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Effexor (Venlafaxine) Information

Effexor (venlafaxine) is a prescription medication belonging to the class of Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs). It is widely used to treat various psychiatric conditions, including Major Depressive Disorder (MDD), Generalized Anxiety Disorder (GAD), Social Anxiety Disorder (SAD), and Panic Disorder. Venlafaxine works by altering the balance of key neurotransmitters in the brain, resulting in improvements in mood, anxiety levels, and overall functioning. It is available in both immediate-release (IR) and extended-release (XR) formulations, with the XR capsule being the preferred form due to better patient tolerability and convenient once-daily dosing. Consistent daily use is essential for this medication, as its full therapeutic effects for both mood and anxiety may take several weeks to become noticeable.

The mechanism of action for venlafaxine is characterized by its dual inhibition of serotonin (5-HT) and norepinephrine (NE) reuptake. At low doses (below 150 mg/day), venlafaxine acts primarily as a Selective Serotonin Reuptake Inhibitor (SSRI). However, at moderate to higher doses, the inhibition of norepinephrine reuptake becomes significant, thereby classifying it as an SNRI. This dose-dependent, dual-action mechanism is believed to be responsible for its broad spectrum of efficacy across different psychiatric conditions. Venlafaxine is metabolized in the liver to its major active metabolite, O-desmethylvenlafaxine (desvenlafaxine), which is also an SNRI.

Effexor is available in Canada as a prescription-only medication. The dose is highly individualized, starting low and gradually increasing over several weeks to find the optimal balance between efficacy and tolerability. The usual starting dose for the XR formulation is 75 mg once daily, which may be increased up to a maximum of 225 mg or 375 mg daily, depending on the specific indication. It is approved for use in adults 18 years of age and older.

Effexor Side Effects

While Effexor is generally effective, it is associated with a high incidence of side effects, particularly during the initial phase of dose titration. The most common adverse effects reported are often mild and include nausea (which is very common but usually transient, especially with the XR formulation), dry mouth, headache, insomnia, dizziness, increased sweating, and constipation. Sexual dysfunction is also a widespread side effect, including ejaculatory delay or anorgasmia.

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, gastrointestinal hemorrhage) due to the drug's potential to impair platelet aggregation, mainly when used concurrently with antiplatelet agents or anticoagulants.

• Angle-Closure Glaucoma: Venlafaxine can cause pupillary dilation (mydriasis), which may trigger an acute episode of angle-closure glaucoma in susceptible patients with anatomically narrow angles.

• Serotonin Syndrome: A potentially life-threatening reaction that results from an excessive amount of serotonin, typically when Effexor 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: Venlafaxine is notorious for causing severe and rapid withdrawal symptoms upon abrupt cessation or rapid dose reduction. Symptoms may include dizziness, electric-shock-like sensations ("brain zaps"), nausea, headache, anxiety, and insomnia, necessitating an extremely slow, medically supervised taper. • Sustained Hypertension and Cardiovascular Effects: Venlafaxine, particularly at higher doses, can cause a persistent, dose-dependent increase in blood pressure and/or heart rate. This requires regular monitoring and may necessitate discontinuation of the drug if the blood pressure increase is sustained or unmanageable.

• Suicidality and Worsening of Depression (Boxed Warning): Antidepressants, including Effexor, 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.

Effexor Precautions

Before taking Effexor, it is essential to have a thorough discussion with a healthcare provider about your medical history and any other medications you are taking. Effexor is absolutely contraindicated for use with Monoamine Oxidase Inhibitors (MAOIs) due to the severe, potentially fatal risk of Serotonin Syndrome and is also contraindicated in patients with unmanaged narrow-angle glaucoma. Due to the high risk of sustained hypertension, blood pressure must be monitored regularly before and during therapy, especially during dose increases. The drug should be used with caution in patients with a history of heart disease, uncontrolled high blood pressure, or a recent myocardial infarction. Patients with pre-existing kidney or liver impairment may require a lower dose, as venlafaxine clearance is reduced in these conditions. Caution is also needed in individuals with a history of seizure disorder or mania/hypomania. Like other SNRIs, venlafaxine 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, especially if pregnant or breastfeeding; the risks and benefits must be carefully weighed with a doctor. Finally, treatment should never be stopped abruptly; the dose must be tapered slowly under medical supervision over several weeks to months to avoid the severe discontinuation syndrome.

Do I need a prescription to order Effexor?

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