Velafax®

Pharmachologic effect:

antidepressant

Pharmacodynamics:

The antidepressant effect of venlafaxine is due to increased neurotransmitter activity in the CNS. Preclinical studies have shown that venlafaxine and its active metabolite, O-desmethylvenlafaxine (ODV), are strong serotonin and norepinephrine reuptake inhibitors and weak dopamine reuptake inhibitors.

Pharmacokinetics:

After oral administration, venlafaxine is well absorbed and extensively metabolized in the liver. After taking a single dose, at least 92% is absorbed, the absolute bioavailability is about 45% (due to presystemic metabolism). Food intake does not significantly affect the absorption and biotransformation of venlafaxine.
Venlafaxine is excreted mainly by the kidneys: approximately 87% of the dose is excreted in the urine within 48 hours (5% unchanged, 29% as unconjugated EFA, 26% as conjugated EFA, 27% as other inactive metabolites).

Indications:

Depression, generalized anxiety disorder, social phobia, panic disorder.

Contraindications:

Hypersensitivity, concomitant use of MAO inhibitors

Use with caution:

Recent myocardial infarction and unstable angina, changes in blood pressure, increased intraocular pressure and angle-closure glaucoma, history of manic states, initially low body weight, renal / hepatic insufficiency, age under 18 years (safety and efficacy have not been established).

Pregnancy and breast-feeding:

During pregnancy, use is possible only if absolutely necessary (adequate and well-controlled studies of the safety of use in pregnant women have not been conducted).
The FDA fetal category is C.

Side effects:

The most common effects (>1%) considered to be drug-related (i.e. about 2 or more times more common with venlafaxine than with placebo) were as follows (percentage in placebo group given in parentheses): drowsiness 3 % (1%), insomnia 3% (1%), dizziness 3% (<1%), headache 3% (1%), anxiety 2% (1%), nervousness 2% (<1%), asthenia 2% (<1%); dry mouth 2% (<1%), nausea 6% (1%), ejaculation disorder 3% (<1%), sweating 2% (<1%).

Interaction:

Incompatible with MAO inhibitors.
Venlafaxine does not affect the pharmacokinetics of imipramine and its active metabolite, similarly, imipramine does not affect the pharmacokinetics of venlafaxine and its active metabolite.
There was no interaction between diazepam and its active metabolite desmethyldiazepam and venlafaxine and its metabolite (ODV).

Dosing and Administration:

Venlafaxine is taken with food. The dosage regimen is selected individually, it is desirable to prescribe the minimum effective doses. The recommended initial dose is 75 mg / day (tablets - the daily dose is divided into 2-3 doses, capsules - 1 time / day, at about the same time of day - in the morning or in the evening). For some patients, a starting dose of 37.5 mg/day (for 4-7 days) may be desirable. If necessary, it is possible to increase the dose (gradually, by 75 mg / day, 1 time in 4 days or more) up to 225 mg / day (recommended dose for moderate depression), in the hospital (for severe depression), it is possible to increase the dose to the maximum - 375 mg/day
In patients with impaired liver function from mild to moderate severity, a reduction in the daily dose by 50% is required, with cirrhosis of the liver - and more than 50%. Against the background of impaired renal function (glomerular filtration rate - 10-70 ml / min), it is necessary to reduce the dose by 25-50%, with hemodialysis - by 50%, the drug should be taken after hemodialysis. In elderly patients, special dose adjustments are not required, however, care should be taken when treating this category of patients, especially when increasing the dose.

Overdose:

Symptoms: ECG changes (prolongation of the QT interval, blockade of the bundle legs, expansion of the QRS complex, etc.), sinus and ventricular tachycardia, bradycardia, hypotension, dizziness, impaired consciousness of varying severity (from drowsiness to coma), convulsions, up to lethal outcome.
Treatment: use of activated charcoal, induction of vomiting, gastric lavage (to reduce absorption). Maintain airway patency to ensure adequate ventilation and oxygenation. Careful observation and monitoring of the heart rhythm and other vital functions, symptomatic and supportive therapy is recommended. The effectiveness of measures such as forced diuresis, dialysis, hemoperfusion and exchange transfusion is unlikely. There is no specific antidote.
In post-marketing studies, cases of overdose of venlafaxine were observed mainly with the simultaneous use of alcohol and / or other drugs.

Special instructions:
Although venlafaxine did not increase the effect of ethanol on psychomotor responses in volunteers, concomitant use of venlafaxine and alcohol should be avoided.

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