constipation

see also:

• laxatives
• RCH guideline - constipation

• encourage good fluid intake with adequate dietary fibre
• avoid repression of desire to use bowels
• encourage regular bowel habits
• increasing dietary fibre to the recommended daily intake of approximately 30 g or the use of fibre supplements such as psyllium should help in those patients with fibre deficiency.
  • BUT excessive dietary fibre will result in bloating, cramps, flatulence due to fermentation in the colon.
• adequate exercise
• reduce stress
• high thiamine diet
  • higher dietary thiamine intake appears to be associated with more frequent bowel movements although this effect depends upon a person's genetic makeup at the SLC35F3 and XPR1 genes ¹⁾²⁾
• avoid medications which cause constipation if possible:
  • anti-muscarinic anticholinergic agents including antihistamines, tricyclic antidepressants, phenothiazines
  • opiates and opioids
  • non-steroidal anti-inflammatory drugs (NSAIDs)
  • antihypertensive agents
  • calcium channel blockers
  • iron supplements
  • antacids containing aluminium
• treat underlying causes such as hypothyroidism
• warn patients to take extra care and consider simple prophylactic laxatives such as coloxyl with senna if they must take these medications or they are at risk (eg. painful anal conditions or prolonged bed rest)

• acute or recent constipation
• obstipation
• rectal blood loss, melaena or mucus
• weight loss
• fever
• rectal pain
• change in stool calibre
• anorexia, nausea or vomiting
• FH of inflammatory bowel disease (IBD) or colorectal cancer (bowel cancer)
• age > 50 years

• if there is fecal impaction, this should be relieved BEFORE discharging patient home:
  • consider Fleet enemas x 1-2 if no C/I
    • phosphate enemas may cause volume depletion, hypotension, hypokalaemia, hypocalcaemia, hyperphosphataemia (especially if impaired renal function)
  • in elderly patients, daily 100mL warm water enemas are safer than phosphate enemas (Fleet, etc)
  • may require medical admission to hospital for Rx with oral Go-Lytely &/or manual disimpaction

• docusate
  • 240mg (2 x 120mg tablets) daily
  • takes 1-3 days to work
  • can be used in pregnancy

• useful if there is a dietary fibre deficiency
• onset is usually by 24 hours, with peak action at 2-3 days following dosing
• Ispaghula
  • 1 sachet or teaspoon in water
• Psyllium
  • as directed on packet, 1- 3 times a day
  • can be used in pregnancy
• Sterculia
  • 1–2 teaspoons 1–2/day

• lactulose (Duphalac)
  • 15-30ml once or twice a day
  • takes 1-2 days to work
  • can be used in pregnancy
• other agents

• avoid long term use as they may induce melanosis coli, tolerance or cathartic colon and there is little evidence for their efficacy.
• not proven to be safe in pregnancy
• Bisacodyl
  • 1–2 x 5 mg tablets daily
  • works in 6-12hrs
  • can be used in pregnancy
  • bisacodyl's active metabolite, deacetyl bisacodyl (DAB), acts on the TRPM4 ion channel which is a central regulator of intestinal fluid balance - when activated, TRPM4 allows sodium ions to rush into intestinal epithelial cells. That electrical shift sets off a chain reaction: calcium flows in, activating a chloride channel that releases chloride ions into the gut and water naturally follows. A laxative effect results.³⁾
• sennosides
  • works in 6-12hrs

• consider adding prucalopride if not pregnant and constipation persists > 6 months despite Rx
• patients on long term opiates and opioids such as for palliative care, should be considered for methylnaltrexone s/c injections