Provigil (Modafinil) Dosing
The standard recommended dose of Provigil (modafinil) is 200 mg once daily in the morning for narcolepsy and obstructive sleep apnea, with a maximum daily dose of 400 mg. 1
FDA-Approved Dosing by Indication
Narcolepsy and Obstructive Sleep Apnea
- Standard dose: 200 mg once daily in the morning 1
- Maximum dose: 400 mg daily 2
- The 200-400 mg range is typically administered as a single morning dose or divided into two doses 2
Shift Work Sleep Disorder
- 200 mg once daily, taken approximately one hour prior to the start of the work shift 1
Dose Optimization Based on Clinical Goals
The target symptom influences optimal dosing strategy:
- For excessive daytime sleepiness: Higher doses (200-400 mg/day) are more effective 2
- For concentration problems and fatigue: Lower doses (50-200 mg/day) may be more appropriate 2
Special Population Dosing
Elderly Patients
- Start with 100 mg once upon awakening 2, 3
- Increase at weekly intervals as necessary 3
- Consider lower doses due to age-related changes in drug elimination 1, 4
Severe Hepatic Impairment
- Reduce dose to half the recommended dose 1
- Elimination processes are slowed in hepatically compromised patients 4
Severe Renal Insufficiency
- Use caution due to substantial increases in levels of modafinil acid metabolite 5
Pharmacokinetic Considerations
- Half-life: Approximately 12-15 hours 2, 4
- Peak plasma concentrations occur 2-4 hours after administration 4
- Steady state is reached after 2-4 days of dosing 2, 4
- Pharmacokinetics are dose-independent between 200-600 mg/day 4
Clinical Efficacy Data
Long-term studies demonstrate sustained efficacy:
- In 40-week open-label studies, approximately 75% of narcolepsy patients received 400 mg daily 6
- Disease severity was "much improved" or "very much improved" in 58-59% of patients at weeks 24 and 40 6
- No evidence of tolerance developing during 40 weeks of treatment 6
Common Adverse Effects
Monitor for these dose-related side effects:
- Headache (most common, reported in 13-52% depending on study) 1, 5, 6
- Nervousness (8%) 1, 6
- Nausea (5%) 1, 6
- Insomnia 2, 5
- Back pain 2
- Dyspepsia 2
Critical Safety Considerations
- Modafinil is a Schedule IV controlled substance 1
- Has less abuse potential compared to traditional stimulants like amphetamines 2
- Discontinue immediately at first sign of rash due to risk of Stevens-Johnson Syndrome 1
- May reduce effectiveness of oral contraceptives; use alternative contraception during treatment and for one month after discontinuation 1
- Contraindicated in patients with known hypersensitivity to modafinil or armodafinil 1
Dosing Pitfalls to Avoid
- Do not exceed 400 mg daily - this is the maximum recommended dose 2, 1
- Avoid late-day dosing to prevent insomnia; last dose should be no later than 4:00 PM if using caffeine adjunctively 3
- Do not assume higher doses are always better; for fatigue and concentration, lower doses (50-200 mg) may be preferable 2
- In elderly patients, do not start at standard adult doses; begin at 100 mg 2, 3