Schunack W
Institute of Pharmacy, Free University of Berlin, FRG.
Aliment Pharmacol Ther. 1987;1 Suppl 1:493S-503S. doi: 10.1111/j.1365-2036.1987.tb00658.x.
The H2-receptor antagonists which are used for ulcer therapy fall into four main structural classes. Cimetidine is an imidazole derivative; ranitidine belongs to the basically substituted furans, famotidine is a member of the guanidinothiazole group; and roxatidine belongs to the aminoalkylphenoxy series. Famotidine is the most potent, selective H2-receptor antagonist yet available for ulcer therapy. On a weight basis, famotidine is approximately eight times more potent than ranitidine and 40 times more potent than cimetidine. Cimetidine, ranitidine and famotidine are competitive antagonists, while the long-acting H2-receptor antagonists, e.g. loxtidine and lamitidine, are insurmountable H2-receptor blockers. Famotidine has a longer duration of action than either ranitidine or cimetidine. Because famotidine does not interact with cytochrome P-450 of the hepatic enzyme system, it does not appear to affect the metabolism of drugs metabolized by this system. The overall number of side-effects of the H2-receptor antagonists is in the range of 2-3% and no irreversible adverse effects are known. Famotidine has been found to be generally well tolerated. In a first post-marketing study, the number of patients with side-effects was only 0.43%. Side-effects such as headache, dizziness, constipation and diarrhoea have been observed only occasionally. Thus, famotidine is a safe and potent H2-receptor blocker of acid secretion.
用于溃疡治疗的H2受体拮抗剂主要分为四大结构类别。西咪替丁是一种咪唑衍生物；雷尼替丁属于碱性取代呋喃类；法莫替丁是胍基噻唑类的一员；罗沙替丁属于氨基烷基苯氧基系列。法莫替丁是目前可用于溃疡治疗的最有效、选择性最强的H2受体拮抗剂。按重量计算，法莫替丁的效力约为雷尼替丁的八倍，西咪替丁的四十倍。西咪替丁、雷尼替丁和法莫替丁是竞争性拮抗剂，而长效H2受体拮抗剂，如洛替丁和拉米替丁，是不可克服的H2受体阻滞剂。法莫替丁的作用持续时间比雷尼替丁或西咪替丁都长。由于法莫替丁不与肝酶系统的细胞色素P - 450相互作用，它似乎不影响由该系统代谢的药物的代谢。H2受体拮抗剂的副作用总数在2 - 3%的范围内，且尚无不可逆的不良反应。已发现法莫替丁总体耐受性良好。在一项上市后的首次研究中，出现副作用的患者数量仅为0.43%。诸如头痛、头晕、便秘和腹泻等副作用只是偶尔观察到。因此，法莫替丁是一种安全有效的胃酸分泌H2受体阻滞剂。
