Bioequivalence and Pharmacokinetics Study of Two Zidovudine/Lamivudine Tablets in Chinese Healthy Volunteers.

Zidovudine/lamivudine tablets are nucleoside reverse transcriptase inhibitors that are used to treat human immunodeficiency virus. The objective of this study was to investigate the bioequivalence and pharmacokinetics (PKs) of test and reference preparations of zidovudine/lamivudine tablets in healthy Chinese subjects. We designed a randomized, open, single-center, single-dose, 2-crossover experiment with a 7-day washout period involving 20 healthy subjects. The subjects were given a single dose of the test or reference preparation after fasting overnight for 10 hours. Blood samples were subsequently collected at scheduled time points from 0 hour (preadministration) up to 24 hours postadministration. The plasma concentrations of zidovudine and lamivudine were determined by a validated ultra-performance liquid chromatography-tandem mass spectrometry method. Analysis of variance (ANOVA) was used to compare differences in the mean values of key PK parameters between the 2 preparations. Bioequivalence was evaluated by 2 one-sided t-tests and 90% confidence intervals (CIs) of the geometric mean ratio (GMR). In total, 19 of the 20 subjects completed the trial. Based on the analysis of PK parameters, the relative bioavailability of zidovudine and lamivudine was 101.1% ± 2.0% and 100.3% ± 1.5%, respectively. ANOVA found no significant difference in primary PK parameters when compared between the 2 formulations, and the 90% CIs of the GMR of the 2 formulations were within the bioequivalence margins of 80%-125%. No serious adverse events occurred. Thus, we confirmed that the 2 preparations were bioequivalent in healthy Chinese volunteers. Our analysis demonstrated that both products showed good tolerance in all subjects.

Pharmacokinetics, Tolerability, and Safety of Doravirine and Doravirine/Lamivudine/Tenofovir Disoproxil Fumarate Fixed-Dose Combination Tablets in Adolescents Living With HIV: Week 24 Results From IMPAACT 2014.

BACKGROUND: We studied the pharmacokinetics (PK) and safety of 100-mg doravirine and doravirine/lamivudine/tenofovir disoproxil fumarate fixed-dose combination (100/300/300 mg DOR FDC) treatment in adolescents with HIV-1. METHODS: Adolescents ages 12 to younger than 18 years were enrolled in 2 sequential cohorts. Cohort 1 evaluated intensive PK and short-term safety of 100-mg single-dose doravirine in adolescents ≥35 kg. Cohort 2 participants either initiated treatment with DOR FDC (antiretroviral (ARV)-naïve) or switched to DOR FDC from a previous ARV regimen (virologically suppressed). The first 10 Cohort 2 participants had intensive PK evaluations, and safety, sparse PK, and HIV RNA were assessed through week 24. RESULTS: Fifty-five adolescents, median age 15.0 years and baseline weight 51.5 kg, were enrolled. Nine participants completed Cohort 1 PK assessments (8 of the 9 participants weighed ≥45 kg) and 45 initiated study drug in Cohort 2. The doravirine geometric mean (GM) AUC 0-∞ was 34.8 µM∙hour, and the GM C 24 was 514 nM after a single dose, with a predicted steady-state GM C 24,ss,pred of 690 nM. Cohort 2 enrolled adolescents weighing ≥45 kg. Plasma concentrations of doravirine, tenofovir, and lamivudine achieved by Cohort 2 participants were similar to those reported in adults. No drug-related serious or grade 3 or 4 adverse events occurred. Forty-two of 45 participants (93.3%; 95% CI: [81.7, 98.6]) achieved or maintained HIV-1 RNA <40 copies/mL. CONCLUSIONS: Doravirine and DOR FDC achieved target PK in adolescents with HIV-1. DOR FDC was well-tolerated and maintained excellent virologic efficacy through 24 weeks, offering a favorable option for adolescents.

Pharmacokinetics and Safety of the Abacavir/Lamivudine/Lopinavir/Ritonavir Fixed-Dose Granule Formulation (4-in-1) in Neonates: PETITE Study.

BACKGROUND: Antiretroviral options for neonates (younger than 28 days) should be expanded. We evaluated the pharmacokinetics, safety, and acceptability of the "4-in-1" fixed-dose pediatric granule formulation of abacavir/lamivudine/lopinavir/ritonavir (30/15/40/10 mg) in neonates. METHODS: The PETITE study is an ongoing phase I/II, open-label, single-arm, 2-stage trial conducted in South Africa. In stage 1, term neonates exposed to HIV on standard antiretroviral prophylaxis (nevirapine ± zidovudine) received single dose(s) of the 4-in-1 formulation, followed by intensive pharmacokinetic sampling and safety assessments. At each PK visit, blood was drawn after an observed dose at 1, 2, 4, 8, and 12 hours postdose. In this study, we have reported the planned interim pharmacokinetic and safety analysis after completion of the single-dose administration. RESULTS: Sixteen neonates, with a median (range) birth weight of 3130 g (2790-3590 g), completed 24 pharmacokinetic visits. The 4-in-1 formulation imposed relatively high doses of abacavir [8.6 mg/kg (6.6-11.4)] and lamivudine [4.3 mg/kg (3.3-5.7)] but lower doses of lopinavir [11.5 mg/kg (8.8-15.2)]. The geometric means (GM, 90% CI) AUC0-12 of abacavir, lamivudine, and lopinavir were 29.87 (26.29-33.93), 12.61 (10.72-14.83), and 3.49 (2.13-5.72) µg.h/mL, respectively. Lopinavir GM AUC0-12 was below the predefined target (20-100 µg.h/mL), and ritonavir concentrations were only detectable in 4 of the 120 (3%) samples. No adverse events were related to study drugs. No neonate had difficulty swallowing the 4-in-1 formulation. CONCLUSIONS: The high doses of abacavir and lamivudine (in mg/kg) and AUCs were safe, and the formulation was well tolerated; however, lopinavir/ritonavir exposures were extremely low, preventing its use in neonates use in neonates. Alternative pediatric solid antiretroviral formulations must be studied in neonates.

Hybrid Cyclic-Linear Cell-Penetrating Peptides Containing Alternative Positively Charged and Hydrophobic Residues as Molecular Transporters.

The cell membrane properties create a significant obstacle in intracellular delivery of cell-impermeable and negatively charged molecules. Herein, we report the synthesis and biological evaluation of a novel series of hybrid cyclic-linear peptides containing alternative positive and hydrophobic amino acids on the ring and side chain [(RW)5]K(RW)X (X = 1-5) to compare their molecular transporter efficiency. The peptides were synthesized through Fmoc solid-phase peptide synthesis. In vitro cytotoxicity of the peptides showed that the peptides did not exhibit any significant cytotoxicity at the concentration of 10 µM in human leukemia carcinoma cell line (CCRF-CEM), human ovarian adenocarcinoma cells (SK-OV-3), human epithelial embryonic kidney healthy (HEK-293), and human epithelial mammary gland adenocarcinoma cells (MDA-MB-231) after 3 h incubation. The cellular uptake of a fluorescence-labeled phosphopeptide (F'-GpYEEI) and anti-human immunodeficiency virus (HIV) drugs (lamivudine (F'-3TC), emtricitabine (F'-FTC), Stavudine (F'-d4T)), where F' is carboxyfluorescein, was measured in the presence of the peptides in CCRF-CEM and SK-OV-3 cells. Among all peptides, [(RW)5K](RW)5 (10 µM) was the most efficient transporter that improved the cellular uptake of F'-GpYEEI (2 µM) by 18- and 11-fold in CCRF-CEM and SK-OV-3, respectively, compared with F'-GpYEEI alone. Fluorescence-activated cell sorting (FACS) analysis results indicated that the cellular uptake of fluorescence-labeled peptide (F'-[(RW)5K](RW)5) was only partially inhibited by chlorpromazine as an endocytosis inhibitor after 3 h incubation in MDA-MB-231 cells. These data suggest the potential of this series of hybrid cyclic-linear peptides as cell-penetrating peptides and molecular transporters.

Pharmacokinetics, Safety, and Tolerability of a Single Oral Dose of Abacavir/Dolutegravir/Lamivudine Combination Tablets in Healthy Japanese Study Participants.

Pharmacokinetics, safety, and tolerability of abacavir 600 mg/dolutegravir 50 mg/lamivudine 300 mg were assessed in this phase 1, single-arm, open-label, single-dose study in fasted healthy male (n = 4) and female (n = 8) participants of Japanese heritage. Participants received a single dose of abacavir 600 mg/dolutegravir 50 mg/lamivudine 300 mg after an 8-hour fast, with safety assessments and blood samples for pharmacokinetic parameters collected through 72 hours after dosing. Geometric mean maximum plasma concentrations were 5.22 µg/mL (time to maximum concentration [tmax ], 1.01 hours) for abacavir, 4.13 µg/mL (tmax , 3.50 hours) for dolutegravir, and 3.35 µg/mL (tmax , 2.98 hours) for lamivudine. Geometric mean area under the concentration-time curve values were 18.20, 71.60, and 16.60 µg • h/mL for abacavir, dolutegravir, and lamivudine, respectively. No adverse events were reported, and no clinically significant findings were observed in laboratory values, physical examinations, or 12-lead electrocardiographic parameters. Single-tablet administration of abacavir 600 mg/dolutegravir 50 mg/lamivudine 300 mg was well tolerated in Japanese participants. Exposure to abacavir and lamivudine was comparable with that seen in previous studies. A modest increase in exposure to dolutegravir vs previous clinical studies was observed but is not expected to impact the clinical management of HIV-1 or increase the risk for adverse events.

Testicular disposition of clofarabine in rats is dependent on equilibrative nucleoside transporters.

Acute lymphoblastic leukemia (ALL) is the most common cancer in children and adolescents. Although the 5-year survival rate is high, some patients respond poorly to chemotherapy or have recurrence in locations such as the testis. The blood-testis barrier (BTB) can prevent complete eradication by limiting chemotherapeutic access and lead to testicular relapse unless a chemotherapeutic is a substrate of drug transporters present at this barrier. Equilibrative nucleoside transporter (ENT) 1 and ENT2 facilitate the movement of substrates across the BTB. Clofarabine is a nucleoside analog used to treat relapsed or refractory ALL. This study investigated the role of ENTs in the testicular disposition of clofarabine. Pharmacological inhibition of the ENTs by 6-nitrobenzylthioinosine (NBMPR) was used to determine ENT contribution to clofarabine transport in primary rat Sertoli cells, in human Sertoli cells, and across the rat BTB. The presence of NBMPR decreased clofarabine uptake by 40% in primary rat Sertoli cells (p = .0329) and by 53% in a human Sertoli cell line (p = .0899). Rats treated with 10 mg/kg intraperitoneal (IP) injection of the NBMPR prodrug, 6-nitrobenzylthioinosine 5'-monophosphate (NBMPR-P), or vehicle, followed by an intravenous (IV) bolus 10 mg/kg dose of clofarabine, showed a trend toward a lower testis concentration of clofarabine than vehicle (1.81 ± 0.59 vs. 2.65 ± 0.92 ng/mg tissue; p = .1160). This suggests that ENTs could be important for clofarabine disposition. Clofarabine may be capable of crossing the human BTB, and its potential use as a first-line treatment to avoid testicular relapse should be considered.

Pharmacokinetics and Safety of Zidovudine, Lamivudine, and Lopinavir/Ritonavir in HIV-infected Children With Severe Acute Malnutrition in Sub-Saharan Africa: IMPAACT Protocol P1092.

BACKGROUND: Severe acute malnutrition (SAM) may alter the pharmacokinetics (PK), efficacy, and safety of antiretroviral therapy. The phase IV study, IMPAACT P1092, compared PK, safety, and tolerability of zidovudine (ZDV), lamivudine (3TC), and lopinavir/ritonavir (LPV/r) in children with and without SAM. MATERIALS AND METHODS: Children living with HIV 6 to <36 months of age with or without World Health Organization (WHO)-defined SAM received ZDV, 3TC, and LPV/r syrup for 48 weeks according to WHO weight band dosing. Intensive PK sampling was performed at weeks 1, 12, and 24. Plasma drug concentrations were measured using liquid chromatography tandem mass spectrometry. Steady-state mean area under the curve (AUC0-12h) and clearance (CL/F) for each drug were compared. Grade ≥3 adverse events were compared between cohorts. RESULTS: Fifty-two children were enrolled across 5 sites in Africa with 44% (23/52) female, median age 19 months (Q1, Q3: 13, 25). Twenty-five children had SAM with entry median weight-for-height Z-score (WHZ) -3.4 (IQR -4.0, -3.0) and 27 non-SAM had median WHZ -1.0 (IQR -1.8, -0.1). No significant differences in mean AUC0-12h or CL/F were observed (P ≥ 0.09) except for lower 3TC AUC0-12h (GMR, 0.60; 95% CI, 0.4-1.0; P = 0.047) at week 12, higher ZDV AUC0-12h (GMR, 1.52; 1.2-2.0; P = 0.003) at week 24 in the SAM cohort compared with non-SAM cohort. Treatment-related grade ≥3 events did not differ significantly between cohorts (24.0% vs. 25.9%). CONCLUSION: PK and safety findings for ZDV, 3TC, and LPV/r support current WHO weight band dosing of syrup formulations in children with SAM.

Comparison of three galenic forms of lamivudine in young West African children living with Human Immunodeficiency Virus.

BACKGROUND: Few pharmacokinetic data were reported on dispersible tablets despite their increasing use. One hundred fifty HIV-infected children receiving lamivudine were enrolled in the MONOD ANRS 12,206 trial. Three galenic forms were administered: liquid formulation, tablet form and dispersible scored tablet. METHOD: HIV-infected children <4 years old were enrolled in the MONOD ANRS 12,206 trial designed to assess the simplification of a successful 12-months lopinavir-based antiretroviral treatment with efavirenz. Lamivudine plasma concentrations were analysed using nonlinear mixed effects modelling approach. RESULTS: One hundred and fifty children (age: 2.5 years (1.9-3.2), weight 11.1 (9.5-12.5) kg (median (IQR)) were included in this study. Over the study period, 79 received only the syrup form, 29 children switched from syrup form to tablet 3TC/AZT form, 36 from syrup to the orodispersible ABC/3TC form and two from the 3TC/AZT form to the orodispersible ABC/3TC form. The 630 lamivudine concentrations were best described by a two-compartment model allometrically scaled. Galenic form had no significant effect on 3TC pharmacokinetic. CONCLUSION: This trial provided an opportunity to compare three galenic forms (liquid formulation, tablet form and dispersible scored tablet) of lamivudine in the target population of young HIV-1-infected children. Galenic form had no significant effect on lamivudine pharmacokinetics.

Pharmacogenomics and pharmacokinetics of efavirenz 400 or 600 mg in 184 treatment-naive HIV-infected patients in China.

Background: The pharmacogenomics and pharmacokinetics/pharmacodynamics of 400 mg efavirenz have rarely been reported. Materials & methods: A total of 184 treatment-naive HIV-infected patients were randomly assigned (1:1) to receive a lower dose (tenofovir disoproxil 200 mg, efavirenz 400 mg and lamivudine) or a standard dose regimen. Relationships between pharmacogenomics and efavirenz pharmacokinetics/pharmacodynamics were explored at 48 weeks. Results: There was no relationship between pharmacogenomics and adverse reactions of the central nervous system and antiretoviral efficacy. CYP2B6 516G>T, 785A>G, 18492C>T and ABCB1 3435C>T T/C were associated with higher efavirenz plasma levels in the standard but not the lower dose group. No relationship was found between pharmacogenomics and antiretoviral efficacy. Patients who were <60 kg had higher efavirenz concentration compared with those with weight ≥60 kg when using 600 mg efavirenz, this was not observed with 400 mg efavirenz. Conclusion: The effect of pharmacogenomics and body weight on the efavirenz concentration was significant in the 600 mg group but not in the 400 mg group.

Mechanistic Insight into Antiretroviral Potency of 2'-Deoxy-2'-ß-fluoro-4'-azidocytidine (FNC) with a Long-Lasting Effect on HIV-1 Prevention.

In preclinical and phase I and II clinical studies, 2'-deoxy-2'-ß-fluoro-4'-azidocytidine (FNC) displays a potent and long-lasting inhibition of HIV-1 infection. To investigate its mechanism of action, we compared it with the well-documented lamivudine (3TC). Pharmacokinetic studies revealed that the intracellular retention of FNC triphosphate in peripheral blood mononuclear cells was markedly longer than that of the 3TC triphosphate. FNC selectively enters and is retained in HIV target cells, where it exerts long-lasting prevention of HIV-1 infection. In addition to inhibition of HIV-1 reverse transcription, FNC also restores A3G expression in CD4+ T cells in FNC-treated HIV-1 patients. FNC binds to the Vif-E3 ubiquitin ligase complex, enabling A3G to avoid Vif-induced ubiquitination and degradation. These data reveal the mechanisms underlying the superior anti-HIV potency and long-lasting action of FNC. Our results also suggest a potential clinical application of FNC as a long-lasting pre-exposure prophylactic agent capable of preventing HIV infection.

Zidovudine and lamivudine reach higher concentrations in ventricular than in lumbar human cerebrospinal fluid.

OBJECTIVE: For the treatment of HIV-1-related brain disease and for the prevention of the brain becoming a viral reservoir, it is important that antiretroviral agents reach sufficient concentrations in the CNS. To date, human brain pharmacokinetic data are solely derived from lumbar cerebrospinal fluid (CSF) and mostly originate from single samples. DESIGN: We determined concentrations of antiretroviral drugs in serial samples of ventricular CSF and compared these to the concentrations in serum and lumbar CSF of these patients. METHODS: Two treatment-naïve HIV-1-infected patients received external ventricular drainage for obstructive hydrocephalus. Starting with a combination antiretroviral regimen (cART), ventricular CSF, and subsequently lumbar CSF, with parallel serum, was frequently collected. Drug concentrations were determined and CSF-to-serum ratios were calculated. RESULTS: High concentrations, resulting in high CSF-to-serum ratios, were found in the ventricular CSF of the three substances zidovudine, lamivudine and indinavir, whereas this was not observed for stavudine, ritonavir, saquinavir and efavirenz. Concentrations of zidovudine and lamivudine were up to four times greater in CSF from the ventricles than in lumbar CSF of the same patient. The zidovudine concentrations in the ventricular CSF exceeded serum concentrations by a factor of 1.4. CONCLUSION: Unexpectedly high concentrations of some antiretrovirals in the ventricular CSF, the site close to the brain parenchyma where HIV is located, should be considered when the cART regimen is aiming at CNS viral replication.

Development of lamivudine liposomes by three-level factorial design approach for optimum entrapment and enhancing tissue targeting.

Aim: This work aimed to encapsulate lamivudine in liposomes for targeted delivery to HIV reservoirs and thereby reduce its side effects.Methods: The lamivudine liposomes were prepared by thin film hydration method using 32 factorial design and characterised for vesicle size, % drug entrapment efficiency, polydispersity index etc. Optimisation by graphical and numerical methods was carried out by fixing minimum and maximum limits for each response. In vivo plasma and tissue distribution of plain lamivudine and lamivudine encapsulated optimised liposomes were compared in rats.Results: The optimised liposomes displayed vesicle size 276.20 ± 13.36 nm, percent entrapment 60.20 ± 2.86% and PDI 0.291 ± 0.053. Compared to plain lamivudine, the liposomes were rapidly cleared from the plasma and displayed 10.97 ± 0.72 and 1.38 ± 0.52 fold accumulation in liver and spleen tissues respectively.Conclusions: Lamivudine encapsulated in liposomes remains in the body for a longer period of time with well distribution in tissues.

The effect of veno-arterial extracorporeal oxygenation and nasogastric tube administration on the pharmacokinetic profile of abacavir, lamivudine and dolutegravir: a case report.

BACKGROUND: Pharmacokinetic (PK) changes can affect antiretroviral (ARV) systemic exposure for critically ill patients living with HIV (CI-PLWH). Studies to guide ARV adjustments in this population are limited. METHODS: A PK analysis was conducted in a 44-year-old CI-PLWH who presented for a heart and lung transplant on veno-arterial extracorporeal membrane oxygenation (VA ECMO). Home ARV therapy (ART) of co-formulated abacavir/lamivudine/dolutegravir (ABC/3TC/DTG) was continued. ARV serum concentrations were obtained during and after VA ECMO. Two blood levels were drawn at 1 h, for maximum serum concentration (Cmax) and a serum trough (Ct). ARVs were given as a single tablet crushed via nasogastric tube. RESULTS: Area under the concentration-time curve (AUC0-t) was calculated using non-compartmental analysis. Cmax and AUC0-t were higher during VA ECMO compared with post-decannulation. The Cmax of ABC was >2.5-fold higher than the mean in the reference. Cmax and Ct post VA ECMO were within range of referenced literature for all ARVs. Cmax and AUC0-t of DTG post VA ECMO was approximately four- to fivefold lower than referenced literature. HIV virological suppression was maintained throughout the hospitalization. CONCLUSIONS: ART adjustments would not be required for this patient. Additional studies are needed to assess effects of VA ECMO and crushed tube administration of ARVs in CI-PLWH.

Influence of a herbal preparation on the pharmacokinetics of highly active antiretroviral therapy drugs in rats.

Shenlin Fuzheng Capsule (SLFZC) is a herbal preparation used for HIV/AIDS in Guangxi, China. This study was designed to evaluate the influence of SLFZC on the pharmacokinetics of highly active antiretroviral therapy (HAART) drugs, zidovudine (3'-azido-3'-deoythymidine, AZT), 2',3'-dideoxy-3'-thiacytidine (3TC) and efavirenz (EFV). Thirty-six male SD rats were divided into three groups. Group A was given a combination of AZT, 3TC and EFV (AZT/3TC/EFV). Group B rats were given AZT/3TC/EFV simultaneously with SLFZC. Group C rats were given AZT/3TC/EFV 2h prior to SLFZC. Blood samples were collected at fixed time intervals. Plasma concentration of each antiretroviral drug was tested for calculation of pharmacokinetic parameters. There was significant difference among groups with respect to t1/2 for AZT (F=3.371, P<0.05), but the Student-Newman-Keuls (SNK) pairwise multiple comparison procedure showed no statistical differences in all pairwise comparisons (P>0.05). There were no significant differences among groups in terms of Cmax, T max, AUC0-12h and CL for AZT, and t1/2, Cmax, Tmax, AUC0-12h and CL for 3TC and EFV, respectively. The results indicate that SLFZC has little impact on pharmacokinetic properties of AZT, 3TC and EFV.

Comparative Bioavailability of Oral Granule Formulations of the HIV Antiretroviral Drugs Doravirine, Lamivudine, and Tenofovir Disoproxil Fumarate.

Doravirine is a non-nucleoside reverse transcriptase inhibitor indicated for the treatment of human immunodeficiency virus-1 infection, available as a single tablet in combination with other antiretroviral agents or as a fixed-dose regimen with lamivudine and tenofovir disoproxil fumarate (TDF). Alternative formulations of these drugs are being developed for individuals who have difficulty swallowing tablets. Two phase 1 trials were conducted, both in 24 healthy adults, to assess the pharmacokinetics of uncoated and coated oral granule formulations of doravirine, lamivudine, and TDF administered alone and with vanilla pudding or apple sauce. The pharmacokinetics for all uncoated granules, and of coated lamivudine and TDF granules, were similar to those of currently marketed tablets (geometric mean ratios [GMRs] 0.92-1.04). Coated doravirine granules had decreased AUC0-∞ (11%) and Cmax (23%) values versus the tablet. The pharmacokinetics were similar for uncoated and coated doravirine granules administered with or without pudding (GMRs 0.96-1.10); administration with apple sauce increased doravirine AUC0-∞ (26-29%), Cmax (56-59%), and C24 (20-21%) versus administration of granules alone. Lamivudine granules administered with pudding or apple sauce decreased AUC0-∞ and Cmax (14-25%) versus granules alone. Tenofovir AUC0-∞, Cmax, and C24 increased for TDF granules administered with pudding or apple sauce versus alone (11-23%). Pharmacokinetic differences when administering doravirine, lamivudine, or TDF as uncoated or coated granules versus tablets, or when granules were administered with (versus without) pudding or apple sauce, are not considered clinically meaningful, supporting further development of these granule formulations.

Case Report of Increased Exposure to Antiretrovirals following Sleeve Gastrectomy.

Bariatric surgery is increasingly performed in morbidly obese HIV patients. Limited data exist regarding antiretroviral drug exposure after bariatric surgery. We report a case of a morbidly obese HIV patient who underwent sleeve gastrectomy. Abacavir, lamivudine, and dolutegravir therapeutic drug monitoring was performed at several time points pre- and postsurgery. Significantly increased levels were measured, particularly for abacavir, whose levels increased ∼12-fold. Several mechanistic explanations for these findings are discussed.

Using PBPK Modeling to Predict Drug Exposure and Support Dosage Adjustments in Patients With Renal Impairment: An Example with Lamivudine.

BACKGROUND: Lamivudine is a nucleoside reverse transcriptase inhibitor used to treat HIV and hepatitis B. It is primarily cleared by the kidney with renal secretion mediated by OCT2 and MATE. OBJECTIVE: To use PBPK modeling to assess the impact of renal impairment on lamivudine pharmacokinetics using the Simcyp® Simulator. METHODS: The model incorporated the Simcyp® Mechanistic Kidney Model option to predict renal disposition. The model was initially verified using the Simcyp® Healthy Volunteer population. Two discrete patient populations were then created for moderate (GFR 10-40 mL/min) and severe (GFR < 10 mL/min) renal failure (RF), and model simulations were compared to published data. The developed model was then utilized in a clinical study evaluating the clinical experience and plasma exposure of lamivudine when administered at higher than recommended doses to HIV-infected patients with varying degrees of renal impairment. RESULTS: Predicted systemic exposure metrics (Cmax, AUC) compared favorably to published clinical data for each population, with the following fold errors (FE, ratio of predicted and observed data) for Cmax/AUC: Healthy Volunteers 1.04/1.04, Moderate RF 1.03/0.78, Severe RF 0.89/0.79. The model captured lamivudine plasma concentrations measured pre- and post-dose (0.5-1.5hr) in study participants (n = 34). Model simulations demonstrated comparable systemic profiles across patient cohorts, supporting the proposed dosage adjustment scheme. CONCLUSION: This study illustrates how PBPK modeling can help verify dosing guidelines for patients with varying levels of renal impairment. This approach may also be useful for predicting potential changes in exposure during renal insufficiency for compounds undergoing clinical development.

Pharmacokinetic profiles of boosted darunavir, dolutegravir and lamivudine in aging people living with HIV.

OBJECTIVES: The pharmacokinetics of antiretroviral drugs may differ in elderly people living with HIV (PLWH) because of age-related physiological changes. We aimed to assess the pharmacokinetics of several antiretroviral drugs in aging PLWH enrolled in the Swiss HIV Cohort (SHCS). DESIGN: Full pharmacokinetic profiling nested in a multicenter, observational, prospective cohort study. Additional collection of single point pharmacokinetic data during SHCS follow-up visits (unselected PLWH). METHODS: PLWH were eligible for the full pharmacokinetics investigation if they were over the age of 55 years, on a stable boosted darunavir-containing or dolutegravir-containing regimen. Single point measurements were prospectively collected during SHCS follow-up visits to compare antiretroviral drug exposure in aging (≥65 years) and younger (<65 years) PLWH. RESULTS: Nineteen PLWH with a median age of 64 years participated in the full pharmacokinetic investigations. Single point pharmacokinetic data were collected for 804 PLWH with a median age of 52 years. Boosted darunavir clearance was 40% lower in aging (≥65 years) compared with younger (<65 years) PLWH, consistent with other drugs predominantly metabolized by CYP3A. Dolutegravir exposure was similar between age groups whereas lamivudine exposure increased by 11% in aging PLWH. Median boosted darunavir, dolutegravir and lamivudine t1/2 were 148%, 45% and 32% higher in aging compared with younger PLWH. CONCLUSION: Advanced age did not affect boosted darunavir exposure to a clinically significant extent despite the observed high variability in exposure. Age minimally affected dolutegravir and lamivudine exposure. Thus, dose adjustment based on age is a priori not warranted.

Bioequivalence and Food Effect Assessment of 2 Fixed-Dose Combination Formulations of Dolutegravir and Lamivudine.

This single-dose study evaluated the bioequivalence, food effect, and safety of 2 experimental, 2-drug, fixed-dose formulations of 50 mg dolutegravir and 300 mg lamivudine (formulation AH and formulation AK) as compared with coadministration of single-entity tablets of 50 mg dolutegravir and 300 mg lamivudine (reference). In fasted subjects, formulation AH lamivudine exposure was similar to the reference; however, dolutegravir exposure was consistently higher in formulation AH, with area under the concentration-time curve (AUC) and maximum concentration (Cmax ) approximately 27% to 28% greater than reference. Formulation AK met bioequivalence standards to the reference for dolutegravir (AUC0-∞ and Cmax ) and lamivudine (AUC0-∞ and AUC0-t ) exposure; however, dolutegravir AUC0-t and lamivudine Cmax were approximately 16% and 32% higher than the reference, respectively. A high-fat meal increased dolutegravir AUC and Cmax by up to 33% and 21%, respectively, and decreased lamivudine Cmax by approximately 30%. Both test and reference formulations were well tolerated. The results support further development of formulation AK as a novel, 2-drug, fixed-dose combination tablet treatment for patients with HIV.