Peroral and parenteral administration of long-acting neuroleptics: a double-blind study of penfluridol compared to flupenthixol decanoate in the treatment of schizophrenia.

Fifty-six out of 60 schizophrenic patients completed a double-blind study of two long-acting neuroleptics, penfluridol (peroral) and flupenthixol decanoate (parenteral). Half of the patients were on maintenance therapy of flupenthixol prior to the study, the other half on penfluridol. The actual double-blind study (12 weeks) was commenced after a preliminary period of 4 weeks, the patients in the two main groups being randomly divided into two further groups, one continuing the medication unchanged, the other changing to the alternative drug. It was found possible to make a sudden switch from penfluridol to flupenthixol decanoate and vice versa without any significant change in the condition of the patient. The same dosage (in 70% of the patients from 40 to 80 mg) of penfluridol was used per week as was employed for flupenthixol decanoate per fortnight. Changes in the intensity of the symptoms (total Brief Psychiatric Rating Scale (BPRS) score) were moe pronounced in the preliminary period (during unchanged treatment) than on changed medication in the blind period. Both drugs induced approximately the same degree of akathisia, Parkinsonism and autonomic side effects. The practical consequences of equipotent therapeutical effect of a peroral and parenteral long-acting neuroleptic are briefly discussed.