Effects of isradipine on methamphetamine-induced changes in attentional and perceptual-motor skills of cognition
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- Johnson, B.A., Roache, J.D., Ait-Daoud, N. et al. Psychopharmacology (2005) 178: 296. doi:10.1007/s00213-004-1998-0
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While the effects of d-amphetamine in increasing performance have been established, there is a paucity of information on the effects of methamphetamine on cognition in drug-naive subjects, and no published information on the effects of intravenous methamphetamine administration in dependent individuals. The dihydropyridine-class calcium channel antagonist, isradipine, has been posited as a putative treatment to prevent methamphetamine-associated hypertensive crisis and its sequelae. Yet, isradipine’s effects on cognitive performance in methamphetamine-dependent individuals are not known.
Since individuals whose dependence on methamphetamine is attributable to the need to enhance performance may be loath to take a cognition-impairing medication, even for the treatment of life-threatening hypertensive crisis, it would be important to determine isradipine’s effects on performance.
We therefore examined in a blinded, placebo-controlled, crossover design the cognitive effects of low and high doses of intravenous methamphetamine (15 mg and 30 mg, respectively) in both the presence and absence of isradipine.
Intravenous d-methamphetamine produced dose-dependent increases in attention, concentration, and psychomotor performance. Isradipine, both with and without methamphetamine, had a modest effect to decrease attention.
Our results do not support the further testing of isradipine as a medication for improving the cognitive impairments that have been associated with chronic methamphetamine use.