Labetalol

BackgroundHypertension 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.MethodsIn 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.FindingsBetween 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 (InterpretationAll 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.FundingPREEMPT (University of British Columbia, Vancouver, BC, Canada; grantee of Bill & Melinda Gates Foundation).

PurposeAntihypertensive 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.MethodsA 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.ResultsA 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.ConclusionWe 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.

Hypertensive disorders of pregnancy complicate up to 10% of pregnancies and remain the major cause of maternal and neonatal morbidity and mortality. Hypertensive disorders of pregnancy can be classified into four groups depending on the onset of hypertension and the presence of target organ involvement: chronic hypertension, preeclampsia, gestational hypertension, and superimposed preeclampsia on chronic hypertension. Hypertension during pregnancy is associated with a higher risk of cardiovascular disease and kidney failure. Early diagnosis and proper treatment for pregnant women with hypertension remain a priority since this leads to improved maternal and fetal outcomes. Labetalol, nifedipine, methyldopa, and hydralazine are the preferred medications to treat hypertension during pregnancy. In this comprehensive review, we discuss the diagnostic criteria, evaluation, and management of pregnant women with hypertension.

Lipid emulsion has recently emerged as an effective agent for improving the cardiotoxicity of highly lipophilic drugs. However, its effect on cardiotoxicity induced by labetalol, a nonselective beta-blocker, remains unknown. In this study, we investigated the effects of lipid emulsion on the cardiotoxicity of labetalol in rat cardiomyoblasts and tried to decipher the underlying mechanisms. The effects of lipid emulsion on labetalol-induced changes in cell viability, expression of Bax/Bcl-2, cleaved caspase-3, and cleaved caspase-9, and phosphorylation of GSK-3β, Akt, and PI3K were examined. Lipid emulsion inhibited labetalol-induced decrease in cell viability, whereas LY294002, MK2206, and SB216763, the inhibitors of phosphoinositide 3-kinase (PI3K), Akt, glycogen synthase kinase-3β (GSK-3β), respectively, partially attenuated this restoration of cell viability. Lipid emulsion reversed the increase in expression of cleaved caspase-3, cleaved caspase-9, and Bax/Bcl-2 and decrease in the phosphorylation of GSK-3β, Akt, and PI3K by labetalol. Lipid emulsion and cyclosporin, a mitochondrial permeability transition pore (MPTP) inhibitor, reduced the labetalol-induced increase in the number of TUNEL-positive cells and promoted late-stage apoptosis. Overall, lipid emulsion inhibited apoptotic cell death caused by labetalol toxicity via the inhibition of intrinsic apoptotic pathway and MPTP in rat cardiomyoblasts, which appears to involve PI3K, Akt, and GSK-3β signaling pathways.