Multiresponse Optimization of HPLC Method: Simultaneous Estimation of Protease Inhibitors and NNRTI in Human Plasma

Multiresponse optimization approach to develop a simple isocratic, highly sensitive and accurate HPLC method for the simultaneous determination of Efavirenz, Atazanavir, Lopinavir and Ritonavir in human blood plasma along with carvedilol as an internal standard. Optimized the factors (ACN, buffer concentration and flow rate) effecting and interacting with the responses (k1, Rs2,1, Rs3,2 and tR5) applying Central Composite Design a chemometric tool. All the mathematical models as well as response surfaces were defined and derived for the separation using this strategy. Chromatography was performed on Thermo Hypersil C18 column using mobile phase comprising of ACN: 10 mM KH2PO4 (51.2:48.8) with 1 mL min-1 flow rate and detection wavelength was fixed at 210 nm. The analysis time was within 9 min. The method developed was validated by following "Bioanalytical method validation" [USFDA-CDER, 2001]. The developed method can be applied for bioavailability and pharmacokinetic studies.

Development and validation of an assay to analyze atazanavir in human hair via liquid chromatography/tandem mass spectrometry

RATIONALE

Assays to quantify antiretrovirals in hair samples are increasingly used to monitor adherence and exposure in both HIV prevention and treatment studies. Atazanavir (ATV) is a protease inhibitor used in combination antiretroviral therapy (ART). We developed and validated a liquid chromatography/tandem mass spectrometry (LC/MS/MS)-based method to quantify ATV in human hair, per the NIH Division of AIDS Clinical Pharmacology Quality Assurance (CPQA) program and the FDA bioanalytical method validation guidelines.

METHODS

ATV was extracted from hair using optimized methods and the extracts were injected onto a BDS C-18 column (5 μm, 4.6 × 100 mm), followed by isocratic elution via a mobile phase composed of 55% acetonitrile, 45% water, 0.15% acetic acid, and 4 mM ammonium acetate, at a flow rate of 0.8 mL/min prior to analysis by MS/MS. Levels were quantified using positive electrospray ionization by multiple reaction monitoring (MRM) for the transitions MH⁺ m/z 705.3 to m/z 168.0 and MH⁺ m/z 710.2 to m/z 168.0 for ATV and ATV-d5 (internal standard), respectively.

RESULTS

Our assay demonstrated a linear standard curve (r = 0.99) over the concentration range of 0.0500 ng ATV/mg hair to 20.0 ng/mg hair. The inter- and intraday accuracy of ATV quality control (QC) samples was -1.33 to 4.00% and precision (% coefficient of variation (%CV)) was 1.75 to 6.31%. The %CV for ATV levels in hair samples from highly adherent patients (incurred samples) was less than 10%. No significant endogenous peaks or crosstalk were observed in the specificity test with other HIV drugs. The overall extraction efficiency of ATV from incurred hair samples was greater than 95%.

CONCLUSIONS

This highly sensitive, highly specific and validated assay can be considered for therapeutic drug monitoring for HIV-infected patients on ATV-based ART.

Therapeutic Drug Monitoring of Anti-human Immunodeficiency Virus Drugs in a Patient with Short Bowel Syndrome

An elderly woman with human immunodeficiency virus-1 infection developed short bowel syndrome as a result of extensive intestinal resection. Considering the possibility of poor absorption of antiretroviral drugs (ARVs), therapeutic drug monitoring (TDM) was performed. A single-dose test of 6 ARVs (darunavir, ritonavir, lopinavir, etravirine, maraviroc, and raltegravir) did not provide information on the appropriate ARV, and repeated TDM under continuous antiretroviral therapy resulted in viral suppression below 50 copies/mL, which was considered to be treatment success. These assessments suggest the importance of TDM in the steady state for the successful treatment of individuals with impaired gastrointestinal function using ARVs.

Nanoparticle-Based ARV Drug Combinations for Synergistic Inhibition of Cell-Free and Cell-Cell HIV Transmission

Nanocarrier-based drug delivery systems are playing an emerging role in human immunodeficiency virus (HIV) chemoprophylaxis and treatment due to their ability to alter the pharmacokinetics and improve the therapeutic index of various antiretroviral (ARV) drug compounds used alone and in combination. Although several nanocarriers have been described for combination delivery of ARV drugs, measurement of drug-drug activities facilitated by the use of these nanotechnology platforms has not been fully investigated for topical prevention. Here, we show that physicochemically diverse ARV drugs can be encapsulated within polymeric nanoparticles to deliver multidrug combinations that provide potent HIV chemoprophylaxis in relevant models of cell-free, cell-cell, and mucosal tissue infection. In contrast to existing approaches that coformulate ARV drug combinations together in a single nanocarrier, we prepared single-drug-loaded nanoparticles that were subsequently combined upon administration. ARV drug-nanoparticles were prepared using emulsion-solvent evaporation techniques to incorporate maraviroc (MVC), etravirine (ETR), and raltegravir (RAL) into poly(lactic-co-glycolic acid) (PLGA) nanoparticles. We compared the antiviral potency of the free and formulated drug combinations for all pairwise and triple drug combinations against both cell-free and cell-associated HIV-1 infection in vitro. The efficacy of ARV-drug nanoparticle combinations was also assessed in a macaque cervicovaginal explant model using a chimeric simian-human immunodeficiency virus (SHIV) containing the reverse transcriptase (RT) of HIV-1. We observed that our ARV-NPs maintained potent HIV inhibition and were more effective when used in combinations. In particular, ARV-NP combinations involving ETR-NP exhibited significantly higher antiviral potency and dose-reduction against both cell-free and cell-associated HIV-1 BaL infection in vitro. Furthermore, ARV-NP combinations that showed large dose-reduction were identified to be synergistic, whereas the equivalent free-drug combinations were observed to be strictly additive. Higher intracellular drug concentration was measured for cells dosed with the triple ARV-NP combination compared to the equivalent unformulated drugs. Finally, as a first step toward evaluating challenge studies in animal models, we also show that our ARV-NP combinations inhibit RT-SHIV virus propagation in macaque cervicovaginal tissue and block virus transmission by migratory cells emigrating from the tissue. Our results demonstrate that ARV-NP combinations control HIV-1 transmission more efficiently than free-drug combinations. These studies provide a rationale to better understand the role of nanocarrier systems in facilitating multidrug effects in relevant cells and tissues associated with HIV infection.

Ritonavir-boosted darunavir is rarely associated with nephrolithiasis compared with ritonavir-boosted atazanavir in HIV-infected patients

Background

Although ritonavir-boosted atazanavir (ATV/r) is known to be associated with nephrolithiasis, little is known about the incidence of nephrolithiasis in patients treated with ritonavir-boosted Darunavir (DRV/r), the other preferred protease inhibitor.

Methods

In a single-center cohort, the incidence of nephrolithiasis was compared between HIV-infected patients who commenced DRV/r-containing antiretroviral therapy and those on ATV/r. The effects of ATV/r use over DRV/r were estimated by univariate and multivariate Cox hazards models.

Results

Renal stones were diagnosed in only one patient (0.86 per 1000 person-years) of the DRV/r group (n=540) and 37 (20.2 per 1000 person-years) of the ATV/r group (n=517). The median [interquartile (IQR)] observation period in the DRV/r group was 27.1 months (IQR 18.1-38.4 months), and 40.6 months (IQR 17.5-42.7) for the ATV/r group. The total observation period was 1,163.6 person-years and 1,829.6 person-years for the DRV/r group and for the ATV/r group, respectively. In the 37 patients on ATV/r who developed nephrolithiasis, the median time from commencement of ATV/r to diagnosis was 28.1 months (IQR 18.4–42.7), whereas nephrolithiasis in the single patient of the DRV/r group occurred 11.2 month after the introduction of DRV/r. ATV/r use over DRV/r was significantly associated with nephrolithiasis by uni- and multivariate analyses (HR=26.01; 95% CI, 3.541–191.0; p=0.001) (adjusted HR=21.47; 95% CI, 2.879–160.2; p=0.003).

Conclusion

The incidence of nephrolithiasis was substantially lower in patients on DRV/r than those on ATV/r. The results suggest that DRV/r should be selected for treatment of HIV-infected patients at risk of chronic kidney disease.

Simultaneous quantification of lopinavir and ritonavir in human plasma by high performance liquid chromatography coupled with UV detection

High performance liquid chromatography was coupled with UV detection for simultaneous quantification of lopinavir (LPV) and ritonavir (RTV) in human plasma. This assay was sensitive, accurate and simple, and only used 200 μL of plasma sample. Samples were liquid-liquid extracted, and diazepam was used as an internal standard. The chromatographic separation was achieved on a C18 reversed-phase analytic column with a mobile phase of acetonitrile-sodium dihydrogen phosphate buffer (10 mmol L(-1), pH 4.80) (60:40, v/v). UV detection was conducted at 205 nm and the column oven was set at 40°C. Calibration curves were constructed between 0.5-20 μg mL(-1) for LPV and 0.05-5 μg mL(-1) for RTV. The relative standard deviations were 2.16%-3.20% for LPV and 2.12%-2.60% for RTV for intra-day analysis, and 2.34%-4.04% for LPV and 0.31%-4.94% for RTV for inter-day analysis. The accuracy was within 100%±10%. The mean extraction recoveries were 79.17%, 52.26% and 91.35% for RTV, LPV and diazepam, respectively. This method was successfully applied to human plasma samples from patients orally administered a salvage regimen of lopinavir-ritonavir tablets.

Detection of protease activities by flash chronopotentiometry using a reversible polycation-sensitive polymeric membrane electrode

A novel electrochemical method, termed flash chronopotentiometry (FCP), is used to develop a rapid and sensitive method for detecting protease activities. In this method, an appropriate current pulse is applied across a polycation-selective polymer membrane to induce a strong flux of the polycationic peptides from the sample phase into the organic membrane of the electrode. During this current pulse, the cell potential (EMF) is monitored continuously, and is a function of the polypeptide concentration. The imposed current causes a local depletion of the polypeptide at the sample/membrane interface, which yields a drastic potential change in the observed chronopotentiogram at a characteristic time, called the transition time (τ). For a given magnitude of current, the square root of τ is directly proportional to the concentration of the polypeptide. Proteases cleave polypeptides into smaller fragments that are not favorably extracted into the membrane of the sensor. Therefore, a decrease in the transition time is observed during the proteolysis process. The degree of change in the transition time can be correlated to protease activity. To demonstrate this approach, the activities of trypsin and α-chymotrypsin are detected using protamine and synthetic polycationic oligopeptides that possess specific cleavage sites that are recognized by these proteases.