Toxicity profile of lisdexamfetamine dimesylate in three independent rat toxicology studies.
Lisdexamfetamine dimesylate (LDX) is a d-amphetamine prodrug developed for the treatment of attention-deficit/hyperactivity disorder. The toxicity profile of orally administered LDX has been evaluated in rats. In an acute study, LDX doses of 60 mg/kg and higher caused increased motor activity. At 1000 mg/kg, one rat died and another was euthanized. In a 7-day repeat-dose study, all rats dosed with LDX (14 per dose group for each sex) showed increased activity; 10 male rats and 11 female rats at 300 mg/kg/day and 3 female rats at 100 mg/kg/day were euthanized because of self-mutilation and 1 male rat at 300 mg/kg/day was found dead. In a 28-day study, only rats at 80 mg/kg showed signs of self-mutilation and thin body condition. In both the 7- and 28-day studies, LDX caused significant changes in some blood chemistry parameters (e.g. blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase) and organ weights (e.g. particularly heart, liver, brain, and spleen). Overall, no apparent treatment-related histopathologic changes were observed. Toxicokinetic assessments indicated that as the dose of LDX was increased, rats were exposed to increasing levels of LDX and d-amphetamine. The extent of exposure to LDX and d-amphetamine increased after repeated-dose in the 28-day study. The findings of the repeat-dose studies indicate that the toxicity profile in rats administered LDX orally is comparable to that for d-amphetamine; however, the apparent lethal dose of LDX in rats is more than five times higher than the LD(50) of orally administered d-amphetamine, supporting a putative protective effect of conjugating amphetamine with lysine.
Krishnan
Suma
S
Shire Development Inc., 725 Chesterbrook Boulevard, Wayne, PA 19087, USA. skrishnan@nrpharma.com
Montcrief
Scott
S
D000284:Administration, Oral; D000818:Animals; D001774:Blood Chemical Analysis; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000633:toxicity*; D003913:Dextroamphetamine / Q000008:administration & dosage / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D007928:Lethal Dose 50; D000069478:Lisdexamfetamine Dimesylate; D008297:Male; D009929:Organ Size / Q000187:drug effects; D011355:Prodrugs / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012652:Self Mutilation; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic
D000697:Central Nervous System Stimulants; D011355:Prodrugs; D000069478:Lisdexamfetamine Dimesylate; D003913:Dextroamphetamine