Agonist - antagonist - wikipedia Agonist - antagonist In pharmacology the term agonist - antagonist or mixed agonist / antagonist is used to refer to a drug which under some conditions behaves as an agonist ( a substance that fully activates the receptor that it binds to ) while under other conditions, behaves as an antagonist ( a substance that binds to a receptor but does not activate and can block the activity of other agonists ). Types of mixed agonist / antagonist include receptor ligands that act as agonist for some receptor types and antagonist for others or agonist in some tissues while antagonist in others ( also known as selective receptor modulators ). Agonist - antagonist opioids The best known agonist - antagonists are opioids. Examples of such opioids are : pentazocine, agonist at the kappa ( κ ) and sigma ( σ ) and has a weak antagonist action at the mu opioid receptor ( μ ). butorphanol, partial agonist at μ - and a pure agonist at κ - opioid receptor and antagonist activity at the delta opioid receptor ( δ ) nalbuphine, κ - agonist / μ - antagonist analgesic Agonist -- antagonist opioids usually have a ceiling effect -- over particular dose they do n't increase their potency. Hence agonist -- antagonist opioids have a lower addiction potential but also lower analgesic efficacy and are more likely to produce psychotomimetic effects. Agonist -- antagonist opioids that block delta while activating mu opioid receptors produce analgesia without the development of tolerance. See also Partial agonist Competitive antagonist Inverse agonist References Jump up ^ Hoskin PJ, Hanks GW ( 1991 ). `` Opioid agonist - antagonist drugs in acute and chronic pain states ''. Drugs. 41 ( 3 ) : 326 -- 44. doi : 10.2165 / 00003495 - 199141030 - 00002. PMID 1711441. Jump up ^ Hollister LE ( 17 July 1991 ). `` AMA Drug Evaluations Annual 1991 ''. JAMA : The Journal of the American Medical Association. 266 ( 3 ) : 97. doi : 10.1001 / jama. 1991.03470030126039. Jump up ^ Commiskey S, Fan LW, Ho IK, Rockhold RW ( 2005 ). `` Butorphanol : effects of a prototypical agonist - antagonist analgesic on kappa - opioid receptors ''. Journal of Pharmacological Sciences. 98 ( 2 ) : 109 -- 16. doi : 10.1254 / jphs. CRJ05001X. PMID 15942128. Jump up ^ Schmidt WK, Tam SW, Shotzberger GS, Smith DH, Clark R, Vernier VG ( 1985 ). `` Nalbuphine ''. Drug and Alcohol Dependence. 14 ( 3 - 4 ) : 339 -- 62. doi : 10.1016 / 0376 - 8716 ( 85 ) 90066 - 3. PMID 2986929. Jump up ^ Benson GJ, Tranquilli WJ ( 1992 ). `` Advantages and guidelines for using opioid agonist - antagonist analgesics ''. Veterinary Clinics of North America : Small Animal Practice. 22 ( 2 ) : 363 -- 5. doi : 10.1016 / S0195 - 5616 ( 92 ) 50637 - 4. PMID 1585578. Jump up ^ Lasagna L ( 1987 ). `` Benefit - risk ratio of agonist - antagonist analgesics ''. Drug and Alcohol Dependence. 20 ( 4 ) : 385 -- 93. doi : 10.1111 / j. 1360 - 0443.1989. tb00595. x. PMID 2894291. Jump up ^ Dietis N, Guerrini R, Calo G, Salvadori S, Rowbotham DJ, Lambert DG ( 2009 ). `` Simultaneous targeting of multiple opioid receptors : a strategy to improve side - effect profile ''. British Journal of Anaesthesia. 103 ( 1 ) : 38 -- 49. doi : 10.1093 / bja / aep129. PMID 19474215. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Agonist-antagonist&oldid=812938132 '' Categories : Pharmacodynamics Talk About Wikipedia Add links This page was last edited on 30 November 2017, at 19 : 53. About Wikipedia

Question: what is the difference between an opiate agonist and antagonist
Answer: a substance that fully activates the receptor that it binds to