If you have not read my first post on agomelatine, do so now (1).
This is my usual shtick wherein I review research articles and crap all over them. The main questions I am seeking to answer through the next series of posts are:
Is agomelatine superior to SSRI anti-depressants? And,
Does it have a more tolerable side-effect profile?
Before I address those questions through the available literature, I want to bring a certain bias to everyone's attention. The bias is not mine, but rather Stuart A. Montgomery's bias.
Have you heard of the Montgomery-Asberg Depression Rating Scale (MADRS, 2)? It's that Montgomery. Here is a brief biography (3). Here is the important part: "Dr Montgomery is editor of International Clinical Psychopharmacology and editor of European Neuropsychopharmacology. He also serves on the editorial board of 18 other scientific journals." I point this out because much of the published research (including his own research) on this drug just happen to be in the two journals for which he is the editor (4, 5, 6, 7, 8, 9, 10). A siginifcant portion of these articles were published in supplement issues (i.e., pharma sponsored). He is also a "consultant" for the company (Servier) that manufactures the drug. For you lay readers, this is our much cherished "peer-review process" at work.
The Research: Part 1
The first published study demonstrating general efficacy for major depressive disorder (MDD) was in 2002 by Loo et al (10). In this study different doses of agomelatine (1, 5, and 25mg once a day) were compared to paroxetine (20mg) and placebo in people with MDD for 8 weeks.
Here are the results:
There were more patients in remission on agomelatine 25mg and on paroxetine compared to placebo. No statistical comparisons were done between the two active drugs. Here is a finding I saw quoted in almost every article I read hereafter, "25mg of agomelatine was significantly better than placebo at 2 weeks..., whereas this significant advantage for paroxetine...did not emerge until 4 weeks." I've circled the area on the graph this is in reference to:
Here are the results for severely depressed patients:
Here are the common side-effects:
Overall, both drugs were superior to placebo. Compared to severely depressed patients (i.e., HAM-D score >25), only agomelatine was superior to placebo. Patients on agomelatine 25mg responded sooner than paroxetine. Paroxetine had more side-effects when compared to agomelatine and placebo, with a significant difference for nausea. Neither drug was associated with a high incidence of sexual dysfunction.
Comment: I'm not seeing anything here that I would call a major breakthrough. The HAM-D standard deviations are pretty large (+/- 8 points or more) so there is a lot of variability in individual patient performance (common in AD clinical trials), which limits the generalizability of the study results. I wonder how both drugs would have compared to an active placebo (11). There are not too many differences in reported side-effects except for nausea. I would have expected a far worse side-effect profile for paroxetine given agomelatine's short-half life compared to paroxetine's 24hr half-life (agomelatine patients supposedly will sleep through any acute side-effects).
This study had a one-week placebo wash-out period (which they refer to as "placebo run-in"), which biases the study against placebo. The patients (including the severely depressed patients) were not actually that severely depression, "mean duration of current episode before inclusion was 4.8 months." I can't remember the last time I saw a depressed patient with an episode duration that short.
During the study, two participants committed suicide (congrats to the researchers for reporting these data!); one on paroxetine after 11 days and one on agomelatine 25mg after 10 days. There were 7 suicide attempts: 1 on agomelatine 1mg, 3 on agomelatine 5mg, 1 on agomelatine 25mg, 2 on paroxetine, and NONE on placebo (does that mean there's no risk of not treating with AD's?).
"Among these, one was an overdose with agomelatine. A patient ingested 18 capsules of 5 mg (90mg) with an unknown quantity of alcohol." This is very important: One major downfall of the tricyclic anti-depressants (TCA's) is that patients could use them to commit suicide. Doctors use to prescribe one weeks amount at a time to prevent suicides. Overdose with SSRI's is extremely difficult. A drug with hypnotic properties, when consumed with alcohol (which is commonly abused in depressed people) might suggest that this drug is contraindicated in suicidal patients; however, there was no mention of this in the article.
Part 3 coming soon.
Loo, H., Hale, A., & D'haenen, H. (2002). Determination of the dose of agomelatine, a melatoninergic agonist and selective 5-HT2C antagonist, in the treatment of major depressive disorder: a placebo-controlled dose range study International Clinical Psychopharmacology, 17 (5), 239-247 DOI: 10.1097/00004850-200209000-00004