I have heard that there is a two-week window for the use of polyethylene glycol? Does it lose its effectiveness after a certain time period?
Information is limited regarding the long-term use of polyethylene glycol (PEG). Some of the information available suggests that it is the most effective for the first 14 days of treatment. However, geriatric resources produced by the American Society of Consultant Pharmacists suggest continuing the use of PEG if it still meets your therapeutic goal. There is very little literature in the area of long-term use of PEG.
Reference
Twycross R, Wilcock A, Dean M. Canadian Palliative Care Formulary, 1st Canadian ed. Nottingham, UK: Palliativedrugs.com; 2010.