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Laxatives
- 1. Laxatives
- 2. Contents Types of Laxatives (Overview) Bulk-forming Osmotic Stimulant Laxative Abuse
- 3. Types of Laxatives Docusate Sodium Lactulose Bulk-forming OsmoticStimulant Ispaghula husk Methylcellulose Sterculia Macrogol Phosphate enema Senna Bisacodyl Glycerol suppositories
- 4. Bulk-forming laxatives – methylcelluose, isphagula husk, sterculia • Indications - constipation, fecal impaction and mild chronic diarrhoea. • MOA - hydrophilic substance not absorbed or broken down in gut. Attracts H20 into stool increasing its mass & stimulating peristalsis. • S/E - well tolerated. Abdominal distension, flatulence. Avoid in GI blockages. Caution in fecal impaction and ileus • Prescribing – regular section of drug chart, around meal times e.g. ispaghula husk 1 sachet BD.
- 5. • Administration – water soluble granules/powder (ispaghula husk, sterculia) or tablets (methycelluose) • Patient advice – take with meal and plenty of water. Storage advice • Cost – cheap ; ispaghula husk <10p/sachet.
- 6. Osmotic laxatives – lactulose, macrogol, phosphate enema • Indications – constipation fecal impaction, bowel prep, hepatic encephalopathy • MOA – osmotically active substances remain in gut lumen. Hold water in stool, maintain volume, stimulate peristalsis. • Lactulose in liver failure –reduces ammonia absorption. NH3 key role in pathogenesis of hepatic encephalopathy • S/E – cramps, flatulence and nausea common. Phosphate enemas; local irritation and electrolyte imbalance (2nd line)
- 7. • C/I – intestinal obstruction, risk of perforation. Caution with phosphate enemas in heart failure, ascites and electrolyte imbalance. • Interactions – effects of warfarin slightly increased. • Prescribing – 15ml BD. Few days for effect. Phosphate enema for impaction; max one enema in 24h. Prevention of hepatic encephalopathy; 30-50ml TDS aiming for 3 soft stools p/day. • Administration – with or w/o food. Enemas given with pt in rectal exam position • Patient advice- drink 6-8 glasses liquid p/day. • Monitor – stool charts for inpatients, electrolytes in hepatic encephalopathy
- 8. Stimulant laxatives – senna, docusate sodium, bisacodyl, glycerol sup. • Indications – constipation, fecal impaction (suppositories), opioid tx • MOA – increase water and electrolyte secretion from colonic mucosa, increase volume of colonic content and peristalsis. • S/E – cramps, flatulence and diarrhoea. Melanosis coli w/prolonged use • C/I – intestinal obstruction, risk of perforation. Avoid rectal preps w/hemorrhoids or anal fissures.
- 9. • Prescribing – Typical dose 1-2 tablets of senna BD. Rectal stimulants given once only PRN. Max dose frequency once in 24h. • Administration – PO or PR • Patient advice- drink 6-8 glasses liquid p/day. • Cost – cheap. ~10p/dose
- 10. Laxative abuse – >3x weekly for at least 1 year • Associated with eating disorders • Attempt to get rid of unwanted calories • Laxative dependency • Consequences of abuse • Clinical findings - abnormally high conc. of Mg2+ in fecal water, cathartic colon and melanosis coli Normal Colon Melanosis Coli
Notes de l'éditeur
- hydrophillic substance – polysaccharide or cellulose. Fecal impaction (esp. pts who can’t ^ dietary fiber intake). mild chronic diarrhoea – associated w/diverticular disease and IBS. . Increased bulk stimulates peristalsis
- Due to MOA adequate fluid intake important. No clinically significant adverse interactions. Minimum water 300ml. You are offering a laxative that works as a fiber supplement that will hopefully make their stool easier to pass. Pts can adjust dose according to their symptoms but must not exceed Max dose. Store in dry place as these laxatives absorb water. Those who pay may be better buying from pharmacy/wilkos Don’t use this type in pts with new onset constipation after abdo surgery. They may have paralytic ileus and will be at ^ risk of GI obstruction.
- Osmotic substances e.g sugars and alcohols. Lactulose reduces ammonia absorption by ^ gut transit rate + acidyfying stool. This inhibits proliferation of ammonia producing bacteria Before PO3 enema try stimulant glycerol suppository as less likely to cause elctrolyte imbalance. Common side effects may decrease with time. As with other laxatives, diarrhoea Is a possible complication. Phosphate enemas cause significant fluid shifts. After enma pt should lie in position for a few minutes or until they need to poop as enema given in volume of >100ml. Can be uncomfortable when given.
- You are offering a rx with laxative that will make their stool softer and easier to pass. Dose can be adjusted to maintain comfort. If regularly passing >2-3 soft stools per day, dose should be Reduced or stopped unless used for hepatic encephalopathy.
- AKA irritant or contact lax. They also have direct pro-peristaltic action but MOA differs between agents. Bacterial metabolism of senna in intestine produces metabolites that have a direct effect on the enteric Nervous system, stimulating peristalsis. Rectal admin of stimulant lax. Produces similar but more localized effect. Docusate has both stimulant and stool softener effects. Melanosis coli is reversible pigmentation of the intestinal wall.
- Explain you are offering a laxative to help stool to pass. They do not work immediately and need a few doses before a sustained effect is noticed. Dose can be adjusted and if passing > 2-3 soft stools p/day Dose can be reduced or stopped. s/e can get better over time. A stimulant is a reasonable choice to co-prescribe with opioids. Pts find constipation uncomfortable and it can contribute to confusion in the elderly. Prevention can increase adherence to opioid rx and control of symptoms
- Mistaken belief they will rush food and calories through gut/bowels before they can be absorbed. Loss of water, minerals, electrolytes, fiber and wastes. Water weight returns as soon as individual drinks. If they don’t drink, they risk dehydration and can lead to death. Laxative dependency occurs when the colon stops reacting to usual doses of laxatives so that larger and larger amounts of laxatives may be needed to produce bowel movements. Consequences of Laxative Abuse: imbalances of electrolyte and minerals needed for proper functioning of the nerves and muscles, including those of the colon and heart. Severe dehydration may cause tremors, weakness, blurry vision, fainting, kidney damage, and, in extreme cases, death. Clinical findings: Cathartic colon occurs when there is nerve damage to the colon as a result of laxative abuse, defined as using laxatives more than three times weekly for at least one year. Patients with cathartic colon experience a thinness in the colon wall, which causes the colon to poorly function Melanosis coli: a brown pigmentation of the colon caused by pigment accumulation in macrophages of the lamina propria. Normally diagnoses ate endoscopy and analysis of biopsy specimens but in severe cases may be seen at radiology as colonic wall thickening.