Browsing by Author "Scarsi, Kimberly K."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    The Effect of Gene Variants on Levonorgestrel Pharmacokinetics when Combined with Antiretroviral Therapy containing Efavirenz or Nevirapine
    (Clinical Pharmacology & Therapeutics, 2017) Neary, Megan; Lamorde, Mohammed; Olagunju, Adeniyi; Darin, Kristin M.; Merry, Concepta; Byakika-Kibwika, Pauline; Back, David J.; Siccardi, Marco; Owen, Andrew; Scarsi, Kimberly K.
    Reduced levonorgestrel concentrations from the levonorgestrel contraceptive implant was previously seen when given concomitantly with efavirenz. We sought to assess whether single nucleotide polymorphisms (SNPs) in genes involved in efavirenz and nevirapine metabolism were linked to these changes in levonorgestrel concentration. SNPs in CYP2B6, CYP2A6, NR1I2 and NR1I3 were analysed. Associations of participant demographics and genotype with levonorgestrel pharmacokinetics were evaluated in HIV-positive women using the levonorgestrel implant plus efavirenz- or nevirapine-based ART, in comparison to ART-naïve women using multivariate linear regression. Efavirenz group: CYP2B6 516G>T was associated with lower levonorgestrel log10 Cmax and log10 AUC. CYP2B6 15582C>T was associated with lower log10 AUC. Nevirapine group: CYP2B6 516G>T was associated with higher log10 Cmax and lower log10 Cmin. Pharmacogenetic variations influenced subdermal levonorgestrel pharmacokinetics in HIV-positive women, indicating that the magnitude of the interaction with non-nucleoside reverse transcriptase inhibitors (NNRTIs) is influenced by host genetics.
  • Thumbnail Image
    Item
    Suboptimal Nevirapine Steady-State Pharmacokinetics During Intrapartum Compared With Postpartum in HIV-1–Seropositive Ugandan Women
    (Journal of acquired immune deficiency syndromes, 2010) Lamorde, Mohammed; Byakika-Kibwika, Pauline; Okaba-Kayom, Violet; Flaherty, John P.; Boffito, Marta; Namakula, Rhoda; Ryan, Mairin; Nakabiito, Clemensia; Back, David J.; Khoo, Saye; Merry, Concepta; Scarsi, Kimberly K.
    Conflicting data exist regarding the effect of pregnancy on steady-state nevirapine pharmacokinetics (PK), although steady-state nevirapine concentrations during pregnancy have never been characterized in sub-Saharan Africa. Methods: This was a longitudinal intensive PK study in Ugandan pregnant women receiving nevirapine-based antiretroviral therapy. Participants underwent intensive 12-hour PK sampling during the second trimester (T2; n = 4), third trimester (T3; n = 15) and 6 weeks postpartum (PP; n = 15). HIV-1 RNAwas performed within 2weeks of each visit. Nevirapine C12 above 3000 ng/mLwas classified as optimal based on the suggested value for therapeutic drug monitoring.
  • Thumbnail Image
    Item
    Unintended Pregnancies Observed With Combined Use of the Levonorgestrel Contraceptive Implant and Efavirenz-based Antiretroviral Therapy: A Three-Arm Pharmacokinetic Evaluation Over 48 Weeks
    (Clinical Infectious Diseases, 2016) Scarsi, Kimberly K.; Darin, Kristin M.; Nakalema, Shadia; Back, David J.; Byakika-Kibwika, Pauline; Else, Laura J.; Penchala, Sujan Dilly; Buzibye, Allan; Cohn, Susan E.; Merry, Concepta; Lamorde, Mohammed
    Levonorgestrel subdermal implants are preferred contraceptives with an expected failure rate of <1% over 5 years. We assessed the effect of efavirenz- or nevirapine-based antiretroviral therapy (ART) coadministration on levonorgestrel pharmacokinetics. Methods. This nonrandomized, parallel group, pharmacokinetic evaluation was conducted in three groups of human immunodeficiency virus–infected Ugandan women: ART-naive (n = 17), efavirenz-based ART (n = 20), and nevirapine-based ART (n = 20). Levonorgestrel implants were inserted at baseline in all women. Blood was collected at 1, 4, 12, 24, 36, and 48 weeks. The primary endpoint was week 24 levonorgestrel concentrations, compared between the ART-naive group and each ART group by geometric mean ratio (GMR) with 90% confidence interval (CI). Secondary endpoints included week 48 levonorgestrel concentrations and unintended pregnancies.