More threads by David Baxter PhD

David Baxter PhD

Late Founder
SSRIs Begin Working as Early as the First Week: Study
By Megan Rauscher

NEW YORK (Reuters Health) Nov 24 - People with depression who take selective serotonin reuptake inhibitors (SSRIs) may start to feel a lessening of symptoms by the end of the first week of treatment, with further improvements developing over the following weeks, according to a report in the November issue of Archives of General Psychiatry.

These findings are derived from pooled estimates of the anti-depressant treatment effect of SSRI therapy for weeks 1 through 6 derived from 28 randomized placebo-controlled trials involving 5872 patients.

"Treatment with SSRIs rather than placebo was associated with clinical improvement by the end of the first week of use," report Dr. Matthew J. Taylor from University of Oxford, Warneford Hospital, Oxford, England and colleagues in the November Archives of Psychiatry.

Data analysis showed increased odds of achieving a 50% reduction in Hamilton Depression Rating Scale scores by 1 week (relative risk, 1.64) with SSRI treatment compared with placebo.

"Because we used data from studies that had not re-assessed participants earlier (we can't) be sure at exactly what point in that first week they started to work," Dr. Taylor noted in comments to Reuters Health.

"As a clinician, this work will help my patients and I make better informed decisions about treatment," the clinician said. "Previously," he continued, "if a patient had started taking an SSRI and described feeling better after only a week of treatment, we might have thought that response was too quick, and perhaps they would have improved even without the medication."

"Now we will know that the treatment may have played a role, and that should help us make better informed decisions about important questions like stopping medications," Dr. Taylor said.

Clearly, an early response to an SSRI is not necessarily a placebo response, the authors conclude in their report.

Arch Gen Psychiatry 2006;63:1217-1223.


Re: SSRIs Begin Working as Early as the First Week: Study

(SSRIs) may start to feel a lessening of symptoms by the end of the first week of treatment,

Do we know if the data in this study showed variation in onset of action among SSRI's with differnt biologic half lives?

It is my understanding that SSRI's with a long biologic half lfe, such as Prozac, reach steady state blood levels much later than short half life SSRI's such as Paxil.

The importance of knowing if such a variation exists would be important for the clinician to understand the timing of when dosages should to be altered if the patient is experiencing adverse effects or has not achieved the full therapeutic effect.

If the dosage is increased with a long half life drug before steady state is achieved, the effective dose would be higher that anticipated.

Pharmacokinetics, which isthe understanding of how a medication is absorbed, distributed and excreted by the body is generally within the domain of specialists, in the mental health field these would be Psychiatrists and Psycho-Pharmacologists.

David Baxter PhD

Late Founder
Re: SSRIs Begin Working as Early as the First Week: Study

I don't know of any studies examining that issue but based on clinical experience with Prozac I don't think it takes any longer to evidence its effectiveness in patients.
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