Home Drug Guide Venlafaxine Besylate

Drug Guide

Generic Name

Venlafaxine Besylate

Brand Names Effexor, Effexor XR

Classification

Therapeutic: Antidepressant, Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)

Pharmacological: Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)

FDA Approved Indications

Major depressive disorder (MDD)
Generalized anxiety disorder (GAD)
Social anxiety disorder (SAD)
Panic disorder

Mechanism of Action

Venlafaxine inhibits the reuptake of serotonin and norepinephrine in the central nervous system, increasing the levels of these neurotransmitters in synaptic clefts.

Dosage and Administration

Adult: Initial dose typically 75 mg/day, divided into 2 or 3 doses; may be increased based on response and tolerability, up to 225 mg/day. Extended-release: starting at 37.5 mg once daily, titrated as needed.

Pediatric: Not approved for pediatric use.

Geriatric: Initial dose usually lower, caution due to potential increased side effects.

Renal Impairment: Use with caution; dose adjustments may be necessary based on severity.

Hepatic Impairment: Use with caution; reduced doses recommended.

Pharmacokinetics

Absorption: Well absorbed orally, food does not significantly affect absorption.

Distribution: Widely distributed, protein binding approximately 27%.

Metabolism: Metabolized primarily by the liver to active and inactive metabolites.

Excretion: Excreted mainly in urine; inactive metabolites.

Half Life: Approximately 5 hours for venlafaxine, 11 hours for its active metabolite.

Contraindications

Hypersensitivity to venlafaxine or its components.
Use with monoamine oxidase inhibitors (MAOIs).

Precautions

History of hypertension, bleeding abnormalities, seizures, bipolar disorder, mania, or recent alcohol use. Caution in elderly, hepatic/renal impairment, and pregnancy/lactation.

Adverse Reactions - Common

Nausea (Frequent)
Dizziness (Frequent)
Insomnia (Frequent)
Sweating (Frequent)
Headache (Frequent)

Adverse Reactions - Serious

Hypertension (Less common)
Withdrawal syndrome upon discontinuation (Less common)
Suicidal thoughts or behavior, especially in young adults (Serious)
Serotonin syndrome (Serious)
Elevated blood pressure (Less common)

Drug-Drug Interactions

SSRIs, SNRIs, MAOIs, triptans, tramadol, lithium, other serotonergic drugs (risk of serotonin syndrome).

Drug-Food Interactions

Alcohol (may increase risk of side effects).

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor blood pressure, mental status, mood changes, and suicidal ideation. Assess for serotonin syndrome symptoms.

Diagnoses:

Risk for violence, self-harm or injury.
Risk for cardiovascular issues (hypertension).

Implementation: Administer with food to minimize GI upset. Titrate slowly as tolerated.

Evaluation: Assess for therapeutic response, side effects, and adherence.

Patient/Family Teaching

Take medication exactly as prescribed.
Notify provider about any new or worsening symptoms, especially suicidal thoughts.
Avoid alcohol and hazardous activities until response is known.
Report any signs of serotonin syndrome (agitation, hallucinations, tachycardia, hyperthermia).

Special Considerations

Black Box Warnings:

Increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults.

Genetic Factors: CYP2D6 metabolism may affect drug levels.

Lab Test Interference: N/A

Overdose Management

Signs/Symptoms: Dizziness, hallucinations, seizures, tachycardia, changes in blood pressure, agitation, coma.

Treatment: Supportive care, monitoring vital signs, symptomatic treatment, activated charcoal if ingestion is recent, and possible gastric lavage. Dialysis may be ineffective due to high protein binding.

Storage and Handling

Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F).

Stability: Stable in original container.