Drug Management of Constipation, Diarrhoea and pancreatic insufficiency Flashcards
What causes constipation?
Dietary: Lack of fiber and inadequate caloric intake
Medical conditions: Colon cancer - alarm symptoms, Parkinson’s disease, hypothyroidism, electrolyte disturbances, myopathies
Drugs: Opioids, 5-HT3 receptor antagonists, TCAs, CCB
Idiopathic
What is constipation?
Constipation is a syndrome defined by bowel symptoms: Difficult/infrequent stools, hard stools, feeling of incomplete evacuation.
Either found in isolation or secondary to another underlying disorder.
How is constipation investigated?
Perineal and rectal examination (anal tone, haemorrhoids, fissures, and rectocele)
How is constipation classified?
Normal and slowed transit constipation.
Defecatory disorders/pelvic floor dysfunction (impaired rectal evacuation or can have slowed or normal colonic transit)
What non-pharmacological measures are taken to treat constipation?
Increasing fluid intake
Physical exercise
Probiotics (may accelerate transit)
Dietary fiber (through diet or supplementation) [Soluble vs insoluble, usually a first line therapy, takes time to have effect]
What is the main side effect of taking more fiber?
Bloating
How do osmotic laxatives work?
Work by increasing water content of stools.
What are some examples of osmotic laxatives?
Polyethylene glycol (PEG) (Movicol - lower dose as aperient, colonlytely - larger doses as bowel prep)
Magnesium citrate (Epsom salts, some Mg absorbed)
Sodium phosphate (Risk of electrolyte disorders and is used in enemas)
Nonabsorbable carbohydrates (lactulose/sorbitol)
How are anti-constipation drugs administered?
Orally: Take time to reach distal colon
Suppositories: Access to rectum
Enemas: Access to rectum and distal sigmoid
What are the types of drugs used to treat constipation?
Osmotic laxatives (soften stools by increasing water content)
Stimulants (encourage bowel motility)
5-HT4 receptor agonists (prucalopride, stimulates colonic mass movements and provides propulsive force for defecation)
Opioid antagonists (does not cross BBB and is specifically for opioid induced constipation in palliative care setting, example of this is methylnaltrexone) Very fast onset of action
What are the currently used bowel stimulants?
Senna (Converted into sennosides A and B by colonic bacteria)
Docusate sodium - coloxyl (Detergent, also a stool softener)
Sodium picosulphate (picoprep)
Bisacodyl (Oral and suppository formulations)
What causes diarrhoea?
Mostly infective (viral > bacterial > protozoal)
What is the aim of diarrhoea treatment?
Maintain fluid and electrolyte balance
Treat underlying causes if appropriate
Anti-diarrhoeals assist comfort. (Use caution in bloody diarrhoea, significant abdominal tenderness/bloating and ensure cultures are sent)
What causes chronic diarrgoea?
Malabsorption (coeliac, pancreatic insufficiency, bowel resection)
Chronic constipation (overflow)
Inflammatory bowel disease
Medications (laxatives, antibiotics, cytotoxics)
IBD
How is diarrhoea treated?
Treat the cause
Use anti-diarrhoeal drugs for comfort (mu-opioid receptor agonists, bulking agents
