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. 2012 Feb;6(1):11-6.
doi: 10.1177/2049463712438493.

Basic opioid pharmacology: an update

Hasan Pathan  1 , John Williams  2
Affiliations

Basic opioid pharmacology: an update

Hasan Pathan et al. Br J Pain. 2012 Feb.

Abstract

Opioids are a group of analgesic agents commonly used in clinical practice. There are three classical opioid receptors (DOP, KOP and MOP), while the novel NOP receptor is considered to be a non-opioid branch of the opioid receptor family. Opioids can act at these receptors as agonists, antagonists or partial agonists. Opioid agonists bind to G-protein coupled receptors to cause cellular hyperpolarisation. Most clinically relevant opioid analgesics bind to MOP receptors in the central and peripheral nervous system in an agonist manner to elicit analgesia. Opioids may also be classified according to their mode of synthesis into alkaloids, semi-synthetic and synthetic compounds.

Keywords: Analgesics; opioid classification; opioid/pharmacology; pharmacokinetics.

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Conflict of interest statement

The authors declare that they do not have any conflict of interest.

Figures

Figure 1.
Figure 1.
Intracellular changes occurring following the binding of an opioid agonist to a G-protein-coupled opioid receptor.
Figure 2.
Figure 2.
This figure shows schematically the descending inhibitory pathways. Areas shaded grey display a high expression of opioid receptors and their endogenous ligands. MOP agonists produce analgesia either by indirectly increasing neuronal traffic through the descending pathway at the NRPG and PAG, or by directly inhibiting nociceptive afferents in the periphery. MOP agonists act at the NRM to indirectly inhibit spinal pain transmission and, in addition, reduce spinal nociception. PAG = periaqueductal grey; NRPG = nucleus reticularis paragigantocellularis; NRM = nucleus raphe magnus; LC = locus correolus.
See this image and copyright information in PMC

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