Search

There is both experimental and clinical evidence to suggest a role for 5-hydroxytryptamine (5-HT) in Parkinson's disease. The effect of ritanserin, a highly selective 5-HT2 receptor antagonist, on Parkinsonian symptomatology was investigated in 10 patients in a single-blind placebo-controlled study. Akinesia and gait improved significantly in a dose-dependent manner in 5 and 7 patients respectively. However there was no significant improvement in tremor. The effects of ritanserin on akinesia and gait are consistent with a role for 5-HT in Parkinson's disease.

Eight patients with generalised anxiety disorder (GAD) and eight matched healthy controls had their polysomnogram measured on two occasions separated by 1 week. On one occasion they received the 5-HT2 receptor antagonist, ritanserin (5 mg orally) and on the other matching placebo. The increase in slow wave sleep produced by ritanserin was the same in GAD patients as in healthy controls. These findings do not support the hypothesis that GAD is associated with a generalised hypersensitivity of brain 5-HT2 receptors; however, the present data cannot exclude the presence of a regionally specific change in this receptor subtype in anxiety disorders.

Rats that had received 3% alcohol, 0.01% cocaine, or 0.002% fentanyl as the only beverage over 10 days showed marked preference for the drug solution when water was made available as a second fluid in a separate bottle. Treatment with low doses of ritanserin, a specific central serotonin 5-HT2 antagonist, rapidly reversed drug preference without changing total fluid intake. Quantitatively, the reduction in drug consumption was greater for alcohol than for cocaine and greater for cocaine than for fentanyl. This is probably related to differences in the reinforcing potential of the three drugs.

The efficacy of the S2-antagonist ritanserin has not yet been clarified satisfactorily. In an open indication finding study to generate new hypotheses concerning its possible therapeutic application carried out in the psychiatric university clinic 25 patients (10 patients with vitalized neurotic depression (ICD No. 296.1), 7 with florid depressively tinged schizophrenia (ICD No. 295.3)) were treated with an average of 15.5 mg/day of ritanserin for a period of 4 weeks. Alterations in the psychopathological findings were documented by means of the Brief Psychiatric Rating Scale (BPRS), the Hamilton Depression Scale (HAMD), the Hamilton Anxiety Scale (HAMA), and the psychopathological findings (page 4) of the AMDP system. The results suggest that ritanserin improves depressive rather than schizophrenic symptomatology. In 4 of the 7 schizophrenic patients of our study an intensification of the psychotic symptomatology could even be observed. On the basis of our open study findings ritanserin could be classified as a substance with antidepressive effects, with a low incidence of side-effects and a rapid onset of action. In placebo controlled clinical studies this indication should be examined in different patient groups.