Chemistry:Lactulose

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Short description: Treatment for constipation and hepatic encephalopathy
Lactulose
Lactulose structure.svg
Lactulose-from-xtal-3D-bs-17.png
Clinical data
Pronunciation/ˈlæktjʊloʊs/
Trade namesCholac, Generlac, Consulose, others
Other names4-O-β-D-Galactosyl-D-fructose
AHFS/Drugs.comMonograph
MedlinePlusa682338
Routes of
administration		By mouth
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityPoorly absorbed
Metabolism100% in colon by enteric bacteria
Onset of action8 to 48 hours[1][2]
Elimination half-life1.7–2 hours
ExcretionFecal
Identifiers
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
Chemical and physical data
FormulaC12H22O11
Molar mass342.297 g·mol−1
3D model (JSmol)
  (verify)

Lactulose is a non-absorbable sugar used in the treatment of constipation and hepatic encephalopathy.[3][4] It is administered orally for constipation, and either orally or rectally for hepatic encephalopathy.[3] It generally begins working after 8–12 hours, but may take up to 2 days to improve constipation.[1][2]

Common side effects include abdominal bloating and cramps.[3] A potential exists for electrolyte problems as a result of the diarrhea it produces.[3] No evidence of harm to the baby has been found when used during pregnancy.[3] It is generally regarded as safe during breastfeeding.[5] It is classified as an osmotic laxative.[6]

Lactulose was first made in 1929, and has been used medically since the 1950s.[7][8] Lactulose is made from the milk sugar lactose, which is composed of two simple sugars, galactose and glucose.[9][3] It is on the World Health Organization's List of Essential Medicines.[10] It is available as a generic medication.[4] In 2021, it was the 265th most commonly prescribed medication in the United States, with more than 1 million prescriptions.[11][12]

Medical uses

Constipation

Lactulose is used in the treatment of chronic constipation in patients of all ages as a long-term treatment.[13] The dosage of lactulose for chronic idiopathic constipation is adjusted depending on the constipation severity and desired effect, from a mild stool softener to causing diarrhea. Lactulose is contraindicated in case of galactosemia, as most preparations contain the monosaccharide galactose due to its synthesis process.[14][15]

Lactulose may be used to counter the constipating effects of opioids, and in the symptomatic treatment of hemorrhoids as a stool softener.

Lactulose is commonly prescribed for children who develop fear of their bowel movements and are withholders. This is because lactulose, when dosed in the proper amount, causes a bowel movement that is impossible to retain for very long. Lactulose is also used for the elderly because of its gentle and consistent results.

Hyperammonemia

Lactulose is useful in treating hyperammonemia (high blood ammonia), which can lead to hepatic encephalopathy. Lactulose helps trap the ammonia (NH3) in the colon and bind to it.[16] It does this by using gut flora to acidify the colon, transforming the freely diffusible ammonia into ammonium ions (NH+4), which can no longer diffuse back into the blood.[17] It is also useful for preventing hyperammonemia caused as a side effect of administration of valproic acid.[18]

Small intestine bacterial overgrowth

Lactulose is used as a test of small intestine bacterial overgrowth (SIBO). Recently, the reliability of it for diagnosing SIBO has been seriously questioned.[19][20][21][22] A large amount of it is given with subsequent testing of molecular hydrogen gas in the breath. The test is positive if an increase in exhaled hydrogen occurs before that which would be expected by normal digestion by the normal gut flora in the colon. An earlier result has been hypothesized to indicate digestion occurring within the small intestine. An alternate explanation for differences in results is the variance in small bowel transit time among tested subjects.[22]

Pregnancy

No evidence of harm to the baby has been found when used during pregnancy.[3] It is generally regarded as safe during breastfeeding.[5]

Side effects

Common side effects of lactulose are abdominal cramping, borborygmus, and flatulence. In normal individuals, overdose is considered uncomfortable, but not life-threatening.[23] Uncommon side effects are nausea and vomiting. In sensitive individuals, such as the elderly or people with reduced kidney function, excess lactulose dosage can result in dehydration and electrolyte disturbances such as low magnesium levels. Ingestion of lactulose does not cause a weight gain because it is not digestible, with no nutritional value. Although lactulose is less likely to cause dental caries than sucrose, as a sugar, a potential for this exists. This should be taken into consideration when taken by people with a high susceptibility to this condition.[citation needed]

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:[24] 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).[25] It is produced commercially by isomerization of lactose.[citation needed]

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.[citation needed]

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).[17] 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.[26] Specifically, it is effective as secondary prevention of hepatic encephalopathy in people with cirrhosis.[27] Moreover, research showed improved cognitive functions and health-related quality of life in people with cirrhosis with minimal hepatic encephalopathy treated with lactulose.[28]

Society and culture

Name

Lactulose is its international nonproprietary name (INN).[29] It is sold under various brand names.[citation needed]

Availability

Lactulose is available as a generic medication.[4] It is available without prescription in most countries, but a prescription is required in the United States,[3] Philippines, and Austria.[citation needed]

Food additive

In some countries where lactulose may be obtained without a prescription, lactulose is commonly used as a food additive to improve taste and promote intestinal transit.[citation needed]

Veterinary use

Lactulose is used in veterinary medicine.[30]

References

  1. ↑ 1.0 1.1 "Gastrointestinal Symptoms". Oxford textbook of palliative care for children (2nd ed.). Oxford: Oxford University Press. 2006. p. 352. ISBN 9780198526537. https://books.google.com/books?id=f1fTsoA4wDMC&pg=PA352. 
  2. ↑ 2.0 2.1 "Constipation and diarrhea". Textbook of therapeutics : drug and disease management (8th ed.). Philadelphia, Pa. [u.a.]: Lippincott Williams & Wilkins. 2006. p. 1310. ISBN 9780781757348. https://books.google.com/books?id=aVmRWrknaWgC&pg=PA1310. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 "Lactulose". The American Society of Health-System Pharmacists. https://www.drugs.com/monograph/lactulose.html. 
  4. ↑ 4.0 4.1 4.2 "Gastroenterology". Tarascon pocket pharmacopoeia : 2013 classic shirt-pocket edition (27th ed.). Burlington, Ma.: Jones & Bartlett Learning. 2013. p. 111. ISBN 9781449665869. https://books.google.com/books?id=lwueJ4IAl4oC&pg=PA111. 
  5. ↑ 5.0 5.1 Breastfeeding and Medication. Routledge. 2013. p. 127. ISBN 9781136178153. https://books.google.com/books?id=0Y8lbCnF1mgC&pg=PA127. 
  6. ↑ "Operative and Nonoperative Therapy for Chronic Constipation". Improved Outcomes in Colon and Rectal Surgery. New York: Informa Healthcare. 2009. p. 366. doi:10.3109/9781420071535-36. ISBN 9781420071535. https://books.google.com/books?id=9FfvBQAAQBAJ&pg=PT378. 
  7. ↑ "Non-Enzymatic Degradation Pathways of Lactose and Their Significance in Dairy Products". Advanced dairy chemistry. (3rd ed.). New York: Springer-Verlag. 2009. p. 236. ISBN 9780387848655. https://books.google.com/books?id=hz9U9nzy-rQC&pg=PA236. 
  8. ↑ "Medical, nutritional and technological properties of lactulose. An update". European Journal of Nutrition 41 (Suppl 1): I17–I25. November 2002. doi:10.1007/s00394-002-1103-6. PMID 12420112. 
  9. ↑ Hepatology textbook and atlas : history, morphology, biochemistry, diagnostics, clinic, therapy (3rd ed.). Heidelberg: Springer. 2008. p. 887. ISBN 9783540768395. https://books.google.com/books?id=oL6d9KuVqLQC&pg=PA887. 
  10. ↑ The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization. 2023. WHO/MHP/HPS/EML/2023.02. 
  11. ↑ "The Top 300 of 2021". https://clincalc.com/DrugStats/Top300Drugs.aspx. 
  12. ↑ "Lactulose - Drug Usage Statistics". https://clincalc.com/DrugStats/Drugs/Lactulose. 
  13. ↑ "Lactulose". nih.gov. https://www.nlm.nih.gov/medlineplus/druginfo/meds/a682338.html. 
  14. ↑ "Lactulose: production, purification and potential applications". Biotechnology Advances 29 (6): 940–948. 1 November 2011. doi:10.1016/j.biotechadv.2011.08.008. PMID 21856402. 
  15. ↑ "Long-term safety of PEG 4000 in children with chronic functional constipation: A biochemical perspective". Korean Journal of Pediatrics 53 (7): 741–744. July 2010. doi:10.3345/kjp.2010.53.7.741. PMID 21189949. 
  16. ↑ "Meta-analysis: the effects of gut flora modulation using prebiotics, probiotics and synbiotics on minimal hepatic encephalopathy". Alimentary Pharmacology & Therapeutics 33 (6): 662–671. March 2011. doi:10.1111/j.1365-2036.2010.04574.x. PMID 21251030. 
  17. ↑ 17.0 17.1 "Comparative modes of action of lactitol and lactulose in the treatment of hepatic encephalopathy". Gut 28 (3): 255–259. March 1987. doi:10.1136/gut.28.3.255. PMID 3570029. 
  18. ↑ "Valproic acid induced encephalopathy--19 new cases in Germany from 1994 to 2003--a side effect associated to VPA-therapy not only in young children". Seizure 15 (6): 443–448. September 2006. doi:10.1016/j.seizure.2006.05.007. PMID 16787750. 
  19. ↑ "The lactulose breath test for diagnosing SIBO in IBS patients: another nail in the coffin". The American Journal of Gastroenterology 103 (4): 964–965. April 2008. doi:10.1111/j.1572-0241.2008.01798.x. PMID 18371132. 
  20. ↑ "Comparison of the prevalence of fructose and lactose malabsorption across chronic intestinal disorders". Alimentary Pharmacology & Therapeutics 30 (2): 165–174. July 2009. doi:10.1111/j.1365-2036.2009.04018.x. PMID 19392860. 
  21. ↑ "Small intestinal bacterial overgrowth in irritable bowel syndrome: association with colon motility, bowel symptoms, and psychological distress". Neurogastroenterology and Motility 20 (9): 998–1008. September 2008. doi:10.1111/j.1365-2982.2008.01142.x. PMID 18482250. 
  22. ↑ 22.0 22.1 "Combined oro-caecal scintigraphy and lactulose hydrogen breath testing demonstrate that breath testing detects oro-caecal transit, not small intestinal bacterial overgrowth in patients with IBS". Gut 60 (3): 334–340. March 2011. doi:10.1136/gut.2009.205476. PMID 21112950. 
  23. ↑ "Safety Data Sheet Lactulose". 2015. http://static.usp.org/pdf/EN/referenceStandards/msds/1356803.pdf. 
  24. ↑ "Milk lactose and lactulose determination by the differential pH technique". Le Lait 83 (5): 409–16. September–October 2003. doi:10.1051/lait:2003022. http://lait.dairy-journal.org/articles/lait/pdf/2003/05/L3503.pdf. 
  25. ↑ "Heat-treated milk differentiation by a sensitive lactulose assay". Food Chemistry 84 (3): 447–50. 2004. doi:10.1016/S0308-8146(03)00268-1. http://www.parmalat.it/documents/10157/29233/upload_00001438_Heat-treated%20milk%20differentiation%20by%20a%20sensitive.pdf. 
  26. ↑ "Non-absorbable disaccharides versus placebo/no intervention and lactulose versus lactitol for the prevention and treatment of hepatic encephalopathy in people with cirrhosis". The Cochrane Database of Systematic Reviews 2016 (5): CD003044. May 2016. doi:10.1002/14651858.CD003044.pub4. PMID 27153247. 
  27. ↑ "Secondary prophylaxis of hepatic encephalopathy: an open-label randomized controlled trial of lactulose versus placebo". Gastroenterology 137 (3): 885–91, 891.e1. September 2009. doi:10.1053/j.gastro.2009.05.056. PMID 19501587. 
  28. ↑ "Lactulose improves cognitive functions and health-related quality of life in patients with cirrhosis who have minimal hepatic encephalopathy". Hepatology 45 (3): 549–559. March 2007. doi:10.1002/hep.21533. PMID 17326150. 
  29. ↑ "International Nonproprietary Names for Pharmaceutical Preparations. Recommended International Non-Proprietary Names (Rec. I.N.N.): List 7". World Health Organization. 1967. p. 8. https://www.who.int/medicines/publications/druginformation/innlists/RL07.pdf. 
  30. ↑ "Constipation and Obstipation in Small Animals - Digestive System" (in en). https://www.msdvetmanual.com/digestive-system/diseases-of-the-stomach-and-intestines-in-small-animals/constipation-and-obstipation-in-small-animals. 

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