ABSTRACT
Adverse Effects of Treatment Drugs in Short-Term Use Short-Term Use of Psychostimulants Psychostimulants, such as methylphenidate and dextroamphetamine, are effective in controlling the somnolence of narcolepsy (1-3). However, they often show side effects due to stimulation of the sympathetic nervous system. Constitutional factors may contribute to the development and severity of side effects. These include dry mouth, headache, palpitations, sweating, tremor, anorexia, gastritis, nausea, insomnia, irritation, and hyperactivity (3,4). The half-life of methylphenidate is approximately three to four hours, and administration twice a day, in the morning and at lunchtime, is recommended. Pemoline has a longer half-life of about 12 hours and can be used in one dose in the morning. It has less sympathetic nervous system stimulation and longer effectiveness as compared with methylphenidate (5-8). However, because of its association with idiosyncratic hepatic failure leading to transplantation or death, it is no longer available in the United States. Half-lives of amphetamine and methamphetamine are reported to be 8 to 20 hours (7,9,10). Development of paradoxical somnolence may occasionally appear, usually 15 minutes after ingestion of psychostimulants (11-13). Such somnolence usually lasts for less than half an hour, and then an awakening effect appears and lasts for several hours depending on the half-life of the drug. Ingestion of one tablet of psychostimulant one hour before the scheduled time of awakening in the morning may help reduce this effect. After a short sleep, the patients can awake feeling refreshed at a scheduled time in the morning. In rare cases, the paradoxical sleepiness effect of psychostimulants is severe and lasts for an entire day (6). In such cases, administration of psychostimulants is useless. Modafinil has little effect on the sympathetic nervous system and lacks most of the short-term side effects (14-17). Its half-life is about 12 hours. Amphetamine and methamphetamine show little short-term side effects. They have a longer half-life of more than 20 hours (7,9,18). Selegiline, also known as l-deprenyl, is a selective monoamine oxidase (MAO)-B inhibitor. This drug has been used for daytime sleepiness, but it also has more frequent hepatic side effects (19,20).
