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Published online: 17 February 2017
© Springer International Publishing Switzerland 2017
Abstract Lactulose (a non-digestible disaccharide) has been in medical use for >50 years and is commonly used in the treatment of constipation and hepatic encephalopathy. Depending on the dosage, oral lactulose is effective as a prebiotic, an osmotic laxative or a detoxifying agent. Lactulose also decreases levels of various deleterious elements, especially nitrogen products in patients with chronic kidney disease. According to recent studies, lactulose is also effective in treating post-partum constipation and is safe to use during pregnancy. Because of its various benefits in multiple disorders, the use of lactulose is not limited to only constipation and hepatic encephalopathy.
The burden of constipation
Chronic constipation is one of the most commonly diagnosed conditions in gastroenterology practice. The prevalence of constipation is 2-27% worldwide, depending on the definition of constipation [1]. Constipation is more common in the elderly, and is present in one in five adults aged >65 years [2]. Considering the amount spent on laxatives worldwide, constipation is a major healthcare burden. In addition, it also affects the quality of life of patients. Even though constipation is typically managed at home by using over over-the-counter medications, or in an out-patient setting, data analyzed by Sommers et al. showed a 41.5% increase in constipation-related emergency department visits from 2006 to 2011 [3].
Constipation and hepatic encephalopathy
Hepatic encephalopathy (HE) is a spectrum of neuropsychiatric abnormalities in patients with hepatic dysfunction. Ammonia (produced in the gut by nitrogenous products in the diet and the bacterial metabolism of urea) is converted to urea by the liver; urea is subsequently excreted by the kidneys. In patients with hepatic dysfunction, the liver is unable to detoxify ammonia, leading to an increase in the level of ammonia in the blood. High levels of ammonia produce neuronal damage, leading to neurological manifestations [4]. Constipation allows the absorption of ammonia to increase because of the slow transit of food, and can precipitate HE in patients with hepatic impairment [5]. Devrajani et al. have reported that 49% of episodes of HE are precipitated by constipation [6].
Lactulose: prebiotic, osmotic and detoxifying agent
Lactulose is derived from lactose through the process of isomerization (Fig. 1). Lactulose (a semi-synthetic disaccharide) has been used...