1. Clinical Overview
Almotriptan is a selective serotonin (5-HT1B/1D) receptor agonist, commonly known as a 'triptan', used for the acute treatment of migraine attacks with or without aura in adults. It is a second-generation triptan with a favorable tolerability profile and is considered effective for the rapid relief of migraine pain and associated symptoms like nausea, photophobia, and phonophobia. Its pharmacokinetic profile offers a balance of rapid onset and sustained duration of action.
| Onset | Duration | Bioavailability |
|---|---|---|
| Pain relief can begin within 30 minutes to 2 hours post-dose. | The therapeutic effect typically lasts for 24 hours, preventing recurrence of headache in a significant proportion of patients. | Approximately 70%. |
2. Mechanism of Action
Almotriptan exerts its therapeutic effects by binding with high affinity to serotonin 5-HT1B and 5-HT1D receptors located on intracranial blood vessels and sensory nerve terminals of the trigeminal system. This dual action causes vasoconstriction of dilated cerebral blood vessels and inhibits the release of pro-inflammatory neuropeptides (like CGRP and substance P) from perivascular trigeminal nerves.
3. Indications & Uses
- Acute treatment of migraine attacks with aura in adults
- Acute treatment of migraine attacks without aura in adults
4. Dosage & Administration
Adult Dosage: 12.5 mg taken as a single dose at the onset of migraine pain. If headache recurs, a second dose may be taken after at least 2 hours. Maximum: 25 mg in 24 hours.
Administration: Tablet should be swallowed whole with a glass of water. Can be taken with or without food. The tablet should be taken as soon as migraine symptoms begin. It is not effective if taken during the aura phase before the headache starts. Do not crush or chew.
5. Side Effects
Common side effects may include:
- Dizziness
- Somnolence (drowsiness)
- Nausea
- Dry mouth
- Paresthesia (tingling sensation)
- Fatigue
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Monoamine Oxidase-A Inhibitors (e.g., Phenelzine, Tranylcypromine, Moclobemide) | Markedly increased plasma concentration of almotriptan (up to 60%) due to inhibition of its primary metabolic pathway. Risk of serotonin syndrome and increased adverse effects. | Contraindicated |
| Other 5-HT1 Agonists (Triptans: Sumatriptan, Rizatriptan) or Ergot Derivatives (Ergotamine, Dihydroergotamine) | Increased risk of prolonged vasospastic reactions. A 24-hour interval should separate the administration of these agents. | Major |
| Selective Serotonin Reuptake Inhibitors (SSRIs e.g., Sertraline, Fluoxetine) or Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs e.g., Venlafaxine) | Potential increased risk of serotonin syndrome (characterized by agitation, hallucinations, hyperthermia, autonomic instability). | Moderate |
| Potent CYP3A4 Inhibitors (e.g., Ketoconazole, Itraconazole, Clarithromycin) | May increase almotriptan plasma levels. Monitor for increased adverse effects. | Moderate |
| Propranolol | Increases almotriptan AUC by about 20%. No dosage adjustment is routinely required, but be aware of potential for increased effects. | Minor |
7. Patient Counselling
- DO take the tablet as soon as the migraine headache pain begins.
- DO take a second tablet only if headache returns after initial relief, but wait at least 2 hours between doses.
- DO NOT take more than 2 tablets (25 mg) in a 24-hour period.
- DO NOT use to treat more than 4 migraine headaches in a 30-day period without consulting your doctor (risk of medication-overuse headache).
- DO NOT take if you have taken any other triptan or ergot-type medicine (like ergotamine) in the last 24 hours.
8. Toxicology & Storage
Overdose: Symptoms may include hypertension, cardiovascular events, drowsiness, seizures, and serotonin syndrome. In clinical trials, doses up to 200 mg have been administered without severe adverse events, but overdose should be treated seriously.
Storage: Store at room temperature (15-30°C), protected from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.