Cytogenetic effects of psychotropic drug haloperidol on human lymphocytes.

Haloperidol is used for long-term therapy of psychiatric disorders. The cytogenetic effect of this drug was studied on human chromosomes in lymphocyte cultures in vitro and in vivo. There was no increase in the chromosomal aberration frequency in vitro with haloperidol at concentrations equivalent to plasma level and slightly higher than plasma level. However, a significant increase in the frequency of chromosome aberrations was seen in patients on therapeutic doses of haloperidol as compared to the two types of controls: 1. Psychiatric patients before starting the drug therapy and 2. normal healthy individuals from the general population. The most frequently observed aberrations were chromatid gaps and breaks. Our study indicates that haloperidol is not clastogenic in vitro at plasma concentration but significantly clastogenic in vivo.