Dr. Karen L. Swartz, Director of the Johns Hopkins Mood Disorders Center, answers a reader’s question about the therapeutic benefits of Pristiq, a new antidepressant: I am currently on Effexor (venlafaxine), which has a similar generic name, so I'm wondering how Pristiq differs from Effexor and other SNRIs? Chester, VT
Dr. Swartz: Pristiq (desvenlafaxine succinate) is an antidepressant in the serotonin and norepinephrine reuptake inhibtor (SNRI) class of drugs. Pristiq is indeed very closely related to Effexor (venlafaxine hydrochloride) chemically. In fact, it is metabolic byproduct of Effexor. Pristiq, like Effexor XR, is dosed once daily.
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What is reported to be different about Pristiq is that the antidepressant medication can be started at a dose high enough to potentially be therapeutic. One of the great challenges with antidepressants is that, for almost all of them, they need to be started at low doses and slowly increased to a potentially therapeutic dose. Since it is impossible to predict which antidepressant will be effective for a given person, the time spent adjusting the dose can be very frustrating, especially if the antidepressant dose not eventually help.
For Pristiq, it is recommended to start with a dose of 50 mg daily, which is also typical maintenance dosage. This guideline is based on two things: data showing inconsistent improvement with dosage increments and the finding that patients are generally able to tolerate 50 mg daily as a starting dose.
Pristiq has been shown to be safe at higher doses, but a decision to increase dosage should be made in collaboration with the your psychiatrist and/or primary care physician.
Pristiq, Effexor, and other SNRI's such as Cymbalta have not proven markedly different in their effectiveness. (For that matter, there is not strong evidence that any particular antidepressant or class of antidepressants is superior to another for everyone.) For this reason, if someone is doing well on Effexor, it would be wise to consider staying on that medication rather than switching to another SNRI, including Pristiq.
