White L M, Gardner S F, Gurley B J, Marx M A, Wang P L, Estes M
Department of Pharmacy Practice, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
J Clin Pharmacol. 1997 Feb;37(2):116-22. doi: 10.1002/j.1552-4604.1997.tb04769.x.
The purpose of this study was to evaluate heart rate and blood pressure responses to a commercially available source of ma-haung, a natural source of the sympathomimetic substance, ephedrine, and to evaluate the pharmacokinetic properties of the product in normotensive, healthy adults. On day 1, twelve study participants were monitored with an ambulatory blood pressure device between hours 7 and 20. On day 2, they ingested four capsules of powdered ma-huang at hours 8 and 17 while again wearing the monitor between hours 7 and 20. Serial plasma samples were obtained and concentrations of ephedrine were analyzed by high-performance liquid chromatography. Pharmacokinetic parameters of ephedrine were determined from plasma concentration-time profiles. The ephedrine alkaloid content of each capsule was also determined by high-performance liquid chromatography. Six participants experienced a statistically significant increase in heart rate, but the effects on blood pressure were variable. The half-life, volume of distribution, clearance, and maximum concentration in plasma of ephedrine in the ma-huang product were similar to values previously reported for a 20 mg, immediate-release ephedrine tablet. Values for the absorption rate were considerably lower and time to reach maximum concentration was longer for the capsules, compared with the standard tablet. Variability in alkaloid content of ephedrine was low and yielded a mean dose of ephedrine at 19.4 mg; pseudoephedrine at 4.9 mg; and methylephedrine at 1.2 mg for a four-capsule dose. In summary, ma-haung had variable effects on blood pressure and increased heart rate in healthy, normotensive adults. Pharmacokinetic parameters for ephedrine were in agreement with those previously reported; however, the absorption rate was much slower after ingestion of ma-huang.
本研究的目的是评估服用一种市售麻黄（一种天然的拟交感神经物质麻黄碱来源）后心率和血压的反应，并评估该产品在血压正常的健康成年人中的药代动力学特性。第1天，12名研究参与者在7点至20点期间使用动态血压监测仪进行监测。第2天，他们在8点和17点时服用4粒麻黄粉胶囊，同时在7点至20点期间再次佩戴监测仪。采集系列血浆样本，采用高效液相色谱法分析麻黄碱浓度。根据血浆浓度-时间曲线确定麻黄碱的药代动力学参数。每粒胶囊中麻黄碱生物碱含量也采用高效液相色谱法测定。6名参与者的心率出现了具有统计学意义的增加，但对血压的影响各不相同。麻黄产品中麻黄碱的半衰期、分布容积、清除率和血浆最大浓度与先前报道的20mg速释麻黄碱片的值相似。与标准片剂相比，胶囊的吸收速率明显较低，达到最大浓度的时间更长。麻黄碱生物碱含量的变异性较低，4粒胶囊剂量的麻黄碱平均剂量为19.4mg；伪麻黄碱为4.9mg；甲基麻黄碱为1.2mg。总之，麻黄对血压的影响各不相同，且会使健康、血压正常的成年人的心率增加。麻黄碱的药代动力学参数与先前报道的一致；然而，服用麻黄后吸收速率要慢得多。
