HPLC-MS method for simultaneous quantification of the antiretroviral agents rilpivirine and cabotegravir in rat plasma and tissues.

The antiretroviral agents rilpivirine (RPV) and cabotegravir (CAB) are approved as a combined treatment regimen against human immunodeficiency virus (HIV). To fully understand the biodistribution of these agents and determine their concentration levels in various parts of the body, a simple, selective and sensitive bioanalytical method is essential. In the present study, a high performance liquid chromatography method with mass spectrometry detection (HPLC-MS) was developed for simultaneous detection and quantification of RPV and CAB in various biological matrices. These included plasma, skin, lymph nodes, vaginal tissue, liver, kidneys and spleen, harvested from female Sprague Dawley rats. The suitability of the developed method for each matrix was validated based on the guidelines of the International Council for Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) on bioanalytical method validation. Analytes were extracted from biological samples employing a simple one-step protein precipitation method using acetonitrile. Samples were analysed using an Apex Scientific Inertsil ODS-3 column (4.6 mm × 250 mm, 5 µm particle size), maintained at 40 °C, on a HPLC system coupled with a single quadrupole MS detector. RPV was detected at a mass-to-charge ratio (m/z) of 367.4 and CAB at 406.3. Separation was achieved using isocratic elution at 0.3 mL/min with a mixture of acetonitrile and 0.1% (v/v) trifluoroacetic acid in water (81:19, v/v) as the mobile phase. The run time was set at 13 min. The presented method was selective, sensitive, accurate and precise for detection and quantification of RPV and CAB in all matrices. The developed and validated bioanalytical method was successfully employed for in vivo samples with both drugs simultaneously.

Long-acting rilpivirine as potential pre-exposure prophylaxis for HIV-1 prevention (the MWRI-01 study): an open-label, phase 1, compartmental, pharmacokinetic and pharmacodynamic assessment.

BACKGROUND: Long-acting injectable antiretroviral agents are being developed for HIV-1 prevention. The MWRI-01 study was done to characterise the safety, acceptability, and pharmacokinetic and pharmacodynamic profile of long-acting rilpivirine. METHODS: We did a phase 1 open-label study at the University of Pittsburgh. We enrolled healthy individuals (aged 18-45 years) who were seronegative for HIV-1. Participants were assigned alternately one intramuscular dose of either 1200 mg or 600 mg long-acting rilpivirine, beginning with the 1200 mg dose. We obtained plasma specimens, genital and rectal fluids, and tissue samples (rectal, cervical, and vaginal) before and after exposure to long-acting rilpivirine for assessment of pharmacokinetics and ex-vivo biopsy challenge with HIV-1. Our primary objective was to characterise product safety, and the analysis included all enrolled participants. This trial is registered with ClinicalTrials.gov, number NCT01656018. FINDINGS: 36 participants were enrolled into the study, of whom 24 were women and 12 men. 12 women and six men received each dose. 204 adverse events were reported among the 36 participants, of which 200 (98%) were grade 1-2. The most common adverse event was injection site reaction. All grade 3 and 4 adverse events were deemed not related to rilpivirine. Geometric mean (90% CI) concentrations in plasma of rilpivirine at day 28 post dose were 53 ng/mL (38-67) in women and 43 ng/mL (23-63) in men for the 1200 mg dose and 28 ng/mL (19-37) in women and 17 ng/mL (9-24) in men for the 600 mg dose. The tissue-to-plasma ratio for rilpivirine in rectal tissue was about two-fold higher than in vaginal and cervical tissue (1·10-1·53 vs 0·61-0·72 and 0·50-0·71, respectively). Exposure to long-acting rilpivirine suppressed viral replication significantly in rectal tissue (p<0·0001), and this suppression persisted for up to 4 months. By contrast, no viral suppression was seen in cervical or vaginal tissue. INTERPRETATION: Ongoing research will characterise longer term safety and acceptability of multiple injections and help ascertain whether long-acting rilpivirine should advance to assessment of efficacy in preventing HIV-1 infection. FUNDING: Bill & Melinda Gates Foundation.