The impact of pregnancy on antihypertensive drug metabolism and pharmacokinetics: current status and future directions

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.

Comparing the efficacy of oral labetalol with oral amlodipine in achieving blood pressure control in women with postpartum hypertension: randomized controlled trial (HIPPO study-Hypertension In Pregnancy & Postpartum Oral-antihypertensive therapy)

De novo - or as a continuum of antenatal hypertension -postpartum hypertension complicates ~2% of pregnancies. Many maternal complications, such as eclampsia and cerebrovascular accidents, occur in the postpartum period. Despite widespread use of antihypertensives during pregnancy and childbirth, there is a paucity of data on preferred medications in the postpartum period. This randomized controlled study enrolled 130 women who were started on antihypertensives. They were randomized to receive oral Labetalol(LAB, maximum 900 mg per day in three doses) or oral Amlodipine(AML, maximum 10 mg per day given in two doses). In the immediate postpartum, all women were closely monitored for neurological symptoms, blood pressure, heart rate, respiratory rate, urine output, and deep tendon reflex. The primary outcome was the time to achieve sustained blood pressure control for 12 h from the initiation of medication; secondary outcomes included side effects of both medications. Mean time to achieve sustained blood pressure control was lower in women who received AML than in those who received LAB-(mean difference 7.2 h; 38 95% CI 1.4, 12.9, p = 0.011). There were fewer severe hypertensive episodes among those with AML than in those who received LAB. However, the proportion of women who continued to require antihypertensives at discharge was higher in the AML group than in the LAB group (55.4% versus 32.3%, p = 0.008). None of the participants developed drug-related side effects. Among women with postpartum persistence or new-onset hypertension, oral AML achieved sustained blood pressure control in a shorter duration, with fewer hypertensive emergencies than oral LAB. (CTRI/2020/02/023236).Trial Registration details: The study protocol was registered with Clinical Trial Registry of India with CTRI Number CTRI/2020/02/023236 dated 11.02.2020. Protocol can be accessed at https://www.ctri.nic.in/Clinicaltrials/pdf_generate.php?trialid=40435&EncHid=&modid=&compid=%27,%2740435det%27 .

Beta-Blockers and Their Current Role in Maternal and Neonatal Health: A Narrative Review of the Literature

Beta-blockers are a class of medications that act on beta-adrenergic receptors and are categorized as cardio-selective and non-selective. They are principally used to treat cardiovascular conditions such as hypertension and arrhythmias. Beta-blockers have also been used to treat non-cardiogenic indications in non-pregnant individuals and the pediatric population. In pregnancy, labetalol is the mainstay treatment for hypertension and other cardiovascular indications. However, contraindications to certain sub-types of beta-blockers include bradycardia, heart failure, obstructive lung diseases, and hemodynamic instability. There is conflicting evidence of the adverse effects on fetal and neonatal health due to a scarce safety and efficacy profile, and further studies are necessary to understand the pharmacokinetics of the different classes of beta-blockers in pregnancy and fetal health. Understanding the hemodynamic changes during the stages of pregnancy is important to target a more beneficial therapy for both mother and fetus as well as better neonatal outcomes. Beta-blocker use in the pediatric population is less documented in studies but does have the potential to treat various cardiogenic and non-cardiogenic conditions. Future comprehensive studies would further benefit the direction of beta-blocker treatment during pregnancy in neonates and pediatrics.

Antihypertensive medication use during pregnancy in a real-world cohort of patients diagnosed with a hypertensive disorder of pregnancy

Hypertensive disorders of pregnancy (HDP) are rising in prevalence and associated with adverse maternal and infant health outcomes. Current guidelines recommend labetalol, nifedipine, and methyldopa as acceptable first-line agents to treat HDP in outpatient settings. However, the current practice regarding antihypertensive medication usage and selection remain unclear. A retrospective, observational cohort study was conducted in 1,641 patients with a physician diagnosis of HDP who delivered at two academic medical centers in North Carolina from 2014 to 2017. Use of any antihypertensive medication, and the agent selected, at any encounter during pregnancy or on the delivery date was collected from the electronic health record. Proportions were compared across HDP diagnosis (eclampsia/severe preeclampsia, chronic hypertension with superimposed preeclampsia, preeclampsia, gestational hypertension) by Chi-square tests and multivariable logistic regression. Antihypertensive medications were used in 1,276 (77.8%) patients overall. Among treated patients, labetalol (74.9%) was the most frequently used medication followed by nifedipine (29.6%) and hydralazine (20.5%). Methyldopa was used infrequently (4.4%). HDP type was the strongest factor associated with use of an antihypertensive agent. Relative to gestational hypertension, antihypertensive use was significantly more likely [odds ratio (95% CI)] in patients with severe preeclampsia [5.94 (3.85-9.16)], chronic hypertension with superimposed preeclampsia [4.99 (3.46-7.19)], and preeclampsia [2.13 (1.61-2.82)]. In a real-world setting, antihypertensive medication use among HDP patients was common, labetalol, nifedipine, and hydralazine were the most commonly selected agents, and increasing HDP severity was associated with a higher likelihood of antihypertensive use. Future studies comparing medication effectiveness in pregnant patients with distinct HDP diagnoses are needed.

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.

Physiologic Changes During Pregnancy and Impact on Small-Molecule Drugs, Biologic (Monoclonal Antibody) Disposition, and Response

Pregnancy is a unique physiological state that results in many changes in bodily function, including cellular, metabolic, and hormonal changes. These changes can have a significant impact on the way small-molecule drugs and monoclonal antibodies (biologics) function and are metabolized, including efficacy, safety, potency, and adverse effects. In this article, we review the various physiologic changes that occur during pregnancy and their effects on drug and biologic metabolism, including changes in the coagulation, gastrointestinal, renal, endocrine, hepatic, respiratory, and cardiovascular systems. Additionally, we discuss how these changes can affect the processes of drug and biologic absorption, distribution, metabolism, and elimination (pharmacokinetics), and how drugs and biologics interact with biological systems, including mechanisms of drug action and effect (pharmacodynamics) during pregnancy, as well as the potential for drug-induced toxicity and adverse effects in the mother and developing fetus. The article also examines the implications of these changes for the use of drugs and biologics during pregnancy, including consequences of suboptimal plasma drug concentrations, effect of pregnancy on the pharmacokinetics and pharmacodynamics of biologics, and the need for careful monitoring and individualized drug dosing. Overall, this article aims to provide a comprehensive understanding of the physiologic changes during pregnancy and their effects on drug and biologic metabolism to improve the safe and effective use of drugs.

Beta-Blockers in Pregnancy: Clinical Update

PURPOSE OF REVIEW

The aim of this review was to determine the anticipated benefits and adverse effects of beta-blockers in pregnant women with hypertension. The other issue was to assess the possible adverse effects of beta-blockers for their babies and provide current consensus recommendations for appropriate selection and individualized antihypertensive treatment with beta-blockers in pregnancy-associated hypertension.

RECENT FINDINGS

Hypertensive disorders of pregnancy are a major cause of maternal and fetal morbidity, with consequences later in life. Certain beta-blockers are useful for ameliorating hypertension in pregnancy and may have a protective role in endothelial dysfunction. However, some aspects of beta-blocker use in pregnancy are contentious among providers. Evidence on their safety, although well documented, is variable, and recent research reveals areas of controversy. Besides intrauterine growth restriction, other neonatal and obstetric complications remain a concern and should be explored thoroughly. Attention is necessary when treating pregnancy-associated hypertensive disorders with beta-blockers. Specific beta-blockers are considered safe in pregnancy, although the associated effects in the fetus are not clearly known and evidence is lacking for many safety outcomes, other than intrauterine growth restriction. Nevertheless, beta-blockers with specific indications in pregnancy under individualized selection and monitoring may confer substantial improvements in pregnant women with hypertension.

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

Pregnancy alters the disposition and exposure to multiple drugs indicated for pregnancy-related complications. Previous in vitro studies have shown that pregnancy-related hormones (PRHs) alter the expression and function of certain cytochrome P450s (CYPs) in human hepatocytes. However, the impact of PRHs on hepatic concentrations of non-CYP drug-metabolizing enzymes (DMEs) and transport proteins remain largely unknown. In this study, sandwich-cultured human hepatocytes (SCHH) from five female donors were exposed to vehicle or PRHs (estrone, estradiol, estriol, progesterone, cortisol, and placental growth hormone), administered individually or in combination, across a range of physiologically relevant PRH concentrations for 72 h. Absolute concentrations of 33 hepatic non-CYP DMEs and transport proteins were quantified in SCHH membrane fractions using a quantitative targeted absolute proteomics (QTAP) isotope dilution nanoLC-MS/MS method. The data revealed that PRHs altered the absolute protein concentration of various DMEs and transporters in a concentration-, isoform-, and hepatocyte donor-dependent manner. Overall, eight of 33 (24%) proteins exhibited a significant PRH-evoked net change in absolute protein concentration relative to vehicle control (ANOVA p &lt; 0.05) across hepatocyte donors: 1/11 UGTs (9%; UGT1A4), 4/6 other DMEs (67%; CES1, CES2, FMO5, POR), and 3/16 transport proteins (19%; OAT2, OCT3, P-GP). An additional 8 (24%) proteins (UGT1A1, UGT2B4, UGT2B10, FMO3, OCT1, MRP2, MRP3, ENT1) exhibited significant PRH alterations in absolute protein concentration within at least two individual hepatocyte donors. In contrast, 17 (52%) proteins exhibited no discernable impact by PRHs either within or across hepatocyte donors. Collectively, these results provide the first comprehensive quantitative proteomic evaluation of PRH effects on non-CYP DMEs and transport proteins in SCHH and offer mechanistic insight into the altered disposition of drug substrates cleared by these pathways during pregnancy.