A controlled double-blind study of haloperidol versus thioridazine in the treatment of restless mentally subnormal patients. Serum levels and clinical effects.

A randomized cross-over trial was conducted in 30 restless mentally subnormal patients by increasing the dosage of haloperidol from 10 to 60 mg and of thioridazine from 100 to 600 mg daily. The effects of drug holidays and serum drug levels were also examined. Mesoridazine had 5-6 times higher serum levels than the parent compound and relatively high serum levels are achieved already with moderate doses. The observed differences between haloperidol and thioridazine treatment were surprisingly few. Serum cholesterol was higher (P < 0.05) at the end of the thioridazine administration. Drug holidays may benefit may patients.