Pristiq: New antidepressant medication approved

[David Baxter]

Pristiq: New antidepressant medication approved
By Gabrielle J. Melin, M.D, Mayo Clinic
January 27, 2009

As I talked about last week, it takes quite a while for a new medication to be approved by the Food and Drug Administration (FDA). Additionally, medications can be granted additional indications (diseases the medication is approved to treat) over time. For instance, Rogaine was first developed for treating high blood pressure. The side effect of hair growth led to the additional indication of treatment for hair loss.

Pristiq (desvenlafaxine) was approved by the FDA in February of 2008 for the treatment of major depressive disorder in adults. Pristiq is not available in generic at this time and will not be for some time.

Pristiq works by preventing the reuptake of the serotonin and norepinephrine in the brain. We know that certain neurotransmitters such as norepinephrine, serotonin and dopamine are not in proper balance when a person is depressed. We don't routinely check neurotransmitter levels because we don't completely know what the levels mean. Someday checking these levels may be part of a depression screening.

Like many antidepressants, Pristiq can have side effects, which may include:

• Nausea
• Dizziness
• Trouble sleeping
• Hyperhidrosis (increased sweating)
• Constipation
• Fatigue
• Decreased appetite
• Anxiety
• Sexual dysfunction in men

If you've been diagnosed with depression, Pristiq might be a good option if other medications haven't worked well. And, if you've taken Pristiq, please share your experiences.

[NicNak]

Is this a different class of anti Depressants different than an SSRI , like Prozac or a SNRI like Effexor

[David Baxter]

From the name (desvenlafaxine) and description I'd say it's similar to Effexor (venlafaxine).

Just like Celexa (Citalopram) and Cipralex/Lexapro (Escitalopram) are very similar chemically and in their mode of action.

[Charity]

Interesting to hear, but I'd better not try it! Celexa and Lexapro both work very well for me, and do indeed feel very similar... Effexor made me sick as a dog, so I don't think I want to try its "cousin!"

[TSOW]

Pristiq was (desvenlafaxine) developed by Wyeth, the manufacturer of Effexor (venlafaxine).

Wyeth is expected to be acquired by Pfizer later in 2009, in a major pharmaceutical development announced this past week.

It looks like their researchers took the major metabolite of venlafaxine, which is O-desvenlafaxine (ODV) and transformed it into the active compound.

Doing so enabled the effective dose to be standardized at 50 mg. per day, with no titration required except in cases of renal or hepatic deficiency. Their studies indicate a discontinuation rate equal to placebo, suggesting this medication is well tolerated. O-desvenlafaxine appears to have low potential drug interactions due to the way in which it is metabolized.

The half life of ODV is 11 hours, moderately short, so discontinuation should be tapered under a physician's direction. The advantage is that steady state is reached fairly quickly, in a matter of a few days after initiating therapy.

According to the manufacturer's studies, improvements were reported in about eight weeks.

Like Effexor, the most frequent adverse effect when starting therapy was reported as being nausea (16%) but dropped off significantly after the first week as the body became acclimated to the new brain chemistry. Only 1% of patients discontinued treatment due to the nausea.

Your physician should be receiving information about this new treatment option in the days and weeks to come.

It is unclear at this time if ODV is being marketed in Canada or in other Countries.

Attached is the U.S. product monograph for Pristiq (desvenlafaxine). The product monograph is the official prescribing information submitted by the manufacturer to the FDA. This monograph should not be used for prescribing information for Countries other than the U.S.