THE EFFECTS OF PSYCHOPHARMACOLOGICAL THER APY ON HEART-RATE VARIATION

Twenty patients suffering from schizophrenia and 36 patients suffering from endogenous depression underwent a standardized heart rate analys is before drug therapy. The patients' parameters of heart rate variabi lity (HRV), which are controlled by the parasympathetic nervous system and which are independent of heart rate, did not significantly differ from the HRV parameters of normal control subjects. Ten of the patien ts with schizophrenia were treated with 200-400 mg of clozapine/day as monotherapy, while the other ten patients received a combination of d ifferent psychotropic drugs. The depressed patients were either treate d with 150 mg of amitriptyline/d (n = 24) or 20 mg of paroxetine/d (n = 12) as monotherapy, respectively. After treatment with an average of 300 mg of clozapine/d for 4 weeks or with 150 mg of amitriptyline/day for 2 weeks, all of the patients HRV parameters had significantly dec reased (P<0.001). At this time, about 90 % of these patients fulfilled the criteria of cardiovascular autonomic neuropathy. However, treatme nt with 20 mg of paroxetine/day for 2 weeks had no impact on any of th e heart rate parameters. Under amitriptyline treatment, HRV parameters were found to correlate significantly with the plasma levels of amitr iptyline/nortriptyline in a group of 104 depressed patients. Thus, det ermination of decreased HRV parameters is suggested to be a useful too l for the detection of overdosage with amitriptyline. It has not yet b een elucidated whether or not the observed HRV decrease, which is prob ably at least in part due to the anticholinergic side effects of cloza pine and amitriptyline, has any impact on patient health. Determinatio n of renormalized HRV might be considered a biological criterion for a sufficient wash-out phase after treatment with tricyclic agents.