The Corpus Callosum

i-533541a12d5fe7ca61b84d1010e77d44-220px-Agomelatine.svg.png href="http://en.wikipedia.org/wiki/Agomelatine" rel="tag">Agomelatine
is a new chemical entity that is nearing approval for treatment of
depression.  It was developed by href="http://www.servier.co.uk/aboutus/history.asp" rel="tag">Servier
Laboratories; they have entered into an agreement with href="http://www.novartis.com/" rel="tag">Novartis
for commercialization of the product ( href="http://www.medicalnewstoday.com/articles/85521.php"
rel="tag">Valdoxan®).

This represents a new approach to the pharmaceutical treatment of
depression.  The putative mechanism of action is that it
stimulates
receptors, and blocks a subtype of href="http://en.wikipedia.org/wiki/Serotonin" rel="tag">serotonin
receptor.  Specifically, it has agonist properties at the MT1
and MT2 receptors, and antagonist properties at the 5HT-2c receptors
(5HT is shorthand for 5-hydroxytryptamine, another name for serotonin).

The melatonin receptor action is not new: the href="http://www.takeda.com/index.html" rel="tag">Takeda
product, rel="tag">ramelteon ( href="http://www.rozerem.com/" rel="tag">Rozerem®)
also is an agonist at the MT1 and MT2 receptors.  It is
marketed as a nonaddictive sleep aid.  

Likewise, the antagonist activity at the 5HT-2c receptor is not new.
 Many other antidepressants do that as well, such as

and rel="tag">mirtazapine.  Note that this
action does not
modulate the activity of serotonin.  Rather, it href="http://jpet.aspetjournals.org/cgi/content/full/306/3/954">indirectly
increases
the activity of frontocortical dopaminergic and adrenergic pathways.
 

What is new is that agomelatine is the first drug to have this
particular combination of receptor activities.  


The action at the melatonin receptors should result in
improved sleep,
without causing somnolence during the daytime.  What is does,
is href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T0N-475J6C7-1JG&_user=10&_coverDate=09%2F30%2F1993&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6e0183c0979c82483e908bca5a997c26">advance
the sleep phase, much like melatonin does.  Because
agomelatine does not inhibit reuptake of serotonin, it should href="http://www.pslgroup.com/dg/254e06.htm">not cause
sexual dysfunction,
nausea, or agitation.  In fact, the antagonist activity at the
5HT-2c receptor might prevent the sexual dysfunction caused by SSRIs,
if used in combination.  One study indicated a href="http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=15289700&ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum">lack
of discontinuation (withdrawal) syndrome.

Premarketing human and animal studies ( href="http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&dopt=AbstractPlus&list_uids=16436938">1
href="http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=16377959&ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum">2
3
href="http://www.future-drugs.com/doi/abs/10.1586/14737175.6.11.1595">4
5)
indicate that agomelatine should be beneficial for treatment of
depression, and that it should alleviate some anxiety symptoms.
 

Sharp-eyed readers will be wondering about the effect on weight.
 Blockade of the 5HT-2c receptor has been href="http://jop.sagepub.com/cgi/content/abstract/20/4_suppl/15">implicated
in weight gain associated with some atypical
antipsychotics.  However, I was not able to find any
indication that agomelatine will share this problem.

I must say I will be glad to see this product on the market.
 However, as with any new product, I would use it sparingly in
the first six months after it reaches the pharmacy shelves.
 During that period, I would use it for persons who have
demonstrated a lack of response to multiple adequate trials of other
antidepressants.

The reason to be cautious, is that it is common for drugs to be
released with great fanfare, often with unrealistic expectations about
lack of particular adverse effects.  The thing is, you never
really know about the incidence of adverse effects until the drug has
been given to tens of thousands, if not millions, of persons.  

Once the drug has been on the market for a while, say about a year, it
might be worth trying it for off-label things, such as anxiety.
 I suspect it may find a role in treatment of insomnia even in
the absence of a mood disorder.

One thing everyone will be watching for is the possibility that
agomelatine, like other antidepressants, could provoke a polarity
switch.  I don’t have a specific reason to worry about this,
but since nobody understands why it happens, it is impossible to
anticipate the risk based upon the pharmacology of the drug.
 Premarketing studies generally are done in carefully selected
patients, so they do not tell you what will happen in a broader
population.

Comments

  1. #1 Dirkh
    November 26, 2007

    Wouldn’t it be great if more prescribing physicians would bestir themselves to provide this sort of information to the public on new medications? Thanks, Corpus.

    One thought: Why is it that Agomelatine won’t cause daytime sleepiness?

  2. #2 laura
    November 26, 2007

    what do you mean by a “polarity switch”?

    *goes off to read some*

  3. #3 Joseph j7uy5
    November 26, 2007

    Polarity switch refers to switching from depression to mania or hypomania, or back the other way.

    Melatonin is not directly sedating. What it does is change your biological clock so that your brain thinks it is time to go to sleep. If you want to stay awake, of if something demands your attention, you will stay awake.

    It is important to keep in mind, however, that everyone is different. Unexpected things do happen. The pharmacology of the drug does not always tell us ahead of time what will happen to any individual when they take a drug.

  4. #4 Dirkh
    December 1, 2007

    Here’s an intriguing abstract on melatonin’s effect on nighttime memory formation:

    Science 16 November 2007:

    Reports
    Melatonin Suppresses Nighttime Memory Formation in Zebrafish

    Oliver Rawashdeh, Nancy Hernandez de Borsetti, Gregg Roman,* Gregory M. Cahill

    Memory processes are modulated by the biological clock, although the mechanisms are unknown. Here, we report that in the diurnal zebrafish both learning and memory formation of an operant conditioning paradigm occur better during the day than during the night. Melatonin treatment during the day mimics the nighttime suppression of memory formation. Training in constant light improves nighttime memory formation while reducing endogenous melatonin concentrations. Treatment with melatonin receptor antagonists at night dramatically improves memory. Pinealectomy also significantly improves nighttime memory formation. We adduce that melatonin is both sufficient and necessary for poor memory formation during the night.

  5. #5 oyunlar
    March 7, 2008

    Hi,
    Thanks for this good article.

  6. #6 youtube
    March 28, 2008

    Wouldn’t it be great if more prescribing physicians would bestir themselves to provide this sort of information to the public on new medications? Thanks, Corpus.

  7. #7 araba kiralama
    April 1, 2008

    This is an important concern, one that deserves some consideration

  8. #8 Rize
    April 14, 2008

    Treatment with melatonin receptor antagonists at night dramatically improves memory. Pinealectomy also significantly improves nighttime memory formation. We adduce that melatonin is both sufficient and necessary for poor memory formation during the night.

  9. #9 zucchini189
    May 13, 2008

    I was in an 8-week double-blind trial for agomelatine in Feb-Mar 07, then had a full year on 50 mg of this wonder drug. Far better than any SSRI I’ve taken with no side effrects of any kind, agomelatine gave me my sweetest year of vitality and health in the last decade.
    But, of course, the trial ended, and I’ve now been off it for 5 weeks, and am beginning to feel myself slip back into depression. My sleep—perfect, refreshing 8 hours per night for a full year–is once again erratic and interrupted.
    Any idea when this golden drop of sweetness will be approved for the market?

  10. #10 Karadeniz
    June 20, 2008

    Treatment with melatonin receptor antagonists at night dramatically improves memory. Pinealectomy also significantly improves nighttime memory formation. We adduce that melatonin is both sufficient and necessary for poor memory formation during the night.

  11. #11 oyunzamani
    May 28, 2009

    The melatonin receptor action is not new: the Takeda product, ramelteon (Rozerem®) also is an agonist at the MT1 and MT2 receptors. It is marketed as a nonaddictive sleep aid. :)

  12. #12 Kath
    February 5, 2011

    A little confusing – does this drug result in weight loss? How would it go when combined with lexapro and respirdal? I have previously had a problem with occulogyric crisis (particularly in response to aropax) – will the drug cause this?

  13. #13 Joseph j7uy5
    February 5, 2011

    Kath, studies lasting up to ten months indicate that agomelatine is weight-neutral, causing neither weight gain nor weight loss. There is no reason to think that it could cause oculogyric crisis. As for interactions, here is the available information:
    (;TLDR no interaction with Lexapro or Risperdal)

    Potential interactions affecting agomelatine:
    Agomelatine is metabolised mainly by cytochrome P450 1A2 (CYP1A2) (90%) and by CYP2C9/19 (10%). Medicinal products that interact with these isoenzymes may decrease or increase the bioavailability of agomelatine.
    Fluvoxamine, a potent CYP1A2 and moderate CYP2C9 inhibitor markedly inhibits the metabolism of agomelatine resulting in a 60-fold (range 12-412) increase of agomelatine exposure.
    Consequently, co-administration of Valdoxan with potent CYP1A2 inhibitors (e.g. fluvoxamine, ciprofloxacin) is contraindicated.
    Combination of agomelatine with oestrogens (moderate CYP1A2 inhibitors) results in a several fold increased exposure of agomelatine. While there was no specific safety signal in the 800 patients treated in combination with oestrogens, caution should be exercised when prescribing agomelatine with other moderate CYP1A2 inhibitors (e.g. propranolol, grepafloxacine, enoxacine) until more experience has been gained (see section 4.4).

    Potential for agomelatine to affect other medicinal products:
    In vivo, agomelatine does not induce CYP450 isoenzymes. Agomelatine inhibits neither CYP1A2 in vivo nor the other CYP450 in vitro. Therefore, agomelatine will not modify exposure to medicinal products metabolised by CYP 450.

    Medicinal products highly bound to plasma protein:
    Agomelatine does not modify free concentrations of medicinal products highly bound to plasma proteins or vice versa.

  14. #14 Laptop
    August 8, 2011

    It is important to keep in mind, however, that everyone is different. Unexpected things do happen. The pharmacology of the drug does not always tell us ahead of time what will happen to any individual when they take a drug.

    sorryy

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