Formulary
Modafinil: Indications, Dosing, Side Effects and Interactions
Modafinil clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 3 min read
Modafinil: Indications, Dosing, Side Effects and Interactions
Modafinil clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Excessive sleepiness associated with narcolepsy with or without cataplexy**
- **Adult** (By Mouth): Initially 200 mg daily in 2 divided doses, dose to be taken in the morning and at noon, alternatively initially 200 mg once daily, dose to be taken in the morning, adjusted according to response to 200-400 mg daily in 2 divided doses, alternatively adjusted according to response to 200-400 mg once daily.
- **Elderly** (By Mouth): Initially 100 mg daily.
Cautions
History of alcohol abuse; history of depression; history of drug abuse; history of mania; history of psychosis; possibility of dependence
Contraindications
Arrhythmia; history of clinically significant signs of CNS stimulant-induced mitral valve prolapse (including ischaemic ECG changes, chest pain and arrhythmias); history of cor pulmonale; history of left ventricular hypertrophy; moderate to severe uncontrolled hypertension
Side effects
Common or very common Anxiety; appetite abnormal; arrhythmias; asthenia; chest pain; confusion; constipation; depression; diarrhoea; dizziness; drowsiness; dry mouth; gastrointestinal discomfort; headaches; mood altered; nausea; palpitations; sensation abnormal; sleep disorders; thinking abnormal; vasodilation; vision disorders Uncommon Allergic rhinitis; arthralgia; asthma; behaviour abnormal; central nervous system stimulation; cough aggravated; diabetes mellitus; dry eye; dysphagia; dyspnoea; eosinophilia; epistaxis; gastrointestinal disorders; hypercholesterolaemia; hyperglycaemia; hyperhidrosis; hypertension; hypotension; increased risk of infection; leucopenia; libido decreased; memory loss; menstrual disorder; movement disorders; muscle complaints; muscle tone increased; muscle weakness; oral disorders; pain; peripheral oedema; psychiatric disorders; skin reactions; speech disorder; suicidal behaviours; taste altered; thirst; tremor; urinary frequency increased; urine abnormal; vertigo; vomiting; weight changes Rare or very rare Hallucination; psychosis Frequency not known Angioedema; delusions; fever; hypersensitivity; lymphadenopathy; severe cutaneous adverse reactions (SCARs) Side-effects, further information Discontinue treatment if rash develops. Discontinue treatment if psychiatric symptoms develop.
Interactions
**Severe interactions:**
- Modafinil may increase its own metabolism via induction of CYP3A4/5 activity but the effect is modest and unlikely to have significant clinical consequences.
**Other interactions (13):**
- Anticonvulsants: Co-administration of potent inducers of CYP activity, such as carbamazepine and phenobarbital, could reduce the plasma levels of modafinil.
- Due to a possible inhibition of CYP2C19 by modafinil and suppression of CYP2C9 the clearance of phenytoin may be decreased when modafinil is administered concomitantly.
- Patients should be monitored for signs of phenytoin toxicity, and repeated measurements of phenytoin plasma levels may be appropriate upon initiation or discontinuation of treatment with modafinil.
- Steroidal contraceptives: The effectiveness of steroidal contraceptives may be impaired due to induction of CYP3A4/5 by modafinil.
- Alternative or concomitant methods of contraception are recommended for patients treated with modafinil.
- Adequate contraception will require continuation of these methods for two months after stopping modafinil.
Pregnancy
Important safety information For modafinil MHRA/CHM advice (updated November 2020): Modafinil ( Provigil ): increased risk of congenital malformations if used during pregnancy A European review and other safety data found that use of modafinil during pregnancy potentially increases the risk of congenital malformations such as heart defects, hypospadias, and orofacial clefts. Healthcare professionals are advised that modafinil should not be used during pregnancy; alternative treatment options should be considered, including behaviour modifying measures, sleep hygiene, and scheduled daytime naps. Modafinil may also reduce the effectiveness of some hormonal contraceptives, including oral contraceptives, therefore alternative or additional methods of contraception are required-see also Interactions . Females of childbearing potential should be advised on the use of contraception (see Conception and contraception ) and informed of the risk of congenital malformations.
Breast feeding
Avoid-present in milk in animal studies.
Hepatic impairment
Manufacturer advises caution in severe impairment (risk of increased plasma concentrations). Dose adjustments Manufacturer advises dose reduction of 50% in severe impairment.
Renal impairment
Use with caution-limited information available. M
Medicinal forms
Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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