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The tablet Donepezil (cholinesterase inhibitors) for Alzheimer's disease has some procholinergic actions that cause diarrhea and increased urinary frequency. So the tablet Darifenacin (antimuscarinics) should help as it is anticholinergic and reduces the frequency of urination. Also, it is bladder specific with minimal crossing into brain tissue, so it is safe. Also, whenever you are at home for a full day, you can try noting frequency-volume diary for 24 hours, measuring the intake of fluids versus urine output in terms of the number of episodes and volume. Volume can be measured in a urine pot or, if using diapers, by weighing diapers before and after use. This gives an approximate daytime and nighttime (sleep) urine output, and we can see if she has nighttime polyuria. If yes, medication can be given for that. Take the tablet Darifenacin 7.5 mg half the dose, to begin with. If suitable, we can increase the dose to 15 mg once daily after 15 days. (Consult a specialist doctor, talk to him or her, and start the medicine with their consent).
I hope this helps.