Major Depressive Disorder, Obsessive Compulsive Disorder, Panic Disorder, Social Anxiety Disorder, Generalized Anxiety Disorder, Post-traumatic Stress Disorder.
Selective Serotonin Re-uptake Inhibitor; Antidepressant
The efficacy of Paroxetine is presumed to be linked to potentiation of serotonergic activity in the central nervous system resulting from inhibition of neuronal reuptake of serotonin (5-hydroxy-tryptamine, 5 HT). Studies at clinically relevant doses in humans have demonstrated that paroxetine blocks the uptake of serotonin into human platelets. In vitro studies in animals also suggest that paroxetine is a potent and highly selective inhibitor of neuronal serotonin reuptake and has only very weak effects on norepinephrine and dopamine neuronal reuptake. In vitro radioligand binding studies indicate that paroxetine has little affinity for muscarinic, alpha1, alpha2, beta adrenergic, dopamine (D2), 5-HT1, 5 HT2 and histamine (H1)-receptors; antagonism of muscarinic, histaminergic and alpha1-adrenergic receptors has been associated with various anticholinergic, sedative and cardiovascular effects for other psychotropic drugs. Because the relative potencies of paroxetine’s major metabolites are at most 1/50 of the parent compound, they are essentially inactive.
20 mg as a single daily dose.
Food/antacids: The absorption and pharmacokinetics of Paroxetine are not affected by food or antacids.
Tryptophan: As with other 5-HT re uptake inhibitors, animal studies indicate that an interaction between Paroxetine and Tryptophan may occur, resulting in a ‘serotonin syndrome’ suggested by a combination of agitation, restlessness and gastrointestinal symptoms including diarrhoea.
Drug metabolizing enzyme inducers /inhibitors: The metabolism and pharmacokinetics of Paroxetine may be affected by drugs, which induce or inhibit hepatic drug metabolizing enzymes. When Paroxetine is to be coadministered with a known drug metabolizing inhibitor, consideration should be given to using doses at the lower end of the range. No initial dosage adjustment of Paroxetine is considered necessary when it is to be co-administered with known drug metabolizing enzyme inducers. Any subsequent dosage adjustment should be guided by clinical effect (tolerabilityand efficacy).
Alcohol: Although Paroxetine does not increase the impairment of mental and motor skill caused by alcohol, the concomitant use of Paroxetine and alcohol in depressed patients is not advised.
Haloperidol/amylobarbitone/oxazepam: Experience in a limited number of healthy subjects has shown that Paroxetine did not increase the sedation and drowsiness associated with haloperidol, amylobarbitone or oxazepam when given in combination.
MAOls: As with other 5-HT re uptake inhibitors, animal studies indicate that an interaction between Paroxetine and monoamine oxidase (MAO) inhibitors may occur.
Lithium: Since there is little clinical experience, and there have been reports of interaction of lithium with other 5-HT re-uptake inhibitors, the concurrent administration of Paroxetine and lithium should be undertaken with caution.
Lithium levels should be monitored. Phenytoin / anticonvulsants: Co-administration of Paroxetine and phenytoin is associated with decreased plasma concentrations of Paroxetine and increased adverse experiences. Co-administration of Paroxetine with other anticonvulsants may also be associated with an increased incidence of adverse experiences.
Warfarin: Preliminary data suggest that there may be a pharmacodynamic interaction between Paroxetine and warfarin, which may result in increased bleeding in the presence of unaltered prothrombin times. Paroxetine should therefore be administered with great caution to patients receiving oral anticoagulants.
MAOIs or thioridazine, hypersensitivity. Cardiac conditions, epilepsy. Patients should be cautioned about their ability to drive a car & operate machinery.
Asthenia, sweating, nausea, decreased appetite, somnolence, dizziness, insomnia, tremor, nervousness, ejaculatory disturbance & other male genital disorders, nausea, dry mouth, constipation, dizziness, somnolence, impotence, female genital disorders.
The drug should be used during pregnancy & lactation if potential benefit justifies the potential risk to the fetus.
Keep out of the reach of children. Store at a cool and dry place. Protect from light and moisture.
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