Geriatrics
Wilkins has described the deleterious effects of chronic constipation on the physical and mental well-being of the elderly. Untreated constipation easily leads to faecal impaction, and the resultant intestinal obstruction can have fatal results. Overflow incontinence with spurious diarrhoea is a common complication of rectal impaction and can have serious social consequences for the patient.

Exton-Smith et al. carried out a study aimed at quantifying the stool softening action of a standardised senna preparation by the use of a penetrometer.

They found that senna medication increased frequency of defaecation, stool wet weight, and stool softening.
(Referring to a patient with a lifelong ideopathic slow transit constipation and one large motion passed with difficulty once a week:)

This case history presents some interesting features. Apparently, because of a neuropathy of the colonic neuromusculature a high fibre diet alone failed to correct the constipation and the additional stimulus provided by senna was found necessary. Although taken continuously for 23 years there was no evidence of structural or other damage, and the response to minimal dosage remained unchanged.