1 What is this medicine
and what is it used for?
Agomelatine is an antidepressant with a unique, novel
mechanism of action that distinguishes it from all other antidepressants. It
works in two ways: it acts as an agonist (activator) at melatonin MT1 and MT2
receptors (resynchronising circadian rhythms and improving sleep architecture),
while simultaneously acting as an antagonist (blocker) at serotonin 5-HT2C
receptors (enhancing dopamine and noradrenaline release in the prefrontal
cortex without affecting serotonin reuptake).
Because it does not inhibit serotonin reuptake, agomelatine
has a distinctive side effect profile — it does not cause the sexual
dysfunction, weight gain, or discontinuation syndrome commonly associated with
SSRIs and SNRIs.
It is indicated for: the treatment of major depressive
disorder (MDD) in adults.
2 How to take this
medicine
The starting dose is one 25 mg tablet taken once daily at
bedtime. After 2 weeks, the dose may be increased to 50 mg (two 25 mg tablets)
at bedtime if response is insufficient. Always take at bedtime — agomelatine's
melatonergic mechanism is tied to the evening circadian rhythm. Do not take in
the morning. Swallow whole with water.
|
Always take at bedtime
— this is essential for the medicine to work with your body's natural
sleep/wake cycle. Do not take with
alcohol — severe hepatotoxicity risk. Liver function tests
are MANDATORY before starting and during treatment — do not skip blood tests. |
3 Possible side effects
|
Frequency |
Side Effect |
What to Do |
|
Very Common (>10%) |
Headache |
Usually mild; take
paracetamol if needed. |
|
Very Common (>10%) |
Dizziness |
Take at bedtime; avoid
driving until stabilised. |
|
Very Common (>10%) |
Nausea |
Usually mild and
transient; improves after first 2 weeks. |
|
Very Common (>10%) |
Somnolence / fatigue |
Intended to improve
sleep quality; usually beneficial. |
|
Common (1–10%) |
Elevated liver enzymes
(hepatotoxicity) |
MANDATORY liver
function monitoring — see warning box. |
|
Common (1–10%) |
Migraine |
Report recurrent
severe headaches to your doctor. |
|
Common (1–10%) |
Anxiety, irritability |
Report mood changes;
dosage review may be needed. |
|
Common (1–10%) |
Abdominal pain /
diarrhoea / constipation |
Usually mild; ensure
good hydration. |
|
Uncommon |
Hallucinations,
agitation, mania |
Report to psychiatrist
/ doctor immediately. |
|
Rare |
Severe hepatitis,
liver failure |
Stop immediately and
seek urgent medical attention if jaundice, dark urine, or severe right-sided
abdominal pain develop. |
|
CRITICAL HEPATOTOXICITY WARNING: Agomelatine can cause
serious liver injury including hepatitis, liver failure and death. MANDATORY liver
function tests (ALT, AST, bilirubin) BEFORE starting, then at 3, 6, 12, and
24 weeks, and thereafter if clinically indicated. Do NOT prescribe to
patients with pre-existing hepatic impairment or transaminases > 3 x ULN. STOP agomelatine
immediately if ALT/AST exceeds 3 x ULN during treatment — do not wait for the
next scheduled blood test. ABSOLUTELY AVOID
alcohol during treatment — alcohol substantially increases hepatotoxicity
risk. Patients should be
counselled to report any symptoms of liver injury: dark urine, jaundice
(yellow skin/eyes), abdominal pain, fatigue, nausea. |
||
4 Contraindications
Agomelatine must not be used in: hepatic impairment
(Child-Pugh A, B, or C) or transaminases > 3 x ULN at baseline; patients
taking strong CYP1A2 inhibitors (fluvoxamine, ciprofloxacin); known
hypersensitivity to agomelatine or excipients; lactose intolerance (contains
lactose); patients under 18 (not indicated); or patients with dementia.
5 Drug interactions
• Strong CYP1A2 inhibitors
(fluvoxamine, ciprofloxacin): CONTRAINDICATED — dramatically increase
agomelatine plasma levels and hepatotoxicity risk.
• Moderate CYP1A2 inhibitors
(propranolol, grepafloxacin, enoxacin): use with caution — increased
agomelatine exposure.
• CYP1A2 inducers (rifampicin,
carbamazepine, smoking): reduce agomelatine levels — reduced efficacy.
• Alcohol: ABSOLUTELY CONTRAINDICATED —
severe additive hepatotoxicity risk.
6 Storage
Store at room temperature below 30°C. Keep in original
blister packaging. Keep out of reach of children. Do not use after expiry date.
7 Prescription
requirement
|
PRESCRIPTION-ONLY
MEDICINE (POM) — Prescribed by a psychiatrist or physician experienced in
depression management. Liver function
monitoring is mandatory at defined intervals and is a prescribing
requirement, not optional. |
8 Guidance for patients
& caregivers
Agomelatine has a very different mechanism to SSRIs and SNRIs
— rather than simply boosting serotonin, it works with your body's natural
melatonin system to restore healthy sleep-wake rhythms while also lifting mood.
For patients who have experienced sexual dysfunction, significant weight gain,
or discontinuation syndrome with SSRIs, agomelatine can be a very
well-tolerated alternative.
Liver function testing before and during treatment is not
optional — it is essential for your safety. Keep your blood test appointments.
If you develop yellow eyes or skin, dark urine, or pain in the right upper
abdomen, stop the tablet and go to your doctor immediately.
Avoid alcohol completely during treatment — even moderate
alcohol consumption significantly increases the risk of liver damage with
agomelatine.
9 Pharmacist &
prescriber notes
Agomelatine's unique mechanism results in a distinctive
clinical profile: no weight gain, no sexual dysfunction, no discontinuation
syndrome (can be stopped without tapering), and no QT prolongation —
significant advantages over SSRIs in patients where these effects are
problematic.
The mandatory LFT monitoring schedule is: before starting,
then at weeks 3, 6, 12, 24. Reinitiation after a gap also requires fresh LFT
baseline. The 25 mg dose is the starting dose; 50 mg (2 tablets) is the maximum
dose.
Hepatotoxicity risk: estimated at <1% but includes severe
outcomes; do not underestimate. Prescribers should document LFT results in
records at each monitoring point. Agomelatine is not associated with
suicidality — its safety profile in this regard appears favourable compared to
some antidepressants.
10 Frequently asked
questions
Why must I always take it at bedtime?
Agomelatine's mechanism is designed
to work with your body's evening melatonin surge to resynchronise your
sleep-wake cycle and restore healthy sleep architecture. Taking it in the
morning or at midday will significantly reduce its effectiveness.
What should I do if I miss a dose?
Take it the following bedtime as
usual. Do not double up. If you miss several doses, speak to your doctor before
restarting — a fresh liver function test may be required.
Can I drink alcohol while taking Valdoxan?
No, you must completely avoid
alcohol. The combination of agomelatine and alcohol significantly increases the
risk of serious liver damage. This is one of the most important restrictions
with this medicine.
How long before I notice improvement in my depression?
Like most antidepressants,
agomelatine takes 2–4 weeks to produce noticeable mood improvement. Sleep
quality often improves sooner — within the first 1–2 weeks — which itself can
benefit mood and energy levels.
Do I need to taper the dose when stopping?
Unlike SSRIs, agomelatine does not
require gradual tapering. It can be stopped without discontinuation syndrome.
However, always discuss stopping with your doctor rather than stopping abruptly
without advice.