Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 518

Osmotic laxatives improve stool form and bowel movement frequency by increasing the amount of water retained in the lumen of the gut. Polyethylene glycol (PEG) (e.g. macrogol) and lactulose have therapeutic value in the treatment of constipation.⁴⁷ Other osmotic laxatives include sorbitol, magnesium salts, and saline salts. PEG, lactulose, and sorbitol have the greatest safety margins. Use of saline or magnesium salts comes with a risk for significant electrolyte disturbance, especially in older people. Elders with normal renal function may become hypermagnesemic with chronic use, especially at higher doses.⁴⁸ Magnesium salts should not be used in renal disease; and saline salts should be avoided in chronic renal failure, end‐stage liver disease, and heart failure. PEG appears to be the best tolerated overall in elders. Lactulose and sorbitol undergo bacterial metabolism in the gut, leading to increased symptoms of bloating, abdominal cramping, and flatulence in some patients and limiting their tolerability. A meta‐analysis of randomised controlled trials found osmotic laxatives to be superior to placebo in functional constipation.⁴⁹ Compared with placebo, PEG improves stool consistency and stool frequency. In comparative trials, PEG was superior to lactulose, showing improved efficacy and fewer side effects.⁵⁰ Trials also showed that PEG was non‐inferior to prucalopride (a prosecretory medication discussed below).⁵¹