Moya-Huff F A, Maher T J
Department of Pharmacology, Massachusetts College of Pharmacy, Boston 02115.
J Pharm Pharmacol. 1988 Dec;40(12):876-8. doi: 10.1111/j.2042-7158.1988.tb06292.x.
Phenylpropanolamine (PPA, (+/-)-norephedrine) is commonly found in appetite suppressants and nasal decongestants. Within the cardiovascular system of the pithed rat, the drug and its two component enantiomers ((-)- and (+)-norephedrine) are largely direct-acting agonists. The interaction between simultaneous alpha 1-, alpha 2- and beta 2-adrenoceptor mediated effects of the drug and its two enantiomers have been examined using the cardiovascular system of the pithed rat. On all adrenoceptors tested the potency was (-)- greater than (+/-)-, greater than (+)-norphedrine. The alpha 1- and alpha 2-mediated pressor responses of each were enhanced in the presence of the beta 2-adrenoceptor antagonist, ICI 118,551, and diminished in the presence of the selective beta 2-adrenoceptor agonist salbutamol. It is concluded that each form of the drug possesses the intrinsic ability to interact with the alpha 1-, alpha 2- and beta 2-adrenoceptors in the system used and that the interaction with those adrenoceptors determines the net increase in diastolic blood pressure that follows the intravenous administration of the compounds. These findings have a bearing on the recent controversy regarding the use of beta-blocking agents in the treatment of overdosage of the drug.
苯丙醇胺（PPA，（±）-去甲麻黄碱）常见于食欲抑制剂和减充血剂中。在脊髓麻醉大鼠的心血管系统中，该药物及其两种对映体成分（（-）-和（+）-去甲麻黄碱）在很大程度上是直接作用的激动剂。利用脊髓麻醉大鼠的心血管系统，研究了该药物及其两种对映体同时作用于α1、α2和β2肾上腺素能受体时的相互作用。在所测试的所有肾上腺素能受体上，效力顺序为（-）-大于（±）-，大于（+）-去甲麻黄碱。在β2肾上腺素能受体拮抗剂ICI 118,551存在的情况下，每种对映体由α1和α2介导的升压反应增强，而在选择性β2肾上腺素能受体激动剂沙丁胺醇存在的情况下则减弱。得出的结论是，在所使用的系统中，该药物的每种形式都具有与α1、α2和β2肾上腺素能受体相互作用的内在能力，并且与这些肾上腺素能受体的相互作用决定了静脉注射这些化合物后舒张压的净升高。这些发现与最近关于使用β受体阻滞剂治疗该药物过量的争议有关。
