Parkinson disease with constipation: clinical features and relevant factors. NMS.
Qiu-Jin Yu, Shu-Yang Yu, [...], and Wei Zhang.
2018.
Parkinson disease with constipation: clinical features and relevant factors. NMS.
Qiu-Jin Yu, Shu-Yang Yu, [...], and Wei Zhang.
2018.
This is a tough nut, I don't know what good solutions are, but I do know that part of constipation is a very frequent side effect of the anticholinergic anti-depressants, many of them of the older but very useful "tricyclic" tree such as the imipramine groups and derivatives (norpramine, desipramine as examples) and the amitryptiline groups and derivatives. The "serotonin uptake inhibitors" were partly an effort to develop alternatives to this and some of the other unwanted side effects.
The co-occurence of depression and PD and some common mechanisms in their treatments finds that there is often some crossover in using anti-depressants for PD and vice versa. So maybe if one happens to be using one of these heavily "anticholinergic" treatments, which by themselves induce considerable constipation as a side effect and perhaps make it worse with PD, would an alternative to explore be duloxetine to ask after? It's a very well tolerated "SNRI" (you can look that up).