Possible Interaction: Amphetamine and Methylphenidate

“Forty milligrams methylphenidate produced significant increases on the stimulant portions of the VAS and ARS and the benzedrine, amphetamine , morphine-benzedrine and lysergic acid diethylamine (LSD) subscales of the ARCI relative to placebo.”

“Mice that received five daily injection of methylphenidate HCl, 10–75 mg/kg, showed an increased running response to methylphenidate, cocaine, and amphetamine.”

“A possible explanation that Ross (1978) suggested for his findings was that methylphenidate inhibited the postulated active uptake of amphetamine into the dopamine nerve terminals, thereby preventing the release of dopamine by amphetamine (such release is thought to be the mechanism by which stereotypy is produced by amphetamine).”

“Recently Ross (1978) reported that methylphenidate antagonized the stereotyped behaviour produced by amphetamine in reserpinized rats.”

“One drug methylphenidate ) augmented it, while metamphetamine and physostigmine were ineffective.”

“Irritability, anxiety, obsessive thoughts, depressed mood, and euphoria scored significant RORs for all drugs, overall with an increasing risk from methylphenidate to atomoxetine, lisdexamfetamine, and amphetamine.”

“Atomoxetine or amphetamines may improve cognitive symptoms, while methylphenidate should be avoided in patients with schizophrenia.”

“One large and 3 small studies have recently examined the risk of major congenital malformations following the use of methylphenidate and amphetamines during the first trimester of pregnancy.”

“Even worse, it is equally stated (unreferenced) in the Summary of Product Characteristics (SPC) of both Ritalin tablets (Novartis Pharmaceuticals) and Concerta prolonged release tablets (Janssen-Cilag), that “this product contains methylphenidate which may induce a false positive laboratory test for amphetamines , particularly with immunoassay screen test” (3, 4).”

“Indeed, although tianeptine did not significantly change any ARCI scores, methylphenidate significantly increased amphetamine and morphine benzedrine scores of the ARCI compared with placebo.”

“In particular, information about QOL effects in adults and in subjects of all ages taking methylphenidate and amfetamine treatments is urgently needed.”