导语：
在剖宫产过程中，静脉注射钙剂是常见的临床操作，但对于葡萄糖酸钙和氯化钙的剂量比例以及注射后血清离子钙浓度变化的时间过程，相关研究较少。本文将为您介绍一项关于剖宫产中静脉注射钙剂的生物等效性与药代动力学的研究成果。
一、研究背景
钙剂在剖宫产中的应用广泛，但关于葡萄糖酸钙与氯化钙的剂量比例以及注射后血清离子钙浓度变化的研究不多。为了更好地指导临床实践，本研究旨在评估这两种钙剂在剖宫产中的生物等效性及其药代动力学特性。
二、研究方法
在这项生物等效性（剂量比例）试验中，接受剖宫产的患者被随机分配接受0.5克氯化钙或1.5克或2克葡萄糖酸钙，通过10分钟静脉输注。在钙剂输注前和输注开始后大约5、10、15、30和60分钟，测量静脉血清离子钙浓度。我们将这些数据与最近两项临床试验中接受1克氯化钙或盐水安慰剂的产妇的血清离子钙浓度测量结果相结合，以定义药物给药期间和给药后第一个小时内静脉注射钙的药代动力学。
三、研究结果
生物等效性研究共纳入34名参与者，收集了181份血清离子钙浓度测量数据。葡萄糖酸钙与氯化钙的剂量比例为3.11（95% CI: 2.77-3.48）。通过对70名产妇的311份血清离子钙浓度测量数据，确定了钙的群体药代动力学。静脉注射钙的药代动力学由一个两室模型描述，系统清除率为0.18（95% CI: 0.07-0.27）L/min，分布清除率为1.25（95% CI: 1.03-1.56）L/min，中心容积为10.9（95% CI: 9.3-12.6）L，外周容积为16.5（95% CI: 12.5-24.7）L。调整剂量比例后，葡萄糖酸钙和氯化钙的时间过程相同。在10分钟输注后，一克氯化钙的输注导致血清离子钙浓度峰值增加0.39（0.38-0.42 mmol/L），29（23-40）分钟后减少一半。
四、研究结论
我们确认了钙葡萄糖酸与氯化钙的3:1剂量比例，
并估计了静脉给药后第一个小时的药代动力学。这些数据为临床护理提供了信息，并可能指导未来评估钙剂在减少产科患者出血方面的疗效的试验。
总结：
本研究为剖宫产中静脉注射钙剂的应用提供了重要的科学依据，有助于临床医生更好地理解和使用钙剂，从而提高剖宫产手术的安全性。
原文摘要
Bioequivalence and pharmacokinetics of intravenous calcium during cesarean delivery
Background: Few studies have assessed the dose ratio of calcium gluconate to calcium chloride or defined the time course of change in serum ionized calcium concentration after intravenous injection.
Methods: In a bioequivalence (dose ratio) trial, parturients undergoing cesarean delivery were randomly assigned to receive calcium chloride 0.5 grams or calcium gluconate 1.5 or 2 grams by 10-minute intravenous infusion. Venous serum ionized calcium concentration was measured prior to calcium infusion and approximately 5, 10, 15, 30, and 60 minutes after infusion start. We combined these data with serum ionized calcium concentration measurements in parturients who received 1 gram calcium chloride or saline placebo in two recent clinical trials to define the pharmacokinetics of intravenous calcium over the first hour during and after drug administration.
Results: The bioequivalence study enrolled 34 participants, from whom we collected 181 serum ionized calcium concentration measurements. The dose ratio of calcium gluconate to calcium chloride was 3.11 (95% CI: 2.77-3.48). Population pharmacokinetics of calcium were determined using 311 serum ionized calcium concentration measurements from 70 parturients. The pharmacokinetics of intravenous calcium were described by a two-compartment model with systemic clearance of 0.18 (95% CI: 0.07-0.27) L/min, distributional clearance of 1.25 (95%CI: 1.03-1.56) L/min, central volume of 10.9 (95% CI: 9.3-12.6) L, and peripheral volume of 16.5 (95% CI: 12.5-24.7) L. After adjusting for the dose ratio, calcium gluconate and calcium chloride had identical time courses. A one-gram infusion of calcium chloride results in a peak increase in serum ionized calcium concentration of 0.39 (0.38-0.42 mmol/L), which decreases by half 29 (23-40) minutes after initiation of the 10-minute infusion.
Conclusions: We confirmed a 3:1 dose ratio of calcium gluconate to calcium chloride and estimated the pharmacokinetics over the first hour following intravenous delivery. These data inform clinical care and may guide future trials assessing calcium efficacy to reduce bleeding in obstetric patients.
