RT Book, Section A1 Katzung, Bertram G. A1 Kruidering-Hall, Marieke A1 Trevor, Anthony J. SR Print(0) ID 1156529267 T1 Opioid Analgesics & Antagonists T2 Katzung & Trevor's Pharmacology: Examination & Board Review, 12e YR 2019 FD 2019 PB McGraw-Hill Education PP New York, NY SN 9781259641022 LK accesspharmacy.mhmedical.com/content.aspx?aid=1156529267 RD 2024/03/29 AB The opioids include natural opiates and semisynthetic alkaloids derived from the opium poppy, pharmacologically similar synthetic surrogates, and endogenous peptides. On the basis of their interaction with several opioid receptors (μ[mu], δ [delta], and κ [kappa] receptors), individual drugs are classified as agonists, mixed agonist-antagonists, and antagonists at one or more of these receptors. Because of their psychic effects, opioids are important drugs of abuse and are responsible for severe personal and social problems.Opioid peptides (opiopeptins) released from nerve endings modulate transmission in the brain and spinal cord and in primary afferents via their interaction with one or more of the above receptors. Most of the pharmacologic actions of opiates and synthetic opioid drugs are effected via their interactions with opioid peptide receptors.