Pharmacokinetic Characterization of Labetalol in Pregnancy (The CLIP Study): A Prospective Observational Longitudinal Pharmacokinetic/Pharmacodynamic Cohort Study During Pregnancy and Postpartum

Background/Objectives: Hypertensive disorders of pregnancy are a leading cause of pregnancy-related deaths in the United States, accounting for 7% of maternal mortality. Labetalol and nifedipine are the first-line drugs for the management of hypertension in pregnancy, but there are little data guiding the choice of one drug over the other. The current pilot longitudinal study aims to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of labetalol stereoisomers throughout pregnancy and postpartum. Methods: This is a single-center clinical study recruiting up to 40 pregnant individuals ≥ 18 years of age at the time of enrollment, taking labetalol as per the standard of care. The exclusion criteria include any pathophysiology impacting the PK of labetalol, e.g., liver failure. Maternal plasma, urine, amniotic fluid, cord blood, and breast milk will be collected, and labetalol stereoisomers will be measured using a validated LC-MS/MS assay. Heart rate and blood pressure will be measured as the PD endpoints. These may be assessed throughout a participant's dosing interval at scheduled PK study visits, which will occur every 6-10 weeks during pregnancy, at delivery, during the 1st week postpartum, and up to 20 weeks postpartum. The primary aim is to characterize the PK and PD of labetalol during pregnancy and in the postpartum period. The secondary aim is to determine the extent of breast milk excretion of and infant exposure to labetalol from breast milk. The data will be analyzed using population PK modeling to evaluate the PK/PD relationship and ultimately develop trimester-specific dosing recommendations. Results/Conclusions: To our knowledge, this is the first study aiming to characterize the PK of labetalol stereoisomers across pregnancy and postpartum, utilizing individual stereoisomer data to evaluate the PK/PD relationship, and collecting postpartum samples, including breast milk, to model infant exposure to labetalol through breast milk. This study will provide important PK/PD data and knowledge which will be combined with large multi-center clinical trial data to develop trimester-specific dosing regimens for anti-hypertensive agents.

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..

PBPK/PD Modeling of Nifedipine for Precision Medicine in Pregnant Women: Enhancing Clinical Decision-Making for Optimal Drug Therapy

OBJECTIVE

This study aims to develop physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) predictive models for nifedipine in pregnant women, enhancing precision medicine and reducing adverse reactions for both mothers and infants.

METHODS

A PBPK/PD model was constructed using PK-Sim, MoBi, and MATLAB software, integrating literature and pregnancy-specific physiological information. The process involved: (1) establishing and validating a PBPK model for serum clearance after intravenous administration in non-pregnant individuals, (2) establishing and validating a PBPK model for serum clearance after oral administration in non-pregnant individuals, (3) constructing and validating a PBPK model for enzyme clearance after oral administration in non-pregnant individuals, and (4) adjusting the PBPK model structure and enzyme parameters according to pregnant women and validating it in oral administration. (5) PK/PD model was explored through MATLAB, and the PBPK and PK/PD models were integrated to form the PBPK/PD model.

RESULTS

The Nifedipine PBPK model's predictive accuracy was confirmed by non-pregnant and pregnant validation studies. The developed PBPK/PD model accurately predicted maximum antihypertensive effects for clinical doses of 5, 10, and 20 mg. The model suggested peak effect at 0.86 h post-administration, achieving blood pressure reductions of 5.4 mmHg, 14.3 mmHg, and 21.3 mmHg, respectively. This model provides guidance for tailored dosing in pregnancy-induced hypertension based on targeted blood pressure reduction.

CONCLUSION

Based on available literature data, the PBPK/PD model of Nifedipine in pregnancy demonstrated good predictive performance. It will help optimize individualized dosing of Nifedipine, improve treatment outcomes, and minimize the risk of adverse reactions in mothers and infants.

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.

Feasibility, acceptability, and preliminary effects of mindfulness training on antenatal blood pressure

BACKGROUND

Hypertensive disorders of pregnancy (HDP) are one of the greatest causes of perinatal morbidity and mortality. Mindfulness training (MT) significantly reduces blood pressure in non-pregnant adults, yet MT has not been tested to reduce blood pressure in the prenatal period.

OBJECTIVES

The objectives of this pilot randomized clinical trial were to test the feasibility, acceptability, and effects of MT on rates of HDP among pregnant participants at risk for HDP. Exploratory analyses examined effects of MT on antenatal blood pressure.

STUDY DESIGN

Participants were randomized to an 8-week phone-delivered MT intervention or usual care. Feasibility was defined by MT completion. Acceptability was defined by participants' satisfaction with the intervention. HDP outcomes were collected by medical chart review. Antenatal blood pressure values were extracted from medical records.

RESULTS

Twenty-nine participants were randomized to phone-based MT (N = 15) or usual care (N = 14). 73% participants completed >5 MT sessions, indicating that MT was feasible. One hundred percent of participants indicated they were "satisfied" or "very satisfied" with the intervention, suggesting the intervention was acceptable. Rates of HDP were lower in the MT vs. usual care condition (9% vs. 29%; OR: 0.25, 95% C.I.: 0.02-2.65) although this did not reach statistical significance. Systolic and diastolic blood pressure levels were significantly lower at follow up among those randomized to MT vs. usual care.

CONCLUSIONS

Results from this pilot trial suggest that prenatal MT is feasible and acceptable and may be a useful adjunctive preventative treatment for HDP among at-risk pregnant patients.

CLINICALTRIALS

gov identifier is NCT03679117.

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

INTRODUCTION

Hypertensive disorders of pregnancy (HDP) are rising in prevalence, and increase risk of adverse maternal and fetal outcomes. Physiologic changes occur during pregnancy that alter drug pharmacokinetics. However, antihypertensive drugs lack pregnancy-specific dosing recommendations due to critical knowledge gaps surrounding the extent of gestational changes in antihypertensive drug pharmacokinetics and underlying mechanisms.

AREAS COVERED

This review (1) summarizes currently recommended medications and dosing strategies for non-emergent HDP treatment, (2) reviews and synthesizes existing literature identified via a comprehensive Pubmed search evaluating gestational changes in the maternal pharmacokinetics of commonly prescribed HDP drugs (notably labetalol and nifedipine), and (3) offers insight into the metabolism and clearance mechanisms underlying altered HDP drug pharmacokinetics during pregnancy. Remaining knowledge gaps and future research directions are summarized.

EXPERT OPINION

A series of small pharmacokinetic studies illustrate higher oral clearance of labetalol and nifedipine during pregnancy. Pharmacokinetic modeling and preclinical studies suggest these effects are likely due to pregnancy-associated increases in hepatic UGT1A1- and CYP3A4-mediated first-pass metabolism and lower bioavailability. Accordingly, higher and/or more frequent doses may be needed to lower blood pressure during pregnancy. Future research is needed to address various evidence gaps and inform the development of more precise antihypertensive drug dosing strategies.

Anatomical and physiological alterations of pregnancy

The extensive metabolic demands of pregnancy require specific physiological and anatomical changes. These changes affect almost all organ systems, including the cardiovascular, respiratory, renal, gastrointestinal, and hematologic system. The placenta adds another layer of complexity. These changes make it challenging for clinicians to understand presenting signs and symptoms, or to interpret laboratory and radiological tests. Furthermore, these physiological alterations can affect the pharmacokinetics and pharmacodynamics of drugs. Drug safety in lactation is only supported by limited evidence. In addition, the teratogenic effects of medications are often extrapolated from animals, which further adds uncertainties. Unfortunately, pregnant women are only rarely included in clinical drug trials, while doses, regimens, and side effects are often extrapolated from studies conducted in non-pregnant populations. In this comprehensive review, we present the changes occurring in each system with its effects on the pharmacokinetic variables. Understanding these physiological changes throughout normal pregnancy helps clinicians to optimize the health of pregnant women and their fetuses. Furthermore, the information on pregnancy-related physiology is also critical to guide study design in this vulnerable 'orphan' population, and provides a framework to explore pregnancy-related pathophysiology such as pre-eclampsia.

Pre-eclampsia with severe features: management of antihypertensive therapy in the postpartum period

Introduction

there is variance in both the types and combinations of antihypertensive drugs used for managing pre-eclampsia in the postpartum period. Knowledge of the most common and suitable single or combination antihypertensive drug therapies in the postpartum period will minimize harmful effects, promote adherence to medications, overcome any fears that lactating mothers may have about these drugs and will assist in healthcare planning. Objective: to determine the types of antihypertensive drug therapies used in managing pre-eclampsia with severe features (sPE) in the postpartum period in a regional hospital in South Africa.

Methods

fifty consecutively presenting pregnant women with sPE were followed up prospectively from the pre-delivery period (within 48 hours before delivery) until day 3 postpartum. The antihypertensive drug therapies administered to the participants were observed. Their blood pressures were measured daily at 04: 00, 08: 00, 14: 00 and 22: 00 hours.

Results

nifedipine was the commonest rapid-acting agent used for severe hypertension. Prepartum, 9 different combinations of antihypertensive drugs were prescribed; alpha-methyldopa was the commonest single long-acting agent used. Postpartum, the number of different drug combinations administered were 15, 18, 22 and 16 on days 0, 1, 2 and 3 respectively. Alpha-methyldopa was the commonest single agent used on postpartum days 0 - 2 while hydrochlorothiazide was the most frequently used single agent on postpartum day 3. Postpartum, the commonest combination therapy was alpha-methyldopa and amlodipine on day 0; alpha-methyldopa and amlodipine as a regimen as well as alpha-methyldopa, amlodipine and hydrochlorothiazide as another regimen on day 1; alpha-methyldopa and amlodipine on day 2; and many amlodipine-based regimens on day 3.

Conclusion

a variety of antihypertensive drug combinations were used in the postpartum period indicating the need for standardised guidelines; however, detailed studies are required to evaluate their efficacies completely.

Pharmacotherapy for hypertension in pregnant patients: special considerations

INTRODUCTION

Hypertensive disorders of pregnancy (HDP) represent a major cause of maternal, fetal and neonatal morbidity and mortality and identifies women at risk for cardiovascular and other chronic diseases later in life. When antihypertensive drugs are used during pregnancy, their benefit and harm to both mother and fetus should be evaluated.

AREAS COVERED

This review summarizes the pharmacological characteristics of the recommended antihypertensive drugs and their impact on mother and fetus when administered during pregnancy and/or post-partum. Drugs were identified using MEDLINE and the main international Guidelines for the management of HDP.

EXPERT OPINION

Although there is a consensus that severe hypertension should be treated, treatment of mild hypertension without end-organ damage (140-159/90-109 mmHg) remains controversial and there is no agreement on when to initiate therapy, blood pressure targets or recommended drugs in the absence of robust evidence for the superiority of one drug over others. Furthermore, the long-term outcomes of in-utero antihypertensive exposure remain uncertain. Therefore, evidence-based data regarding the treatment of HDP is lacking and well designed randomized clinical trials are needed to resolve all these controversial issues related to the management of HDP.

Drugs in lactation

Although most medications can be taken safely during breastfeeding, potential risks of infant toxicity do exist because all medications will be excreted into the breast milk to some extent. The amount of medication excreted in the milk depends mainly on (i) within-drug variation, such as dosing; (ii) between-drug variation including chemical characteristics of the medication; and (iii) host factors, such as maternal pharmacokinetics (PK), including variations of pregnancy-associated changes and their post-partum recovery. Neonatal drug exposure is usually assessed by calculating an expected total infant daily dose through breast milk and comparing it to the normal therapeutic dose. However, clinical PK studies in this population are challenging to conduct. Recently, research methods using population PK analyses and physiologically-based PK modeling and simulation techniques have been recognized as a complementary approach to the conventional PK studies in this field. These efforts are important for rational risk assessment balancing the toxicity risk against the benefits of human milk. Health benefits of lactation for both mother and child are significant and a decision to withhold from this should not be taken lightly. In case limited information is present, additional expertise from pharmacists or clinical pharmacologist with expertise in this area should be sought.

Feasibility of the Von Willebrand disease PREVENT trial

BACKGROUND

Despite treatment, women with von Willebrand disease (VWD) have lower von Willebrand factor (VWF) levels and greater blood loss at delivery than controls. Current weight-based dosing does not account for the ~1.5-fold increase in blood volume in pregnancy.

METHODS

To evaluate the feasibility of a trial to prevent postpartum hemorrhage (PPH), we reviewed pre-pregnancy and 8th month VWF levels in women with VWD with and without PPH following vaginal delivery, assessed VWF concentrate use at delivery by U.S. hemophilia treatment center physician survey, and reviewed thrombosis risk with VWF concentrate by literature review. We determined trial interest and acceptability by structured interviews of physicians and patients. Analysis was by Student's t-test for continuous data, and chi-square or Fisher's exact test for discrete data.

RESULTS

PPH was associated with lower pre-pregnancy VWF:RCo, p<0.005; higher pre-pregnancy, 8th and 9th-month weight, each p<0.001; a family bleeding history, p=0.036; and VWF concentrate treatment, p=0.005. Surveyed physicians reported first-line therapy at delivery was VWF concentrate, at a mean dose 50IU/kg. A trial of a 1.5-fold volume-based dose increase was acceptable to physicians and patients, if it is safe and if costs and visits are minimized. A literature review determined thrombosis risk with VWF concentrate is low, 0.4%.

CONCLUSIONS

This study suggests pre-pregnancy VWF:RCo may predict PPH, but 50-80IU/kg VWF concentrate dosing may not prevent PPH. If pharmacokinetic modeling confirms volume-based dosing achieves VWF levels comparable to pregnant controls, it may be possible to determine if volume-modified VWF concentrate dosing will reduce PPH in VWD.

Blood volume-based von Willebrand factor to prevent postpartum hemorrhage in von Willebrand disease

Publisher's Note: This article has a companion Point by Kouides. Publisher's Note: Join in the discussion of these articles at Blood Advances Community Conversations.

Effect of type 2 diabetes mellitus on the pharmacokinetics and transplacental transfer of nifedipine in hypertensive pregnant women

AIMS

Diabetes mellitus can inhibit cytochrome P450 3A4, an enzyme responsible for the metabolism of nifedipine, used for the treatment of hypertension in pregnant women. We aimed to assess the effect of type 2 diabetes mellitus (T2DM) on the pharmacokinetics, placental transfer and distribution of nifedipine in amniotic fluid in hypertensive pregnant women.

METHODS

The study was conducted in 12 hypertensive pregnant women [control group (CG)] and 10 hypertensive pregnant women with T2DM taking slow-release nifedipine (20 mg, 12/12 h). On the 34th week of gestation, serial blood samples were collected (0-12 h) after administration of the medication. At delivery, samples of maternal and fetal blood and amniotic fluid were collected for determination of nifedipine distribution in these compartments.

RESULTS

The median pharmacokinetic parameters of CG were: peak plasma concentration (C_max ) 26.41 ng ml^-1 , time to reach C_max (t_max ) 1.79 h, area under the plasma concentration vs. time curve from 0-12 h (AUC_0-12 ) 235.99 ng.h ml^-1 , half-life (t½) 4.34 h, volume of distribution divided by bioavailability (Vd/F) 560.96 l, and Cl_T /F 84.77 l h^-1 . The parameters for T2DM group were: C_max 23.52 ng ml^-1 , t_max 1.48 h, AUC_0-12 202.23 ng.h ml^-1 , t½ 5.00 h, Vd/F 609.40 l, and apparent total clearance (Cl_T /F) 98.94 l h^-1 . The ratios of plasma concentrations of nifedipine in the umbilical vein, intervillous space and amniotic fluid to those in the maternal vein for CG and T2DM were 0.53 and 0.44, 0.78 and 0.87, respectively, with an amniotic fluid/maternal plasma ratio of 0.05 for both groups. The ratios of plasma concentrations in the umbilical artery to those in the umbilical vein were 0.82 for CG and 0.88 for T2DM.

CONCLUSIONS

There was no influence of T2DM on the pharmacokinetics or placental transfer of nifedipine in hypertensive women with controlled diabetes.

Pregnancy-Associated Changes in Pharmacokinetics: A Systematic Review

BACKGROUND

Women are commonly prescribed a variety of medications during pregnancy. As most organ systems are affected by the substantial anatomical and physiological changes that occur during pregnancy, it is expected that pharmacokinetics (PK) (absorption, distribution, metabolism, and excretion of drugs) would also be affected in ways that may necessitate changes in dosing schedules. The objective of this study was to systematically identify existing clinically relevant evidence on PK changes during pregnancy.

METHODS AND FINDINGS

Systematic searches were conducted in MEDLINE (Ovid), Embase (Ovid), Cochrane Central Register of Controlled Trials (Ovid), and Web of Science (Thomson Reuters), from database inception to August 31, 2015. An update of the search from September 1, 2015, to May 20, 2016, was performed, and relevant data were added to the present review. No language or date restrictions were applied. All publications of clinical PK studies involving a group of pregnant women with a comparison to nonpregnant participants or nonpregnant population data were eligible to be included in this review. A total of 198 studies involving 121 different medications fulfilled the inclusion criteria. In these studies, commonly investigated drug classes included antiretrovirals (54 studies), antiepileptic drugs (27 studies), antibiotics (23 studies), antimalarial drugs (22 studies), and cardiovascular drugs (17 studies). Overall, pregnancy-associated changes in PK parameters were often observed as consistent findings among many studies, particularly enhanced drug elimination and decreased exposure to total drugs (bound and unbound to plasma proteins) at a given dose. However, associated alterations in clinical responses and outcomes, or lack thereof, remain largely unknown.

CONCLUSION

This systematic review of pregnancy-associated PK changes identifies a significant gap between the accumulating knowledge of PK changes in pregnant women and our understanding of their clinical impact for both mother and fetus. It is essential for clinicians to be aware of these unique pregnancy-related changes in PK, and to critically examine their clinical implications.

Pharmacokinetics of metoprolol during pregnancy and lactation

The objective of this study was to evaluate the steady-state pharmacokinetics of metoprolol during pregnancy and lactation. Serial plasma, urine, and breast milk concentrations of metoprolol and its metabolite, α-hydroxymetoprolol, were measured over 1 dosing interval in women treated with metoprolol (25-750 mg/day) during early pregnancy (n = 4), mid-pregnancy (n = 14), and late pregnancy (n = 15), as well as postpartum (n = 9) with (n = 4) and without (n = 5) lactation. Subjects were genotyped for CYP2D6 loss-of-function allelic variants. Using paired analysis, mean metoprolol apparent oral clearance was significantly higher in mid-pregnancy (361 ± 223 L/h, n = 5, P < .05) and late pregnancy (568 ± 273 L/h, n = 8, P < .05) compared with ≥3 months postpartum (200 ± 131 and 192 ± 98 L/h, respectively). When the comparison was limited to extensive metabolizers (EMs), metoprolol apparent oral clearance was significantly higher during both mid- and late pregnancy (P < .05). Relative infant exposure to metoprolol through breast milk was <1.0% of maternal weight-adjusted dose (n = 3). Because of the large, pregnancy-induced changes in metoprolol pharmacokinetics, if inadequate clinical responses are encountered, clinicians who prescribe metoprolol during pregnancy should be prepared to make aggressive changes in dosage (dose and frequency) or consider using an alternate beta-blocker.

Basic obstetric pharmacology

Pregnancy is associated with a variety of physiological changes that can alter the pharmacokinetics and pharmacodynamics of several drugs. However, limited data exists on the pharmacokinetics and pharmacodynamics of the majority of the medications used in pregnancy. In this article, we first describe basic concepts (drug absorption, bioavailability, distribution, metabolism, elimination, and transport) in pharmacokinetics. Then, we discuss several physiological changes that occur during pregnancy that theoretically affect absorption, distribution, metabolism, and elimination. Further, we provide a brief review of the literature on the clinical pharmacokinetic studies performed in pregnant women in recent years. In general, pregnancy increases the clearance of several drugs and correspondingly decreases drug exposure during pregnancy. Based on current drug exposure measurements during pregnancy, alterations in the dose or dosing regimen of certain drugs are essential during pregnancy. More pharmacological studies in pregnant women are needed to optimize drug therapy in pregnancy.

Drug treatment of hypertension in pregnancy

Hypertensive disorders represent major causes of pregnancy-related maternal mortality worldwide. Similar to the non-pregnant population, hypertension is the most common medical disorder encountered during pregnancy and is estimated to occur in about 6-8 % of pregnancies. A recent report highlighted hypertensive disorders as one of the major causes of pregnancy-related maternal deaths in the USA, accounting for 579 (12.3 %) of the 4,693 maternal deaths that occurred between 1998 and 2005. In low-income and middle-income countries, preeclampsia and its convulsive form, eclampsia, are associated with 10-15 % of direct maternal deaths. The optimal timing and choice of therapy for hypertensive pregnancy disorders involves carefully weighing the risk-versus-benefit ratio for each individual patient, with an overall goal of improving maternal and fetal outcomes. In this review, we have compared and contrasted the recommendations from different treatment guidelines and outlined some newer perspectives on management. We aim to provide a clinically oriented guide to the drug treatment of hypertension in pregnancy.

The endogenous substrates of brain CYP2D

CYP2D6, one of the major cytochrome P450 isoforms present in the human brain, is associated with the incidence and prevalence of central nervous system (CNS) diseases. Human CYP2D6 and rat CYP2D are involved in the metabolism of various neurotransmitters and neurosteroids. Brain CYP2D can be regulated by endogenous steroids, including sex hormones. The alteration of CYP2D-mediated metabolism induced by endogenous steroids may cause changes in sensitivity to environmental and industrial toxins and carcinogens as well as physiological and pathophysiological processes controlled by biologically active compounds. This review summarizes the current knowledge regarding the distribution, endogenous substrates, and regulation of brain CYP2D.

Placental transfer of intravenous nicardipine and disposition into breast milk during the control of hypertension in women with pre-eclampsia

OBJECTIVE

To assess nicardipine safety for fetuses and neonates.

METHODS

Nicardipine was measured in maternal plasma (MP), umbilical cord arterial (UaP) and venous (UvP) plasma and breast milk (BrM) of 18 women with severe preeclampsia.

RESULTS

Nicardipine was infused for a mean 11.9 ± 10.5 days before and 4.6 ± 1.6 days after delivery. Nicardipine dose and MP concentration were linearly correlated, as were MP with UaP, UvP, and BrM concentrations. The BrM/MP ratio was 0.06 to 0.30. The mean relative infant dose was 0.082%.

CONCLUSION

Nicardipine is safe for fetuses and neonates due to its low levels of placental transfer and disposition in BrM.

Trends in using beta-blockers and methyldopa for hypertensive disorders during pregnancy in a Canadian population

OBJECTIVE

To describe trends in and patterns of antihypertensive drug use in a general obstetric population.

STUDY DESIGN

Historical cohort study. A total of 18,117 women who gave birth in a Saskatchewan hospital between January 1, 1980 and December 31, 2005 with a diagnosis of hypertensive disorders in pregnancy were identified and included in the analysis.

RESULTS

The rate of treatment with antihypertensive drugs for pregnant women with chronic hypertension rose from 19.94% in 1980-1984 to 37.63% in 2000-2005. There were similar increases in antihypertensive drug use from 1.51% to 14.47% for gestational hypertension/non-severe preeclampsia, and from 1.56% to 20.86% for severe preeclampsia/eclampsia. Methyldopa was the most frequently used drug, followed by beta-blockers, with other antihypertensive drugs accounting for about 18.43% of total uses. The use of both methyldopa and labetalol has increased in recent years while the use of other antihypertensive drugs has decreased. Other antihypertensive drugs were more commonly prescribed in earlier gestation, while methyldopa and labetalol were generally prescribed in later gestation.

CONCLUSION

The use of antihypertensive drugs in pregnancy is relatively common and is increasing, with the liberal use of methyldopa and (especially) labetalol contributing appreciably to this increase.

Isoform-specific regulation of cytochromes P450 expression by estradiol and progesterone

Results from clinical studies suggest that pregnancy alters hepatic drug metabolism in a cytochrome P450 (P450) isoform-specific manner, and rising concentrations of female hormones are potentially responsible for the changes. The objective of this study was to comprehensively characterize the effects of estrogen and progesterone on the expression and activity of major drug-metabolizing P450s. To this end, primary human hepatocytes were treated with estradiol and progesterone, and mRNA expression and activity levels of 10 different P450 isoforms were determined. The results showed that estradiol enhances CYP2A6, CYP2B6, and CYP3A4 expression, whereas progesterone induces CYP2A6, CYP2B6, CYP2C8, CYP3A4, and CYP3A5 expression. The induction was mainly observed when the average hormone concentrations were at the levels reached during pregnancy, suggesting that these effects are likely pregnancy-specific. Estradiol also increased enzyme activities of CYP2C9 and CYP2E1 without affecting the mRNA expression levels by unknown mechanisms. Taken together, our results show differential effects of estrogen and progesterone on P450 expression, suggesting involvement of different regulatory mechanisms in female hormone-mediated P450 regulation. Our findings potentially provide a basis in mechanistic understanding for altered drug metabolism during pregnancy.

A PBPK Model to Predict Disposition of CYP3A-Metabolized Drugs in Pregnant Women: Verification and Discerning the Site of CYP3A Induction

Besides logistical and ethical concerns, evaluation of safety and efficacy of medications in pregnant women is complicated by marked changes in pharmacokinetics (PK) of drugs. For example, CYP3A activity is induced during the third trimester (T₃). We explored whether a previously published physiologically based pharmacokinetic (PBPK) model could quantitatively predict PK profiles of CYP3A-metabolized drugs during T₃, and discern the site of CYP3A induction (i.e., liver, intestine, or both). The model accounted for gestational age-dependent changes in maternal physiological function and hepatic CYP3A activity. For model verification, mean plasma area under the curve (AUC), peak plasma concentration (C_max), and trough plasma concentration (C_min) of midazolam (MDZ), nifedipine (NIF), and indinavir (IDV) were predicted and compared with published studies. The PBPK model successfully predicted MDZ, NIF, and IDV disposition during T₃. A sensitivity analysis suggested that CYP3A induction in T₃ is most likely hepatic and not intestinal. Our PBPK model is a useful tool to evaluate different dosing regimens during T₃ for drugs cleared primarily via CYP3A metabolism.

Medical treatment of early-onset mild gestational hypertension reduces total peripheral vascular resistance and influences maternal and fetal complications

OBJECTIVE

Complications in early-onset mild gestational hypertension (GH) are better predicted by total peripheral vascular resistance (TPVR) > 1350 dyne than by blood pressure. We therefore aimed to assess the possible reduction of severe complications by lowering TPVR with nitric oxide (NO) donors, oral fluids and standard antihypertensive therapy in women with early-onset mild GH.

METHODS

A group of 400 patients with early-onset (20-27 weeks' gestation) mild GH (systolic and diastolic blood pressure < 170/110 mmHg) and TPVR > 1350 dyne were enrolled in a prospective non-randomized trial with sequential allocation: 100 patients were treated with nifedipine (Group A); 100 with nifedipine and NO donors (Group B); 100 with nifedipine and oral fluids (Group C); and 100 with nifedipine, NO donors and oral fluids (Group D). TPVR was checked 1 month after initiation of therapy, and the number of patients with severe maternal and fetal complications was recorded in each group. The relationship between reduction in TPVR and the frequency of severe complications was assessed.

RESULTS

Severe complications developed in 51% of patients in Group A, 48% in Group B, 53% in Group C and 35% in Group D, the frequency in Group D being significantly lower than that in the other treatment groups (P < 0.05). A reduction in TPVR of < 15% predicted the occurrence of severe complications with sensitivity 95.2% and specificity 88.3%. In Group D a reduction in TPVR of ≥ 15% was more probable (odds ratio (OR) = 2.03; 95% CI, 1.15-3.60; P < 0.015) and severe complications were less probable (OR = 0.52; 95% CI, 0.29-0.91; P < 0.023).

CONCLUSION

In women with early-onset mild GH, combined treatment with NO donors, oral fluids and nifedipine optimally reduces TPVR and seems to reduce maternal and fetal complications.

A GENS-based approach to cardiovascular pharmacology: impact on metabolism, pharmacokinetics and pharmacodynamics

Pharmacological outcomes depend on many factors, with many of them being sexually dimorphic. Thus, physiological gender/sex (GENS) differences can influence pharmacokinetics, pharmacodynamics and, thus, bioavailability and resulting in efficacy of treatment, meaning GENS differences should be an important consideration in therapeutics. In particular, drug response can change according to different hormonal environments. Therefore, GENS-specific differences have a particular clinical relevance in terms of drug delivery, especially for those substances with a narrow therapeutic margin. Since adverse effects are more frequent among women, safety is a key issue. Overall, the status of women, from a pharmacological point of view, is often different and less studied than that of men and deserves particular attention. Further studies focused on women's responses to drugs are necessary in order to make optimal pharmacotherapeutic decisions.

Nutrition and human health from a sex-gender perspective

Nutrition exerts a life-long impact on human health, and the interaction between nutrition and health has been known for centuries. The recent literature has suggested that nutrition could differently influence the health of male and female individuals. Until the last decade of the 20th century, research on women has been neglected, and the results obtained in men have been directly translated to women in both the medicine and nutrition fields. Consequently, most modern guidelines are based on studies predominantly conducted on men. However, there are many sex-gender differences that are the result of multifactorial inputs, including gene repertoires, sex steroid hormones, and environmental factors (e.g., food components). The effects of these different inputs in male and female physiology will be different in different periods of ontogenetic development as well as during pregnancy and the ovarian cycle in females, which are also age dependent. As a result, different strategies have evolved to maintain male and female body homeostasis, which, in turn, implies that there are important differences in the bioavailability, metabolism, distribution, and elimination of foods and beverages in males and females. This article will review some of these differences underlying the impact of food components on the risk of developing diseases from a sex-gender perspective.

Isoform-specific regulation of cytochrome P450 expression and activity by estradiol in female rats

Estradiol (E2) is the major endogenous estrogen, and its plasma concentration increases up to 100-fold during pregnancy in humans. Accumulating evidence suggests that an elevated level of E2 may influence hepatic drug metabolism, potentially being responsible for altered drug metabolism during pregnancy. We characterized effects of E2 on expression and activities of cytochrome P450 enzymes (CYPs) in an in vivo system using rats. To this end, female rats were treated with estradiol benzoate (EB) or known CYP inducers. Liver tissues were obtained after 5 days of treatment, and mRNA and protein expression levels as well as activities of major hepatic CYPs were determined by qRT-PCR, immunoblot, and microsomal assay. E2 increased CYP1A2 expression and activity to a smaller extent than β-naphthoflavone did. E2 also enhanced CYP2C expression (CYP2C6, CYP2C7, and CYP2C12) to levels comparable to those observed by phenobarbital. E2 upregulated CYP3A9 expression, while expression of CYP3A1 was downregulated. Expression of hepatic nuclear receptors (PXR and CAR) and the obligate redox partner of CYPs (POR) was downregulated in EB-treated rats, suggesting their potential involvement in regulation of CYP expression and activity by E2. In summary, in female rats E2 regulates expression of hepatic CYPs in a CYP isoform-specific manner although the directional changes are different from those clinically observed during human pregnancy. Further study is warranted to determine whether the changes in drug metabolism during human pregnancy are attributable to involvement of hormones other than E2.