Point-of-Care Detection of Nonadherence to Antiretroviral Treatment for HIV-1 in Resource-Limited Settings Using Drug Level Testing for Efavirenz, Lopinavir, and Dolutegravir: A Validation and Pharmacokinetic Simulation Study.

BACKGROUND: Virological failure during antiretroviral treatment (ART) may indicate the presence of drug resistance, but may also originate from nonadherence. Qualitative detection of ART components using drug level testing may be used to differentiate between these scenarios. We aimed to validate and implement qualitative point-of-care drug level tests for efavirenz (EFV), lopinavir (LPV), and dolutegravir (DTG) in rural South Africa. METHODS: Qualitative performance of immunoassays for EFV, LPV, and DTG was assessed by calculating limit of detection (LoD), region of uncertainty, and qualitative agreement with a reference test. Minimum duration of nonadherence resulting in a negative drug level test was assessed by simulation of treatment cessation using validated population pharmacokinetic models. RESULTS: LoD was 0.05 mg/L for EFV, 0.06 mg/L for LPV, and 0.02 mg/L for DTG. Region of uncertainty was 0.01-0.06 mg/L for EFV, 0.01-0.07 mg/L for LPV, and 0.01-0.02 mg/L for DTG. Qualitative agreement with reference testing at the LoD in patient samples was 95.2% (79/83) for EFV, 99.3% (140/141) for LPV, and 100% (118/118) for DTG. After simulated treatment cessation, median time to undetectability below LoD was 7 days [interquartile range (IQR) 4-13] for EFV, 30 hours (IQR 24-36) for LPV, and 6 days (IQR 4-7) for DTG. CONCLUSIONS: We demonstrate that qualitative ART drug level testing using immunoassays is feasible in a rural resource-limited setting. Implementation of this technology enables reliable detection of recent nonadherence and may allow for rapid and cost-effective differentiation between patients in need for adherence counseling and patients who require drug resistance testing or alternative treatment.

Assessment of CYP-Mediated Drug Interactions for Evocalcet, a New Calcimimetic Agent, Based on In Vitro Investigations and a Cocktail Study in Humans.

Evocalcet is a novel calcimimetic agent for the treatment of secondary hyperparathyroidism (SHPT). This study evaluated the effects of evocalcet on inhibition and induction of cytochrome P450 (CYP) isozymes. Although drug interactions arising from reversible inhibition of CYP isozymes by evocalcet were considered unlikely based on the results of in vitro studies and static model analyses, the potential for evocalcet to cause time-dependent inhibition of CYP3A or induction of several CYP isozymes could not be ruled out. Therefore, a clinical drug-drug interaction (DDI) study to evaluate the effects of evocalcet on the pharmacokinetics (PKs) of probe substrates for CYP isozymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, and CYP3A) was conducted in healthy male volunteers using a novel cocktail combination. Evocalcet did not significantly affect the PKs of the probe substrates, confirming that CYP-mediated interactions were unlikely.

Combined bronchodilators (tiotropium plus olodaterol) for patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD), a respiratory disease characterized by a progressive decline in lung function, is considered to be a leading cause of morbidity and mortality. Long-acting inhaled bronchodilators, such as long-acting ß2 agonists (LABAs) or long-acting muscarinic antagonists (LAMAs), are the cornerstone of maintenance therapy for patients with moderate-to-very-severe COPD. For patients not sufficiently controlled on a single long-acting bronchodilator, a combination of different bronchodilators has shown a significant increase in lung function. Tiotropium, a once-daily dosing LAMA, demonstrated sustained improvements in lung function as well as improved health-related quality of life, reduced exacerbations, and increased survival without altering the rate of decline in the mean forced expiratory volume in 1 second (FEV1) with fairly tolerable side effects. Olodaterol is a once-daily dosing LABA that has proven to be effective in improving lung function, reducing rescue medication use, and improving dyspnea and health-related quality of life, as well as improving exercise endurance with an acceptable safety profile. The combination of olodaterol and tiotropium provided additional improvements in lung function greater than monotherapy with each drug alone. Several well-designed randomized trials confirmed that the synergistic effect of both drugs in combination was able to improve lung function and health-related quality of life without a significant increase in adverse effects. The objective of this paper is to review available evidence on the clinical efficacy and safety of tiotropium, olodaterol, and their combination in patients with COPD.

Dose reduction of efavirenz: an observational study describing cost-effectiveness, pharmacokinetics and pharmacogenetics.

AIM: Antiretroviral treatment implies a high cost to the healthcare system. The aim of this study was to evaluate the clinical and economic impact of efavirenz (EFV) dose adjustment by monitoring plasma concentrations and pharmacogenetic analysis of the 516G>T CYP2B6 polymorphism. MATERIALS & METHODS: One hundred and ninety HIV patients treated with EFV were studied. Plasma EFV concentrations were measured by HPLC with ultraviolet detection, and pharmacogenetic analysis was performed by Real Time (RT)-PCR. RESULTS: One hundred and ninety patients initially treated with a standard dose of EFV (600 mg/day) were studied. In 31 (16.3%) patients, EFV dose was reduced. A total of 87.1% of patients were heterozygous/homozygous carriers (GT/TT). CD4(+) count increased while the minimum steady-state plasma concentration and adverse effects decreased significantly after dose adjustment. Considering only the dose reduction, the adjustments accounted for a saving of 43,539 €/year. CONCLUSION: The individualization of EFV dosage guided by genotyping 516G>T CYP2B6 and therapeutic drug monitoring could increase the efficiency of EFV use in antiretroviral treatment.

Assessment of pharmacokinetic interactions of the HCV NS5A replication complex inhibitor daclatasvir with antiretroviral agents: ritonavir-boosted atazanavir, efavirenz and tenofovir.

BACKGROUND: Approximately one-third of all HIV-infected individuals are coinfected with HCV, many of whom will receive concomitant treatment for both infections. With the advent of direct-acting antivirals (DAAs) for HCV, potential drug interactions between antiretrovirals and DAAs require evaluation prior to co-therapy. METHODS: Three open-label studies were conducted in healthy subjects to assess potential interactions between the investigational first-in-class HCV NS5A replication complex inhibitor daclatasvir and representative antiretrovirals atazanavir/ritonavir, efavirenz and tenofovir disoproxil fumarate. RESULTS: Target exposure was that of 60 mg daclatasvir alone. Dose-normalized (60 mg) geometric mean ratios of daclatasvir AUCτ for 20 mg ± atazanavir/ritonavir (2.10 [90% CI 1.95, 2.26]) and 120 mg ± efavirenz (0.68 [0.60, 0.78]) showed less than the three-fold elevation and two-fold reduction, respectively, in systemic exposure predicted by prior interaction studies with potent inhibitors/inducers of CYP3A4. Daclatasvir dose adjustment to 30 mg once daily with atazanavir/ritonavir and 90 mg once daily with efavirenz is predicted to normalize AUCτ relative to the target exposure (geometric mean ratios 1.05 [0.98, 1.13] and 1.03 [0.90, 1.16], respectively). Atazanavir exposure (Cmax, AUCτ and C24 trough) and efavirenz Ctrough under coadministration were similar to historical data without daclatasvir. No clinically relevant interactions between daclatasvir and tenofovir disoproxil fumarate were observed for either drug, and no dosing adjustments were indicated. Daclatasvir was well tolerated in all three studies. CONCLUSIONS: The pharmacokinetic data support coadministration of daclatasvir with atazanavir/ritonavir, efavirenz and/or tenofovir. A Phase III study in HIV-HCV coinfection has commenced using the described dose modifications.

[Evidence-based therapeutic drug monitoring for efavirenz]. / Niveau de preuve du suivi thérapeutique pharmacologique de l'efavirenz.

The efavirenz, a non nucleoside reverse transcriptase inhibitor of HIV-1, presents a marked pharmacokinetics variability related to an intense hepatic metabolism. Efavirenz is also a potent inducer. Central nervous system (CNS) toxicity associated with efavirenz therapy is a major cause of non adherence and therefore treatment failure. The literature has been analyzed to evaluate the level of evidence of the interest of a therapeutic drug monitoring for efavirenz. Several studies have reported that an efavirenz plasma concentration >1 000 ng/mL is a predictive factor of the viral response. Efavirenz plasma concentrations >4 000 ng/mL were associated to an increase frequency of CNS side effects. CNS toxicity was also more frequent in patients carrying the 516G > T mutation (CYP2B6*6 allele), associated with a significantly greater efavirenz plasma exposure. Non-randomized studies have reported the interest of efavirenz therapeutic drug monitoring to optimize viral response and prevent CNS toxicity, allowing to suggest a level of evidence "recommended" for efavirenz.

A highly concentrated and taste-improved aqueous formulation of efavirenz for a more appropriate pediatric management of the anti-HIV therapy.

Pediatric HIV is scarce in developed countries; 90% of pediatric HIV patients are in developing countries. In contrast, children represent 15% of the new infections in poor countries. Approximately 90% of the HIV-positive children do not have access to antiretrovirals (ARVs). Without treatment, 50% of the patients die before the 2 years of age. Efavirenz (EFV, aqueous solubility approximately 4 microg/mL, 40-45% bioavailability), a non-nucleoside reverse transcriptase inhibitor (NNRTI), is a first-choice pediatric ARV. To assure therapeutic plasma concentrations, the low oral bioavailability demands the administration of relatively high EFV doses. Aqueous EFV irritates the oral mucosa, causing a Burning Mouth Syndrome (BMS). A triglyceride-based liquid formulation of EFV (30 mg/mL) is not commercially available worldwide, making the appropriate dose adjustment and the swallowing difficult. More importantly, clinical trials indicated that the oral bioavailability of this oily solution is lower than that of the solid one. Moreover, a relatively high inter-subject variability has been found. The present work reports the development and full characterization of a concentrated (20 mg/mL, 2%) and taste-masked aqueous formulation of EFV for a more appropriate management of the pediatric anti-HIV therapy. Formulations displayed high physicochemical stability over time under regular storage conditions. Release assays in vitro showed a burst effect (2 h) and zero-order kinetics later on (between 2 and 24 h), compatible with the oral administration route and release. Finally, taste tests performed by adult healthy volunteers indicated that the unique combination of flavors and sweeteners employed (i) reduced the intensity of the BMS and (ii) shortened its duration significantly. Overall results indicate that the cost-effective and scalable nanotechnological strategy proposed could enable the more convenient and compliant administration of lower EFV doses. Due to a better pharmacokinetic profile, this would result in similar plasma levels than higher doses administered in solid or triglyceride-soluble form. In this context, some reduction of the treatment cost can be envisioned. This could improve the access of less affluent pediatric patients to medication in poor countries.