venlafaxine, Effexor; Effexor XR

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GENERIC NAME: venlafaxine

BRAND NAME: Effexor, Effexor XR

DRUG CLASS AND MECHANISM: Venlafaxine is a selective serotonin and norepinephrine reuptake inhibitor (SNRI) used for treating depression. Other drugs in this class include milnacipran (Savella), duloxetine (Cymbalta), and desvenlafaxine (Pristiq). Venlafaxine affects neurotransmitters, the chemicals that nerves within the brain make and release in order to communicate with one another. Neurotransmitters either travel across the space between nerves, attach to receptors on the surface of nearby nerves, or they attach to receptors on the surface of the nerves that produced them, to be taken up by the nerve and released again (a process referred to as re-uptake).

Many experts believe that an imbalance among neurotransmitters is the cause of depression as well as other psychiatric disorders. Serotonin and norepinephrine are two neurotransmitters released by nerves in the brain. Venlafaxine works by preventing the reuptake of serotonin and epinephrine by nerves after they have been released. Since uptake is an important mechanism for removing released neurotransmitters and terminating their actions on adjacent nerves, the reduced uptake caused by venlafaxine increases the effect of serotonin and norepinephrine in the brain. Venlafaxine is available in an extended release formulation (Effexor XR). The FDA approved venlafaxine in December 1993.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 25, 37.5, 50, 75, and 100 mg and extended release capsules: 37.5, 75, and 150 mg.

STORAGE: Store in a dry place at 20 C  to 25 C (68 F to 77 F).

PRESCRIBED FOR: Venlafaxine is prescribed for the treatment of depression, depression with associated symptoms of anxiety, generalized anxiety disorder, and social anxiety disorder. Effexor XR is approved for the treatment of adults with panic disorder.

DOSING: Venlafaxine should be taken with food at doses specifically directed by a physician. Individual doses vary greatly among individuals. The anti-depressant effects are not maximal for 1-2 weeks. If discontinued, the dose of venlafaxine should gradually be reduced under the direction of a physician. For patients with difficulty swallowing tablets or capsules, capsules of Effexor XR can be opened and the contents sprinkled on a spoonful of applesauce but removal from the capsule allows immediate release of the drug so it is no longer an extended release drug.

The dose for treatment of depression using the immediate release formulation is 75 to 375 mg daily divided in 2 or 3 doses and given every 8 or 12 hours. The extended release dose is 37.5 mg to 225 mg once daily. Dosing is usually begun with low initial concentrations and adjusted as needed by the treating doctor.

Generalized anxiety and panic disorder are treated with 37.5 mg to 225 mg once daily using the extended release formulation. Social anxiety is treated with 75 mg daily using the extended release formulation.

DRUG INTERACTIONS: Venlafaxine should not be used in combination with a monoamine oxidase inhibitor (MAOI) such as phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), and selegiline (Eldepryl), or within 14 days of discontinuing the MAOI. At least 5 days should be allowed after stopping venlafaxine before starting an MAOI. Combinations of SNRIs and MAOIs may lead to serious, sometimes fatal, reactions including very high body temperature, muscle rigidity, rapid fluctuations of heart rate and blood pressure, extreme agitation progressing to delirium, and coma. Similar reactions may occur if venlafaxine is combined with antipsychotics, tricyclic antidepressants or other drugs that affect serotonin in the brain. Examples include tryptophan, sumatriptan (Imitrex), lithium, linezolid (Zyvox), tramadol (Ultram), and St. John's Wort.

Medically Reviewed by a Doctor on 7/7/2014



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