Switching or bridging with another drug, usually of a longer half-life, is a recognized way to get off antidepressants, particularly those that people find difficult to taper.
Many people with failed tapers from venlafaxine (Effexor), desvenlafaxine (Pristiq), paroxetine (Paxil), and duloxetine (Cymbalta) find they need to bridge in order to go off the drug.
Fluoxetine (Prozac) has the longest half-life of any of the modern antidepressants. Because it takes about a week for a dose to be metabolized completely, if a switch to fluoxetine is successful -- that is, does not cause withdrawal symptoms from the original drug -- a careful taper off fluoxetine is easier for most people -- see information about Tapering off Prozac. And, at least fluoxetine comes in a liquid.
(Citalopram or Celexa and its sibling escilatopram or Lexapro have half-lives of about 35 hours, a relatively long half-life among SSRIs, and are other candidates for a bridging strategy. They also come in a liquid form. The drawbacks and advantages of switching to another drug to get off the first drug, described below, apply to a switch to citalopram or escilatopram as well as fluoxetine.)
While going off fluoxetine usually has less risk, one might still develop withdrawal symptoms going off fluoxetine. No bridging strategy is risk-free.
You must find a knowledgeable doctor to help you to with a bridging strategy. You might wish to print this post out to discuss it with your doctor.
When to switch or bridge
A direct taper from the drug to which your nervous system is accustomed carries less risk than a switch to a new drug. You may have a bad reaction to a new drug, or the substitution may not work to forestall withdrawal symptoms. This is the "the devil you know is better than the devil you don't know" rule.
The risk of a switch is justified if you find a taper from the original drug is simply too difficult. Usually people will do a switch when they find reducing the original antidepressant by even a small amount -- 10% or even 5% -- causes intolerable withdrawal symptoms. (I have heard doctors say they don't even try tapering off Effexor and Paxil, they do the Prozac switch from the beginning.)
Sometimes when people go down to a low dose of an antidepressant (such as paroxetine), they find further reduction is very difficult. Substituting a longer-acting SSRI such as fluoxetine may be worth the risk.
If you're thinking of switching simply as a matter of convenience, you need to weigh the risks against the amount of convenience you would gain. Generally, switching for convenience is a bad idea.
Risks of bridging
For most people the switch goes smoothly but for some it doesn't. A bridging strategy has the following drawbacks for a minority of those who try it:
- Adverse reaction to the bridge drug, such as Prozac.
- Dropping the first antidepressant in the switch causes withdrawal symptoms even though you're taking a bridge drug.
- If withdrawal symptoms are already underway, switching to a bridge drug doesn't help
- Difficulty tapering off the bridge drug. All of the bridge drugs can be difficult to taper themselves.
So, like anything else, the Prozac switch is not guaranteed to work. But if you are having intolerable withdrawal from another antidepressant, it may be worth risking the worst case in the Prozac switch: It doesn't help and you have withdrawal syndrome anyway.
CAUTION: A switch to a bridge drug is not guaranteed to work. It's safer to slow down a taper than count on a switch. A switch really should be used only when a taper becomes unbearable or there are other serious adverse effects from the medication. You must work with a doctor who is familiar with bridging, in case you develop severe symptoms.
Below is information I've gathered from doctors about exactly how to do the Prozac switch.
Healy 2009 method for the Prozac switch
From Healy 2009 Halting SSRIs withdrawal guidelines:
- 1A Convert the dose of SSRI you are on to an equivalent dose of Prozac liquid. Seroxat/Paxil 20mg, Effexor 75mg, Cipramil/Celexa 20mgs, Lustral/Zoloft 50mgs are equivalent to 20mg of Prozac liquid. Or 40 mg of Paxil/Seroxat to 40 mg Prozac. The rationale for this is that Prozac has a very long half-life, which helps to minimise withdrawal problems. The liquid form permits the dose to be reduced more slowly than can be done with pills.
- Some people may become agitated on switching from Paxil/Seroxat to fluoxetine in which cases one option is take a short course of diazepam until this settles down. Whether this agitation is caused by fluoxetine or because for some people the substitution simply cannot be made may be difficult to determine. If the agitation gets better when the dose of fluoxetine is reduced then its more likely to be caused by fluoxetine, if it gets worse, then it is more likely to be linked to withdrawal.
- 1B A further option is to convert to a liquid form of whatever drug you are on. Many people cannot change easily from paroxetine tablets to fluoxetine and switching to paroxetine liquid may do the trick instead.
- 1C Yet another option is to change from paroxetine to a mixture of half the previous dose in the form of paroxetine and the other half in the form of fluoxetine, and then to reduce the dose of paroxetine gradually.
Phelps-Kelly 2010 method for Prozac switch
From Clinicians share information about slow tapering (2010)
For any anti-depressant you can add in 20 mg of Prozac, get them off the anti-depressant, then taper the Prozac.
Jim Phelps, one of the authors of the above, posted in 2005 in some detail about the so-called "Prozac bridging" strategy. He said it is described in Joseph Glenmullen's book, Prozac Backlash, maybe in the chapter titled of "Held Hostage."
The technique Dr. Phelps described in this post skips doses and finishes with alternating dosages, which we do not recommend for people who are sensitive to withdrawal symptoms. Given that Prozac liquid is available, this is completely unnecessary.
Foster 2012 method for Prozac switch
Dr. Mark Foster, a GP whose mission is to get people safely off psychiatric drugs includes this in a presentation he gives to doctors. http://www.gobhi.org...[autosaved].ppt.
Special Situations: The Prozac Switch
- For patients that have a hard time withdrawing from other SSRIs (such as Effexor or Paxil), switching to Prozac can be effective bridging.
- Prozac has the longest half-life and therefore the most gradual withdrawal effects.
- Start the patient on a low dose of Prozac when severe withdrawal symptoms occur.
- Wait two to four weeks, and then resume the prior tapering schedule.
- Once the first SSRI has been stopped, then taper the low dose of Prozac over another 4-8 weeks.
His method involves overlapping Prozac with the other antidepressant.
Note on above: If you have tapered to a lower dose of Seroxat/Paxil, Effexor, Cipramil/Celexa, Lustral/Zoloft, etc., a lower dose of Prozac may be more tolerable. If you are about half-way down, you might want to try 10mg Prozac. If you have decreased further, you may wish to try 5mg Prozac. More is not better for nervous systems sensitized by withdrawal.
Prey 2012 method for Prozac switch
Another knowledgeable doctor (whom I trust) explained his technique to me (this is the technique I personally would prefer if I had to do it, it seems much gentler):
- For a "normal" dose of Effexor (150mg per day or more) or Paxil (20mg) or Cymbalta (20mg), he would switch to 10mg Prozac with a week of overlap. In other words, take both medications for a week and then drop the Effexor. Lower doses of Effexor or other antidepressant require lower doses of Prozac as a "bridge."
- The lower dose of Prozac reduces the risk of excessive serotoninergic stimulation from the combination of the two antidepressants during the overlap period.
- Do not stay on the combination of the first antidepressant and Prozac for more than 2 weeks, or you run the risk of your nervous system accommodating to the combination and having difficulty tapering off both antidepressants.
- 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.
WARNING Serotonergic effects of an SSRI such as Prozac, Celexa, or Lexapro are ADDED when you are taking an SNRI such as desvenlafaxine (Pristiq), duloxetine (Cymbalta), venlafaxine (Effexor), venlafaxine XR (Effexor XR), milnacipran (Savella), and levomilnacipran (Fetzima). You run the risk of serotonergic toxicity if you are taking an SNRI, particularly at a high dose, with an SSRI. This is why doctors familiar with the Prozac switch will add in a LOW DOSE of Prozac to an SNRI.
In addition, escilatopram (Lexapro) is several times stronger, milligram for milligram, than the other SSRIs. If you add 10mg Lexapro to, for example, the high dose of 60mg Cymbalta, you will run the risk of serotonergic toxicity -- 10mg Lexapro is equal to approximately 30mg Prozac.
Edited by Altostrata, 15 July 2016 - 10:45 AM.