Impact of pregnancy related hormones on drug metabolizing enzyme and transport protein concentrations in human hepatocytes

Mechanisms of altered hepatic drug disposition during pregnancy: small molecules

INTRODUCTION

Pregnancy alters the systemic exposure and clearance of many hepatically cleared drugs that are commonly used by obstetric patients. Understanding the molecular mechanisms underlying the changes in factors that affect hepatic drug clearance (blood flow, protein binding, and intrinsic clearance) is essential to more precisely predict systemic drug exposure and dose requirements in obstetric patients.

AREAS COVERED

This review (1) summarizes the anatomic, physiologic, and biochemical changes in maternal hepatic, cardiovascular, endocrine, and renal systems relevant to hepatic drug clearance and (2) reviews the molecular mechanisms underlying the altered hepatic metabolism and intrinsic clearance of drugs during pregnancy via a comprehensive PubMed search. It also identifies knowledge gaps in the molecular mechanisms and factors that modulate hepatic drug clearance during pregnancy.

EXPERT OPINION

Pharmacokinetic studies have shown that pregnancy alters systemic exposure, protein binding, and clearance of many drugs during gestation in part due to pregnancy-associated decreases in plasma albumin, increases in organ blood flow, and changes in the activity of drug-metabolizing enzymes (DMEs) and transporters. The changes in the activity of certain DMEs and transporters during pregnancy are likely driven by hormonal-changes that inhibit their activity or alter the expression of these proteins through activation of transcription factors.

Development of a PBPK Model for Lamotrigine which Incorporates Metabolism by UGT2B10: Impact of UGT2B10 Poor Metabolizer Phenotype and Pregnancy

An updated physiologically based pharmacokinetic (PBPK) model was developed for lamotrigine by incorporating a component of metabolism due to a UDP-glucuronyltransferase (UGT) 2B isozyme. This was assigned to UGT2B10 based on recent in vitro data in our laboratory demonstrating metabolism of lamotrigine by this isozyme (Tang et al. AAPS J 26:107, 2024). The PBPK model developed in this work was able to reasonably recapitulate the exposure of lamotrigine after single (IV and Oral) and multiple (Oral) doses. The predicted/observed maximal plasma concentration (Cmax) ratio ranged from 0.8 to 1.4 across all simulated studies and for 16 out of 18 simulated studies was between 0.8 and 1.25. Similarly, the predicted/observed area under the curve (AUC) ratio ranged from 0.6 to 1.44 across all simulated studies and for 18 out of 26 of the simulated studies the ratio was between 0.8 and 1.25. There was a slight tendency to overpredict the lamotrigine AUC on multiple dosing. The median predicted fraction metabolised (fm) by UGT2B10 in the model was 60%. With this fm value, the in vivo clinical DDI between lamotrigine and valproate was reasonably recapitulated considering only UGT2B10 inhibition (Predicted/Observed AUC ratios ranged from 0.65 - 1.2). Information on the prevalence of UGT2B10 poor metabolizer phenotypes and longitudinal changes in UGT1A4 and UGT2B10 expression during pregnancy were incorporated into the PBPK model and the plasma concentrations in subjects with different UGT2B10 phenotypes and in different trimesters of pregnancy were simulated. The simulated concentrations in pregnant subjects were in line with those reported during pregnancy.

Impact of sex and pregnancy on hepatic CYP3A4 expression and activity in a humanized mouse model

Cytochrome P450 (CYP) 3A4 is an essential drug-metabolizing enzyme in humans, which shows substantial interindividual variation in response to various intrinsic and extrinsic factors such as sex and pregnancy. In humans, higher CYP3A4 metabolism has been observed in females compared with that in males and in pregnant compared with that in nonpregnant individuals, which has been linked to increased CYP3A4 expression in liver. However, sex differences and pregnancy-mediated changes in hepatic CYP3A4 expression and activity in vivo are not fully understood. In this study, we investigated the utility of a genetically engineered humanized mouse model that carries human CYP3A4/7, pregnane X receptor (PXR) and constitutive androstane receptor (CAR) (huPXR/CAR/CYP3A4/7) to recapitulate sex-associated and pregnancy-associated differences in the hepatic CYP3A4 expression and metabolism observed in humans. We found that female huPXR/CAR/CYP3A4/7 mice exhibited higher basal CYP3A4 mRNA levels and CYP3A4 absolute protein concentrations in liver, and higher 1-hydroxymidazolam formation in liver microsomes, compared with male humanized mice. In contrast, pregnant huPXR/CAR/CYP3A4/7 mice exhibited lower CYP3A4 mRNA levels, CYP3A4 absolute protein concentrations, and 1-hydroxymidazolam formation compared with nonpregnant and postpartum humanized mice. Expression of CAR and Cyp2b10 (a CAR responsive gene) were also higher in females and decreased during pregnancy and were positively correlated with hepatic CYP3A4 mRNA levels. Overall, the huPXR/CAR/CYP3A4/7 mouse model demonstrated utility to study higher basal hepatic CYP3A4 metabolism in females compared with that in males in vivo; however, this humanized mouse model did not demonstrate utility to study pregnancy-mediated increases in CYP3A4 drug substrate metabolism and clearance observed in humans. SIGNIFICANCE STATEMENT: This study assessed the impact of sex and pregnancy on hepatic CYP3A4 protein concentrations and metabolism in humanized PXR/CAR/CYP3A4 mice. Consistent with humans, female mice demonstrated higher hepatic CYP3A4 expression and activity than male mice. In contrast, pregnant mice showed decreased CYP3A4 expression and metabolism compared with nonpregnant mice. The humanized mouse model appeared useful to evaluate sex differences in basal hepatic CYP3A4 metabolism in vivo, but not to study the pregnancy-mediated increase in CYP3A4 metabolism observed during human pregnancy.

Daily versus Twice Daily Nifedipine for Blood Pressure Control in Pregnancy and Postpartum

OBJECTIVE

 The objective of this study was to compare 60 mg daily (QD) extended released (XR) nifedipine to 30 mg twice daily (BID) for blood pressure (BP) control antepartum and postpartum.

STUDY DESIGN

 This is a retrospective chart review conducted at the Mount Sinai Health System. Patients admitted from January 1, 2015, to April 30, 2021, diagnosed with a hypertensive disorder of pregnancy, who received nifedipine XR 30 mg BID or 60 mg QD for intrapartum or postpartum BP control were included. The primary outcome was the need for up-titration (i.e., the need for an increase in nifedipine dose or addition of another antihypertensive) after reaching one of the study doses (30 mg BID or 60 mg QD). Patients were excluded if they had preexisting renal disease or were already on oral antihypertensives. In a 1:1 ratio between single- and twice-daily dosing groups, the sample size needed to detect a 20% difference in up-titration rate to achieve 0.80 power is 97 patients per group, for a total of 194 patients. This is based on a Pearson chi-square test with a significance level of 0.05.

RESULTS

 A total of 237 patients were included, 139 (59%) received 30 mg BID and 98 (41%) 60 mg QD. There was no statistically significant difference in the need for an increase in nifedipine dose or addition of another oral antihypertensive agent between those receiving 30 mg BID versus 60 mg QD (33.8 vs. 35.7%; adjusted odds ratio [aOR], 95% confidence interval [CI]: 0.90 [0.50-1.60]; p = 0.71). There was no difference in the need for emergency hypertensive treatment after reaching the study dose (p = 0.19) or readmission for BP control between groups (p > 0.99).

CONCLUSION

 These findings suggest that BID dosing does not confer better BP control in the antepartum or postpartum periods. Thus, daily dosing is reasonable and may be preferable for patient convenience and compliance.

KEY POINTS

· Nifedipine metabolism may increase in pregnancy.. · nifedipine 30 mg BID versus 60 mg QD were compared.. · There was no difference in the need for additional medication.. · There was no difference in the need for readmission.. · Daily dosing may be preferable for convenience..

The Application of Nano Drug Delivery Systems in Female Upper Genital Tract Disorders

The prevalence of female reproductive system disorders is increasing, especially among women of reproductive age, significantly impacting their quality of life and overall health. Managing these diseases effectively is challenging due to the complex nature of the female reproductive system, characterized by dynamic physiological environments and intricate anatomical structures. Innovative drug delivery approaches are necessary to facilitate the precise regulation and manipulation of biological tissues. Nanotechnology is increasingly considered to manage reproductive system disorders, for example, nanomaterial imaging allows for early detection and enhances diagnostic precision to determine disease severity and progression. Additionally, nano drug delivery systems are gaining attention for their ability to target the reproductive system successfully, thereby increasing therapeutic efficacy and decreasing side effects. This comprehensive review outlines the anatomy of the female upper genital tract by highlighting the complex mucosal barriers and their impact on systemic and local drug delivery. Advances in nano drug delivery are described for their sustainable therapeutic action and increased biocompatibility to highlight the potential of nano drug delivery strategies in managing female upper genital tract disorders.

Physiologically based pharmacokinetic modeling of long-acting extended-release naltrexone in pregnant women with opioid use disorder

Opioid use disorders (OUD) are a major issue in the U.S. Current treatments for pregnant women, like methadone and buprenorphine require daily dosing and have adverse effects. Monthly injectable naltrexone (XR-NTX) mitigates these adverse effects but is not recommended during pregnancy due to limited pharmacokinetic and safety data. This study developed a physiologically based pharmacokinetic (PBPK) model to describe XR-NTX pharmacokinetics during pregnancy, and to predict dosing recommendations. Model predictions were successfully validated with observed data. Maternal plasma XR-NTX profiles were simulated for 400 non-pregnant virtual females at the approved dose of 380 mg, then randomized to continue with either 380, 285, 190, or 95 mg during pregnancy. The non-pregnant virtual females had a mean predicted Cmax, AUC0-7days, and AUC0-28days of 23.3 ng/mL, 142 ng·d/mL, and 148 ng·d/mL, respectively. Maternal XR-NTX exposure (AUC0-28days) were predicted to increase by 1.37, 1.43, and 1.72 times during the first, second, and third trimester of pregnancy. However, the fetal-to-maternal exposure (AUC0-28days) was lower in the first (15%), second (7%), and third (9%) trimesters. A dose of 285 mg of XR-NTX in pregnancy during the first/second trimester and dose of 190 mg in the third trimester were predicted to provide maternal exposures that were comparable to non-pregnant levels at the standard dose. This study provides crucial insights into XR-NTX pharmacokinetics and proposes a dosing strategy during pregnancy, potentially aiding further clinical investigations and decision making regarding XR-NTX use during pregnancy.

The effect of pregnancy-related hormones on hepatic transporters: studies with premenopausal human hepatocytes

Introduction

Pregnancy results in significant changes in drug pharmacokinetics (PK). While previous studies have elucidated the impact of pregnancy-related hormones (PRH) on mRNA or protein expression and activity of major hepatic metabolizing enzymes, their effect on hepatic drug transporters remains largely unexplored. Therefore, we investigated the effect of a cocktail of PRH on the mRNA expression and activity of hepatic transporters.

Methods

Plated human hepatocytes (PHH) from 3 premenopausal donors were incubated, in triplicate, for 72 h, with vehicle (DMSO < 0.01%), rifampin (10 μM; positive control) or a cocktail of PRH consisting of estrone, estradiol, estriol, estetrol, progesterone, cortisol, testosterone, oxytocin, and placental growth hormone. The PRH concentrations replicated 0.1×, 1×, or 10× of the plasma concentrations of these hormones observed during each of the three trimesters of pregnancy. After treatment, mRNA expression (quantified by qPCR) of hepatic influx and efflux transporters as well as the activity of influx transporters was quantified (uptake of a selective substrate ± corresponding transporter inhibitor). The data were expressed relative to that in the control (vehicle) group. Significance was evaluated by ANOVA (followed by Dunn's multiple comparisons) or unpaired t-test when the within-lot data were analyzed, or repeated measures ANOVA (followed by Dunn's multiple comparisons) or paired t-test when data from all 3 lots were analyzed (p < 0.05).

Results and Discussion

In general, a) PRH cocktails significantly induced transporter mRNA expression in the following order OAT2 ≈ NTCP ≈ OCT1 > OATP2B1 and repressed mRNA expression in the following order OATP1B3 > OATP1B1; b) these changes translated into significant induction of OAT2 (T1-T3) and NTCP (T2-T3, in only two lots) activity at the 1× PRH concentration. Compared with the influx transporters, the induction of mRNA expression of efflux transporters was modest, with mRNA expression of MRP2 and BSEP being induced the most.

Conclusion

Once these data are verified through in vivo probe drug PK studies in pregnancy, they can be populated into physiologically based pharmacokinetic (PBPK) models to predict, for all trimesters of pregnancy, transporter-mediated clearance of any drug that is a substrate of the affected transporters.

Successful Prediction of Fetal Exposure to Dual BCRP/P-gp Drug Substrates Using the Efflux Ratio-Relative Expression Factor Approach and PBPK M&S

To inform fetal drug safety, it is important to determine or predict fetal drug exposure throughout pregnancy. The former is not possible in the first or second trimester. In contrast, at the time of birth, fetal drug exposure, relative to maternal exposure, can be estimated as Kp,uu (unbound fetal umbilical venous (UV) plasma area under the curve (AUC)/unbound maternal plasma (MP) AUC), provided the observed UV/MP values, spanning the dosing interval, are available from multiple maternal-fetal dyads. However, this fetal Kp,uu cannot be extrapolated to other drugs. To overcome the above limitations, we have used an efflux ratio-relative expression factor (ER-REF) approach to successfully predict the fetal Kp,uu of P-gp substrates. Because many drugs taken by pregnant people are also BCRP substrates, here, we extend this approach to drugs that are effluxed by both placental BCRP and P-gp or P-gp alone. To verify our predictions, we chose drugs for which UV/MP data were available at term: glyburide and imatinib (both BCRP and P-gp substrates) and nelfinavir (only P-gp substrate). First, the ER of the drugs was determined using Transwells and MDCKII cells expressing either BCRP or P-gp. Then, the ER was scaled using the proteomics-informed REF value to predict the fetal Kp,uu of the drug at term. The ER-REF predicted fetal Kp,uu of glyburide (0.43), imatinib (0.42), and nelfinavir (0.40) fell within two-fold of the corresponding in vivo fetal Kp,uu (0.44, 0.37, and 0.46, respectively). These data confirm that the ER-REF approach can successfully predict fetal drug exposure to BCRP/P-gp and P-gp substrates, at term.

Impact of Pregnancy on the Pharmacokinetics and Metabolism of Nicotinamide in Humans

In pre-eclampsia models, nicotinamide (NAM) has protective effects in pre-eclampsia and is being evaluated as a therapeutic nutraceutical in clinical studies. NAM undergoes extensive hepatic metabolism by NAM N-methyltransferase to methylnicotinamide (MNA), which is subsequently metabolized to methyl-2-pyridone-5-carboxamide (M2PY) by aldehyde oxidase. However, the pharmacokinetics of NAM and its major metabolites has never been studied in pregnant individuals. Blood samples were collected before and 1, 2, 4, 8, and 24 hours after single 1 g oral NAM dose in healthy pregnant (gestational age 24-33 weeks) and nonpregnant female volunteers (n = 6/group). Pooled urine was collected from 0 to 8 hours. NAM, MNA, and M2PY area under the concentration-time curve (AUC) data were analyzed by noncompartmental analysis. No difference in the plasma AUC0→24 of NAM (median (25%-75%): 463 (436-576) vs. 510 (423, 725) μM*hour, P = 0.430) and its intermediate metabolite MNA (89.1 (60.4, 124.4) vs. 83.8 (62.7, 93.7) μM*hour, P = 0.515) was observed in pregnant and nonpregnant volunteers, respectively; however, the terminal metabolite M2PY AUC0 → 24 was significantly lower in pregnant individuals (218 (188, 254) vs. 597 (460, 653) μM*hour, P < 0.001). NAM renal clearance (CLR ; P = 0.184), MNA CLR (P = 0.180), and total metabolite formation clearance (P = 0.405) did not differ across groups; however, M2PY CLR was significantly higher in pregnant individuals (10.5 (9.3-11.3) vs. 7.5 (6.4-8.5) L/h, P = 0.002). These findings demonstrate that the PK of NAM and systemic exposure to its intermediate metabolite MNA are not significantly altered during pregnancy, and systemic exposure to NAM's major metabolite M2PY was reduced during pregnancy due to increased renal elimination.

Intestinal P-gp activity is reduced in postmenopausal women under breast cancer therapy

Intestinal P-glycoprotein (P-gp) activity plays a crucial role in modulating the oral bioavailability of its substrates. Fexofenadine has commonly been used as a P-gp probe, although it is important to note the involvement of other drug transporters like, OATP1B1, OATP1B3, and OATP2B1. In vitro studies demonstrated an upregulation of P-gp protein in response to exposure to pregnancy-related hormones. The objective of this study was to investigate how intestinal P-gp activity is impacted by menopausal status. This study sampled fexofenadine plasma concentrations over 0-12 h after probe drug administration from two groups of patients with breast cancer: premenopausal (n = 20) and postmenopausal (n = 20). Fexofenadine plasma concentrations were quantified using liquid-chromatography tandem mass spectrometry. Area under the plasma concentration-time curve from zero to infinity (AUCinf ) was calculated through limited sampling strategies equation. Multiple linear regression was applied on AUCinf , maximum plasma concentration (Cmax ), and time to Cmax . Postmenopausal patients showed a significant increase in Cmax (geometric mean and 95% confidence interval [CI] 143.54, 110.95-176.13 vs. 223.54 ng/mL, 161.02-286.06 and in AUCinf 685.55, 534.98-878.50 vs. 933.54 ng·h/mL 735.45-1184.99) compared to premenopausal patients. The carriers of the ABCB1 3435 allele T displayed higher Cmax values of 166.59 (95% CI: 129.44-214.39) compared to the wild type at 147.47 ng/mL (95% CI: 111.91-194.34, p = 0.02). In postmenopausal individuals, the decrease in P-gp activity of ~40% may lead to an increased plasma exposure of orally administered P-gp substrates.

Pregnancy related hormones increase CYP3A mediated buprenorphine metabolism in human hepatocytes: a comparison to CYP3A substrates nifedipine and midazolam

Introduction: Pregnancy increases the clearance of CYP3A4 substrate drugs and pregnancy-related hormones (PRHs) induce hepatic CYP3A4 expression and metabolism. However, it remains unclear to what extent the magnitude of PRH-evoked changes in hepatic CYP3A metabolism varies across multiple substrates. This study quantified the impact of PRHs on CYP3A protein concentrations and buprenorphine metabolism in human hepatocytes, and compared the magnitude of these effects to nifedipine and midazolam metabolism. Methods: Sandwich-cultured human hepatocytes (SCHH) from female donors were exposed to PRHs, administered in combination across a range of physiologically relevant concentrations, for 72 h. Absolute protein concentrations of CYP3A4, CYP3A5, and CYP3A7 in SCHH membrane fractions were quantified by nanoLC-MS/MS, and norbuprenorphine (nor-BUP), dehydro-nifedipine (dehydro-NIF), and 1-hydroxy-midazolam (1-OH-MDZ) formation was evaluated. Results: Compared to control, PRH exposure increased CYP3A4, CYP3A7, and total CYP3A protein concentrations, but not CYP3A5 concentrations, and increased nor-BUP, dehydro-NIF, and 1-OH-MDZ formation in a concentration-dependent manner. The formation of nor-BUP, dehydro-NIF, and 1-OH-MDZ each positively correlated with PRH-mediated changes in total CYP3A protein concentrations. The PRH-evoked increase in nor-BUP formation was evident in all donors; however, the PRH induction of dehydro-NIF and 1-OH-MDZ formation was diminished in a hepatocyte donor with high basal CYP3A5 expression. Discussion: These findings demonstrate that PRHs increase buprenorphine, nifedipine, and midazolam metabolism in SCHH via induction of CYP3A4 and total CYP3A protein concentrations, and the magnitude of these effects vary across hepatocyte donors in a substrate-specific manner. These data provide insight into the contribution of PRH induction of CYP3A4 metabolism to increased buprenorphine clearance during pregnancy.