Promethazine HCl and Codeine Phosphate Information

What's inside Promethazine HCl and Codeine Phosphate

Promethazine HCl and Codeine Phosphate Chemical Information

codeine - The phosphate salt form of codeine, a naturally occurring phenanthrene alkaloid and opioid agonist with analgesic, antidiarrheal and antitussive activity. Codeine phosphate mimics the actions of opioids by binding to the opioid receptors at many sites within the central nervous system (CNS). Stimulation of the mu-subtype opioid receptor stimulates the exchange of GTP for GDP on the G-protein complex and subsequently inhibits adenylate cyclase. This results in a decrease in intracellular cAMP and leads to a reduction in the release of neurotransmitters such as substance P, GABA, dopamine, acetylcholine and noradrenaline. The analgesic effect of codeine phosphate is likely due to its metabolite morphine, which induces opening of G-protein-coupled inwardly rectifying potassium (GIRK) channels and blocks the opening of N-type voltage-gated calcium channels, thereby resulting in hyperpolarization and reduced neuronal excitability.

promethazine hydrochloride - The hydrochloride salt form of promethazine, a phenothiazine derivative with antihistaminic, sedative and antiemetic properties. Promethazine hydrochloride selectively blocks peripheral H1 receptors thereby diminishing the effects of histamine on effector cells. Promethazine hydrochloride also blocks the central histaminergic receptors, thereby depressing the reticular system causing sedative and hypnotic effects. In addition, promethazine hydrochloride also has centrally acting anticholinergic properties and probably mediates nausea and vomiting by acting on the medullary chemoreceptive trigger zone.