Methylphenidate is not clastogenic in cultured human lymphocytes and in the mouse bone-marrow micronucleus test.

Methylphenidate (MPH) is one of the most frequently prescribed drugs for the treatment of attention deficit hyperactivity disorder (ADHD). A report on cytogenetic effects observed in peripheral lymphocytes from children treated for 3 months with MPH raised questions about the genetic toxicity of this compound. A critical review of this data concluded that the cytogenetic effects in treated children remain unexplained. A literature review showed that MPH was found negative in most genetox studies performed, but no in vitro chromosome aberration data in human lymphocytes have been published. Therefore, we conducted a chromosomal aberration study in cultured human peripheral lymphocytes. The results of this investigation showed that d,l-methylphenidate (MPH, Ritalin) in concentrations up to 10 mM did neither induce structural nor numerical chromosome abnormalities. An oral mouse bone-marrow micronucleus test in B6C3F(1) mice, with doses up to 250 mg/kg bw, was negative too. The data of these studies confirm the absence of clastogenic activity of MPH in non-clinical studies.