Factors influencing the occurrence of "on-off" symptoms during long-term treatment with L-dopa.
"On-off" symptoms were found to have developed in 43 of 85 parkinsonian patients who had been treated with L-dopa for five years or more, the risk of such symptoms apparently being greater the younger the patient had been at the début of the disease and at the start of treatment. The dopa dose had been higher throughout the treatment in the patients developing "on-off" symptoms than in those maintaining an even effect, and, furthermore, the initial improvement had been more marked and dyskinesia had appeared earlier and in a higher frequency. The clinical observations in the present studies seemed to be related to some pharmacological findings, where different degrees of the nigrostriatal neuron degeneration and the efficacy of the remaining neurons could be of importance for a varying therapeutic response. It also seemed possible that a higher dopa dose could evoke "on-off" symptoms more easily than a lower one in thereto predisposed individuals. As the patients maintaining an even symptomatology during long-term treatment with L-dopa were older, and in particularly as they had dementia in a higher frequency than those developing "on-off" symptoms, the possibility of a more widespread neuron damage, influencing the clinical manifestation in these patients, had to be taken into consideration.
D000328:Adult; D000368:Aged; D004341:Drug Evaluation; D004359:Drug Therapy, Combination; D004409:Dyskinesia, Drug-Induced; D005500:Follow-Up Studies; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D008787:Metoclopramide / Q000008:administration & dosage / Q000627:therapeutic use; D008875:Middle Aged; D010302:Parkinson Disease, Secondary / Q000188:drug therapy*; D013997:Time Factors
D007980:Levodopa; D008787:Metoclopramide