Paroxetine is a selective serotonin reuptake inhibitor (SSRI) widely prescribed for the management of mood, anxiety, and related disorders. Since its approval in the 1990s, it has become one of the most recognized SSRIs worldwide. Paroxetine works by selectively inhibiting the reuptake of serotonin (5-HT) into presynaptic neurons, thereby increasing serotonin availability in the synaptic cleft. This prolonged serotonin signaling helps rebalance neurotransmitter activity in brain regions associated with mood regulation, anxiety control, and stress resilience.
Unlike some other SSRIs, paroxetine is relatively short-acting, with a half-life of about 21 hours, making it suitable for once-daily dosing but also meaning that abrupt discontinuation can produce withdrawal symptoms (discontinuation syndrome). Paroxetine has anticholinergic properties compared to other SSRIs, which can contribute to both therapeutic benefits (e.g., in anxiety or insomnia) and side effects (e.g., dry mouth, constipation). It is available in immediate-release tablets, controlled-release tablets, and liquid formulations, offering dosing flexibility for adults and, in rare circumstances, adolescents under specialist supervision.
Paroxetine has been the subject of extensive clinical research, with evidence supporting its efficacy in a broad spectrum of psychiatric conditions. It remains a mainstay of treatment, although prescribing trends in some regions have shifted toward SSRIs with fewer withdrawal concerns (like escitalopram) or more favourable side-effect profiles. Nevertheless, paroxetine’s versatility, potency, and relatively rapid onset of action maintain its relevance in clinical practice.
Therapeutic effects typically begin after 2–4 weeks, but full benefit may take 6–8 weeks. Dosages vary by condition but commonly start at 20 mg/day, with adjustments based on clinical response and tolerability. Controlled-release formulations may reduce gastrointestinal side effects and improve adherence.
Most side effects are dose-related and can be managed by dose adjustment, switching to another SSRI, or adding supportive therapy. Patients should be counselled about sexual side effects and discontinuation risks.
Patients should be educated about risks, particularly regarding abrupt discontinuation, pregnancy, and self-harm monitoring during treatment initiation.
Patients should provide a full list of medications and supplements to healthcare providers before starting paroxetine. Pharmacogenetic testing may sometimes guide safer prescribing.
Overdose: Symptoms may include severe drowsiness, tremor, seizures, vomiting, rapid heart rate, and in extreme cases, arrhythmias or coma. Supportive management in a hospital setting is standard; no specific antidote exists.
Accidental double dose: Usually results in mild gastrointestinal or central nervous system symptoms. Patients should rest, monitor themselves, and contact a healthcare provider if symptoms escalate.
Missed dose: Take as soon as remembered unless it is close to the next scheduled dose. Do not double up. Maintaining regular dosing times helps prevent withdrawal symptoms.
Patients should be advised to carry an updated medication list and to read package leaflets carefully. Family members should watch for behavioural changes, especially at treatment initiation.
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