From the Guidelines
The maximum recommended dose of modafinil (Provigil) is 400 mg per day. Typically, modafinil is prescribed at 200 mg once daily in the morning for most conditions including narcolepsy, obstructive sleep apnea, and shift work sleep disorder [ 1 ]. Some patients may require the maximum 400 mg dose, which can be taken as a single dose or divided into two doses (200 mg in the morning and 200 mg at noon). It's essential to note that higher doses (200–400 mg/d) of modafinil may be more effective for sleepiness, while lower doses (50–200 mg/d) seem to be better for concentration problems and fatigue [ 1 ]. Patients with severe hepatic impairment should use a reduced dose, typically 100 mg daily. Modafinil works by affecting certain neurotransmitters in the brain, particularly dopamine, to promote wakefulness without the jitteriness of traditional stimulants. Side effects can include headache, nausea, nervousness, and insomnia, especially at higher doses, which is why treatment typically starts at lower doses before considering the maximum 400 mg daily dose [ 1 ].
Key points to consider when prescribing modafinil include:
- Starting with a lower dose (200 mg) and adjusting as needed to minimize side effects
- Avoiding taking modafinil later in the day due to its long half-life (approximately 15 hours) and potential interference with nighttime sleep
- Monitoring patients for common side effects such as headache, nausea, and nervousness
- Considering reduced doses for patients with severe hepatic impairment [ 1 ].
It's crucial to weigh the benefits and risks of modafinil treatment, particularly in patients with cancer-related fatigue, where studies have shown significant improvements in fatigue levels and quality of life [ 1 ].
From the FDA Drug Label
The recommended dosage of modafinil tablets for each indication are as follows: Narcolepsy or OSA: 200 mg once a day in the morning. SWD: 200 mg once a day, taken approximately one hour prior to start of the work shift Severe Hepatic Impairment: reduce dose to half the recommended dose. Geriatric Patients: consider lower dose.
The maximum recommended dose of modafinil (Provigil) per day is 200 mg for patients with narcolepsy or obstructive sleep apnea (OSA), and for patients with shift work disorder (SWD). However, for patients with severe hepatic impairment, the dose should be reduced to half of the recommended dose, which would be 100 mg. For geriatric patients, a lower dose should be considered. 2
From the Research
Modafinil Maximum Recommended Dose
The maximum recommended dose of modafinil per day is:
- 200 or 400 mg/day, given once or twice daily (morning and midday) to patients with narcolepsy 3
- The dose can be increased by 100 mg increments up to a maximum daily dose of 400 mg in non-responders 4
Factors Affecting Dosage
The following factors can affect the dosage of modafinil:
- Age: the pharmacokinetics of modafinil are not affected to a clinically significant extent by volunteer age 3
- Food intake: food does not affect the overall bioavailability of modafinil, but can delay the peak concentration by approximately 2-4 hours 5
- Hepatic or renal impairment: the elimination half-life of modafinil is increased in patients with hepatic or renal impairment 3, 6
Pharmacokinetics
The pharmacokinetics of modafinil are: