Lactulose is a non-absorbable sugar used in the treatment of constipation and hepatic encephalopathy. It is used by mouth for constipation and either by mouth or in the rectum for hepatic encephalopathy. It generally begins working after 8–12 hours, but may take up to 2 days to improve constipation.Common side effects include abdominal bloating and cramps. A potential exists for electrolyte problems as a result of the diarrhea it produces. No evidence of harm to the baby has been found when used during pregnancy. It is generally regarded as safe during breastfeeding. It is classified as an osmotic laxative.Lactulose was first made in 1929, and has been used medically since the 1950s. It is on the World Health Organizations List of Essential Medicines. It is available as a generic and brand-name product. Lactulose is made from the milk sugar lactose, which is composed of two simple sugars, galactose and glucose. History
In 1957, Peitele discovered that lactulose is a bifidobacterium proliferation factor. In 1964, Hoffman found that only bifidobacteria, Lactobacillus and Streptococcus could metabolise lactulose into lactic acid and acetic acid. In 1966, Baicier found that lactulose can promote the growth of basophilic gram-positive bacteria lacking urease (e.g. Escherichia coli) and reduce ammonia production. It has been proven that lactulose reduces blood ammonia, and it has been successfully used in the treatment of hepatic encephalopathy. In 1979, Nianmoleyou treated viral hepatitis with lactulose and he found that lactulose has the effect of reducing plasma endotoxin.
Mechanism of action
It is a disaccharide formed from one molecule each of the simple sugars (monosaccharides) fructose and galactose. Lactulose is not normally present in raw milk, but is a product of heat processes: the greater the heat, the greater amount of this substance (from 3.5 mg/L in low-temperature pasteurized milk to 744 mg/L in in-container sterilized milk). It is produced commercially by isomerization of lactose.Lactulose is not absorbed in the small intestine nor broken down by human enzymes, thus stays in the digestive bolus through most of its course, causing retention of water through osmosis leading to softer, easier-to-pass stool. It has a secondary laxative effect in the colon, where it is fermented by the gut flora, producing metabolites which have osmotic powers and peristalsis-stimulating effects (such as acetate), but also methane associated with flatulence.Lactulose is metabolized in the colon by bacterial flora into short-chain fatty acids, including lactic acid and acetic acid. These partially dissociate, acidifying the colonic contents (increasing the H+ concentration in the gut). This favors the formation of the nonabsorbable NH+4 from NH3, trapping NH3 in the colon and effectively reducing plasma NH3 concentrations. Lactulose is therefore effective in treating hepatic encephalopathy. Specifically, it is effective as secondary prevention of hepatic encephalopathy in people with cirrhosis. Moreover, research showed improved cognitive functions and health-related quality of life in people with cirrhosis with minimal hepatic encephalopathy treated with lactulose. Society and culture
Name
Lactulose  is its international nonproprietary name (INN). It is sold under various brand names.