Drug Interaction:
Modafinils effects on the cytochrome P450 system are of uncertain clinical significance
Inhibition of CYP2C19 and 2 C9 , phenytoin(monitor for features of toxicity)
Warfarin (increase monitoring for the first 2 months of treatment
Induction of CYP3A4/5 , potential for reduced effect of ciclosporin
HIV-protease inhibitors,
Midazolam,calcium -channel blockers, statins and hormonal contraception
Induction of CYPIA2 and 2B6 also occurs
Indication:
Daytime sleepiness due to nacrolepsy, obstructive sleep apnoea or chronic shift
work related disorder, depression where prognosis (<2-4 weeks)
fatigue refractory to correction of underlying contributors
Adverse Reaction:
Undesirable effects
Very common(>10%)- headache
Common (< 10%, >1%)- abnormal LFTs , tachycardia, paliptation, dizziness,
drowsiness, paraesthesia, blurred vision, abdominal pain, nausea, bowel disturbance,
dry mouth,reduced appitite, vasodilation, chest pain, nervousness, insomnia, anxiety,
depression, confusion
Uncommon (<1% >1%)- bradycardia, arrhytmia, movement disorders,hostility,
suicidal ideation
Rare (<0.1%) -psychosis, mania, angioedema, serious skin reactions(rare in adults,
but 1% of children, Stevens Johnson syndrome, toxic epidermal necrolysis
Contra-Indications:
Cautions-
Cardiovascular disease (eg. severe hypertension, arrhythmias, angina.Avoid in mitral
valve prolapse, cor pulmonale and left ventricular hypertrophy), psychiatric illness
(eg. anxiety agitation, psychosis, addiction disorders, epilepsy (possible lowering of
seizure threshold )
Although rare in adults, serious skin reactions occur in 1% of children, consider
altmoderateernatives where possible (eg.methylphenindate)
Contraindications
Uncontrolled moderate -severe hypertension, arrhythmias
Dosages/ Overdosage Etc:
Dose and usage-
Modafinil is an alternative to methylphenindate particularly where the latter is poorly
tolerated. The manufacturer recommends a baseline ECG and monitoring of BP
and heartrate. Dose titration is slower.
start with 100mg each morning after 1 week increase to 200mg each morning
Maximum dose 400mg/24h
The manufacturer recommends either a single morining dose or divided doses in
the morning and at noon. However the half life of modafinil raises the possibility
of sleep disturbances with the latter
PROVGIL*
CEPHALON
100mg, 200mg 28 days @ 200mg each morning
