MODAFINIL — 100 mg / 200 mg tablets

Modafinil is a central nervous system stimulant approved for the treatment of excessive daytime sleepiness associated with narcolepsy, obstructive sleep apnea, and shift work disorder. It is classified as a eugeroic (wakefulness‑promoting agent) and is distinct from traditional amphetamine‑type stimulants in both pharmacology and abuse potential. In the United States, it is a Schedule IV controlled substance, reflecting its relatively low potential for abuse compared to Schedule II stimulants like amphetamine.

Atypical mechanism: The exact mechanism of action remains not fully understood, but research suggests modafinil promotes wakefulness primarily by inhibiting the dopamine transporter (DAT), thereby increasing extracellular dopamine levels in the brain. This effect is shared with addictive psychostimulants, but modafinil is unique in that it produces weaker and slower dopamine elevation, resulting in minimal euphoria and very few reported cases of dependence. Additional interactions with orexin, histamine, norepinephrine, serotonin, GABA, and glutamate systems may contribute to its distinctive pharmacological profile.

Approved vs. off‑label use: Modafinil is FDA‑approved for three specific conditions: narcolepsy, obstructive sleep apnea (as adjunct to CPAP), and shift work disorder. However, it is widely used off‑label for attention deficit hyperactivity disorder, depression‑related fatigue, multiple sclerosis fatigue, and as a cognitive enhancer in healthy individuals. A 2025 meta‑analysis confirmed that while modafinil users share common adverse events, specific risks vary across patient populations — for example, ADHD patients have higher risks of insomnia and decreased appetite, while those with depression show higher rates of anxiety.

Regulatory restrictions: Due to safety concerns, the European Medicines Agency restricted modafinil to narcolepsy only in 2010, and the UK followed with MHRA guidance limiting its use to narcolepsy under specialist initiation. In the US, it remains approved for all three indications but carries a boxed warning equivalent for serious rash and contraindications. Modafinil is not approved for pediatric use due to increased risk of serious cutaneous adverse reactions.

• Known hypersensitivity to modafinil or armodafinil.
• History of serious rash (SJS, TEN, DRESS) with any drug.
• Uncontrolled moderate to severe hypertension (caution advised).
• Cardiac arrhythmias (relative contraindication, use with caution).
• Pediatric patients (not approved, increased rash risk).

• Steroidal contraceptives (pills, patches, implants, IUDs, rings): Modafinil reduces their effectiveness. Use alternative or concomitant non‑hormonal contraception during treatment and for one month after discontinuation.
• CYP3A4 substrates (cyclosporine, midazolam, triazolam): Modafinil may reduce their concentrations. Monitor efficacy.
• CYP2C19 substrates (omeprazole, phenytoin, diazepam, propranolol): Modafinil may increase their concentrations. Consider dose adjustment.
• MAO inhibitors (phenelzine, tranylcypromine): Avoid concomitant use due to potential hypertensive crisis.
• CNS depressants (alcohol, benzodiazepines, opioids): Additive sedation and impairment. Avoid alcohol.
• Anticoagulants (warfarin): Modafinil may increase INR. Monitor closely.

• Severe hepatic impairment (Child‑Pugh C): Reduce dose to half the recommended dose (e.g., 100 mg once daily instead of 200 mg).
• Geriatric patients (>65 years): Consider lower doses due to age‑related decreased clearance.
• Renal impairment: No dose adjustment needed, but caution in severe impairment (limited data).
• Pregnancy: Avoid unless benefit outweighs risk. Enroll in pregnancy registry if used.
• Breastfeeding: Modafinil excreted in milk; caution advised.
• Pediatric (<17 years): Not approved; higher risk of serious rash and psychiatric adverse reactions.

• Symptoms: Agitation, insomnia, restlessness, tachycardia, hypertension, confusion, hallucinations. No fatal overdoses reported with modafinil alone, but fatalities with mixed overdoses have occurred.
• Management: Supportive care, monitoring of vital signs, activated charcoal if recent ingestion. No specific antidote.