Metaraminol 10mg/20ml solution for injection pre-filled syringes

IntroductionPhenylephrine infusion is widely endorsed by guidelines as the preferred prophylactic drug for spinal hypotension in patients undergoing caesarean delivery; however, clinical practice continues to show marked variability in the selection of vasopressor drugs. To address this, we aimed to synthesise current evidence from randomised controlled trials comparing vasopressor infusions for various feto-maternal outcomes in normotensive adult patients undergoing caesarean delivery.MethodsRandomised controlled trials evaluating maternal and fetal outcomes associated with prophylactic vasopressor infusion were identified through comprehensive database searches. Primary outcomes were the incidence of maternal hypotension and umbilical artery base excess. Secondary outcomes comprised maternal and fetal parameters including: umbilical artery and vein pH; umbilical vein base excess; Apgar scores at 1 min and 5 min; and incidence of maternal intra-operative nausea and vomiting, bradycardia, tachycardia and hypertension.ResultsFifty-five trials involving 5487 patients undergoing caesarean delivery under spinal or combined spinal and epidural anaesthesia using a variety of vasopressor infusions were included in the final analysis. Four drugs-metaraminol, noradrenaline, phenylephrine and adrenaline-were judged to be 'definitely superior' to control (no active vasopressor infusion) for the prevention of hypotension. Umbilical vessel analyses indicated that mephentermine and metaraminol provided superior preservation of both umbilical arterial and venous acid-base balance.DiscussionCurrent evidence suggests that continuous infusions of α-agonists with mild β-activity (e.g. noradrenaline, metaraminol) are preferable to mixed adrenergic agonists such as ephedrine for preventing maternal hypotension. While these findings reinforce existing recommendations for maternal haemodynamic management, the evidence base for fetal outcomes remains limited.

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ImportancePeripheral intravenous (PIV) vasopressors are increasingly used but remain associated with adverse events (AEs). Quantifying the incidence of these AEs is essential to guide clinical decision-making regarding PIV vasopressor use.ObjectiveTo assess the incidence of AEs and avoidance of central venous catheter (CVC) placement after PIV vasopressor administration in adults with hypotension, shock, or critical illness.Data sourcesPubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception to December 13, 2025, using medical subject headings and keywords related to peripheral vasopressors.Study selectionEligible studies included critically ill adults receiving vasopressors via PIV catheters and reported AEs and/or CVC avoidance.Data extraction and synthesisFollowing Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 2 investigators independently extracted data and assessed risk of bias. A random-effects model was used, and proportions were pooled using a generalized linear mixed model.Main outcomes and measuresThe primary end point was the pooled incidence of AEs as the proportion among total catheters, and the secondary end point was the pooled proportion of CVC avoidance.ResultsForty-nine studies including 33 060 catheters were analyzed. The pooled minor AE incidence was 2.6% (95% CI, 1.4%-4.7%) for norepinephrine, 0.0% (95% CI, 0.0%-24.6%) for epinephrine, 2.9% (95% CI, 1.8%-4.8%) for phenylephrine, 1.4% (95% CI, 0.3%-5.9%) for dopamine, 0.5% (95% CI, 0.1%-1.8%) for vasopressin, and 0.9% (95% CI, 0.1%-11.5%) for metaraminol. When considering all vasopressors collectively, the pooled minor AE incidence was 2.3% (95% CI, 1.5%-3.7%). Regarding major AEs, 30 venous thromboembolism events occurred, all in the 4 studies (8.1%) using midline catheters (1126 total catheters), with a pooled incidence of 1.4% (95% CI, 0.4%-5.4%). In contrast, only 1 major AE (a tissue necrosis event) was reported in 43 studies (87.8%) using short PIV catheters (29 596 total catheters), with a pooled incidence of 0.0% (95% CI, 0.0%-0.0%). CVC avoidance ranged from 0% to 100%, with a pooled proportion of 59.7% (95% CI, 46.4%-71.7%) in 38 studies (77.6%) including 15 371 catheters.Conclusions and relevanceIn this systematic review and meta-analysis of adult patients, AE incidence was low after short-term vasopressor administration through PIV catheters, particularly short catheters. These findings suggest that PIV administration might reduce the need for CVC placement with appropriate monitoring.

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BACKGROUND Few studies directly compared the effects of metaraminol and norepinephrine on maternal and neonatal outcomes during cesarean delivery. Moreover, the infusion rates are often based on clinical experience rather than high-quality evidence, leading to non-equivalent dosing. This study aims to validate and compare metaraminol and norepinephrine at their 90% effective dose (ED90) in obstetric anesthesia. MATERIALS AND METHODS One hundred parturients undergoing cesarean delivery were randomly assigned to receive either 2.00 μg/kg/min of metaraminol (Group ME) or 0.10 μg/kg/min of norepinephrine (Group NE) to prevent spinal anesthesia-induced hypotension (SAIH). The primary outcomes were neonatal umbilical arterial (UA) pH and incidence of SAIH. Secondary outcomes included hemodynamic changes during the first 15 minutes, maternal adverse events, and additional neonatal outcome parameters. RESULTS Among the 94 participants who completed the study, the UA pH in Group ME [mean: 7.298; 95% confidence interval (CI): 7.255-7.341] was non-inferior to that in Group NE (mean: 7.296; 95% CI: 7.255-7.337), with a mean difference of 0.003 (95% CI: - 0.017 to 0.023), which is within the predefined non-inferiority margin of 0.02 pH units (non-inferiority P = 0.012). The incidence of SAIH was 13.0% in Group ME and 8.3% in Group NE (P = 0.701). No significant differences were observed in hypertension, bradycardia, nausea, and vomiting. Systolic blood pressure (SBP) measurements were comparable between the groups during the first 15 minutes. Additionally, Group NE had a higher heart rate (HR) than Group ME at most time points. Neonatal outcomes were comparable except for a higher UA pO2 in Group ME. CONCLUSION Prophylactic infusion of metaraminol at 2.00 μg/kg/min is non-inferior to norepinephrine at 0.10 μg/kg/min in terms of neonatal outcomes, as assessed by umbilical arterial pH. Our findings further support the use of metaraminol as a suitable vasopressor in obstetric anesthesia for low-risk populations.

Abstract licence: CC BY-SA