Modafinil Zentiva (Modafinil)

Modafinil acts on the central nervous system to reduce excessive daytime sleepiness in several sleep‑related disorders, improving patient functioning.

• Narcolepsy: enhances daytime alertness, reduces the frequency of cataplexy episodes and sudden sleep attacks, supporting functional daily activities.
• Shift work sleep disorder: promotes sustained wakefulness during night or early‑morning shifts, helping workers maintain performance and safety.
• Excessive daytime sleepiness associated with obstructive sleep apnea: mitigates residual sleepiness when used alongside standard apnea treatments, improving overall quality of life.

• Modafinil promotes wakefulness primarily by inhibiting the dopamine transporter, which raises extracellular dopamine concentrations in key brain regions. It also influences orexinergic, histaminergic and noradrenergic pathways, enhancing neuronal activity that supports alertness. Additionally, Modafinil modestly elevates levels of serotonin and glutamate, contributing to its overall arousal profile, while its low affinity for adrenergic receptors limits cardiovascular stimulation.

Modafinil may cause a range of adverse reactions, which are generally categorized by frequency and severity.

Common Side Effects

• Headache: mild to moderate pain often resolving without intervention.
• Nausea: transient stomach discomfort or queasiness.
• Insomnia: difficulty falling or staying asleep.
• Anxiety: feelings of nervousness or restlessness.
• Dry mouth: reduced salivation leading to throat dryness.
• Dizziness: light‑headed sensation, especially when standing quickly.

Serious or Rare Side Effects

• Stevens‑Johnson syndrome: severe skin reactions requiring immediate medical attention.
• Cardiovascular events: chest pain, hypertension or arrhythmia.
• Psychiatric disturbances: hallucinations, mania or severe depression.
• Liver injury: abnormal liver function tests or hepatitis.
• Severe allergic reaction: rash, swelling, or anaphylaxis.

When prescribing Modafinil, clinicians should consider several precautionary measures to ensure safe use.

• Assess cardiac history: evaluate hypertension, arrhythmias or coronary disease before initiation.
• Review psychiatric conditions: monitor patients with a history of psychosis or severe anxiety.
• Avoid use in pregnancy unless clearly needed: discuss potential risks with the patient.
• Caution in hepatic impairment: dose adjustment may be required in moderate to severe liver disease.
• Monitor for allergic reactions: discontinue if rash, swelling or severe skin reactions develop.
• Store at below 25°C: keep in the original container, protect from moisture and direct sunlight.

Modafinil can interact with other medicines, altering their effectiveness or increasing adverse effects.

Major Interactions (Avoid)

• CYP3A4 inducers (e.g., rifampicin, carbamazepine): may markedly reduce Modafinil plasma concentrations, compromising efficacy.
• Hormonal contraceptives: Modafinil may decrease contraceptive effectiveness, requiring additional barrier methods.

Moderate Interactions (Monitor Closely)

• CYP2C19 inhibitors (e.g., fluvoxamine): can increase Modafinil levels and risk of side effects.
• Antidepressants (e.g., SSRIs, SNRIs): may enhance nervous system stimulation, necessitating symptom monitoring.
• Anticoagulants (e.g., warfarin): potential alteration of INR, requiring closer laboratory surveillance.