Abuse liability and safety of oral lisdexamfetamine dimesylate in individuals with a history of stimulant abuse.
Lisdexamfetamine dimesylate (LDX) is the first prodrug stimulant and is indicated for the treatment of attention-deficit/hyperactivity disorder. A single-centre, double-blind, randomised, placebo-controlled, 6-period crossover study evaluated the abuse potential of single oral doses of 50, 100 (equivalent to 40 mg d-amphetamine), and 150 mg LDX, 40 mg d-amphetamine and 200 mg diethylpropion in 36 individuals with a history of stimulant abuse. On the primary abuse liability measure, maximum change of the Drug Rating Questionnaire-Subject Liking Scale compared with placebo, d-amphetamine and diethylpropion showed significant differences of 4.5 and 4.0 units, respectively (P < 0.001 for both vs placebo). LDX, administered at 50, 100 and 150 mg, showed nonsignificant differences of 2.0 and 2.1 units, respectively, at the two lower doses but a significant (P < 0.001 vs placebo) difference of 6.1 units at the highest dose. Subjects significantly favoured d-amphetamine 40 mg versus LDX 100 mg (2.4 units difference; P < 0.05). There was no significant difference in liking scores between d-amphetamine 40 mg and LDX 150 mg. Drug Rating Questionnaire-Subject Feel-Drug-Effect score was significantly lower for 100 mg LDX than for 40 mg d-amphetamine. There were no statistically significant differences between LDX and diethylpropion hydrochloride, a Schedule IV amphetamine-like stimulant, on abuse-related liking scores. Cardiovascular responses of LDX and d-amphetamine were similar at equivalent doses. In conclusion, at an equivalent amount of amphetamine base taken orally, LDX 100 mg had attenuated responses on measures of abuse liability compared with immediate-release d-amphetamine 40 mg. Abuse-related liking scores of LDX at a dose corresponding to a 50% higher amphetamine base (LDX 150 mg) were similar to d-amphetamine 40 mg.