What Factors Affect a Sufficient Venlafaxine Dose?

Venlafaxine is a member of the serotonin-norepinephrine reuptake inhibiting class of drugs that largely supplanted the selective serotonin reuptake medications after their development. The nausea, drowsiness, dry mouth, dizziness, insomnia, constipation, agitation, nervousness, orgasmic abnormality, increased sweating, anorexia, impotence, vomiting, anxiety, visual disturbance, tremors, chills, and chronic sexual debility that may accompany use of the medication occur with increased intensity and frequency as the venlafaxine dose increases. Factors that should be considered when determining the lowest possible venlafaxine dose effective for treatment are the patient's condition, drug regimen, liver and kidney health, and the form of the medication to be administered.

In treating major depressive disorder, an initial oral venlafaxine dose of 37.5 mg can be given twice a day to adult patients when using the immediate release form of the drug. Alternatively, 25 mg can be given three times daily. After the first month of treatment, the dosage may be increased in 75 mg increments every four or more days if required, up to a maximum daily dose of 375 mg. The makers of the extended release form of the drug recommend that adults be given a single 75 mg venlafaxine dose per day initially, with each subsequent 75 mg increase in dose evaluated every four or more days after the previous increase.

When using the drug as a treatment for generalized anxiety disorder, the extended release form is preferred. Initially, a 75 mg venlafaxine dose should be used in adult patients, with increases in dosage explored after the first four weeks of treatment. The dosage should be increased in 75 mg increments no more than every four days, up to a maximum daily dose of 225 mg given in divided doses.

The treatment of panic disorder with the medication is similar to that of depression. An initial immediate release venlafaxine dose of 37.5 mg should be tried, with 75 mg increases considered in four day periods after the first month of treatment. Doses greater than 225 mg per day, however, have not been found to be more effective in the treatment of panic disorders.

Regardless of the condition to be treated, patients suffering from diminished function of the liver or kidneys should be given a lower dosage than that recommended for a standard adult patient. Patients with lowered liver function should be given a venlafaxine dose at least 50 percent less than the standard initial dose, as should patients with dramatically reduced kidney function, defined as having CrCl levels less than 10 ml/min. Patients with CrCl levels between 10 and 70 ml/min can be given 25 to 50 percent of the recommended dose.

Sometimes sold under the brand names Effexor® or Efexor®, venlafaxine was first approved for use in the treatment of major depressive disorder and generalized anxiety disorder by the United State Food and Drug Administration in 1993, and is used off-label for other psychiatric conditions like social phobia, panic disorder, post-traumatic stress disorder, compulsive eating, and obsessive compulsive disorder. It has also been used off-label as a preventative treatment for migraine headaches as well as to treat diabetic neuropathy, cataplexy in patients with narcolepsy, orthostatic intolerance, postural orthostatic tachycardia syndrome, and to reduce the severity of menopausal hot flashes.