Paroxetine is the most potent and one of the most specific
selective serotonin (5-hydroxytryptamine, 5-HT) reuptake
inhibitors (SSRI). This activity of the drug on brain
neurons is thought to be responsible for its antidepressant
effects.
Paroxetine is a phenylpiperidine derivative which
is chemically unrelated to the tricyclic or tetracyclic
antidepressants. In receptor binding studies, paroxetine
did not exhibit significant affinity for the adrenergic
(?1, ?2, ?), dopaminergic, serotonergic (5HT1, 5HT2),
or histamine receptors of rat brain membrane. A weak
affinity for the muscarinic acetylcholine and noradrenaline
receptors was evident. The predominant metabolites
of paroxetine are essentially inactive as 5-HT reuptake
inhibitors.
Chemistry
Paroxetine hydrochloride is an odorless, off-white
powder, having a melting point range of 120° to
138°C and a solubility of 5.4 mg/mL in water.
Formulations
Paroxetine CR (controlled release) was shown to be
associated with a lower rate of nausea during the
first week of treatment than paroxetine immediate
release. However, the rate of treatment discontinuation
due to nausea was not significantly different.
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