However, Pristiq is difficult to taper properly.
Do not alternate doses of Pristiq to taper -- this will cause the levels of this medication in your brain to go up and down and is second only to cold-turkey in causing withdrawal symptoms. AND DON'T COLD-TURKEY EITHER!!!!!!!!!
PLEASE READ THIS ENTIRE TOPIC BEFORE GOING OFF PRISTIQ.
Pristiq is a relatively new drug made of Effexor's (venlafaxine) active metabolite, O-desvenlafaxine. Pristiq is to Effexor as Lexapro is to Celexa -- a tweaked and more powerful isomer molecule. In effect, Pristiq is concentrated Effexor.
It is available only by brand name in extended-release tablets of 50 mg and 100 mg; the more common dosage is 50mg.
Unlike Effexor, which is metabolized primarily by liver enzyme P450 CYP2D6, Pristiq is metabolized via conjugation and liver enzyme P450 CYP3A4. It attains peak plasma concentrations in about 7.5 hours.
I was unable to ascertain the half-life of Pristiq with its extended-release formulation. The mean half-life of desvenlafaxine, without the extended-release matrix formulation, is around 11 hours.
The official prescribing information from the FDA contains this:
Discontinuation of Treatment with Pristiq
Discontinuation symptoms have been systematically and prospectively evaluated in patients treated with Pristiq during clinical studies in Major Depressive Disorder. Abrupt discontinuation or dose reduction has been associated with the appearance of new symptoms that include dizziness, nausea, headache, irritability, insomnia, diarrhea, anxiety, fatigue, abnormal dreams, and hyperhidrosis. In general, discontinuation events occurred more frequently with longer duration of therapy.
During marketing of SNRIs (Serotonin and Norepinephrine Reuptake Inhibitors), and SSRIs (Selective Serotonin Reuptake Inhibitors), there have been spontaneous reports of adverse events occurring upon discontinuation of these drugs, particularly when abrupt, including the following: dysphoric mood, irritability, agitation, dizziness, sensory disturbances (e.g., paresthesia, such as electric shock sensations), anxiety, confusion, headache, lethargy, emotional lability, insomnia, hypomania, tinnitus, and seizures. While these events are generally self-limiting, there have been reports of serious discontinuation symptoms.
Patients should be monitored for these symptoms when discontinuing treatment with Pristiq. A gradual reduction in the dose rather than abrupt cessation is recommended whenever possible. If intolerable symptoms occur following a decrease in the dose or upon discontinuation of treatment, then resuming the previously prescribed dose may be considered. Subsequently, the physician may continue decreasing the dose, but at a more gradual rate.....
There is no way to decrease Pristiq "at a more gradual rate." The tablets come in only two dosages and, officially, they should not be cut up. See http://www.primaryps...?articleid=2464
In a phone conversation with Pfizer medical information (1-800-438-1985), I learned that the extended-release characteristic is incorporated into the tablet itself (Thank you, oaklily, for this information about the matrix formulation.)
Rather than a timed-release coating, the coating on the Pristiq tablet is only protective.
According to Pubmed on Desvenlafaxine: "....The extended-release tablet does not dissolve in the stomach after swallowing. It slowly releases the medicine as it passes through your digestive system. You may notice the tablet coating in the stool...."
There is a description of the similar matrix formulation for quetiapine XR (Seroquel XR) here http://survivinganti...dpost__p__33069
Can the desvenlafaxine tablet be cut or crushed?
Desvenlafaxine is an ER formulation for once-daily administration that is designed to release desvenlafaxine over the course of the dosing interval.3 Desvenlafaxine tablets contain 76 mg or 152 mg of desvenlafaxine in a matrix formulation that is designed to gradually release the equivalent of 50 mg or 100 mg of desvenlafaxine, respectively.3 To maintain the integrity of the ER formulation and prevent “dose dumping” (ie, rapid release of drug from an ER formulation), desvenlafaxine tablets should not be divided, crushed, chewed, or dissolved.3
3. Pristiq [package insert]. Philadelphia, PA: Wyeth Pharmaceuticals Inc; 2008.
PROTEST THIS DANGEROUS DRUG
- Phone Pfizer, Pristiq's manufacturer, to make a complaint: (800) 438-1985 in the US
Pfizer has not provided any specific information on how to taper from a dosage of 50mg extended-release Pristiq, the usual recommended daily dosage.
They may suggest alternating dosages to taper Pristiq. Don't do this -- it's like playing ping-pong with your brain.
File a complaint that there's no way to taper off Pristiq -- the range of dosages is inadequate.
- Also complain to the FDA 1-800-FDA-1088 Mon–Fri between 8:00 a.m. and 4:30 p.m. EST.
OPTIONS FOR TAPERING PRISTIQ
Since medicine knows nothing about tapering Pristiq, the following are all informal suggestions. Try any of them at your own risk. Please let us know how you do in this topic.
- Cut up Pristiq tablets
Despite the warnings not to cut it up, patients have tried cutting up Pristiq tablets to taper.
When you cut Pristiq up, it becomes desvenlafaxine, with an 11-hour half life.
From reports on the Web, results are inconsistent. It does seem to work for some but it makes others ill, possibly because of "dose dumping" (see above) when the entire dose is released at once, instead of being gradually released through the matrix formulation.
It seems to sometimes cause stomach upset, which may be reduced by taking it with food.
Conceivably, like regular Effexor, one might get around the slow-release problem by taking smaller divided doses of Pristiq, more than once a day.
You may find you need a precise way to measure your tablet fragments. See Using a digital scale to measure doses
Or, as you get down to a low dose, you may wish to switch to Effexor to more precisely control dosage decreases, see below.
- Crush Pristiq tablets, weigh powder with a digital scale
This is similar to cutting up tablets in risk -- Pristiq is a "do not crush" medication -- as it has a time-release coating.
Conceivably, dividing the dose and taking a measured amount of powder more than once a day, like regular Effexor, may make this method feasible.
Crushing the tablet and making sure the shell fragments are evenly distributed in the powder would be a more precise way of tapering than cutting up tablets.
Peer discussion of this method starts here http://survivinganti...dpost__p__27417
- Have Pristiq made into smaller dosage capsules by a compounding pharmacy
Compounding pharmacies can crush the tablets and put the powder into smaller capsules by weight.
According to my compounding pharmacy, they can put in a slow-release additive distributing absorption over 8-10 hours. This is not as long as the Pristiq time-release coating, but at least it's something. Check with your compounding pharmacy about this.
(They are looking into whether there's an additive that will extend this to roughly 20 hours, about the length of time Pristiq with its slow-release coating takes. I will update this section when I get the info.)
- Switch to Effexor or Effexor XR
Note: If you've had an adverse reaction to Effexor before, do NOT switch from Pristiq to Effexor.
"Desvenlafaxine (O-desmethylvenlafaxine) is the major active metabolite of venlafaxine."
Since the relationship is so close, switching to regular Effexor tablets, which you can cut up or make into a liquid, this may be the best way to taper off Pristiq. Because it has a mean half-life of 5 hours, you'd have to take regular Effexor twice a day.
According to FDA Prescribing Information for venlafaxine (Effexor), the usual dose of Effexor is 150mg per day.
Like Pristiq, Effexor XR is released gradually and needs to be taken only once a day.
Since 150mg Effexor and 50mg Pristiq are both "normal" dosages of their respective drugs, they may be roughly equivalent. (See discussion of Effexor and Pristiq dosage equivalency starting http://survivinganti...dpost__p__42249 )
You'd have the difficulty of tapering off Effexor or Effexor XR -- themselves notorious for withdrawal difficulties -- but at least you can do that gradually. See Tips for tapering off Effexor and Effexor XR (venlafaxine).
Advice from a psychiatric pharmacist
I have been corresponding with a professor at a prominent US university pharmacy department. Here is his best guess at how to taper Pristiq (he does not want his name published):
Then taper off fluoxetine (Prozac). See Tips for Tapering Prozac
One may want to consider the following options:
- Always taper to lowest available strength (ie – 50mg) before attempting to discontinue
- Switch to venlafaxine IR [regular Effexor immediate-release] product (a non-coated tablet which is splittable) and taper further. [See above.] Although there is no absolute dosing equivalence between the two products, a reasonable assumption might be that 50mg of desvenlafaxine is roughly equivalent to 100-150mg of venlafaxine.
- OR Switch to low-dose fluoxetine (eg – 10mg) [See below.]
The psychiatrist who writes the 1boringoldman.com blog reports success in switching one patient from Pristiq to Effexor, then tapering Effexor, here (see comments)
I had a lady who could not tolerate coming down on the dose for the reason you mentioned. So we moved to Effexor which went fine and then after two weeks, came down successfully.
Another psychiatrist said when he tried this, the switch from Pristiq to Effexor was "seamless."
- Crush Pristiq tablets and mix in liquid -- may not work
In a widely read psychopharmacology guidebook, eminent psychopharmacologist Stephen Stahl advises titration by crushing the tablets and mixing in fruit juice (or, I would assume, water, which is preferable because you can see how well the particles are distributed), see http://survivinganti...dpost__p__14799
I cannot find Stahl's source for this information. Since he's a consultant to pharmaceutical companies, he might have gotten it from Pfizer itself.
According to our member oaklily, Stahl is wrong. Making a liquid from Pristiq does not work, see http://survivinganti...dpost__p__24822
If you successfully make your own Pristiq solution, let us know, and measure your dosage with an oral syringe.
- "Bridging" with Prozac or another antidepressant
Prozac is regularly used to "bridge" off Effexor. Given that Pristiq is a cousin of Effexor and Effexor XR, it is possible that one can, similarly, use Prozac to withdraw from Pristiq.
Attributed to Joseph Glenmullen, the "bridging" technique is described by a doctor here http://www.bipolarwo...2005/ph1354.htm Another doctor explained his technique to me:
For a "normal" dose of Effexor (150mg per day or more), he would switch to 10mg Prozac with a few days of overlap. In other words, take both medications for several days and then drop the Effexor. Lower doses of Effexor require lower doses of Prozac as a "bridge."
Later, taper off Prozac. He acknowledged Prozac can have its withdrawal problems, but given Prozac's long half-life, gradual tapering should be much easier than tapering off Effexor. And, at least Prozac comes in a liquid.
(People are also reporting success with using Celexa or Lexapro as a bridge off Pristiq. Both come in liquid form for tapering.)
To do this, consult a doctor knowledgeable about this technique.
Edited by Altostrata, 29 March 2013 - 11:27 AM.