Quantification of raltegravir (MK0518) in human plasma by high-performance liquid chromatography with photodiode array detection

Selective and rapid determination of raltegravir in human plasma by liquid chromatography-tandem mass spectrometry in the negative ionization mode

A selective and rapid high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of raltegravir using raltegravir-d3 as an internal standard (IS). The analyte and IS were extracted with methylene chloride and n-hexane solvent mixture from 100 µL human plasma. The chromatographic separation was achieved on a Chromolith RP-18e endcapped C₁₈ (100 mm×4.6 mm) column in a run time of 2.0 min. Quantitation was performed in the negative ionization mode using the transitions of m/z 443.1→316.1 for raltegravir and m/z 446.1→319.0 for IS. The linearity of the method was established in the concentration range of 2.0-6000 ng/mL. The mean extraction recovery for raltegravir and IS was 92.6% and 91.8%, respectively, and the IS-normalized matrix factors for raltegravir ranged from 0.992 to 0.999. The application of this method was demonstrated by a bioequivalence study on 18 healthy subjects.

Validation of an UPLC-MS/MS method for quantitative analysis of raltegravir in human plasma samples

BACKGROUND

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the quantification of raltegravir (RTG) plasma concentrations in samples from HIV patients treated with the drug.

METHODS

Plasma samples were extracted by liquid-liquid extraction followed by evaporation to dryness and reconstitution in mobile phase. The chromatographic separation was carried out on an AQUITY UPLC C18 column with an isocratic mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid (50:50 vol/vol). The detection was performed on a triple quadrupole tandem mass spectrometer using multi-reaction monitoring via electrospray ionization source with positive ionization mode.

RESULTS

Under these conditions, a single chromatographic run could be completed within 1 minute. The method was validated by estimating the precision and the accuracy for inter- and intra-day analysis in the concentration range of 5-2560 ng/mL. The method was linear over the investigated range with all the correlation coefficients, r, greater than 0.995 on 5 replicates. The intra- and inter-day precision (percentage of coefficient of variation) ranged from 2.4% to 11.2%, and the inaccuracy (percent of relative standard deviation) ranged from 2.5% to 12.9%. No significant matrix effect was observed. The mean recovery value of RTG was 80%.

CONCLUSIONS

This rapid and sensitive method was validated and could be applied to pharmacokinetic studies for the determination of RTG concentrations in human plasma samples.

Plasma raltegravir exposure influences the antiviral activity and selection of resistance mutations

Raltegravir (RAL) resistance is associated with the selection of integrase mutations at positions 92, 143, 148, and/or 155. A substantial proportion of RAL failures, however, occurs in the absence of these changes. An examination of RAL plasma concentrations may help in interpreting this observation. All early RAL virological failures seen at 22 clinics in Spain during 2009 were identified. HIV integrase sequences and RAL plasma trough concentrations (C(t)) were examined. A total of 106 patients experiencing virological failure on RAL were identified. Only the earliest sample on failure was examined. Integrase sequences could be obtained for 89 (84%), of whom 30 (33.7%) depicted primary RAL resistance mutations (15 N155H, eight Q148H/R, three Y143R, one E92Q, and three more than one of them). Another nine (10.1%) patients showed only secondary changes. The remaining 50 RAL early failures (56.2%) did not select any integrase change. RAL C(t) could be measured in 66 patients at failure and in 21 of them before failure. In a control group of 37 patients with viral suppression on RAL, detectable plasma levels were seen in all cases, with greater median RAL C(t) than in failures, either at the time of viral rebound (p<0.001) or before it (p=0.055). Moreover, median C(t) at the time of failure was greater in patients selecting primary RAL resistance mutations than in the rest of the failures (p<0.001). Undetectable RAL C(t) was seen only in patients failing RAL without integrase resistance mutations (64.1% of them). RAL failures in the absence of integrase resistance mutations mainly reflect poor drug compliance.

Emerging integrase inhibitor resistance mutations in raltegravir-treated HIV-1-infected patients with low-level viremia

BACKGROUND

The emergence of integrase strand-transfer inhibitor (INSTI) resistance-associated mutations was examined in patients with low-level viremia after switching from enfuvirtide to raltegravir in the ANRS 138-Easier trial.

METHODS

Integrase genes of plasma virus from raltegravir-treated patients in the Easier trial with low-level viremia (50-500 copies/ml) were sequenced to determine INSTI resistance-associated mutations. Baseline viral load, baseline and nadir CD4 cell count, antiretroviral treatment, genotypic susceptibility score, level of viremia and degree of treatment adherence during the study period were also analyzed.

RESULTS

Forty-nine patients experienced at least one episode of low-level viremia while receiving raltegravir; integrase genotyping was successful in samples from 39 individuals (80%). Among them, three [7.7%, 95% confidence interval (CI) 1.6-20.9%] had significant INSTI resistance mutations consisting of N155H in two and P145S in one. Absence of these mutations from proviral DNA at baseline suggested selection of INSTI resistance during episodes of low-level viremia. No specific factors significantly associated with emergence of INSTI resistance mutations during low-level viremia were identified.

CONCLUSION

Emergence of INSTI resistance mutations can occur during episodes of low-level viremia in patients receiving raltegravir-containing regimens.

Simultaneous determination of raltegravir and raltegravir glucuronide in human plasma by liquid chromatography-tandem mass spectrometric method

Raltegravir is a highly efficacious inhibitor of HIV integrase. Large pharmacokinetic variability has been reported in clinical trials and this could be due to glucuronidation of raltegravir, the only reported metabolism pathway. In order to precisely evaluate and monitor the raltegravir and raltegravir glucuronide simultaneously, a novel, sensitive and robust liquid chromatography-tandem mass spectrometric method was developed and validated for simultaneous determination of raltegravir and raltegravir glucuronide in human plasma. A simple protein precipitation with acetonitrile was utilized for plasma sample preparation prior to analysis. Baseline chromatographic separation was achieved on a ZORBAX Eclipse XDB-C8 using gradient elution mode. The run time was 9 min at a constant flow rate of 0.4 ml/min. The mass spectrometer was operated under a positive electrospray ionization condition. Excellent linearity (r(2) ≥ 0.9997) was achieved for raltegravir and raltegravir glucuronide in the range of 2-2000 nmol/l. The average recovery of raltegravir and raltegravir glucuronide was 105.8% and 102.2%, respectively. The precision (coefficient of variation) was 1.6-6.6% for raltegravir and 2.1-6.9 for raltegravir glucuronide, respectively. The accuracy was 98.6-106.1% for raltegravir and 96.3-100.3% for raltegravir glucuronide. The plasma samples were tested to be stable after nine freeze-thaw cycles and exposure to room temperature for 24 h. This well-validated assay was applied for the quantification of raltegravir and raltegravir glucuronide in plasma samples within 24 h after a single oral dose of 400 mg raltegravir in six healthy subjects.

Resistance analyses in highly experienced patients failing raltegravir, etravirine and darunavir/ritonavir regimen

OBJECTIVES

ANRS 139 TRIO trial was a phase II noncomparative trial that evaluated in highly experienced patients, a combination of raltegravir, etravirine and darunavir boosted with ritonavir. We analyzed emergence of resistant viruses at the time of virological failure and investigated the impact of baseline integrase polymorphisms on virological failure occurrence.

METHODS

Bulk sequencing of protease, reverse transcriptase and integrase genes was performed for 103 patients at baseline and 14 patients at the time of virological failure. Additionally, integrase clonal analyses were performed at baseline and at virological failure in patients with successful integrase gene amplification. Impact of baseline integrase polymorphisms on virological failure occurrence was analyzed using Fisher exact and Wilcoxon tests.

RESULTS

In the 14 failing patients median viral load at virological failure was 90 copies/ml (interquartile range = 60-783). Emergence of darunavir and etravirine resistance mutations was observed at virological failure in only one and three patients, respectively. Raltegravir resistance mutations were found neither at baseline nor at the time of virologic failure. Integrase clonal analyses showed neither the presence nor the selection of minority variants carrying raltegravir resistance mutations at baseline or at virological failure. No impact of baseline integrase polymorphisms was observed on virological failure either at week 24 or at week 48.

CONCLUSION

Virological failure occurred in a small proportion of patients with low viral load. No raltegravir resistance mutations were observed using bulk sequencing or clonal analyses, and darunavir and etravirine resistance-associated mutations were detected in only one and three patients, respectively at virological failure. No impact of baseline integrase polymorphism was observed on virological failure occurrence.

Pharmacokinetics of etravirine, raltegravir and darunavir/ritonavir in treatment experienced patients

Etravirine is an enzyme inducer and could lower the concentration of combined drugs. Ten HIV-1-infected patients with multiple treatment failure received raltegravir (400 mg, twice daily) and darunavir/ritonavir (600/100 mg, twice daily). Addition of etravirine (200 mg, twice daily) leads to a significant increase in raltegravir and darunavir trough concentrations (405 vs. 118 and 3837 vs. 2241 ng/ml) and darunavir area under the curve (AUC(12h)) (50 083 vs. 36 277 ng h/ml). All pharmacokinetic parameters appeared to be highly variable regardless to the addition of etravirine.

High concentration of raltegravir in semen of HIV-infected men: results from a substudy of the EASIER-ANRS 138 trial

Raltegravir concentrations and human immunodeficiency virus type 1 (HIV-1) RNA levels in semen samples from 10 treatment-experienced HIV-1-infected patients were measured after 24 weeks of raltegravir-based highly active antiretroviral therapy (HAART). Semen and plasma HIV-1 RNA levels were below 100 copies/ml and 50 copies/ml, respectively, in all samples. The median raltegravir concentrations in semen samples (n=10) and in plasma samples (n=9) drawn simultaneously were 345 (range, 83 to 707) ng/ml and 206 (range, 106 to 986) ng/ml, respectively. The median semen-to-plasma ratio of raltegravir concentration was 1.42 (range, 0.52 to 6.66), indicating good although variable levels of drug penetration of raltegravir in the seminal compartment.