Gastrointestinal dysfunction and levodopa therapeutic response in Parkinson’s disease: a Brazilian cross-sectional study

Abstract

Background: Levodopa therapeutic response depends on factors that determine the optimization of drug absorption and distribution. In this perspective, gastrointestinal disorders in Parkinson's disease (PD), such as constipation and gastroparesis, act as an important barrier to effective treatment, increasing the degradation of levodopa and resulting in variations in the time of onset of its effect and the occurrence of fluctuations. Objective: To investigate the relation between constipation and the onset time of levodopa therapeutic effect in Parkinson's disease. Methods: This cross-sectional study was conducted with patients diagnosed with PD, treated at a reference center in Bahia, Brazil. Clinical and demographic data were collected by reviewing the records of medical evaluations from 2020 to 2025, in which patients were assessed for levodopa treatment and disease progression through the application of the Unified Parkinson's Disease Rating Scale-Part III (UPDRS-III) for severity of motor symptoms. Constipation was defined as an interval of more than 2 days between evacuations and the Mann-Whitney test was used to identify its association with levodopa latency. Results: A total of 50 patients were selected, of whom 35 (70%) were men. The mean age at admission to the study was 66.4 (±8.8). Regarding clinical status, the mean disease duration was 12.9 (±4.7) years, the mean Levodopa Equivalent Daily Dose (LEDD) was 1141 (±563) and the severity of motor symptoms, as assessed by UPDRS III, had a mean score of 46 (±17). Of the patients analyzed, 19 (38%) presented with constipation and their mean latency time was 32.1 (±16.5), while the other individuals had a mean latency time of 39.7 (±22.5). In the analysis, no association between constipation and levodopa latency time were identified (p > 0.05). Conclusion: Constipation was found not to be associated with levodopa latency time in the treatment for Parkinson’s Disease. However, factors such as patients' memory bias regarding the latency time and the sample’s size may have had an impact in the results, and larger studies may be necessary to better assess this analysis.