Definition

A narcotic analgesic structurally related to METHADONE. Only the dextro-isomer has an analgesic effect; the levo-isomer appears to exert an antitussive effect.

Description

Propoxyphene is only found in individuals that have used or taken this drug. It is a narcotic analgesic structurally related to methadone. Only the dextro-isomer has an analgesic effect; the levo-isomer appears to exert an antitussive effect. [PubChem]Propoxyphene acts as a weak agonist at OP1, OP2, and OP3 opiate receptors within the central nervous system (CNS). Propoxyphene primarily affects OP3 receptors, which are coupled with G-protein receptors and function as modulators, both positive and negative, of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine, and noradrenaline is inhibited. Opioids such as propoxyphene also inhibit the release of vasopressin, somatostatin, insulin, and glucagon. Opioids close N-type voltage-operated calcium channels (OP2-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (OP3 and OP1 receptor agonist). This results in hyperpolarization and reduced neuronal excitability.

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Related Pathways

General Information

Toxicity

Mechanism of Action

Dextropropoxyphene Interacts with Diseases

Dextropropoxyphene Interacts with Genes