Drug Interactions
Metabolized principally by MAO-A, CYP3A4, and CYP2D6.
Drugs Affecting Hepatic Microsomal Enzymes
Potential pharmacokinetic interaction (decreased almotriptan metabolism) with concomitant use of CYP3A4 inhibitors.
Specific Drugs
| Drug |
Interaction |
Comments |
| Alcohol |
Pharmacokinetic or pharmacologic interaction unlikely |
|
| Antidepressants, SSRIs (e.g., citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline) and SNRIs (e.g., duloxetine, venlafaxine) |
Potentially life-threatening serotonin syndrome
Potential increase in plasma almotriptan concentrations with concurrent fluoxetine administration |
Observe carefully if used concomitantly, particularly during treatment initiation, dosage increases, or when another serotonergic agent is initiated
No dosage adjustment required if fluoxetine is used concomitantly |
| Ergot alkaloids (e.g., ergotamine, dihydroergotamine, methysergide) |
Additive vasospastic effects |
Use within 24 hours contraindicated |
| 5-HT1 receptor agonists |
Additive vasospastic effects |
Use within 24 hours contraindicated |
| Itraconazole |
Potential decrease in almotriptan metabolism |
|
| Ketoconazole |
Potential decrease in almotriptan metabolism |
|
| MAO inhibitors |
Potential decrease in almotriptan metabolism |
No dosage adjustment required |
| Propranolol |
Pharmacokinetic interaction unlikely |
|
| Ritonavir |
Potential decrease in almotriptan metabolism |
|
| Verapamil |
Potential increase in plasma almotriptan concentrations |
No dosage adjustment required |
Pharmacokinetics
Absorption
Bioavailability
Well absorbed from GI tract. Absolute bioavailability is approximately 70%.
Peak plasma concentrations attained within 1–3 hours after oral administration.
Food
Food does not affect pharmacokinetics.
Distribution
Extent
Appears to be widely distributed throughout the body.
Distributed into milk in rats; not known whether distributed into milk in humans.
Plasma Protein Binding
Approximately 35%.
Elimination
Metabolism
Metabolized to inactive metabolites principally via MAO-mediated oxidative deamination, CYP3A4, and CYP2D6, with minor contribution of flavin monooxygenase.
Elimination Route
Excreted in urine (75%) and feces (13%), with 40% of dose recovered in urine as unchanged drug.
Half-life
3–4 hours.
Special Populations
Pharmacokinetics not evaluated in patients with hepatic impairment. Based on mechanism of almotriptan clearance, maximum decrease in clearance of 60% would be expected.
In patients with moderate or severe renal impairment, clearance is reduced by approximately 40 or 65%, respectively; peak plasma concentrations increased by approximately 80% in these patients.
In healthy geriatric patients, clearance is decreased, resulting in increases in half-life and AUC compared with younger adults; not considered clinically important.
Stability
Storage
Oral
Tablets
25°C (may be exposed to 15–30°C).
Actions
- Binds with high affinity to 5-HT1D, 5-HT1B, and 5-HT1F receptors.
- Structurally and pharmacologically related to other selective 5-HT1B/1D receptor agonists (e.g., eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan, zolmitriptan).
- Precise mechanism of action not established; may ameliorate migraine through selective constriction of certain intracranial blood vessels, inhibition of neuropeptide release, and reduced transmission in trigeminal pain pathway.
Advice to Patients
- Importance of immediately informing clinician if tightness, pain, pressure, or heaviness in chest, throat, neck, or jaw occurs and of not taking almotriptan again until evaluated by clinician.
- Importance of taking almotriptan exactly as prescribed.
- Importance of providing patient a copy of manufacturer’s patient information.
- Risk of somnolence; importance of exercising caution when driving or operating machinery.
- Importance of informing clinicians of existing or contemplated therapy, including prescription and OTC drugs and herbal supplements, as well as any concomitant illnesses (e.g., cardiovascular disease).
- Importance of informing patients of risk of serotonin syndrome with concurrent use of almotriptan and an SSRI or SNRI. Importance of seeking immediate medical attention if symptoms of serotonin syndrome develop.
- Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.
- Importance of informing patients of other important precautionary information. (See Cautions.)
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