The role of therapeutic drug monitoring in the management of patients with human immunodeficiency virus infection

Antiretroviral therapeutic drug monitoring in a patient with small bowel resection and new HIV diagnosis

Antiretroviral (ARV) absorption in persons living with human immunodeficiency virus (PLWH, HIV) with short bowel syndrome is limited. We describe a case of a 28-year-old male with newly diagnosed HIV and plasmablastic lymphoma with proximal jejunostomy necessitating parenteral nutrition. ARV therapy with dolutegravir 50 mg twice daily and once daily tenofovir/emtricitabine was initiated with documented malabsorption and delayed virologic suppression (VS). Dolutegravir dose titration with therapeutic drug monitoring (TDM) resulted in VS at month 12. ARV TDM with dose titration is an option for PLWH with malabsorptive states to maintain VS.

Is Routine Therapeutic Drug Monitoring of Anti-Retroviral Agents Warranted in Children Living with HIV?

OBJECTIVE

The utility of routine therapeutic drug monitoring (TDM) in children living with HIV has not been extensively studied. The purpose of this study was to assess this strategy.

METHODS

This was a single-center, prospective observational study of routine TDM for protease inhibitors (PIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and integrase strand transfer inhibitors (INSTIs) in children living with HIV who were receiving antiretroviral therapy (ART) between February and December 2014. Outcome measures included the proportion of serum antiretroviral (ARV) medication concentrations in the therapeutic range (target values extrapolated from adult data) and the effect of serum concentrations on virologic control, medication adherence, and toxicity.

RESULTS

Forty-eight children with a median age of 13 years (interquartile range, 3–18) were included. Median viral load (VL) and CD4% were <40 copies/mL (range, <40–124) and 37.4% (range, 8.4–47.9), respectively. Adherence was considered excellent in 95.8% of patients. Of the 50 serum trough concentrations (PI n = 19 [38%]; NNRTI n = 27 [54%]; INSTI n = 4 [8%]), 66% (n = 33) were in the therapeutic range, 12% (n = 6) were subtherapeutic, and 22% (n = 11) were supratherapeutic. There was no statistically significant correlation between serum ARV concentrations and patient demographics, VL, CD4%, or adherence. No clinically significant adverse events were noted. One dose adjustment was made for a subtherapeutic serum raltegravir concentration, likely attributable to interaction with ritonavir.

CONCLUSIONS

This study does not support routine TDM in healthy children living with HIV who are well controlled on antiretroviral medication regimens. A more targeted strategy, such as when adherence is questioned or when there are suspected drug interactions, may be more appropriate.

Seasonal Variation of Antiretroviral Drug Exposure during the Year: The Experience of 10 Years of Therapeutic Drug Monitoring

Although studies show an annual trend for immunosuppressive drugs, particularly during different seasons, no data are available for antiretroviral drugs exposures in different periods of the year. For this reason, the aim of this study was to investigate an association between seasonality and antiretroviral drugs plasma concentrations. Antiretroviral drugs exposures were measured with liquid chromatography validated methods. A total of 4148 human samples were analysed. Lopinavir, etravirine and maraviroc levels showed seasonal fluctuation. In detail, maraviroc and etravirine concentrations decreased further in summer than in winter. In contrast, lopinavir concentrations had an opposite trend, increasing more in summer than in winter. The etravirine efficacy cut-off value of 300 ng/mL seems to be affected by seasonality: 77.1% and 22.9% of samples achieved this therapeutic target, respectively, in winter and summer, whereas 30% in winter and 70% in summer did not reach this value. Finally, age over 50 years and summer remained in the final multivariate regression model as predictors of the etravirine efficacy cut-off. This study highlights the seasonal variation in antiretroviral drugs plasma concentrations during the year, leading to a better understanding of inter-individual variability in drug exposures. Studies are required in order to confirm these data, clarifying which aspects may be involved.

Influence of SULT1A1*2 Polymorphism on Plasma Efavirenz Concentration in Thai HIV-1 Patients

Purpose

Plasma efavirenz (EFV) concentrations within therapeutic levels are essential to successfully treat patients suffering from human immunodeficiency virus (HIV) type 1. In addition to the drug-metabolizing enzyme CYP2B6, other phase II drug-metabolizing enzymes and transporters may have an important role in the pharmacokinetics of EFV. Thus, the influence of phase II drug-metabolizing enzymes and drug transporters on plasma EFV levels was investigated in Thai HIV patients receiving EFV.

Patients and Methods

Genotyping was performed by TaqMan^® real-time PCR in 149 HIV-infected Thai adults, and plasma efavirenz concentration was measured by a validated high-performance liquid chromatography in 12 hours after dosing steady-state plasma samples at week 12 and 24.

Results

Patients with three or more copies of SULT1A1 had significantly lower median plasma EFV concentrations than those carrying two copies at week 12 (p=0.046) and SULT1A1*2 (c.638G>A) carriers had significantly lower median plasma EFV concentrations compared to those not carrying the variant at week 24 (p=0.048). However, no significant association was found after adjusting for CYP2B6 genotype.

Conclusion

Genetic variation in a combination of SULT1A1*2 and SULT1A1 copy number may contribute to variability in EFV metabolism and thereby may impact drug response. The influence of a combination between the SULT1A1 and CYP2B6 genotype on EFV pharmacokinetics should be further investigated in a larger study population.

Therapeutic Drug Monitoring of HIV Antiretroviral Drugs in Pregnancy: A Narrative Review

To date, therapeutic drug monitoring (TDM) has played an important role in the management of pregnant HIV patients on highly active antiretroviral therapy. Historically, in pregnant women living with HIV, the third agent in triple therapy has been either non-nucleoside reverse transcriptase inhibitors or protease inhibitors (PIs). PIs have been the preferred agents because of their robustness from the perspective of viral resistance and the dominant drug class for the management of HIV during pregnancy for the previous decade. As with many drugs used during pregnancy, pharmacokinetic changes decrease exposure to these agents as the pregnancy progresses. This can lead to viral escape at the time of pregnancy and ultimately increase the risk of mother-to-child transmission (MTCT) of HIV. TDM has been well-established for this class of highly active antiretroviral therapy, and appropriate dose adjustment studies have been performed. At present, there is a shift from the traditional treatment paradigm in pregnancy to a new drug class, integrase strand transfer inhibitors (INSTIs). Although INSTIs are affected by pharmacokinetic changes during pregnancy, they do not harbor the same issues with viral escape as seen with PIs at birth and in general eliminate the need for boosting with additional agents like ritonavir (r) and cobicistat (c) [bar elvitegravir (EVG)] that can lead to interactions with treatment of other common infections in HIV, including tuberculosis. Furthermore, INSTIs are the most successful medication for rapidly reducing the viral load (VL) in HIV patients, a useful factor where VL may be unknown, or in late presenters. These merits make INSTIs the best choice in pregnancy, although their use has been hindered in recent years by a report of neural tube defects from a large African study with dolutegravir (DTG). New data from Botswana and Brazil indicate that this risk is less significant than previously reported, necessitating further data to shed light on this critical issue. Current international guidelines including DHHS, EACS, WHO, and BHIVA (for patients with VLs >100,000 copies/mL or late presenters) now recommend INSTIs as first-line agents. The role of TDM in INSTIs shifts to cases of insufficient viral suppression with standard adherence measures, cases of drug-drug interactions, or cases where EVG/c is continued throughout pregnancy, and thus remains an important aspect of HIV care in pregnancy.

Impact of Therapeutic Drug Monitoring of Antiretroviral Drugs in Routine Clinical Management of People Living With HIV: A Narrative Review

BACKGROUND

The treatment of HIV infection has evolved significantly since the advent of highly active antiretroviral therapy. As a result, a response rate of 90%-95% now represents a realistically achievable target. Given this background, it is difficult to imagine the additional benefits that therapeutic drug monitoring (TDM) could provide in the management of HIV infection.

METHODS

This article is not intended to provide a systematic literature review on TDM of antiretroviral agents; rather, the authors aim to discuss the potential added value of TDM in the optimal management of people living with HIV (PLWH) in selected real-life clinical scenarios based on data collected over 10 years by their TDM service.

RESULTS

Some clinical situations, in which the selection of the optimal antiretroviral therapy is challenging, have been identified. These include poorly compliant patients, suboptimal antiretroviral therapies (in terms of both efficacy and toxicity), polypharmacy with a high risk of drug-drug interactions, and different patient populations, such as pregnant women.

CONCLUSIONS

The transformation of HIV infection from a near-universally fatal illness to a lifelong chronic disease has resulted in an HIV population that is growing and aging, placing new and increasing demands on public programs and health services. Increasingly, the management of comorbidities, polypharmacy, and drug-drug interaction, and their impact on antiretroviral therapy will have to be undertaken. These clinical settings represent some of the new frontiers for the use of TDM with the goal of achieving optimal prescription and outcome for PLWH.

Reliability and Validity of a Brief Self-Report Adherence Measure among People with HIV Experiencing Homelessness and Mental Health or Substance Use Disorders

The study examines the reliability and validity of a 3-item self-report adherence measure among people with HIV (PWH) experiencing homelessness, substance use, and mental health disorders. 336 participants were included from nine sites across the US between September 2013 and February 2017. We assessed the validity of a self-report scale for adherence to antiretroviral therapy by comparing it with viral load (VL) abstracted from medical records at baseline, 6, 12, and 18 months. The items had high internal consistency (Cronbach's alpha coefficients at each time point were > 0.8). The adherence scale scores were higher in the group that achieved VL suppression compared to the group that did not. The c-statistic for the receiver-operating characteristic curves pooled across time points was 0.77 for each adherence sub-item and 0.78 for the overall score. The self-report adherence measure shows good internal consistency and validity that correlated with VL suppression in homeless populations.

HIV-1 re-suppression on a first-line regimen despite the presence of phenotypic drug resistance

We have previously reported on HIV-1 infected patients who fail anti-retroviral therapy but manage to re-suppress without a regimen change despite harbouring major drug resistance mutations. Here we explore phenotypic drug resistance in such patients in order to better understand this phenomenon. Patients (n = 71) failing a non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimen, but who subsequently re-suppressed on the same regimen, were assessed for HIV-1 genotypic drug resistance through Sanger sequencing. A subset (n = 23) of these samples, as well as genotypically matched samples from patients who did not re-suppress (n = 19), were further assessed for phenotypic drug resistance in an in vitro single cycle assay. Half of the patients (n = 36/71, 51%) harboured genotypic drug resistance, with M184V (n = 18/36, 50%) and K103N (n = 16/36, 44%) being the most prevalent mutations. No significant difference in the median time to re-suppression (31–39 weeks) were observed for either group (p = 0.41). However, re-suppressors with mutant virus rebounded significantly earlier than those with wild-type virus (16 vs. 33 weeks; p = 0.014). Similar phenotypic drug resistance profiles were observed between patients who re-suppressed and patients who failed to re-suppress. While most remained susceptible to stavudine (d4T) and zidovudine (AZT), both groups showed a reduced susceptibility to 3TC and NNRTIs. HIV- 1 infected patients on an NNRTI-based regimen can achieve viral re-suppression on the same regimen despite harbouring viruses with genotypic and phenotypic drug resistance. However, re-suppression was less durable in those with resistance, reinforcing the importance of appropriate regimen choices, ongoing viral load monitoring and adherence counselling.

DRUGPATH: The Drug Gene Pathway Meta-Database

The complexity of modern-day diseases often requires drug treatment therapies consisting of multiple pharmaceutical interventions, which can lead to adverse drug reactions for patients. A priori prediction of these reactions would not only improve the quality of life for patients but also save both time and money in regards to pharmaceutical research. Consequently, the drug-gene-pathway (DRUGPATH) meta-database was developed to map known interactions between drugs, genes, and pathways among other information in order to easily identify potential adverse drug events. DRUGPATH utilizes expert-curated sources such as PharmGKB, DrugBank, and the FDA's NDC database to identify known as well as previously unknown/overlooked relationships, and currently contains 12,940 unique drugs, 3933 unique pathways, 5185 unique targets, and 3662 unique genes. Moreover, there are 59,561 unique drug-gene interactions, 77,808 unique gene-pathway interactions, and over 1 million unique drug-pathway interactions.

Pharmacokinetics, Placental and Breast Milk Transfer of Antiretroviral Drugs in Pregnant and Lactating Women Living with HIV

BACKGROUND

Remarkable progress has been achieved in the identification of HIV infection in pregnant women and in the prevention of vertical HIV transmission through maternal antiretroviral treatment (ART) and neonatal antiretroviral drug (ARV) prophylaxis in the last two decades. Millions of women globally are receiving combination ART throughout pregnancy and breastfeeding, periods associated with significant biological and physiological changes affecting the pharmacokinetics (PK) and pharmacodynamics (PD) of ARVs. The objective of this review was to summarize currently available knowledge on the PK of ARVs during pregnancy and transport of maternal ARVs through the placenta and into the breast milk. We also summarized main safety considerations for in utero and breast milk ARVs exposures in infants.

METHODS

We conducted a review of the pharmacological profiles of ARVs in pregnancy and during breastfeeding obtained from published clinical studies. Selected maternal PK studies used a relatively rich sampling approach at each ante- and postnatal sampling time point. For placental and breast milk transport of ARVs, we selected the studies that provided ratios of maternal to the cord (M:C) plasma and breast milk to maternal plasma (M:P) concentrations, respectively.

RESULTS

We provide an overview of the physiological changes during pregnancy and their effect on the PK parameters of ARVs by drug class in pregnancy, which were gathered from 45 published studies. The PK changes during pregnancy affect the dosing of several protease inhibitors during pregnancy and limit the use of several ARVs, including three single tablet regimens with integrase inhibitors or protease inhibitors co-formulated with cobicistat due to suboptimal exposures. We further analysed the currently available data on the mechanism of the transport of ARVs from maternal plasma across the placenta and into the breast milk and summarized the effect of pregnancy on placental and of breastfeeding on mammal gland drug transporters, as well as physicochemical properties, C:M and M:P ratios of individual ARVs by drug class. Finally, we discussed the major safety issues of fetal and infant exposure to maternal ARVs.

CONCLUSIONS

Available pharmacological data provide evidence that physiological changes during pregnancy affect maternal, and consequently, fetal ARV exposure. Limited available data suggest that the expression of drug transporters may vary throughout pregnancy and breastfeeding thereby possibly impacting the amount of ARV crossing the placenta and secreted into the breast milk. The drug transporter's role in the fetal/child exposure to maternal ARVs needs to be better understood. Our analysis underscores the need for more pharmacological studies with innovative study design, sparse PK sampling, improved study data reporting and PK modelling in pregnant and breastfeeding women living with HIV to optimize their treatment choices and maternal and child health outcomes.

Sustained virologic suppression with abacavir, emtricitabine, and crushed dolutegravir and tenofovir alafenamide in a patient with HIV and eosinophilic esophagitis

We report the use of crushed dolutegravir (DTG) and tenofovir alafenamide (TAF) tablets in a 27-year-old man with progressive dysphagia due to eosinophilic esophagitis, which severely limited compliance, leading to viral resistance. Based on his drug resistance history, allergies, and inability to swallow tablets intact, he was transitioned to DTG 50 mg (crushed), TAF 25 mg (crushed), liquid abacavir (20 mg/ml) 30 ml, and liquid emtricitabine (10 mg/ml) 24 ml orally daily. After receiving this regimen for five months, the patient’s HIV viral load decreased from 9910 to 59 copies/ml and after ten total months became suppressed at <20 copies/ml. Our case report suggests administration of crushed DTG and TAF tablets may be a viable option for patients with dysphagia and limited treatment options.

Using a Self-Administered Electronic Adherence Questionnaire to Identify Poor Adherence Amongst Adolescents and Young Adults on First-Line Antiretroviral Therapy in Johannesburg, South Africa

INTRODUCTION

The best method to measure adherence to antiretroviral therapy (ART) in resource-limited settings has not yet been established, particularly among adolescents and young adults (AYAs). The use of mobile technology may address the need for standardized tools in measuring adherence in this often marginalized population.

METHODS

We conducted a cross-sectional validation study among AYAs (18-35 years) attending a South African HIV clinic between 07/2015-09/2017. We determine the diagnostic accuracy of two modes of delivering an adherence questionnaire (self-administered electronic vs interviewer-administered paper-adherence questionnaire) comprising two self-reported adherence tools (South African National Department of Health (NDoH) adherence questionnaire and the Simplified Medication Adherence Questionnaire (SMAQ)) to identify poor adherence compared to; 1) a detectable viral load (≥1000 copies/mL) and 2) a sub-optimal concentration of efavirenz (EFV) (EFV ≤1.00 µg/mL) measured by therapeutic drug monitoring (TDM).

RESULTS

Of 278 included participants, 7.1% and 7.3% completing the electronic- and paper-questionnaires had a detectable viral load, while 14.7% and 16.5% had a sub-optimal concentration of EFV, respectively. According to viral load monitoring, the electronic-adherence questionnaire had a higher sensitivity (Se) in detecting poor adherence than the paper-based version across the NDoH adherence questionnaire (Se: 63.6% vs 33.3%) and SMAQ (Se: 90.9% vs 66.7%). In contrast, when using blood drug concentration (EFV ≤1.00 µg/mL), the paper-adherence questionnaire produced a higher sensitivity across both adherence tools; namely the NDoH adherence questionnaire (Se: 50.0% vs 38.1%) and SMAQ (Se: 75.0% vs 57.1%).

CONCLUSION

When using more accurate real-time measures of poor adherence such as TDM in this young adult population, we observe a higher sensitivity of an interviewer-administered paper-adherence questionnaire than an identical set of self-administered adherence questions on an electronic tablet. An interviewer-administered questionnaire may elicit more accurate responses from participants through a sense of increased accountability when engaging with health care workers.

Metabolic syndrome and endocrine status in HIV-infected transwomen

BACKGROUND

HIV-infected transwomen face multiple specific issues. Economic and social marginalization, sex work, substance abuse, hormonal consumption and silicone injection may affect the course of HIV infection and lead to metabolic and endocrine complications.

METHODS

A matched case-control study was performed between 2013 and 2015 in a University Hospital and compared metabolic syndrome (MetS), thyroid and adrenal functions in HIV-infected transwomen (i.e. cases) and cisgender HIV-infected men (i.e. controls) matched for age and antiretroviral therapy. The interaction between hormonal consumption, the course of HIV infection and antiretroviral therapy was also studied. Clinical and biological data (CD4 cell count, HIV RNA load, antiretroviral plasma drug concentration, HDL, triglycerides, glucose, cortisol, thyroid stimulating hormone, free thyroxine, prolactine) were measured.

RESULTS

A total of 292 HIV-infected patients (100 cases and 192 controls) were prospectively included. There was no difference between the two populations in terms of frequency of MetS, but subclinical hypothyroidism and adrenal insufficiency were more frequent in cases than in controls with, respectively, 12 vs. 3% (P < 0.002) for hypothyroidism and 20 vs. 8% (P < 0.001) for adrenal insufficiency. Prolactinemia, only performed in transwomen, was often elevated (21%) but rarely confirmed as true active hyperprolactinemia (monomeric form) (3%). Although hormonal intake was frequent among transwomen (31%), no impact on antiretroviral bioavailability and efficacy was detected.

CONCLUSION

In this study, no increase in the prevalence of MetS was detected in HIV-infected transwomen patients. In contrast, adrenal and thyroid functions abnormalities were frequent and should be systematically assessed in this population. No impact of hormonal intake on antiretroviral bioavailability and efficacy was detected.

Crushed dolutegravir/abacavir/lamivudine given via nasogastric tube in gastric outlet obstruction caused by cancer resulted in rapid viral load suppression

Alternative modes of antiretroviral administration are sought for people with impaired intestinal passage and/or absorption. We present a case of late HIV diagnosis (CD4+ count 160 cells/µL) with gastric outlet obstruction due to stomach adenocarcinoma. Co-morbidities included oesophageal candidiasis, Helicobacter pylori-positive duodenal ulcers and cytomegalovirus duodenitis. The gastric outlet obstruction required total parenteral nutrition and parenteral medication during four weeks of diagnostic work-up leading to pyloric resection. Crushed dolutegravir, abacavir and lamivudine were administered during this time in the evening via nasogastric tube, which was kept clamped overnight. The tube was unclamped in the morning and stomach content was drained during the daytime. This mode of administration resulted in rapid and sustained viral load suppression (from 300,000 to 115 copies per mL in 28 days, 81 copies/mL after 42 days of treatment and less than 40 copies/mL thereafter). Therapeutic drug monitoring confirmed sufficient antiretroviral plasma levels during this mode of administration. The absorption of crushed dolutegravir, abacavir and lamivudine in the stomach may be considered in people with questionable gastrointestinal passage or impaired gastric emptying to achieve viral load suppression.

Antiretroviral considerations in HIV-infected patients undergoing bariatric surgery

WHAT IS KNOWN AND OBJECTIVE

With the advent of antiretroviral therapy and the resultant decrease in mortality among adults living with human immunodeficiency virus (HIV), there is now an increased incidence of obesity and obesity-related comorbidities in these patients. Bariatric surgery is becoming an increasingly common treatment option for patients who are classified as clinically obese. There are limited data regarding the use of antiretroviral therapy in patients who have undergone bariatric surgery. The purpose of this review was to evaluate the available literature regarding antiretroviral therapy and pharmaceutical properties in this special population.

METHODS

Literature review was performed through PubMed, utilizing search terms of bariatric surgery, sleeve gastrectomy, Roux-en-Y, HIV infection, obesity and antiretroviral. Direct medical information requests to antiretroviral pharmaceutical manufacturers were also completed.

RESULTS

Several case series and case reports have been published which demonstrate minimal risk of complications and maintenance of virologic suppression in the vast majority of patients. Bariatric surgery appears to be an effective mechanism for assistance in controlling obesity in patients infected with HIV; however, numerous factors may impact the safe and effective use of antiretroviral therapy.

WHAT IS NEW AND CONCLUSION

Due to the physiologic changes and postoperative management following bariatric surgery, evaluation of the patients' medication regimens must be considered and several factors should be taken into account when choosing the appropriate antiretroviral regimen for these patients. Furthermore, communication between the patients' surgeon, HIV provider and a clinical pharmacist should occur prior to surgery to ensure the patient is optimized to achieve the best outcome including maintaining virologic suppression.

Plasma trough concentrations of antiretrovirals in HIV-infected persons treated with direct-acting antiviral agents for hepatitis C in the real world

Background

Possible drug-drug interactions (DDIs) between antiretrovirals (ARVs) and direct-acting antiviral agents (DAAs) are of some concern.

Objectives

To investigate ARV plasma trough concentrations (Ctrough) before and during DAAs in patients treated in the real world.

Methods

Single-centre, prospective, observational study including HIV/HCV coinfected persons undergoing DAA treatment. Self-reported adherence was assessed and ARVs Ctrough measured by HPLC-UV. Blood samples were collected before and after 2 months of DAA treatment.

Results

One-hundred and thirty-seven patients were included: 21.2% treated with ombitasvir/paritaprevir/ritonavir ± dasabuvir (2D/3D) and 78.8% with sofosbuvir-based regimens. Suboptimal Ctrough before and during DAA was found, respectively, in 3 (10.3%) and 3 (10.3%) cases treated with 2D/3D, and 16 (14.8%) and 11 (10.2%) with sofosbuvir-based regimens, even if self-reported ARV adherence was always ≥93%. In 2D/3D-treated patients, median darunavir Ctrough during DAAs was significantly lower than observed before DAAs [1125 ng/mL (IQR, 810-1616) versus 1903 ng/mL (IQR 1387-3983), respectively] (n = 5; P = 0.009), with a 40.9% decrease. In the same group, no differences in atazanavir or raltegravir concentrations were found. In patients treated with sofosbuvir-based regimens, Ctrough of all ARVs were similar before and during DAAs.

Conclusions

In the real world of HIV/HCV coinfected patients, ARV plasma concentrations during DAAs were generally not different from those found before anti-HCV treatment. Although assessed in a small number of patients, darunavir concentrations during 2D/3D showed a significant reduction when compared with those found before DAAs. ARV plasma concentrations measurement during anti-HCV treatment may give useful information for managing HIV/HCV coinfected persons receiving treatment for both infections.

Hollow mesoporous structured molecularly imprinted polymer as adsorbent in pipette-tip solid-phase extraction for the determination of antiretrovirals from plasma of HIV-infected patients

In this work a hollow mesoporous structured molecularly imprinted polymer was synthetized and used as adsorbent in pipette-tip solid-phase extraction for the determination of lamivudine (3TC), zidovudine (AZT) and efavirenz (EFZ) from plasma of human immunodeficiency virus (HIV) infected patients by high-performance liquid chromatography (HPLC). All parameters that influence the recovery of the pipette tip based on hollow mesoporous molecularly imprinted polymer solid-phase extraction (PT-HM-MIP-SPE) method were systematically studied and discussed in detail. The adsorbent material was prepared using methacrylic acid and 4-vinylpyridine as functional monomers, ethylene glycol dimethacrylate as crosslinker, acetonitrile as solvent, 4,4'-azobis(4-cyanovaleric acid) as radical initiator, benzalkonium chloride as surfactant, 3TC, and AZT as templates. The simultaneous separation of 3TC, AZT and EFZ by HPLC-UV was performed using a Gemini C18 Phenomenex® column (250 mm × 4.6 mm, 5 μm) and mobile phase consisting of acetonitrile: water pH 3.2 (68:32, v/v), flow rate of 1.0 mL/min and λ = 260 nm. The method was linear over the concentration range from 0.25 to 10 μg/mL for 3TC and EFZ, and 0.05 to 2.0 μg mL^-1 for AZT, with correlation coefficients larger than 0.99 for all analytes. Recovery ± relative standard deviations (RSDs %) were 41.99 ± 2.38%, 82.29 ± 1.63%, and 83.72 ± 7.52% for 3TC, AZT, and EFZ, respectively. The RSDs and relative errors (REs) were lower than 15% for intra and interday assays. The method has been successfully applied for monitoring HIV-infected patients outside the therapeutic dosage.

Novel Antiretroviral Drugs in Patients with Renal Impairment: Clinical and Pharmacokinetic Considerations

Highly active antiretroviral therapy (HAART) has dramatically increased the survival of HIV-infected patients from Western countries reducing the incidence of opportunistic infections and AIDS-related malignancies, and improving the patients' quality of life compared with the pre-HAART era. HIV is thus now considered in the West as a chronic disease, with the majority of HIV-infected patients successfully reaching an optimal immune and virological outcome a few months after starting HAART. However, this switch from acute to chronic disease has been accompanied by an increased incidence of chronic kidney disease (CKD), reported in up to 60% of HIV-infected patients. Tenofovir disoproxil fumarate (TDF) is considered to play a significant role in the development of CKD in these patients. It has been proposed that tenofovir alafenamide (TAF), a prodrug formulation able to providing lower systemic and renal drug exposure, could potentially contribute to reduce the development of CKD in HAART-treated patients. On the other hand, the pharmacokinetics of some components of HAART can be significantly altered in HIV-infected patients developing CKD. TDF- or TAF-based antiretroviral regimens should be avoided in patients with a creatinine clearance of less than 50 or 30 mL/min, respectively. This review focuses on the pharmacokinetic changes of novel antiretroviral drugs in HIV-infected patients with renal impairment or requiring renal replacement therapy, and provides some suggestions on how to change drug doses in these clinical settings.

Antiretroviral unbound concentration during pregnancy: piece of interest in the puzzle?

Atazanavir and darunavir total concentrations (drug bound to plasma proteins plus unbound drug) progressively decrease during pregnancy. This pharmacokinetic variation leads physicians to recommend increasing doses. Conversely, the unbound concentration (Cu), i.e. the pharmacologically active form of the drug, remains unchanged. The explanation of this desynchronization lies in the fact that the clearance of the unbound form, corresponding to the intrinsic metabolic capacity of the hepatocytes, is the only factor driving Cu, and is constant during pregnancy. The attention of HIV physicians should be attracted to this aspect of pharmacokinetics, which is often incompletely understood and could lead to inadequate dose adjustment, which could then cause overexposure of the foetus for many months, with unknown consequences.

Pharmacokinetics of Efavirenz at a High Dose of 25 Milligrams per Kilogram per Day in Children 2 to 3 Years Old

The MONOD ANRS 12206 trial was designated to assess simplification of a successful lopinavir (LPV)-based antiretroviral treatment in HIV-infected children younger than 3 years of age using efavirenz (EFV; 25 mg/kg of body weight/day) to preserve the class of protease inhibitors for children in that age group. In this substudy, EFV concentrations were measured to check the consistency of an EFV dose of 25 mg/kg and to compare it with the 2016 FDA recommended dose. Fifty-two children underwent blood sampling for pharmacokinetic study at 6 months and 12 months after switching to EFV. We applied a Bayesian approach to derive EFV pharmacokinetic parameters using the nonlinear mixed-effect modeling (NONMEM) program. The proportion of midinterval concentrations 12 h after drug intake (C_{12 h}) corresponding to the EFV therapeutic pharmacokinetic thresholds (1 to 4 mg/liter) was assessed according to different dose regimens (25 mg/kg in the MONOD study versus the 2016 FDA recommended dose). With both the 25 mg/kg/day dose and the 2016 FDA recommended EFV dose, simulations showed that the majority of C_{12 h} values were within the therapeutic range (62.6% versus 62.8%). However, there were more children underexposed with the 2016 FDA recommended dose (11.6% versus 1.2%). Conversely, there were more concentrations above the threshold of toxicity with the 25 mg/kg dose (36.2% versus 25.6%), with C_{12 h} values of up to 15 mg/liter. Only 1 of 52 children was switched back to LPV because of persistent sleeping disorders, but his C_{12 h} value was within therapeutic ranges. A high EFV dose of 25 mg/kg per day in children under 3 years old achieved satisfactory therapeutic effective levels. However, the 2016 FDA recommended EFV dose appeared to provide more acceptable safe therapeutic profiles. (This study has been registered at ClinicalTrials.gov under identifier NCT01127204.).

Acute Care Management of the HIV-Infected Patient: A Report from the HIV Practice and Research Network of the American College of Clinical Pharmacy

OBJECTIVE

Patients infected with human immunodeficiency virus (HIV) admitted to the hospital have complex antiretroviral therapy (ART) regimens with an increased medication error rate upon admission. This report provides a resource for clinicians managing HIV-infected patients and ART in the inpatient setting.

METHODS

A survey of the authors was conducted to evaluate common issues that arise during an acute hospitalization for HIV-infected patients. After a group consensus, a review of the medical literature was performed to determine the supporting evidence for the following HIV-associated hospital queries: admission/discharge orders, antiretroviral hospital formularies, laboratory monitoring, altered hepatic/renal function, drug-drug interactions (DDIs), enteral administration, and therapeutic drug monitoring.

RESULTS

With any hospital admission for an HIV-infected patient, a specific set of procedures should be followed including a thorough admission medication history and communication with the ambulatory HIV provider to avoid omissions or substitutions in the ART regimen. DDIs are common and should be reviewed at all transitions of care during the hospital admission. ART may be continued if enteral nutrition with a feeding tube is deemed necessary, but the entire regimen should be discontinued if no oral access is available for a prolonged period. Therapeutic drug monitoring is not generally recommended but, if available, should be considered in unique clinical scenarios where antiretroviral pharmacokinetics are difficult to predict. ART may need adjustment if hepatic or renal insufficiency ensues.

CONCLUSIONS

Treatment of hospitalized patients with HIV is highly complex. HIV-infected patients are at high risk for medication errors during various transitions of care. Baseline knowledge of the principles of antiretroviral pharmacotherapy is necessary for clinicians managing acutely ill HIV-infected patients to avoid medication errors, identify DDIs, and correctly dose medications if organ dysfunction arises. Timely ambulatory follow-up is essential to prevent readmissions and facilitate improved transitions of care.

Enteral Administration of Twice-Daily Dolutegravir and Rilpivirine as a Part of a Triple-Therapy Regimen in a Critically Ill Patient with HIV

The administration of antiretroviral therapy (ART) in intubated critically ill patients may be challenging. Limited pharmacokinetic data exist characterizing the effects of crushed ART with subsequent enteral administration on antiretroviral drug concentrations or the clinical impact on HIV virologic suppression. We report a case of a 27-year-old HIV-positive male with presumed multidrug-resistant HIV and a diagnosis of lymphoma who required enteral ART administration after intensive care unit admission. Crushed twice-daily dolutegravir (separated from enteral nutrition by 2 hours) and rilpivirine (concurrently with a bolus feed) were administered via an orogastric tube. Therapeutic drug monitoring for both dolutegravir and rilpivirine demonstrated antiretroviral absorption via the enteral route (both values slightly below the therapeutic laboratory reference range) with continued virologic suppression.

Therapeutic drug monitoring of antiretroviral drugs in HIV-infected patients

INTRODUCTION

Therapeutic drug monitoring (TDM) may be beneficial when applied to antiretroviral (ARV). Even though TDM can be a valuable strategy in HIV management, its role remains controversial. Areas covered: This review provides a comprehensive update on important issues relating to TDM of ARV drugs in HIV-infected patients. Articles from PubMed with keywords relevant to each topic section were reviewed. Search strategies limited to articles published in English. Expert commentary: There is evidence supporting the use of TDM in HIV treatment. However, some limitations need to be considered. The evidence supporting the use of routine TDM for all patients is limited, as it is not clear that this strategy offers any advantages over TDM for selected indications. Selected groups of patients including patients with physiological changes, patients with drug-drug interactions or toxicity, and the elderly could potentially benefit from TDM, as optimized dosing is challenging in these populations.

A single untimed plasma drug concentration measurement during low-level HIV viremia predicts virologic failure

Suboptimal untimed plasma drug levels (UDL) have been associated with lower rates of virologic suppression and the emergence of drug resistance. Our aim was to evaluate whether UDL among patients with low-level viremia (LLV) while receiving highly active antiretroviral therapy (HAART) can predict subsequent virologic failure (plasma viral load ≥1000 copies/mL) and emergence of resistance. The first documented LLV episode of 328 consenting patients was analysed in terms of drug levels, viral load and resistance, which were monitored while patients were on a consistent HAART regimen. UDL of protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), were categorized as 'therapeutic' or 'subtherapeutic' based on predefined target trough concentrations. Drug resistance genotype was assessed using the Stanford algorithm. Time to virologic failure was evaluated by Kaplan-Meier analysis and Cox proportional hazards regression. We found 78 of 328 patients (24%) with subtherapeutic drug levels at time of first detectable LLV, while 19% harboured drug-resistant virus. Both subtherapeutic UDL and drug resistance independently increased the risk of subsequent virologic failure (p <0.001 and p 0.04, respectively). In a multivariable model, variables associated with LLV and virologic failure included subtherapeutic UDL, elevated plasma viral load, and drug resistance. Patients with subtherapeutic UDL accumulated further drug resistance faster during follow-up (p 0.03). Together, resistance and UDL variables can explain a higher proportion of virologic failure than either measure alone. Our results support further prospective evaluation of UDL in the management of low-level viremia.

Co-delivery of HIV-1 entry inhibitor and nonnucleoside reverse transcriptase inhibitor shuttled by nanoparticles: cocktail therapeutic strategy for antiviral therapy

OBJECTIVES

Traditionally, the antiviral efficacy of classic cocktail therapy is significantly limited by the distinct pharmacokinetic profiles of partner therapeutics that lead to inconsistent in-vivo biodistribution. Here we developed a new cocktail-like drug delivery vehicle using biodegradable polymeric nanoparticles (NP) encapsulating nonnucleoside reverse transcriptase inhibitor (NNRTI) DAAN-14f (14f), surface-conjugated with HIV-1 fusion inhibitor T1144, designated T1144-NP-DAAN-14f (T1144-NP-14f), and aiming to achieve enhanced cellular uptake, improved antiviral activity and prolonged blood circulation time.

METHODS

T1144-NP-14f was prepared through the emulsion/solvent evaporation technique and a maleimide-thiol coupling reaction. Particle size and morphology were determined by dynamic light scattering detection and transmission electron microscopy. Anti-HIV-1 activity was assessed by HIV-1 Env-mediated cell-cell fusion and infection by laboratory-adapted, primary, and resistant HIV-1 isolates, respectively. The in-vitro release of 14f was investigated using the equilibrium dialysis method, and the pharmacokinetic study of T1144-NP-14f was performed on Sprague-Dawley rats.

RESULTS

T1144-NP-14f displayed a spherical shape under transmission electron microscopy observation and had a size of 117 ± 19 nm. T1144-NP-14f exhibited the strongest antiviral activity against a broad spectrum of HIV-1 strains, including NNRTI-, T1144-, or T20-resistant isolates, respectively. Both in-vitro release and in-vivo pharmacokinetic profile showed that T1144-NP-14f exhibited a sustained controlled release behavior.

CONCLUSION

Our results demonstrated that the combination of entry inhibitor with NNRTI encapsulated in nanoparticles (T1144-NP-14f) was highly effective in inhibiting HIV-1 infection. This new cocktail-like drug delivery platform could serve as an effective anti-HIV-1 regimen by taking advantage of the extrinsic and intrinsic antiviral activity of individual drugs.

Dosing antiretroviral medication when crossing time zones: a review

International tourism continues to increase worldwide, and people living with HIV and their clinicians are increasingly confronted with the problem of how to dose antiretroviral therapy during transmeridian air travel across time zones. No guidance on this topic currently exists. This review is a response to requests from patient groups for clear, practical and evidence-based guidance for travelling on antiretroviral therapy; we present currently available data on the pharmacokinetic forgiveness and toxicity of various antiretroviral regimens, and synthesize this data to provide guidelines on how to safely dose antiretrovirals when travelling across time zones.

A pharmacogenomic prospective randomized controlled trial of CYP2B6 polymorphisms and efavirenz dose adjustment among HIV-infected Thai patients: a pilot study

OBJECTIVE

We aimed at comparing clinical/immunological outcomes in human immunodeficiency virus (HIV)-infected patients who were treated with CYP2B6-guided and conventional efavirenz (EFV) therapy.

METHODS

This study was a 24-week prospective randomized controlled trial. Eligible patients were HIV-infected adults yet to start antiretroviral therapy. Twenty-four HIV-infected patients were recruited and randomly assigned to genotype CYP2B6 polymorphism before ART initial dose. Patients with CYP2B6 *6/*6 received 400 mg EFV-based regimen and those with other genotypes received 600 mg EFV-based therapy.

RESULTS

For CYP2B6 polymorphism, 12 patients were extensive metabolizers, ten patients were intermediate metabolizers, and only two patients were poor metabolizers (*6/*6). The overall mean EFV plasma concentrations were similar in both groups. The mean drug concentrations (standard deviation) were 1.675 (0.963), 1.445 (0.778), and 1.899 (0.808) µg/mL at week 4, 12, and 24, respectively. The CYP2B6 *6/*6 patient who received low dose of EFV had lower mean EFV level than those who received a normal dose, 1.916 versus 3.915 µg/mL (P<0.001), respectively. Seventy percent of the patients had neuropsychiatric adverse events, especially dizziness.

DISCUSSION

There was a trend toward association of the CYP2B6 polymorphism and plasma EFV concentrations in this study. Reduced EFV dose should be considered in CYPB6 *6/*6 carrier to keep the drug concentration in therapeutic range.

Therapeutic drug monitoring in HIV-infected pregnant women with a focus on protease inhibitors

The goals of HIV therapy in pregnant patients are to ensure health of mother and to prevent mother to child transmission of HIV to the unborn child. Pregnancy is a time of significant physiological alterations that affect all pharmacological aspects of the antiretroviral (ARV) drugs. Studies point toward lower levels of ARVs in maternal blood especially during late stages of pregnancy. Therapeutic drug monitoring is a strategy to ensure that maternal blood contains adequate level of ARVs to achieve these targets. Pharmacokinetics and therapeutic drug monitoring studies of protease inhibitors are reviewed in this article with emphasis on darunavir which is a newer protease inhibitor gaining popularity as a therapeutic choice in pregnant patients.

Magnetic resonance imaging of folic acid-coated magnetite nanoparticles reflects tissue biodistribution of long-acting antiretroviral therapy

Regimen adherence, systemic toxicities, and limited drug penetrance to viral reservoirs are obstacles limiting the effectiveness of antiretroviral therapy (ART). Our laboratory’s development of the monocyte-macrophage-targeted long-acting nanoformulated ART (nanoART) carriage provides a novel opportunity to simplify drug-dosing regimens. Progress has nonetheless been slowed by cumbersome, but required, pharmacokinetic (PK), pharmacodynamics, and biodistribution testing. To this end, we developed a small magnetite ART (SMART) nanoparticle platform to assess antiretroviral drug tissue biodistribution and PK using magnetic resonance imaging (MRI) scans. Herein, we have taken this technique a significant step further by determining nanoART PK with folic acid (FA) decorated magnetite (ultrasmall superparamagnetic iron oxide [USPIO]) particles and by using SMART particles. FA nanoparticles enhanced the entry and particle retention to the reticuloendothelial system over nondecorated polymers after systemic administration into mice. These data were seen by MRI testing and validated by comparison with SMART particles and direct evaluation of tissue drug levels after nanoART. The development of alendronate (ALN)-coated magnetite thus serves as a rapid initial screen for the ability of targeting ligands to enhance nanoparticle-antiretroviral drug biodistribution, underscoring the value of decorated magnetite particles as a theranostic tool for improved drug delivery.

Design of a surface plasmon resonance immunoassay for therapeutic drug monitoring of amikacin

The therapeutic drug monitoring (TDM) of pharmaceutical drugs with narrow therapeutic ranges is of great importance in the clinical setting. It provides useful information towards the enhancement of drug therapies, aiding in dosage control and toxicity risk management. Amikacin is an aminoglycoside antibiotic commonly used in neonatal therapies that is indicated for TDM due to the toxicity risks inherent in its use. Current techniques for TDM such as high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) are costly, time consuming, and cannot be performed at the site of action. Over the last decades, surface plasmon resonance (SPR) biosensors have become increasingly popular in clinical diagnostics due to their ability to detect biomolecular interactions in real-time. We present an SPR-based competitive immunoassay for the detection of the antibiotic amikacin, suitable for TDM in both adults and neonates. We have obtained high specificity and sensitivity levels with an IC50 value of 1.4ng/mL and a limit of detection of 0.13ng/mL, which comfortably comply with the drug's therapeutic range. Simple dilution of serum can therefore be sufficient to analyze low-volume real samples from neonates, increasing the potential of the methodology for TDM. Compared to current TDM conventional methods, this SPR-based immunoassay can provide advantages such as simplicity, potential portability, and label-free measurements with the possibility of high throughput. This work is the foundation towards the development of an integrated, simple use, highly sensitive, fast, and point-of-care sensing platform for the opportune TDM of antibiotics and other drugs in a clinical setting.

The evolution of three decades of antiretroviral therapy: challenges, triumphs and the promise of the future

The evolution of human immunodeficiency virus (HIV) treatment has improved our understanding and management of complex pharmacological issues that have driven improved outcomes and quality of life of the HIV-infected patient. These issues include adherence, long- and short-term toxicities, pharmacoenhancement, pharmacogenomics, therapeutic drug monitoring, differential penetration of drugs into sanctuary sites, such as the central nervous system, genital tract and small bowel, and drug-drug and drug-food interactions related to cytochrome P450 drug-metabolizing enzymes, uridine diphosphate glucuronyltransferases and drug transporters, to name a few. There is future promise, as an increased understanding of the immunopathogenesis of HIV and global public health initiatives are driving novel treatment approaches with goals to prevent, control and, ultimately, eradicate HIV.

Relationships between pazopanib exposure and clinical safety and efficacy in patients with advanced renal cell carcinoma

BACKGROUND

Pazopanib, an oral angiogenesis inhibitor targeting vascular endothelial growth factor receptor (VEGFR)/platelet-derived growth factor receptor (PDGFR)/c-Kit, is approved in locally advanced/metastatic renal cell carcinoma (RCC).

METHODS

Data from trials in advanced solid tumours and advanced/metastatic RCC were used to explore the relationships between plasma pazopanib concentrations and biomarker changes, safety, and efficacy. Initially, the relationships between pharmacokinetic parameters and increased blood pressure were investigated, followed by analysis of steady-state trough concentration (Cτ) and sVEGFR2, safety, progression-free survival (PFS), response rate, and tumour shrinkage. Efficacy/safety end points were compared at Cτ decile boundaries.

RESULTS

Strong correlation between increased blood pressure and Cτ was observed (r(2)=0.91), whereas weak correlation was observed between Cτ and decline from baseline in sVEGFR2 (r(2)=0.27). Cτ threshold of >20.5 μg ml(-1) was associated with improved efficacy (PFS, P<0.004; tumour shrinkage, P<0.001), but there was no appreciable benefit in absolute PFS or tumour shrinkage from Cτ >20.5 μg ml(-1). However, the association of Cτ with certain adverse events, particularly hand-foot syndrome, was continuous over the entire Cτ range.

CONCLUSIONS

The threshold concentration for efficacy overlaps with concentrations at which toxicity occurs, although some toxicities increase over the entire Cτ range. Monitoring Cτ may optimise systemic exposure to improve clinical benefit and decrease the risk of certain adverse events.

Endosomal trafficking of nanoformulated antiretroviral therapy facilitates drug particle carriage and HIV clearance

Limitations of antiretroviral therapy (ART) include poor patient adherence, drug toxicities, viral resistance, and failure to penetrate viral reservoirs. Recent developments in nanoformulated ART (nanoART) could overcome such limitations. To this end, we now report a novel effect of nanoART that facilitates drug depots within intracellular compartments at or adjacent to the sites of the viral replication cycle. Poloxamer 407-coated nanocrystals containing the protease inhibitor atazanavir (ATV) were prepared by high-pressure homogenization. These drug particles readily accumulated in human monocyte-derived macrophages (MDM). NanoATV concentrations were ∼1,000 times higher in cells than those that could be achieved by the native drug. ATV particles in late and recycling endosome compartments were seen following pulldown by immunoaffinity chromatography with Rab-specific antibodies conjugated to magnetic beads. Confocal microscopy provided cross validation by immunofluorescent staining of the compartments. Mathematical modeling validated drug-endosomal interactions. Measures of reverse transcriptase activity and HIV-1 p24 levels in culture media and cells showed that such endosomal drug concentrations enhanced antiviral responses up to 1,000-fold. We conclude that late and recycling endosomes can serve as depots for nanoATV. The colocalization of nanoATV at endosomal sites of viral assembly and its slow release sped antiretroviral activities. Long-acting nanoART can serve as a drug carrier in both cells and subcellular compartments and, as such, can facilitate viral clearance.

IMPORTANCE

The need for long-acting ART is significant and highlighted by limitations in drug access, toxicity, adherence, and reservoir penetrance. We propose that targeting nanoformulated drugs to infected tissues, cells, and subcellular sites of viral replication may improve clinical outcomes. Endosomes are sites for human immunodeficiency virus assembly, and increasing ART concentrations in such sites enhances viral clearance. The current work uncovers a new mechanism by which nanoART can enhance viral clearance over native drug formulations.

Are lopinavir and efavirenz serum concentrations in HIV-infected children in the therapeutic range in clinical practice?

BACKGROUND

In antiretroviral treatment the role of therapeutic drug monitoring via measurement of serum levels remains unclear, especially in children.

AIM

To quantify exposure to LPV and EFV in children receiving therapy in a routine clinical setting in order to identify risk factors associated with inadequate drug exposure.

METHOD

A prospective study was conducted in a routine clinical setting in Tygerberg Children's Hospital, South Africa. A total of 53 random serum levels were analyzed. Serum concentrations were determined by an established high-performance liquid chromatography method.

RESULTS

Of 53 HIV-infected children treated with lopinavir (n = 29, median age 1·83 y) or efavirenz (n = 24, median age 9·3 years), 12 showed serum levels outside the therapeutic range (efavirenz) or below Cmin (lopinavir). Low bodyweight, rifampicin co-treatment, and significant comorbidity were potential risk factors for inadequate drug exposure.

CONCLUSION

These findings, together with previous studies, indicate that therapeutic drug monitoring can improve the management of antiretroviral therapy in children at risk.

Clinical pharmacokinetics of tyrosine kinase inhibitors: implications for therapeutic drug monitoring

The treatment of many malignancies has been improved in recent years by the introduction of molecular targeted therapies. These drugs interact preferentially with specific targets that are mutated and/or overexpressed in malignant cells. A group of such targets are the tyrosine kinases, against which a number of inhibitors (tyrosine kinase inhibitors, TKIs) have been developed. Imatinib, a TKI with targets that include the breakpoint cluster region-Abelson (bcr-abl) fusion protein kinase and mast/stem cell growth factor receptor kinase (c-Kit), was the first clinically successful drug of this type and revolutionized the treatment and prognosis of chronic myeloid leukemia and gastrointestinal stromal tumors. This success paved the way for the development of other TKIs for the treatment of a range of hematological malignancies and solid tumors. To date, 14 TKIs have been approved for clinical use and many more are under investigation. All these agents are given orally and are substrates of a range of drug transporters and metabolizing enzymes. In addition, some TKIs are capable of inhibiting their own transporters and metabolizing enzymes, making their disposition and metabolism at steady-state unpredictable. A given dose can therefore give rise to markedly different plasma concentrations in different patients, favoring the selection of resistant clones in the case of subtherapeutic exposure, and increasing the risk of toxicity if dosage is excessive. The aim of this review was to summarize current knowledge of the clinical pharmacokinetics and known adverse effects of the TKIs that are available for clinical use and to provide practical guidance on the implications of these data in patient management, in particular with respect to therapeutic drug monitoring.

Unexpected vertical transmission of HIV infection

Mother-to-child transmission of HIV infection occurred in a child born from an HIV-infected mother with HIV-RNA undetectable during pregnancy. She was suffering from gastroenteritis in the last 3 weeks of gestation.

Low level of efavirenz in HIV-1-infected Thai adults is associated with the CYP2B6 polymorphism

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) infections with a plasma efavirenz concentration of <1,000 ng/mL appear to have a high risk for the emergence of drug resistance. In the present study, we assessed the influence of the CYP2B6 polymorphism on the plasma efavirenz level.

METHODS

CYP2B6 T18492C (rs2279345) in 149 HIV-infected Thai adults were genotyped. Plasma efavirenz concentrations 12 h after dosing were measured using a validated high-performance liquid chromatography. The relationship between the plasma efavirenz level and the CYP2B6 T18492C polymorphism were analysed.

RESULTS

Among the 149 patients, the frequency of T18492C heterozygous (T/C) and homozygous mutant (C/C) was 38.26 % (n = 57) and 6.04 % (n = 9), respectively. In the entire cohort, the median efavirenz plasma concentration was 2,410 ng/mL [interquartile range (IQR) 1,460-4,120 ng/mL]. The plasma efavirenz concentration for patients with 18492CC (1,200 ng/mL, IQR 1,050-1,990 ng/mL) or 18492TC (1,900 ng/mL, IQR 1,320-2,510 ng/mL) genotypes were significantly lower than those with homozygous wild type (3,380 ng/mL, IQR 2,040-5,660 ng/mL), P-value < 0.001.

CONCLUSIONS

The CYP2B6 T18492C polymorphism was significantly associated with lower efavirenz concentrations compared to those with homozygous wild type in HIV-1 infections. The genetic polymorphism CYP2B6 T18492C may be useful for the optimised efavirenz dose. Further studies in the clinical setting will need to be conducted before such an approach can be recommended for widespread use.

Small magnetite antiretroviral therapeutic nanoparticle probes for MRI of drug biodistribution

AIM

Drug toxicities, compliance and penetrance into viral reservoirs have diminished the efficacy of long-term antiretroviral therapy (ART) for treatment of HIV infection. Cell-targeted nanoformulated ART was developed to improve disease outcomes. However, rapid noninvasive determination of drug biodistribution is unrealized. To this end, small magnetite ART (SMART) nanoparticles can provide assessments of ART biodistribution by MRI.

MATERIALS & METHODS

Poly(lactic-co-glycolic acid), 1,2-distearoyl-sn-glycero-3-phosphocholine- and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy-PEG 2000)-encased particles were synthesized with atazanavir (ATV) and magnetite. Uptake and retention of ATV and magnetite administered at 3:1 ratios (weight/weight) were determined in human monocyte-derived macrophages and mice.

RESULTS

SMART particles were taken up and retained in macrophages. In mice, following parenteral SMART injection, magnetite and drug biodistribution paralleled one another with MRI signal intensity greatest in the liver and spleen at 24 h. Significantly, ATV and magnetite levels correlated.

CONCLUSION

SMART can permit rapid assessment of drug tissue concentrations in viral reservoirs.

Nevirapine inhibits the anti-HIV activity of CD8+ cells

Antiretroviral therapy (ART) significantly reduced the CD8 cell noncytotoxic anti-HIV response in 12 HIV-1-infected subjects (P < 0.0001). In separate experiments, CD8(+) cells from long-term survivors were cocultured with HIV-infected CD4(+) cells using varying concentrations of anti-HIV drugs. The antiviral function of CD8(+) cells from 4 of the 14 LTSs was reduced with exposure to 10 μM of nevirapine (P < 0.05). The antiviral activity of CD8(+) cells from 2 LTSs was inhibited by 5 μM of zidovudine. These studies indicate that nevirapine and probably zidovudine can inhibit the anti-HIV activity of CD8(+) cells and thus could influence the effectiveness of antiretroviral therapy.