ARMODAFINIL
Clinical safety rating: caution
Animal studies have proved adverse effects but may be safe for humans
Armodafinil is a wakefulness-promoting agent. Its mechanism is unclear but may involve inhibition of dopamine reuptake, leading to increased extracellular dopamine levels. It also affects orexin, histamine, norepinephrine, and GABA pathways.
| Metabolism | Metabolized primarily by amide hydrolysis and to a lesser extent by CYP3A4/5. Minor contribution from CYP2C19 and CYP1A2. Metabolites include armodafinil sulfone and armodafinil acid. |
| Excretion | Renal: ~80% as metabolites (major: armodafinil acid, minor: modafinil sulfone); fecal: <1% unchanged; biliary: negligible. |
| Half-life | 12–15 hours (terminal) in adults; longer in hepatic impairment (e.g., 20–30% increase with cirrhosis). |
| Protein binding | ~60% (primarily albumin; minor binding to alpha-1-acid glycoprotein). |
| Volume of Distribution | 0.9–1.1 L/kg (high tissue distribution, e.g., liver, kidney). |
| Bioavailability | Oral: ~90% (relative to oral solution; absolute not determined due to poor solubility). |
| Onset of Action | Oral: 1–2 hours (peak plasma concentration at 2 hours); clinical effect begins within 1 hour. |
| Duration of Action | 10–12 hours for wakefulness; sustained steady-state after 3–5 days of once-daily dosing. |
Adults: 150-250 mg orally once daily in the morning for narcolepsy or obstructive sleep apnea; 200-400 mg orally once daily for shift work disorder.
| Dosage form | TABLET |
| Renal impairment | No specific dose adjustment is recommended for renal impairment, but use with caution in severe renal impairment (CrCl <30 mL/min) due to potential for increased adverse effects. |
| Liver impairment | In severe hepatic impairment (Child-Pugh class C), reduce dose to 100 mg orally once daily. |
| Pediatric use | Not approved for use in pediatric patients; safety and efficacy not established. |
| Geriatric use | In elderly patients, consider starting at the lower end of the dosing range (e.g., 100 mg once daily) and monitor for adverse effects due to age-related changes in drug clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Induces CYP3A4 and inhibits CYP2C19 affecting many drugs Can cause serious skin reactions and psychiatric symptoms.
| Breastfeeding | It is unknown whether armodafinil or its metabolites are excreted in human breast milk. The M/P ratio has not been determined. Due to potential adverse effects on the nursing infant, including insomnia and irritability, breastfeeding is not recommended during therapy. |
| Teratogenic Risk | Armodafinil is classified as Pregnancy Category C. Animal studies have shown developmental toxicity including reduced fetal weight and increased incidence of skeletal variations. There are no adequate and well-controlled studies in pregnant women. First trimester exposure may be associated with an increased risk of major congenital malformations; however, data are limited. Use during pregnancy only if potential benefit justifies potential risk to the fetus. |
■ FDA Black Box Warning
None.
| Common Effects | sleep apnea |
| Serious Effects |
["Known hypersensitivity to armodafinil or modafinil.","Use in children for any indication (safety not established)."]
| Precautions | ["Serious rash requiring hospitalization (including Stevens-Johnson syndrome) – discontinue at first sign.","Angioedema and anaphylactoid reactions.","Psychiatric adverse reactions (e.g., mania, psychosis, aggression) – use caution in patients with history of psychiatric disorders.","Cardiovascular events – not recommended in patients with left ventricular hypertrophy or mitral valve prolapse, or with history of serious cardiac events.","Hepatic impairment – dosage reduction recommended in severe impairment.","Use with caution in patients with history of drug or alcohol abuse.","May impair ability to drive or operate machinery."] |
| Food/Dietary |
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| Fetal Monitoring | Monitor maternal blood pressure and heart rate due to potential sympathomimetic effects. Assess for signs of adverse effects such as insomnia, anxiety, or palpitations. Fetal monitoring includes ultrasound for growth and development if exposure occurs during pregnancy. No specific fetal monitoring guidelines exist; standard prenatal care is advised. |
| Fertility Effects | Armodafinil may reduce the efficacy of hormonal contraceptives, increasing the risk of unintended pregnancy. Women of childbearing potential should use non-hormonal or additional barrier methods. In animal studies, no direct adverse effects on fertility were reported, but clinical data in humans are lacking. |
| Food does not significantly affect absorption; may be taken with or without food. Grapefruit juice may increase armodafinil levels; avoid concurrent use. |
| Clinical Pearls | Armodafinil is the R-enantiomer of modafinil with a longer half-life (12-15 hours). It is a schedule IV controlled substance with low abuse potential but can cause Stevens-Johnson syndrome. Avoid in patients with left ventricular hypertrophy or mitral valve prolapse. Monitor for psychiatric adverse effects including mania, delusions, and suicidal ideation. Hepatic impairment (Child-Pugh B/C) requires dose reduction. May reduce efficacy of hormonal contraceptives; recommend alternative non-hormonal methods during and for 1 month after discontinuation. |
| Patient Advice | Take exactly as prescribed; do not crush or chew tablets. · Common side effects include headache, nausea, and anxiety; report rash or mouth sores immediately as they may indicate serious skin reaction. · Do not engage in activities requiring full alertness until effects are known. · Avoid alcohol and other CNS depressants. · Inform all healthcare providers, especially if you have heart problems, high blood pressure, liver disease, or a history of mental illness. |