Agomelatine Tablets (Valdoxan): A Comprehensive Guide
Comprehensive guide to agomelatine (Valdoxan) for depression treatment, including dosage, side effects, and liver monitoring essentials.
Agomelatine, marketed as Valdoxan, is an antidepressant medication specifically indicated for the treatment of major depressive episodes in adults. Unlike traditional antidepressants, it acts as a melatonergic agonist at MT1 and MT2 receptors and a serotonin 5-HT2C receptor antagonist, helping to resynchronise circadian rhythms disrupted in depression while promoting neurotransmitter release like norepinephrine and dopamine.
About agomelatine tablets
Agomelatine addresses core symptoms of depression, including low mood, anxiety, and sleep disturbances, by mimicking melatonin’s effects on sleep-wake cycles and counteracting 5-HT2C-mediated inhibition of frontal cortex neurotransmitter release. Clinical trials demonstrate its efficacy, with significant improvements in Hamilton Depression Rating Scale (HAMD-17) scores versus placebo in six out of ten short-term studies, and relapse prevention shown in long-term trials where relapse rates were 22% for agomelatine versus 47% for placebo. It restores sleep architecture, increasing slow-wave sleep without altering REM, and does not impair daytime vigilance or memory.
Absorption is rapid with bioavailability around 80%, though low absolute due to first-pass metabolism primarily via CYP1A2 enzyme. Peak plasma levels occur 1-2 hours post-dose, with a short half-life of 1-2 hours, necessitating bedtime dosing to align with its phase-advancing properties. Women exhibit higher bioavailability, and food intake enhances it slightly.
Before taking agomelatine
Consult your doctor before starting agomelatine if you have liver or kidney impairment, as it is contraindicated in moderate to severe hepatic insufficiency due to risk of enzyme elevations. It is not recommended for those under 18, elderly over 75 (limited efficacy data), or patients with dementia, bipolar tendencies, or heavy alcohol use. Inform your doctor of all medications, especially CYP1A2 inhibitors like fluvoxamine or ciprofloxacin (contraindicated), strong CYP2C9 inhibitors like fluconazole (caution), or oestrogens (increased exposure).
- Pregnancy and breastfeeding: Limited data; use only if benefits outweigh risks. Agomelatine and metabolites pass into milk in animal studies.
- Driving and machinery: May cause dizziness, sleepiness; avoid until effects known.
- Alcohol: Avoid, as it may exacerbate side effects.
- Allergies: Report any prior reactions to agomelatine or excipients.
How to take agomelatine
The standard dose is 25 mg (one tablet) once daily at bedtime, with or without food. After two weeks, your doctor may increase to 50 mg if no improvement and liver tests are normal. Swallow whole; do not crush. If a dose is missed, take the next as scheduled—do not double up.
Treatment duration varies; continue even if feeling better to prevent relapse. Regular liver function tests (LFTs) are mandatory: before start, after 3, 6, 12, 24 weeks, then periodically. Discontinue if enzymes exceed 3x upper limit of normal (ULN) on two occasions or 10x ULN anytime.
| Dose | Timing | LFT Monitoring |
|---|---|---|
| 25 mg | Bedtime | Baseline, 3/6/12/24 weeks |
| 50 mg (if needed) | Bedtime | Every 3-6 weeks initially |
Getting the most from your treatment
Effects may build over 1-2 weeks, with full benefits in 2-4 weeks. Do not stop abruptly; taper under medical supervision to avoid withdrawal. Attend all appointments for LFT monitoring—your doctor provides a booklet on liver warning signs. Combine with therapy, exercise, and lifestyle changes for optimal results. Track mood and sleep improvements daily.
In relapse prevention, continuing agomelatine post-acute response significantly lowers recurrence risk.
Side effects of agomelatine
Most side effects are mild and transient. Common ones (>1/100) include headache, nausea, dizziness, somnolence, diarrhoea, constipation, fatigue, insomnia, back pain, abdominal pain, anxiety, increased sweating.
| Side Effect | Frequency | Notes |
|---|---|---|
| Headache, nausea, dizziness | Common | Often resolves in days |
| Liver enzyme elevation (ALT >3x ULN) | Common (1-10%) | Monitor closely; reversible on discontinuation |
| Fatigue, insomnia, anxiety | Common | May improve with time |
Serious effects (seek immediate help): Hepatocellular injury signs—jaundice, dark urine, pale stools, abdominal pain, fatigue, vomiting, itching, bruising. Rare: suicidal thoughts (especially early), mania, severe allergy.
How to manage agomelatine side effects
| Side Effect | Management Tips |
|---|---|
| Feeling sick (nausea), diarrhoea | Stick to bland foods, avoid spicy/fatty; stay hydrated. Ginger tea may help. |
| Dizziness, tiredness, sleepiness | Avoid driving/machinery/alcohol. Rise slowly from sitting. |
| Headache | Hydrate well; paracetamol if approved. Persistent? See doctor. |
| Constipation, stomach pain | Increase fibre (fruits/veg), water; gentle laxatives if needed. |
| Insomnia, anxiety, sweating, back pain | Mild/transient; discuss if persistent. Relaxation techniques aid. |
| Liver signs (dark urine, jaundice, etc.) | Stop and contact doctor urgently. |
Most resolve as body adjusts; report persistent issues.
Frequently Asked Questions (FAQs)
Q: How long does agomelatine take to work?
A: Benefits start in 1-2 weeks, full effect in 2-4 weeks. Patience is key; do not stop early.
Q: Can I drink alcohol on agomelatine?
A: No, it worsens dizziness and liver risks.
Q: What if I miss a dose?
A: Skip and take next at bedtime; no doubling.
Q: Is agomelatine safe for liver patients?
A: Contraindicated in hepatic impairment; requires strict monitoring.
Q: Does it cause weight gain?
A: No significant weight changes reported in trials.
Q: Can children or elderly take it?
A: Not for under 18; limited data in >75 years.
Interactions
- Contradindicated: Potent CYP1A2 inhibitors (fluvoxamine, ciprofloxacin).
- Caution: Oestrogens, fluconazole, propranolol—increase agomelatine levels.
- No interaction: Most antidepressants, benzodiazepines, lithium.
Who can and cannot take agomelatine tablets
- Can take: Adults 18-75 with major depression.
- Cannot take: Hepatic disease, CYP1A2 inhibitor combo, pregnancy/breastfeeding without advice.
References
- Valdoxan EPAR Product Information — European Medicines Agency. 2023-05-15. https://www.ema.europa.eu/en/documents/product-information/valdoxan-epar-product-information_en.pdf
- Agomelatine tablets (Valdoxan) — Patient.info. 2024-01-10. https://patient.info/medicine/agomelatine-tablets-valdoxan
- Agomelatine: A Novel Antidepressant — National Center for Biotechnology Information (PMC). 2011-12-01. https://pmc.ncbi.nlm.nih.gov/articles/PMC3244295/
- Agomelatine: Uses, Interactions, Mechanism of Action — DrugBank Online. 2025-06-20. https://go.drugbank.com/drugs/DB06594
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