Constipation

Question 1

Drugs associated with constipation?

Answer 1

Opioids, calcium/iron tablets, CaCBs, ACEIs, diuretics, antidepressants, antiepileptics, antimuscurinics, HR2A, antacids

Question 2

Secondary causes of constipation?

Answer 2

1. Drugs
2. Neuro: spinal cord, autonomic neuropathy (diabetes), MS, Parkinsons
3. Endocrine: hypercalcaemia, hypermagnesaemia, hypothyroidism, hypokalaemia
4. Colon disease: malignancy, strictures, rectocoele, postnatal damage to pelvic floor

Question 3

What is dyssynergic defecation and what are clinical signs/symptoms suggestive of it?

Answer 3

Pelvic floor mm dysfunction with poor control with abdominal and rectal mm during defecation.
Digital disimpaction, straining at stool, spending long time on the toilet, feeling of incomplete evacuation

Question 4

Red flags on history (six)

Answer 4

PR bleeding, weight loss, new onset, obstructive symptoms, rectal prolapse, age >50

Question 5

How to treat primary constipation with non drug methods?

Answer 5

Address secondary causes; fibre; fluids; exercise; positioning

Question 6

Which laxative to use initially in primary constipation?

Answer 6

Bulk-forming laxatives e.g. isaphagula husks, prunes. +/- stool softener if very hard stools

Question 7

What is the second laxative to add if still symptomatic after initial treatment of primary constipation?

Answer 7

Osmotics e.g. Macrogel

Question 8

What is third line treatment of primary constipation?

Answer 8

a) consider dyssynergic defecation which won’t be helped by laxatives -> refer to physiotherapy b) if not present, senna laxatives. If still symptomatic then specialist advice

Question 9

How do you treat impaction?

Answer 9

Macrogel (may need high doses); suppositories/enemas. Ensure on regular laxatives once cleared

Question 10

What is the pathophysiology of opioid induced constipation?

Answer 10

a) reduced peristalsis b) reduced secretion of fluids –> dry hard stool
c) increased circular mm contraction –> cramps

Question 11

How do you treat opioid-induced constipation?

Answer 11

1. Consider reducing dose
2. Change to less constipating opioid
3. Consider other factors (secondary causes, privacy issues, primary measures)
4. Use softeners / osmotics / stimulants - check not impacted before starting

Question 12

Which laxative should not be used in opioid-induced constipation?

Answer 12

Bulk forming - could cause obstruction

Question 13

Which are the less constipation-inducing opioids?

Answer 13

Fentanyl and bupromorphine