title: [Methylphenidate-induced cytogenetic alterations?].
abstract: OBJECTIVE
  Due to concerns that methylphenidate (MPH) might induce cytogenetic alterations in children, treatment with this drug is a controversial issue. The controversy arose following a report by El-Zein et al. (2005) of increased chromosomal aberrations, sister chromatid exchanges, and micronuclei in twelve children after three months of MPH treatment.
  
  
  METHODS
  The study by El-Zein is discussed with regard to current cytogenetic standards and earlier studies on the mutagenicity, clastogenicity, and carcinogenicity of MPH are reviewed.
  
  
  RESULTS
  Conclusions from the El-Zein study are limited due to methodological shortcomings. Results of animal studies on the mutagenicity and clastogenicity of MPH are inconsistent. While there was no indication of mutagenic effects in bacteria or mammalian cells, MPH might have some potential to induce clastogenic damage in mammalian cells. There was no evidence of carcinogenic activity in rats, while in mice the occurrence of hepatic neoplasms increased. In an epidemiological study, the incidence of cancers following MPH treatment was lower than had been expected.
  
  
  CONCLUSIONS
  Given the ambiguous findings of genetic toxicology studies in animals, the paucity of long-term toxicology data on MPH in humans is disquieting. Although it seems premature to conclude that MPH entails a mutagenic risk, the concern raised by El-Zein et al. warrants profound clarification.
authors.affiliation: Klinik für Psychiatrie und Psychotherapie des Kindes- und Jugendalters, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt. holtmann@em.uni-frankfurt.de
authors.forename: Martin
authors.initials: M
authors.lastname: Holtmann
authors.forename: Bernd
authors.initials: B
authors.lastname: Kaina
authors.forename: Fritz
authors.initials: F
authors.lastname: Poustka
mesh_terms: D000293:Adolescent; D000818:Animals; D015197:Carcinogenicity Tests; D000697:Central Nervous System Stimulants / Q000633:toxicity*; D002648:Child; D006801:Humans; D008774:Methylphenidate / Q000633:toxicity*; D051379:Mice; D009152:Mutagenicity Tests; D051381:Rats; D012306:Risk
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate