Pharmacological effects Modafinil is an adrenergic α1 receptor agonist that primarily affects adrenergic or г-aminobutyric acid neurotransmission and indirectly regulates г-aminobutyric acid (GABA) release. It does not inhibit the spontaneous activity of brainstem noradrenergic and dopaminergic neurons, nor does it bind to receptors known to be involved in sleep/wake regulation mechanisms. Behavioral pharmacology studies in rats and cats have found that the wake-promoting processes of modafinil and amphetamine, a conventional drug for narcolepsy, are different. Compared to amphetamines, modafinil affects a more specialized area of brain tissue, has a less pronounced effect on the motor system outside the pyramidal tract, optionally increases wakefulness, and has minimal adverse effects. Pharmacokinetics Modafinil is rapidly absorbed after oral administration, reaching peak plasma concentrations at about 2 h. Steady-state plasma concentrations are reached after 8 d of continuous dosing, and are metabolized in vivo by amidation and S-oxidation to modafinil acid and modafinil sulfonylates (active metabolites). Modafinil is mainly metabolized by the liver, and the half-life of modafinil after multiple doses is approximately 10-15 h. Clinical Applications It is mainly used for the treatment of episodic sleeping sickness and idiopathic excessive daytime sleepiness. Adults take 200mg daily early in the morning as a dose. 400mg is equivalent to 200mg in efficacy, although it does not increase side effects. The maximum safe dose of modafinil is recommended to be 600 mg/d. The drug is excreted only in small amounts by the kidneys and therefore has little effect on renal insufficiency. In patients with severe hepatic impairment, the dose is reduced by half. In the elderly, drug metabolism and clearance are reduced and the dose should be reduced accordingly. In addition, modafinil is also used to treat narcolepsy associated with Parkinson’s disease. Adverse drug reactions and safety Modafinil has a high safety profile, with mild adverse reactions, including headache, nausea, nervousness, anxiety, and insomnia, etc. The number of patients who withdrew from the trial due to adverse reactions was 5% of the total. In terms of safe dosing, 32 subjects took 1000 mg per day (5 times the normal dose), including 2 cases up to 4000 and 4500 mg, respectively, and no serious life-threatening adverse effects were observed, with only euphoria, nausea, insomnia and slight increase in blood pressure. Only nervousness, palpitations, nausea, sleep disturbances and diarrhea were observed. The subjects’ nighttime sleep was barely affected during continuous dosing|, and no withdrawal symptoms were observed after discontinuation of the drug, indicating that modafinil is non-dependent and, in terms of drug safety, can completely replace traditional central stimulants such as amphetamines that are prone to dependence, which also provides a new way to address the problem of psychotropic drug abuse. The drug is contraindicated in patients with left ventricular hypertrophy, ischemic electrocardiographic changes, chest pain, arrhythmias, or clinically manifested mitral valve prolapse. Modafinil should be used with caution in patients with recent myocardial infarction, unstable angina pectoris, or a history of psychiatric disease. In summary, modafinil has been widely recognized as a new central excitatory drug with high efficiency, low toxicity, and no dependence, and can completely replace traditional central excitatory drugs with high adverse effects and easy dependence. While treating diseases such as narcolepsy, the application of modafinil can help reduce the abuse of traditional psychotropic drugs similar to amphetamines and caffeine.