喷他佐辛（Pentazocine）是第一个临床应用的阿片受体激动/拮抗型镇痛剂，能提供包括吗啡、杜冷丁等阿片样药物相接近的镇痛作用；胃肠外给药产生快速强烈的镇痛作用，起作用时间比吗啡、杜冷丁短，中枢抑制作用轻，特别是在呼吸抑制和恶心呕吐方面都比其他阿片样药物轻，没有低血压反应，药物依赖性比其他阿片样药物小，不影响情绪，半衰期适中，其适宜的半衰期适用于各种手术，手术后遗作用迅速消除；可肌注、皮下、静脉、泵入等多种途径给药。可应用于各种手术麻醉的镇痛，可用于麻醉诱导、术中麻醉、术后镇痛等，各种手术科室的术后镇痛，各种腔镜手术的镇痛，无痛人流的镇痛，适用于癌症病人的镇痛等。

Pentazocine is a synthetically-prepared prototypical mixed agonist–antagonist narcotic (opioid analgesic) drug of the benzomorphan class of opioids used to treat moderate to moderately severe pain. Pentazocine is sold under several brand names, such as Fortral, Sosegon, Talwin NX (with the μ-antagonist naloxone, will cause withdrawal in opioid dependent persons on injection), Talwin, Talwin PX (without naloxone), Fortwin (Lactate injectable form) and Talacen (with acetaminophen). This compound may exist as one of two enantiomers, named (+)-pentazocine and (−)-pentazocine. (−)-pentazocine is a κ-opioid receptor agonist, while (+)-pentazocine is not, instead displaying a ten-fold greater affinity for the σ receptor. Usually, in its oral formulations, it is combined with naloxone so as to prevent people from crushing the tablets, dissolving them in a solvent (like water) and injecting them for a high (as naloxone is not orally bioavailable it produces no effect when the formulation is used orally, but it blocks the opioid effects of pentazocine if injected intravenously for a high). Related drugs include phenazocine, dezocine, cyclazocine and several chemicals used in research on the central nervous system.