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Paroxetine information from DrugsUpdate  

See Available Brands of Paroxetine in India

P - Caution when used during pregnancy
L - Caution when used during lactation
FI - Food *

Paroxetine (trade names Seroxat, Paxil) is a selective serotonin reuptake inhibitor (SSRI) antidepressant. Paroxetine is used to treat major depression, obsessive-compulsive, panic, social anxiety, and generalised anxiety disorders in adult outpatients.

Pharmacodynamics

The efficacy of Paroxetine in the treatment of major depressive disorder, social anxiety disorder, obsessive compulsive disorder (OCD), panic disorder (PD), and generalized anxiety disorder (GAD) 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.

Pharmacokinetics

Paroxetine selectively inhibits the reuptake of serotonin. It has limited direct action at other neurotransmitter sites including muscarinic receptors.

Absorption
Absorbed readily from the GI tract (oral); peak plasma concentrations after 5 hours.

Distribution

Enters breast milk. Protein-binding: 95%.

Metabolism
Extensive hepatic first-pass metabolism; by oxidation followed by methylation then formation of glucuronide and sulfate conjugates.

Excretion
Via urine (64%) and faeces (36%), mainly as metabolites; elimination half-life: 21 hours.

Paroxetine Indications / Paroxetine Uses

Information Not Available

Paroxetine Adverse Reactions / Paroxetine Side Effects

Somnolence, insomnia, headache, dizziness; decreased libido; nausea, xerostomia, constipation, diarrhoea; ejaculatory disturbances; weakness, tremor, diaphoresis; vasodilation, chest pain, palpitation, hypertension, tachycardia, nervousness, anxiety , agitation, abnormal dreams, impaired concentration, yawning, depersonalisation, amnesia, emotional lability, vertigo, confusion, chills; rash, pruritus; orgasmic disturbance, dysmenorrhoea; anorexia, decreased appetite, dyspepsia, flatulence, abdominal pain, appetite increased, vomiting, taste perversion, weight gain; impotence, genital disorder, urinary frequency, UTI; paresthesia, myalgia, back pain, myoclonus, myopathy, myasthenia, arthralgia; blurred vision, abnormal vision; tinnitus; respiratory disorder, pharyngitis, sinusitis, rhinitis; infection.

Precautions

Warnings
Antidepressants increased the risk of suicidal thinking and behavior in short-term studies in children and adolescents with MDD and other psychiatric disorders. Closely observe patients who are started on therapy for clinical worsening, suicidality, or unusual changes in behavior.

Overdosage
Somnolence, nausea, vomiting, hepatic dysfunction, drowsiness, sinus tachycardia, urinary retention, renal failure (acute), dilated pupils, convulsions, status epilepticus, ventricular arrhythmias (including torsade de pointes), serotonin syndrome and manic reaction. No specific antidotes; treatment is supportive; cardiac monitoring is recommended.

Special Precautions

Epilepsy, glaucoma, history of mania, cardiac disease, DM, history of bleeding disorders, on drugs with increased risk of bleeding; renal and hepatic impairment; patients receiving electroconvulsive therapy; achlorhydria or high gastric pH (reduced absorption of oral suspension). Pregnancy and lactation. The risk of suicidal behaviour may be higher in young adults, closely monitor. May impair ability to drive or perform tasks. Avoid abrupt withdrawal.

Other Drug Interactions

Levels/effects inhibited by cyproheptadine, phenytoin. Levels/effects increased by carbamazepine, cimetidine, CYP2D6 inhibitors (e.g. chlorpromazine, delavirdine, fluoxetine, miconazole, pergolide, quinidine, quinine, ritonavir, ropinirole). Increases levels/effects of atomoxetine, carvedilol, clozapine, CYP2B6 substrates (e.g. bupropion, promethazine, propofol, selegiline, sertraline), CYP2D6 substrates (e.g. amphetamines, selected beta-blockers, dextromethorphan, fluoxetine, lidocaine, mirtazapine, nefazodone, risperidone, ritonavir, thioridazine, TCAs, venlafaxine), duloxetine, galantamine, mexilitine, pimozide, procyclidine, propafenone. Decreases levels/effects of CYP2D6 prodrug substrates (e.g. codeine, hydrocodone, oxycodone, tramadol). Inhibits the metabolism of dextromethorphan, haloperidol, thioridazine. Enhances bradycardic effect of beta-blockers. Enhances toxic effects of other CNS depressants. Increased risk of serotonin syndrome with amphetamines, SSRIs, meperidine, nefazodone, trazodone, serotonin agonists, sibutramine, sympathomimetics, tramadol, venlafaxine. Increases risk of bleeding with NSAIDs, aspirin, warfarin, or other drugs affecting coagulation. Increases sensitivity to amphetamines. Neurotoxicity with lithium. Additive hyponatraemia with loop diuretics. Mania or hypertension with selegiline.

Potentially Fatal: Fatal reactions with nonselective MAOI.

Other Interactions

Food Interaction
Peak concentration increased; bioavailability not significantly altered. Avoid valerian, St John's wort, SAMe, kava kava. Ethanol may increase CNS depression.

Dosage

Oral
Depression
Adult: 20 mg daily, increase gradually, if necessary, by 10-mg increments weekly; max: 50 mg/day.
Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week intervals; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Oral
Obsessive compulsive disorder
Adult: Initially, 20 mg daily, increase weekly in 10-mg increments. Maintenance: 40-60 mg daily.
Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week intervals; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Oral
Panic disorder with or without agoraphobia
Adult: Initially, 10 mg daily, increase weekly in 10-mg increments according to clinical response. Maintenance: 40-60 mg daily.
Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week intervals; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Oral

Social anxiety disorder
Adult: Initially, 20 mg daily, increase after several weeks by 10-mg increments; max dose: 50-60 mg/day.
Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week intervals; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Oral

Anxiety
Adult: Initially, 20 mg daily, increase in weekly increments of 10 mg; max dose: 50 mg/day.
Elderly: Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week interval; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Oral
Post-traumatic stress disorder
Adult: 20 mg daily, may be increased in 10-mg increments if necessary; max dose: 50 mg/day.
Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week intervals; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Oral
Premenstrual dysmorphic disorder
Adult: As hydrochloride, modified-release preparation: Initially, 12.5 mg once daily, usually in the morning; may increase up to 25 mg once daily after at least 1 week, if necessary; given throughout the menstrual cycle or limited to the luteal phase.
Elderly: Initially, 10 mg daily, increase if needed by 10 mg/day at 1 week intervals; max: 40 mg daily.

Renal impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.
Hepatic impairment: Hepatic impairment: Severe: 10 mg daily, increase to a max of 40 mg daily as necessary.

Food(before/after)

May be taken with or without food. (May be taken w/ meals to minimise GI upset.)

List of Contraindications

Paroxetine and Pregnancy

Caution when used during pregnancy

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Paroxetine and Lactation

Caution when used during lactation

Paroxetine and Children

Safety and efficacy not established

Paroxetine and Geriatic

SSRIs and SNRIs, including Paroxetine hydrochloride, have been associated with cases of clinically significant hyponatremia in elderly patients, who may be at greater risk for this adverse event.

Paroxetine and Other Contraindications

Use with or within 14 days of MAOIs; concurrent use with thioridazine or pimozide.

Storage

Oral
Store at ≤25°C for suspensions or 15-30°C for tablets.

Lab interference

Oral
Store at ≤25°C for suspensions or 15-30°C for tablets.

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