Levodopa ameliorated anorectal constipation in de novo Parkinson's disease: The QL-GAT study.

Background: Gastrointestinal tract (GIT) dysfunction is common in Parkinson's disease (PD) patients. However, it remains unclear whether levodopa affects GIT function in PD.

Objective: To perform an open study of levodopa's effects on anorectal constipation in de novo PD patients by the quantitative lower-gastrointestinal autonomic test (QL-GAT).

Methods: Nineteen unselected de novo PD patients (10 men, 9 women; mean age, 66 years; mean duration of the disease, 2.2 years) were recruited for the study. Eighteen of the patients reported constipation. These patients were treated with 200/20 mg b.i.d. of levodopa/carbidopa for 3 months. Pre- and post-treatment, objective parameters in the QL-GAT that comprised the colonic transit time (CTT) and rectoanal videomanometry were obtained.

Results: Levodopa was well tolerated by all patients. There was a trend toward subjective improvements in bowel frequency and difficulty defecating. Levodopa did not significantly change CTT of the total colon or any segment of the colon. During rectal filling, levodopa significantly lessened the first sensation (p < 0.05). It also tended to augment the amplitude of spontaneous phasic rectal contraction (not statistically significant). During defecation, levodopa significantly lessened the amplitude in paradoxical sphincter contraction upon defecation (PSD) (p < 0.01). It also tended to augment the amplitude of rectal contraction and lessen the amplitude of abdominal strain (not statistically significant). Overall, levodopa significantly lessened post-defecation residuals (p < 0.05).

Conclusions: The QL-GAT in the present study showed for the first time that levodopa augmented rectal contraction, lessened PSD, and thereby ameliorated anorectal constipation in de novo PD patients.