Pharmacokinetics of the most commonly used antihypertensive drugs throughout pregnancy methyldopa, labetalol, and nifedipine: a systematic review.

PURPOSE: Antihypertensive drugs are among the most prescribed drugs during pregnancy. Methyldopa, labetalol, and nifedipine have been perceived safe to use during pregnancy and are therefore recommended in international guidelines for treatment of hypertension. In this review, we provide a complete overview of what is known on the pharmacokinetics (PK) of the antihypertensive drugs methyldopa, labetalol, and nifedipine throughout pregnancy. METHODS: A systematic search was performed to retrieve studies on the PK of methyldopa, labetalol, and nifedipine used throughout pregnancy. The search was restricted to English and original studies. The systematic search was conducted on July 27, 2021, in Embase, Medline Ovid, Web of Science, Cochrane Library, and Google Scholar. Keywords were methyldopa, labetalol, nifedipine, pharmacokinetics, pregnancy, and placenta. RESULTS: A total of 1459 unique references were identified of which title and abstract were screened. Based on this screening, 67 full-text papers were assessed, to retain 30 PK studies of which 2 described methyldopa, 12 labetalol, and 16 nifedipine. No fetal accumulation is found for any of the antihypertensive drugs studied. CONCLUSION: We conclude that despite decades of prescribing methyldopa, labetalol, and nifedipine throughout pregnancy, descriptions of their PK during pregnancy are hampered by a large heterogeneity in the low number of available studies. Aiming for evidence-based and personalized dosing of antihypertensive medication in the future, further studies on the relationship of both PK and pharmacodynamics (including the optimal blood pressure targeting) during pregnancy and pregnancy-related pathology are urgently needed to prevent undertreatment, overtreatment, and side effects.

Oral antihypertensive regimens (nifedipine retard, labetalol, and methyldopa) for management of severe hypertension in pregnancy: an open-label, randomised controlled trial.

BACKGROUND: Hypertension is the most common medical disorder in pregnancy, complicating one in ten pregnancies. Treatment of severely increased blood pressure is widely recommended to reduce the risk for maternal complications. Regimens for the acute treatment of severe hypertension typically include intravenous medications. Although effective, these drugs require venous access and careful fetal monitoring and might not be feasible in busy or low-resource environments. We therefore aimed to compare the efficacy and safety of three oral drugs, labetalol, nifedipine retard, and methyldopa for the management of severe hypertension in pregnancy. METHODS: In this multicentre, parallel-group, open-label, randomised controlled trial, we compared these oral antihypertensives in two public hospitals in Nagpur, India. Pregnant women were eligible for the trial if they were aged at least 18 years; they were pregnant with fetuses that had reached a gestational age of at least 28 weeks; they required pharmacological blood pressure control for severe hypertension (systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥110 mm Hg); and were able to swallow oral medications. Women were randomly assigned to receive 10 mg oral nifedipine, 200 mg oral labetalol (hourly, in both of which the dose could be escalated if hypertension was maintained), or 1000 mg methyldopa (a single dose, without dose escalation). Masking of participants, study investigators, and care providers to group allocation was not possible because of different escalation protocols in the study groups. The primary outcome was blood pressure control (defined as 120-150 mm Hg systolic blood pressure and 70-100 mm Hg diastolic blood pressure) within 6 h with no adverse outcomes. This study is registered with ClinicalTrials.gov, number NCT01912677, and the Clinical Trial Registry, India, number ctri/2013/08/003866. FINDINGS: Between April 1, 2015, and Aug 21, 2017, we screened 2307 women for their inclusion in the study. We excluded 1413 (61%) women who were ineligible, declined to participate, had impending eclampsia, were in active labour, or had a combination of these factors. 11 (4%) women in the nifedipine group, ten (3%) women in the labetalol group, and 11 (4%) women in the methyldopa group were ineligible for treatment (because they had only one qualifying blood pressure measurement) or had treatment stopped (because of delivery or transfer elsewhere). 894 (39%) women were randomly assigned to a treatment group and were included in the intention-to-treat analysis: 298 (33%) women were assigned to receive nifedipine, 295 (33%) women were assigned to receive labetalol, and 301 (33%) women were assigned to receive methyldopa. The primary outcome was significantly more common in women in the nifedipine group than in those in the methyldopa group (249 [84%] women vs 230 [76%] women; p=0·03). However, the primary outcome did not differ between the nifedipine and labetalol groups (249 [84%] women vs 228 [77%] women; p=0·05) or the labetalol and methyldopa groups (p=0·80). Seven serious adverse events (1% of births) were reported during the study: one (<1%) woman in the labetalol group had an intrapartum seizure and six (1%) neonates (one [<1%] neonate in the nifedipine group, two [1%] neonates in the labetalol group, and three [1%] neonates in the methyldopa group) were stillborn. No birth had more than one adverse event. INTERPRETATION: All oral antihypertensives reduced blood pressure to the reference range in most women. As single drugs, nifedipine retard use resulted in a greater frequency of primary outcome attainment than labetalol or methyldopa use. All three oral drugs-methyldopa, nifedipine, and labetalol-are viable initial options for treating severe hypertension in low-resource settings. FUNDING: PREEMPT (University of British Columbia, Vancouver, BC, Canada; grantee of Bill & Melinda Gates Foundation).

Fatal pulmonary oedema associated with severe pre-eclampsia: challenges and lessons.

Pre-eclampsia complicated by pulmonary oedema, severe hypertension, tachycardia and desaturation is a devastating condition. A comprehensive understanding of the aetiopathogenesis during such an emergency is challenging in the absence of functional and responsive point-of-care imaging, and laboratory and other critical-care services. An unbooked 26-year-old gravida 3 para 1+1 presented to a primary healthcare clinic with features of pre-eclampsia, severe hypertension and pulmonary oedema. The only available antihypertensive drug, methyldopa, was administered. The patient was transferred to a district hospital and subsequently referred to a tertiary hospital. On arrival, she was booked for caesarean delivery and in the maternity ward a central venous pressure (CVP) line was inserted. The patient developed pneumothorax and died in the intensive care unit undelivered. This case highlights many lessons, which are discussed. If CVP monitoring is indicated before caesarean delivery, consideration must be given to line insertion in the operating room to facilitate rapid delivery should the patient's condition deteriorate.

The ability and safety of community-based health workers to safely initiate lifesaving therapies for pre-eclampsia in Ogun State, Nigeria: An analysis of 260 community treatments with MgSO4 and/or methyldopa.

OBJECTIVES: To evaluate community-based health workers' ability to identify cases of hypertension in pregnancy, safely deliver methyldopa and magnesium sulphate and make referrals when appropriate. STUDY DESIGN: This was part of Nigeria Community-Level Interventions for Pre-eclampsia (CLIP) cluster randomized controlled trial (NCT01911494). Community-based Health Workers (CHW) recruited pregnant women from five Local Government Areas (clusters) and used mobile health aid for clinical assessment of pre-eclampsia. MAIN OUTCOME MEASURES: The primary outcome was the number of adverse events that occurred after the administration of magnesium sulphate and/or methyldopa to pregnant women by CHWs. FINDINGS: Of 8790 women receiving mobile health-guided care, community-based health workers in Nigeria provided 309 women with hypertension (4.2% of delivered women), and safely administered 142 doses of intramuscular magnesium sulphate. Community Heath Extension Workers (CHEWs) and nurses gave fifty-two and sixty-seven doses of intramuscular magnesium sulphate respectively, twenty-three doses were given by other health care workers (midwives, community health officers, health assistants). The high rate of administration by nurses can be explained by turf protection as well as their seniority within the health system. Also, CHEWs and nurses gave 124 doses of oral methyldopa and 126 urgent referrals were completed. There were no complications related to administration of treatment or referral. INTERPRETATION: These findings demonstrate the ability of community-based health workers to safely administer methyldopa and intramuscular magnesium sulphate. The use of task-sharing, therefore, could drastically reduce the three delays (triage, transport and treatment) associated with high maternal mortality and morbidity in rural communities in low- and middle-income countries.

A case of hypertension with virilisation during pregnancy.

This case report describes the onset of hypertension and virilisation during pregnancy due to a Brenner tumour.

[Methyldopa-induced acute reactive hepatitis in pregnancy, drug-metabolizing capacity of the liver]. / Methyldopa által indukált akut reaktív hepatitis terhességben, a máj gyógyszer-metabolizáló képességének alakulása.

Alpha-methyldopa is a regularly used antihypertensive drug during pregnancy. Methyldopa, which decreases the sympathoadrenal system, is the first drug of choice since decades. The reactive hepatitis is not frequent, but known serious side effect of alpha-methyldopa. In non-pregnant women the estimated rate of manifest hepatotoxicity is 2.5-10%. In our case, gestation hypertension developed at the 21st gestation week of a 35 year-old pregnant woman. Oral methyldopa, a central alpha adrenergic blocker therapy was introduced. On the 23rd gestation week acute hepatitis developed. During differential diagnosis of hepatitis, the etiology of methyldopa was taken into account. Viral and autoimmune origin was rolled out. No fetal aberration was found during ultrasound examination. The function of drug metabolizing function from blood was measured by CYP phenotyping (CYP gene expression analysis). CYP3A4 enzyme plays a primary role in the metabolism of nifedipine. Antihypertensive therapy was changed from methyldopa to nifedipine. Nifedipine dosage was based on the value of CYP3A4 gene expression. With the reduced nifedipine therapy (30 mg daily), blood pressure was successfully under control. The diagnosis of alpha-methyldopa induced hepatitis was based on anamnesis, clinical picture and the results of chemical and radiological examination and confirmed by the level of drug-metabolizing capacity. The gestation hepatotoxicity of alpha-methyldopa was reported first in 1969 by Elkington Smith, who suggested the monitoring of serum aminotransferase during alpha-methyldopa therapy in pregnancy in their case report. Our case report confirms that monitoring of serum aminotransferase level is still valuable when treating a pregnant woman with alpha-methyldopa.

Alpha-methyldopa hepatotoxicity in pregnancy.

A 12-week pregnant, 33-year-old African American female, presented with jaundice and change in urine colour. Liver function tests revealed raised transamines and normal alkaline phosphatase. She was started on methyldopa 6 weeks prior to presentation. After initial negative investigations including viral and autoimmune hepatitis, she was given prednisone for methyldopa induced hepatitis. Two weeks later, repeat enzymes revealed normal values. Important clinical and management points related to methyldopa induced hepatotoxicity are discussed.

Methyldopa versus nifedipine or no medication for treatment of chronic hypertension during pregnancy: A multicenter randomized clinical trial.

OBJECTIVE: To assess the maternal and fetal outcome in women with mild to moderate chronic hypertension on antihypertensive drug (methyldopa or nifedipine) therapy compared to no medication. METHODS: This multicenter randomized clinical trial was conducted at Menoufia University hospital, Shibin El-kom Teaching hospital and 11 Central hospitals at Menoufia governorate, Egypt.490 pregnant women with mild to moderate chronic hypertension were randomized into three groups; methyldopa group (n = 166), nifedipine group (n = 160) and control or no medication group (n = 164) who were followed from the beginning of pregnancy till the end of puerperium to record maternal and fetal outcome. RESULTS: Mothers in the control (no medication) group were more prone for the development of severe hypertension, preeclampsia, renal impairment, ECG changes, placental abruption and repeated hospital admissions (p < 0.001) when compared to mothers in both treatment groups (methyldopa and nifedipine). Neonates in the control (no medication) group were more prone for prematurity and admission to neonatal ICU (p < 0.001). CONCLUSION: Antihypertensive drug therapy is advisable in mild to moderate chronic hypertension during pregnancy to decrease maternal and fetal morbidity. When considering which agents to use for treatment, oral methyldopa and nifedipine are valid options.

Effects of antihypertensive drugs on lipid metabolism.

Despite the well-established correlation between coronary heart disease (CHD) and hypertension, conventional antihypertensive therapy with diuretics and beta-adrenergic blockers has failed to provide protection against CHD. A possible explanation for this failure is the unfavorable effect such drugs have on lipid metabolism. To compare the lipid profiles of commonly used antihypertensive drugs, a survey was made of selected studies from the literature. Diuretics and selective and nonselective beta-blockers were found to have adverse effects on blood lipids. Beta-blockers with intrinsic sympathomimetic activity, labetalol, methyldopa, and calcium channel blockers are lipid neutral, whereas alpha-adrenergic blockers seemed to have a favorable effect on lipid metabolism. Controlled clinical trials with drugs that have no adverse effects on lipid metabolism are needed to establish the long-term clinical importance of such agents.

Effects of antihypertensive drugs on blood velocity: implications for prevention of cerebral vascular disease.

The treatment of high blood pressure prevents death from congestive heart failure, hypertensive nephropathy, and encephalopathy, and strokes from cerebral arteriolar disease (lacunes, hemorrhage from microaneurysms). However, atherosclerosis, manifested as coronary artery disease is just as frequent a cause of death in well-controlled hypertensives as in poorly-controlled patients. Increasing evidence suggests that increased blood velocity, by causing turbulence and high shear rates at the endothelial surface of arteries, may be important in the pathogenesis of atherosclerosis. Turbulence has been observed in cerebral berry aneurysms. In order to measure the effects of antihypertensive agents on blood velocity, a new method of analysing Doppler ultrasound velocity recordings has been developed. Studies in Rhesus monkeys show the following: In doses which reduce diastolic pressure by 13-28%, propranolol decreased mean blood velocity (MV) by 17%, clonidine decreased MV by 14%, while methyldopa increased MV 12%, and hydralazine increased MV by 52%. (p less than .00001). It is hypothesized that enlargement of berry aneurysms, the progression of cerebral atherosclerosis, and embolism from carotid lesions might all be decreased by the selection of antihypertensive agents which decrease blood velocity.

Preeclampsia with abnormal liver function tests is associated with cholestasis in a subgroup of cases.

OBJECTIVE: To investigate whether women with preeclampsia and abnormal liver function tests have raised serum bile acids. DESIGN: Measurement of serum bile acids in serum specimens collected at the John Radcliffe Hospital, Oxford. SETTING: Imperial College School of Medicine. SAMPLE: Stored sera from 37 women with preeclampsia and abnormal liver function tests and from 19 controls. METHODS: Enzymic total bile acid assay. MAIN OUTCOME MEASURES: Total bile acid levels. RESULTS: Women with preeclampsia and abnormal liver function tests had higher median bile acid levels than controls (5.7 vs. 3.2, p = 0.01). The reason for the raised median serum bile acid levels in the patient group is that three (8%) women with preeclampsia had markedly raised serum bile acids levels. There were no obvious clinical or biochemical features specific to these patients. CONCLUSIONS: The pathological mechanisms causing hepatic impairment in some women with preeclampsia may predispose to cholestasis. As some women with preeclampsia and abnormal liver function complain of pruritus, we recommend checking the serum bile acids in this group of women. If these acids are raised the fetal prognosis may be adversely affected.

Multicentre general practitioner assessment of 'Tenormin' and methyldopa.

A large scale study in general practice was set up to investigate the effects of transferring hypertensive patients from treatment with usually less than 1 g daily of methyldopa to atenolol ('Tenormin') 100 mg daily. The results demonstrate an improvement in blood pressure control with atenolol treatment and a reduction in the incidence of side-effects. The simple dosage regime, combined with proven effectiveness and a relative lack of side-effects makes atenolol a useful treatment for the hypertensive patient.

Successful pregnancies in patients with antiphospholipid syndrome treated with low-dose aspirin.

Four patients with bad obstetrical histories and with positive lupus anticoagulant tests were treated with low-dose aspirin, prednisone or heparin. They had pre-term deliveries of live babies who all survived.