Methylphenidate vigilance

Amphetamines are synthetic sympthetomimetic amines that are powerful CNS stimulators, of few of which, in particular dextroamphetamine (8.1.2.2) and methylphenidate (8.1.2.6), are sometimes used for treating depressive conditions. They elevate mood, stimulate motor activity, vigilance, and allow one to concentrate better. However, depending on the dosage and personality of the patient, it may cause various degrees of euphoria, which frequently leads to dependence and addiction. 

Pemoline is a structurally unique CNS stimulant that exhibits minimal sympatomimetic effects, and possesses the same pharmacological properties as amphetamines and methylphenidate, yet it has less potential to cause addiction than other CNS stimulators. It enhances vigilance and motor activity, and causes weak euphoria, which is possibly linked to an increase in dopaminergic transmissions in CNS structures. 

The effects of methylphenidate on vigilance have not been extensively studied, and the limited amount of available information is conflicting. Some studies... 

A search of the available literature failed to produce evidence that methylphenidate has been used by the military to counteract fatigue in operational environments. However, the U.S. Navy has conducted laboratory studies in which military personnel were administered 10 mg methylphenidate or 37.5 mg pemoline during 64 hr of continuous wakefulness. The results indicated that methylphenidate did not produce improvements in objective and subjective sleepiness, or in straightforward measures of performance (27,46). However, when the performance data from a choice-reaction-time test were analyzed for trial-to-trial variance, methylphenidate was found to decrease the variance compared to placebo on the first of 2 days of sleep deprivation. The effect did not continue into the second day (51). As was the case with the vigilance studies (above), the nonsignificant or relatively small effects of methylphenidate may have resulted from the low dosage that was studied. 

Since pemoline is intended primarily as a treatment for ADHD, its effects on vigilance have not been well established. However, Orzack et al. (60) compared 25 mg and 50 mg pemoline to 100 mg and 200 mg caffeine, 15 mg methylphenidate, and placebo on the performance of a 2-hr psychomotor task (pressing keys corresponding to visual stimuli). They found that performance deteriorated as a function of time on task under the influence of placebo, but that 50 mg pemoline, 200 mg caffeine, and 15 mg methylphenidate maintained consistent performance throughout the 2 hr. 

Peloquin LJ, Klorman R. Effects of methylphenidate on normal children s mood, event-related potentials, and performance in memory scanning and vigilance. J Abnorm Psychol 1986 95(l) 88-98. 

Hink RF, Fenton WH, Tinklenberg JR, Pfefferbaum A, Kopell BS. Vigilance and human attention under conditions of methylphenidate and secobarbital intoxication an assessment using brain potentials. Psychophysiology 1978 15(2) 116-125. 

Strauss J, Lewis JL, Klorman R, Peloquin L, Perlmutter RA, Salzman LF. Effects of methylphenidate on young adults performance and event-related potentials in a vigilance and a paired-associates learning test. Psychophysiology 1984 21(6) 609-621. 

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