PKRxiv: A Best Practice Model for Advancing Pharmacoequity Through Open Pharmacokinetic Data Sharing Shakir Atoyebi, Prajith Venkatasubramanian, Abdulafeez Akinloye, Oluwasegun Eniayewu, Brookie M. Best, et al. Clinical Pharmacology and Therapeutics, 2026 Model‐informed drug development is increasingly integrated across the drug development continuum, enabling more efficient, cost‐effective, and targeted trials while reducing reliance on animal studies. Achieving pharmacoequity requires not only equitable access to medicines but also to the data and knowledge that inform drug development and regulatory decisions. To address challenges in pharmacokinetic data sharing, PKRxiv ( https://pkrxiv.org/ ) was developed as a discipline‐specific repository designed around Findable, Accessible, Interoperable, Reusable (FAIR) principles. This tutorial introduces PKRxiv’s rationale, design, data submission and access workflows, and practical use cases. Available datasets at the end of September 2025 include over 5,500 individual drug concentration‐time data points from over 900 unique participants across 3 continents. The platform supports structured submission of pharmacokinetic, pharmacogenetic, and safety/efficacy data, with persistent digital object identifiers for discoverability and citation. Contributors can apply one of three data sharing models—unrestricted, noncommercial, or contributor‐controlled—with optional embargo periods. Users can explore datasets using the Data Explorer or Data Cards, or submit requests after providing a statement of intended use case. It enables pooling of datasets across multiple studies. Recommendations to help advance the field are proposed as data sharing becomes more widely expected: obtaining consent for unspecified future research use of data, sharing data underlying peer‐reviewed publications as standard practice, including discipline‐specific repositories in data management plans, and incentivizing post‐approval data sharing by industry. Supporting data from all therapeutic areas and population groups, PKRxiv is a critical step toward a more transparent, equitable, and collaborative future in clinical pharmacology research.
Phytochemical Estimations and Neurobehavioural Effects of Albizia coriaria Welw. ex Oliv. (Mimosaceae) in Mice Lateef Akinpelu, Muritala Adebayo, Oyeronke Aiyelero, Oluwasegun Eniayewu, Abdulrasaq Sanusi, et al. Tropical Journal of Natural Product Research, 2026 Albizia coriara is used to treat neuropsychiatric disorders in ethnomedicine but no scientific documentation of its use. Hence, this study evaluated the neuropharmacological potentials of acute oral administration of methanol stem bark extract (MSAC) at 100-400 mg/kg in mice and its phytoconstituents. The anxiolytic potential assessed using elevated plus maze (EPM) and hole board test (HBT); sedative-hypnotic using pentobarbital-induced hypnosis (PIH); antiamnesic using scopolamine-, and diazepam-induced amnesia; antipsychotic using hyperactivity, enhanced immobility in forced swimming (FST) tests induced by ketamine; and anticonvulsant using pentylenetetrazole (PTZ) convulsion models. The MSAC and diazepam (1 mg/kg, i.p.) significantly reduced open arm avoidance indices on open arm of EPM and showed significant dose-dependent decrease in head poking on HBT compared to control. The MSAC and diazepam (1 mg/kg, i.p.) also significantly shortened the sleep latency and extended the sleep duration in PIH compared to control. The MSAC and piracetam (200 mg/kg, p.o.) significantly ameliorated scopolamine-, and diazepam-induced amnesia compared to scopolamine (1 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.) controls respectively. The MSAC and risperidone (0.5 mg/kg, p.o.) significantly mitigated the hypermotility and enhanced immobility in FST compared to ketamine control at 10 mg/kg and 30 mg/kg i.p respectively. The MSAC (200 and 400 mg/kg) and diazepam significantly extended the latencies to tonic-clonic convulsions and death compared to control in PTZ model. This study concluded that MSAC may possess anxiolytic, sedative-hypnotic, anti-amnesic, antipsychotic and anticonvulsant effects ascribed to abundance of total flavonoids (208.20 ± 3.25 mg QE/g MSAC) among other phyochemicals present in MSAC.
Pharmacogenetics of Efavirenz Exposure in Cervicovaginal Fluid during Pregnancy and Postpartum Oluwasegun Eniayewu, Uche Azuka, Jonah Ogah, Ebunoluwa Adejuyigbe, Oluseye Bolaji, et al. Clinical Pharmacology and Therapeutics, 2024 In this study, we investigated the combined influence of pregnancy and genetic polymorphisms on efavirenz pharmacokinetics in cervicovaginal fluid (CVF) of women receiving antiretroviral therapy. Women receiving efavirenz‐containing antiretroviral therapy were recruited from two hospitals in Nigeria during 2017–2020. Sparse CVF and plasma samples were obtained during pregnancy to assess the possible association between drug concentration and CYP2B6 polymorphisms (stage I). Participants were stratified into three CYP2B6 516G>T (rs3745274) genotype groups and re‐enrolled for intensive pharmacokinetic sampling (stage II). Overall, 159 women (142 pregnant and 12 postpartum) contributed samples in stage I (88 CVF, 81 plasma and 73 paired). CYP2B6 516G>T (rs3745274) remained independently associated with log10 efavirenz CVF concentration during pregnancy after adjusting for plasma concentration, with β (Log10 efavirenz concentration, 95%CI) of 0.204 (0.027, 0.382), P = 0.025). Median (IQR) efavirenz Cmin in CVF during pregnancy (n = 12) vs. postpartum (n = 12) was 243 ng/mL (168–402) vs. 447 ng/mL (159–974), Cmax was 1,031 ng/mL (595–1,771) vs. 1,618 ng/mL (675–2,695), and AUC0‐24h was 16,465 ng.h/mL (9,356–30,417) vs. 30,715 ng.h/mL (10,980–43,714). CVF‐to‐plasma AUC ratio was 0.36 during pregnancy and 0.46 postpartum. Upon stratification, efavirenz clearance during pregnancy was 57.9% higher than postpartum in patients with the CYP2B6 516GT genotype; the AUC0‐24h and Cmax were 33.8% and 8.6% lower, respectively. Efavirenz Cmin in CVF exceeded the protein binding‐adjusted IC90 (PBIC90) of 126 ng/mL during pregnancy and postpartum. Efavirenz is well distributed into the CVF; both pregnancy and CYP2B6 polymorphisms affect the extent of exposure.
Prenatal efavirenz exposure is independently associated with maternal, but not fetal CYP2B6 genotype Oluwasegun Eniayewu, Abdulafeez Akinloye, Babajide Shenkoya, Uche Azuka, Oluseye Bolaji, et al. Pharmacogenetics and Genomics, 2024 Objectives Understanding the influence of fetal and maternal genetics on prenatal drug exposure could potentially improve benefit-risk evaluation. In this study, we investigated the impact of two functional polymorphisms in CYP2B6 on prenatal exposure to efavirenz. Methods Dried blood spot (DBS) samples were collected from HIV-positive pregnant women (n = 112) and their newborns (n = 107) at delivery. They were genotyped for single nucleotide polymorphisms in CYP2B6. Efavirenz was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results Significant correlations were observed in efavirenz concentration between maternal and newborn (r = 0.46, R 2 = 0.21, P < 0.001), and maternal and cord (r = 0.83, R 2 = 0.68, P < 0.001) samples. Median (interquartile range) newborn plasma-to-maternal plasma and cord-to-maternal plasma ratios were 0.85 (0.03–3.49) and 0.78 (0.23–1.96), respectively. Newborn efavirenz concentration in DBS varied significantly based on composite maternal CYP2B6 genotype: fast (CYP2B6 516GG and 983TT, n = 26), 747 ng/ml (602–1060); intermediate (CYP2B6 516GT or 983TC n = 50), 1177 ng/ml (898–1765); and slow (CYP2B6 516GT and 983TC or 516TT or 983CC, n = 14), 3094 ng/ml (2126–3812). Composite newborn CYP2B6 genotype was, however, not significantly associated with prenatal exposure. Efavirenz concentration in newborn stratified as fast (n = 25), intermediate (n = 36), and slow metabolizers (n = 19) from prenatal exposure was 999.7 (774–1285), 1240 (709–1984), and 1792 ng/ml (1201–3188), respectively. Conclusion The clinical relevance of the observed influence of maternal genetics on prenatal efavirenz exposure requires further investigation.
Quality assessment of hydroquinone, mercury, and arsenic in skin-lightening cosmetics marketed in Ilorin, Nigeria Olasunkanmi David Bamidele, Blessing Ayomide Kayode, Oluwasegun Ibrahim Eniayewu, Adebanjo Jonathan Adegbola, Raphael Segun Olatoye, et al. Scientific Reports, 2023 Hydroquinone, Mercury (Hg), and Arsenic (As) are hazardous to health upon long-term exposure. Hydroquinone, Hg, and As were analysed in skin-lightening cosmetics randomly purchased from different cosmetic outlets within the Ilorin metropolis, Nigeria. The amount of hydroquinone in the samples was determined using a UV-spectrophotometry method at 290 nm. Hg and As were quantified using atomic absorption spectrophotometry (AAS). UV-spectrophotometry method validation showed excellent linearity (r2 = 0.9993), with limits of detection (0.75 µg/mL), limits of quantification (2.28 µg/mL), relative standard deviation (0.01–0.35%), and recovery (95.85–103.56%) in the concentration range of 5–50 µg/mL. Similarly, r2, LOD, and LOQ for Hg and As were 0.9983 and 0.9991, (0.5 and 1.0 µg/L) and 1.65 and 3.3 µg/L) respectively. All the samples contained hydroquinone, Hg and As in varying amounts. The amounts of hydroquinone, Hg and As present were in the ranges of 1.9–3.3%, 0.08–2.52 µg/g and 0.07–5.30 µg/g respectively. Only three of the analysed samples contained hydroquinone within the permissible limit of 2.0% w/w in cosmetic products. All the samples analysed contained mercury and arsenic in varying amounts. The need to periodically monitor the levels of hydroquinone, mercury, and arsenic in skin-lightening cosmetics marketed in Nigeria is recommended.
Validation and Clinical Application of a Liquid Chromatography–Ultraviolet Detection Method to Quantify Dolutegravir in Dried Blood Spots Abdulafeez Akinloye, Oluwasegun Eniayewu, Babatunde Adeagbo, Oluseye Bolaji, Adeniyi Olagunju Therapeutic Drug Monitoring, 2022 Supplemental Digital Content is Available in the Text. Background: Dolutegravir is currently the preferred component of first-line antiretroviral therapy. To facilitate clinical pharmacology studies in key populations, quantitative analytical methods compatible with microsampling and adaptable to resource-limited settings are desirable. The authors developed and validated a liquid chromatography–ultraviolet detection method to quantify dolutegravir in dried blood spots (DBS). Methods: Calibration standards and quality control samples were prepared by spotting 50 μL of dolutegravir-spiked whole blood on each circle of DBS cards. Three spots (two 6-mm punches/spot) were extracted with methanol. Chromatographic separation was achieved with gradient elution of acetonitrile/potassium phosphate monobasic buffer (pH 5) on a reverse-phase C18 column (flow rate, 1 mL/min) using pioglitazone as the internal standard. UV detection was performed at 260 nm. In the clinical pharmacokinetic study, DBS from finger prick was collected from participants (n = 10) at 8 time points over 12 hours postdosing, with paired plasma at 1 and 12 hours. The method was used to quantify dolutegravir, estimating pharmacokinetic parameters. Agreement between DBS and plasma concentrations was evaluated using linearity and Bland–Altman plots. Results: The method was validated over the concentration range of 0.4–10 mcg/mL, accuracy was 102.4%–114.8%, and precision was 3.4%–14.7%. The mean recovery was 42.3% (%CV: 8.3). The mean (±SD) dolutegravir concentration in DBS was 37.5% (±3.8%) lower than that in the plasma. DBS-derived and measured plasma concentrations showed strong correlation with linearity (R2 = 0.9804) and Bland–Altman plots. Means (%CV) of area under curve, Cmax, and C24 from the DBS-derived plasma concentration were 37.8 (23.2) mcg·h/mL, 2.7 (24.7) mcg/mL, and 1.34 (31.6) mcg/mL, respectively. Conclusions: The application of this simple, accurate, and precise method will expand opportunities for clinical assessment of dolutegravir in resource-limited settings.
Influence of Amlodipine on the Disposition of Quinine in Healthy Volunteers Oluwasegun I. Eniayewu, Adebanjo J. Adegbola, Babatunde A. Adeagbo, Oluseye O. Bolaji American Journal of Therapeutics, 2022 To the Editor: Concurrent administration of 2 or more drugs in patients with co-existing diseases is a common practice. However, this practice increases the complexity of pharmacotherapy and may result in significant drug–drug interactions.1 Patients with hypertension generally require concomitant antimalarial therapy when they present with concurrent malaria infection. With the widespread incidence of malaria and hypertension in the lowand middle-income countries, concurrent administration of therapies for these 2 conditions may arise. Despite the advent of artemisinin-based combination therapies, quinine remains a viable therapeutic option in malaria chemotherapy mainly because of rising resistance to artemisinin-based combination therapies, in some regions.2 On the other hand, amlodipine, a longacting third-generation dihydropyridine calcium channel blocker, is commonly prescribed for the management of hypertension.3,4 Because quinine and amlodipine are substrates for both cytochrome P450 (CYP) drug-metabolizing enzymes and the transporter, P-glycoprotein, and amlodipine also inhibits both drug metabolizing and transporter activities,5–10 concurrent administration of the 2 drugs may result in potential drug–drug interactions. Previous studies found that coadministration of quinine with substrates and inhibitors of CYP3A4 resulted in a significant increase in the systemic exposure of quinine.11,12 This study investigated the effect of the coadministration of amlodipine on quinine pharmacokinetics. A two-phase, randomized, crossover pharmacokinetic study was implemented. The study was approved by the Health Research Ethics Committee of the Institute of Public Health of the Obafemi Awolowo University, Ile-Ife, Nigeria. The study population included healthy nonsmoking individuals, aged 18–36 years and weighing 45–71 kg. Subjects with previous or current evidence of gastrointestinal, psychiatric, cardiovascular, or neurological disorders were excluded from the study. All subjects provided informed consent before enrollment into the study. Subjects were randomly divided into 2 groups, and a single dose of 600 mg quinine was administered alone or with 5 mg of amlodipine in a crossover fashion. Blood samples were collected predose and at intervals over 48 hours and analyzed for quinine and its metabolite, 3-hydroxyquinine (3-HQN) using a validated high-performance liquid chromatographic method. Briefly, 200 mL of plasma was transferred into a 10 mL extraction tube and deproteinated with 200 mL of perchloric acid by whirl-mixing for
Validation and clinical application of a method to quantify efavirenz in cervicovaginal secretions from flocked swabs using liquid chromatography tandem mass spectrometry Adeniyi Olagunju, Jacinta Nwogu, Oluwasegun Eniayewu, Shakir Atoyebi, Alieu Amara, et al. Wellcome Open Research, 2022 Background : A liquid chromatography tandem mass spectrometry method to quantify drugs in dried cervicovaginal secretions from flocked swabs was developed and validated using the antiretroviral efavirenz as an example. Methods: Cervicovaginal swabs (CVS) were prepared by submerging flocked swabs in efavirenz-spiked plasma matrix. Time to full saturation, weight uniformity, recovery and room temperature stability were evaluated. Chromatographic separation was on a reverse-phase C18 column by gradient elution using 1mM ammonium acetate in water/acetonitrile at 400 µL/min. Detection and quantification were on a TSQ Quantum Access triple quadrupole mass spectrometer operated in negative ionisation mode. The method was used to quantify efavirenz in CVS samples from human immunodeficiency virus (HIV)-positive women in the VADICT study (NCT03284645). A total of 98 samples (35 paired intensive CVS and DBS pharmacokinetic samples, 14 paired sparse CVS and DBS samples) from 19 participants were available for this analysis. Results: Swabs were fully saturated within 15 seconds, absorbing 128 µL of plasma matrix with coefficient of variation (%CV) below 1.3%. The method was linear with a weighting factor (1/X) in the range of 25-10000 ng/mL with inter- and intra-day precision (% CV) of 7.69-14.9%, and accuracy (% bias) of 99.1-105.3%. Mean recovery of efavirenz from CVS was 83.8% (%CV, 11.2) with no significant matrix effect. Efavirenz remained stable in swabs for at least 35 days after drying and storage at room temperature. Median (range) CVS efavirenz AUC 0-24h was 16370 ng*h/mL (5803-22088), C max was 1618 ng/mL (610-2438) at a T max of 8.0 h (8.0-12), and C min was 399 ng/mL (110-981). Efavirenz CVS:plasma AUC 0-24h ratio was 0.41 (0.20-0.59). Conclusions: Further application of this method will improve our understanding of the pharmacology of other therapeutics in the female genital tract, including in low- and middle-income countries.
