Paroxetine’s Pharmacokinetic and Pharmacodynamic Factors

Paroxetine is characterized as an antidepressant whose properties are induced by selective inhibition of serotonin uptake. The phenylpiperidine (trans-isomeric) has a low affinity for receptors – muscarinic receptors – translating to non-direct interaction with monoamine receptors which are also neurotransmitters. Paroxetine is actively absorbed in the gastrointestinal tract and undergoes a first pass metabolism leading to its reduced bioavailability. After transformation (in the liver), paroxetine is eliminated into inactive metabolites. Other drugs metabolized through a similar isoenzyme is indicated by Paroxetine’s high affinity for cytochrome P450 – isoenzyme CYP2D6 (Shalimova et al., 2021). As such, it is recommended to avoid comedication of Paroxetine with other antidepressants - especially tricyclic antidepressants.