparable bioavailability ratio change, therefore these results support generic interchangeability and current approval requirements for generics.

HIV-1 resistance against dolutegravir fluctuates rapidly alongside erratic treatment adherence: a case report.

OBJECTIVES: We report a case of incomplete HIV-1 suppression on a dolutegravir, lamivudine, and abacavir single-tablet regimen with the emergence of the H51Y and G118R integrase resistance mutations. METHODS: Integrase sequencing was performed retrospectively by Sanger and next-generation sequencing. Rates of emergence and decline of resistance mutations were calculated using next-generation sequencing data. Dolutegravir plasma concentrations were measured by ultra-performance liquid chromatography-tandem mass spectrometry. The effects of H51Y and G118R on infectivity, fitness, and susceptibility to dolutegravir were quantified using cell-based assays. RESULTS: During periods of non-adherence to treatment, mutations were retrospectively documented only by next-generation sequencing. Misdiagnosis by Sanger sequencing was caused by the rapid decline of mutant strains within the retroviral population. This observation was also true for a M184V lamivudine-resistant reverse transcriptase mutation found in association with integrase mutations on single HIV genomes. Resistance rebound upon treatment re-initiation was swift (>8000 copies per day). Next-generation sequencing indicated cumulative adherence to treatment. Compared to WT HIV-1, relative infectivity was 73%, 38%, and 43%; relative fitness was 100%, 35%, and 10% for H51Y, G118R, and H51Y+G118R viruses, respectively. H51Y did not change the susceptibility to dolutegravir, but G188R and H51Y+G118R conferred 7- and 28-fold resistance, respectively. CONCLUSION: This case illustrates how poorly-fit drug-resistant viruses wax and wane alongside erratic treatment adherence and are easily misdiagnosed by Sanger sequencing. We recommend next-generation sequencing to improve the clinical management of incomplete virological suppression with dolutegravir.