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Paxil (Paroxetine) Information

Paxil (paroxetine hydrochloride) is a prescription medication belonging to the class of Selective Serotonin Reuptake Inhibitors (SSRIs). It is indicated for a wide range of psychiatric conditions, including Major Depressive Disorder (MDD), Obsessive-Compulsive Disorder (OCD), Panic Disorder, Generalized Anxiety Disorder (GAD), Social Anxiety Disorder (SAD), and Post-Traumatic Stress Disorder (PTSD). Paroxetine is considered one of the most potent SSRIs, and it is uniquely associated with a mild anticholinergic effect, which contributes to its higher risk of sedation and constipation compared to other drugs in its class. It is available in immediate-release (Paxil) and controlled-release (Paxil CR) formulations, both intended for consistent, once-daily use.

The mechanism of action for paroxetine involves the highly potent and selective inhibition of the Serotonin Transporter (SERT). By blocking the reuptake of the neurotransmitter serotonin (5-HT) back into the nerve cell, paroxetine effectively increases the concentration and duration of serotonin activity in the synaptic clefts. This enhanced serotonergic activity is responsible for its therapeutic effects on mood and anxiety symptoms. Due to its comparatively short half-life and potent serotonin activity, Paxil is widely known to have the highest risk among the SSRIs for inducing a severe discontinuation syndrome upon abrupt cessation, requiring slow and careful tapering.

Paxil is available in Canada as a prescription-only medication for use in adults 18 years of age and older. The dose is highly individualized, starting low and gradually increasing over several weeks. The usual starting dose for MDD is 20 mg once daily. However, doses can range up to 50-60 mg daily for conditions like OCD, depending on the formulation. Consistent daily use is essential, as the full therapeutic benefit may take several weeks to materialize fully.

Paxil Side Effects

While Paxil is generally effective, it has a notable side effect profile, often including the common effects of other SSRIs, as well as those related to its mild anticholinergic activity. The most common side effects reported are nausea (very common), headache, dizziness, dry mouth, constipation, increased sweating, somnolence (sedation), and blurred vision. Sexual dysfunction (e.g., decreased libido, ejaculatory delay, or anorgasmia) is also reported at a high rate with this medication.

However, more serious side effects can occur, although they are rare. If any of the following symptoms are experienced, the patient should stop taking the medication and seek immediate medical attention:
• Abnormal Bleeding: Increased risk of bleeding events (e.g., bruising, hemorrhage) due to the drug's potential to impair platelet aggregation, mainly when used concurrently with antiplatelet agents or anticoagulants.
• Serotonin Syndrome: This is a potentially life-threatening reaction that results from an excessive amount of serotonin, typically when Paxil is combined with other serotonergic drugs (e.g., MAOIs, triptans, tramadol).

Symptoms may include agitation, hallucinations, a rapid heart rate, fever, muscle rigidity, and incoordination.
• Severe Discontinuation Syndrome: Due to its short half-life and potent reuptake inhibition, Paxil is associated with a high risk of severe withdrawal symptoms upon abrupt cessation. Symptoms can include dizziness, sensory disturbances ("brain zaps"), nausea, vomiting, anxiety, and insomnia, requiring an extremely slow, medically supervised taper over many weeks or months.

• Suicidality and Worsening of Depression (Boxed Warning): Antidepressants, including Paxil, carry a strong risk warning for increasing the risk of suicidal thoughts and behaviour, particularly in young adults (under 25), especially during the initial phase of treatment or following a dose change.

Paxil Precautions

Before taking Paxil, it is essential to have a thorough discussion with a healthcare provider about your medical history and any other medications you are taking. Paxil is absolutely contraindicated for use with Monoamine Oxidase Inhibitors (MAOIs) due to the severe risk of Serotonin Syndrome. It is also contraindicated with the antipsychotics thioridazine and pimozide due to the risk of serious cardiac arrhythmias. Due to the high risk of fetal cardiac malformations (atrial and ventricular septal defects), the use of Paxil during pregnancy, especially the first trimester, should be strongly avoided and must be discussed with a specialist. Caution is required in patients with unmanaged narrow-angle glaucoma or a history of urinary retention due to the drug’s anticholinergic properties. Patients with a history of seizure disorder or mania/hypomania must be monitored carefully. Like other SSRIs, paroxetine can impair platelet aggregation. It should be used with caution in patients with a history of bleeding disorders or those concurrently taking anticoagulants (e.g., warfarin) or NSAIDs. The dosage must be reduced in patients with kidney or liver impairment. Finally, treatment should never be stopped abruptly; the dose must be tapered extremely slowly under medical supervision over several weeks or months to avoid the severe discontinuation syndrome.

Do I need a prescription to order Paxil?

Yes, a prescription is required from your physician to order Paxil.