Constipation

Introduction

Constipation is a very common symptom where public walks into a community pharmacy looking for self-treatment. Symptoms of constipation commonly include:

  • Difficulty passing stools
  • A feeling of incomplete evacuation
  • Abdominal discomfort and bloating



Gather Patient Information

As a community pharmacist, the three things that you should do are:
  • To establish the patient's current bowel habit compared with normal
    • Constipation involves the passage of hard stools less frequently than is normal. "Normal" can be anything from two or three times a day to two or three times a week; it is the change that is important!
  • To identify if there is any indicative of referral
    • Longer than 14 days' duration with no identifiable cause
    • Pain on defecation that might cause the patient to suppress the defecation reflex
    • Constipation alternating with diarrhoea
    • Blood in the stools
    • Infants under the age of 3 months - to exclude organic causes such as Hirschsprung's disease
  • Then concentrate on determine the cause. Common factors that can contribute to constipation include:
    • Inadequate dietary fibre
    • Dehydration
    • Inappropriate bowel habits (e.g. ignoring the urge to defecate)
    • Inadequate physical activity (e.g. from decreased mobility)
    • Painful anorectal disorders (e.g. haemorrhoids, anal fissure)
    • Medications (e.g. opioids, aluminium- and calcium-containing antacids, oral iron supplements, verapamil)
    • Medical conditions can predispose too (e.g. diabetes mellitus, hypothyroidism, depression, eating disorders, pregnancy, multiple sclerosis, etc.)

NOTE: Constipation is a predictable adverse effect of opioids. For patients on long-term opioid therapy, consider non-bulk forming laxative or oxycodone+naloxone combination (Targin).



Recommended Treatment

All people with constipation are likely to benefit from dietary and lifestyle changes (first-line treatment for uncomplicated constipation):

  • Fibre intake 20-30 g for adults daily
  • Adequate fluid intake (at least 2L/day unless contraindicated in heart or renal failure)
  • Increased exercise
  • Responding immediately to the urge to defecate

Laxatives are used when dietary and lifestyle measures are ineffective or not feasible or while waiting for measures to take effect. There are generally three classes of OTC laxatives available in community pharmacy:

  • Bulk-forming agents, e.g. ispaghula, psyllium
    • Effect is usually apparent within 24 hours, but 2 to 3 days of therapy may be required.
    • Faecal impaction should be treated before initiating fibre supplementation.
    • Patients should be advised to increase fluid intake while taking bulk-forming medicines.
    • Adverse effects such as flatulence, abdominal discomfort and bloating are common.
  • Stimulants, e.g. senna, bisacodyl
    • Effects usually occurs within 6 to 12 hours, hence I normally advise patient to take at night and they will have bowel motion the next morning.
    • Patients who abuse stimulant laxatives may have difficulty resuming a normal bowel pattern when these laxatives are stopped.
    • Not recommended in pregnancy.
  • Osmotics, e.g. lactulose, macrogol 3350, glycerin enema
    • Pull water into, or keep water in, the colon, expanding and softening the stool.
    • Rectal (glycerin enema) onset: 5-30 minutes.
    • Lactulose may take 48-72 hours before an effect is seen.
    • Excessive use may cause fluid and electrolyte disturbance.

In an overview, the few factors in deciding laxative medicines should include:

  • Expected time to effect
  • Route of administration (oral or rectal)
  • Cost

NOTE: Stool softener such as docusate is not marketed at Malaysia, so is not included for discussion.



Constipation and Coffee

Caffeine can act as a diuretic and serve to make constipation worse. So, may avoid drinks with caffeine.



Bisacodyl and Antacids

Bisacodyl tablets are enteric-coated, and patients should be told to avoid taking antacids and milk at the same time (leave a gap of 1 hour) because the coating can be broken down, leading to dyspepsia and gastric irritation.



Lactulose and Diabetes

Different form lactose, lactulose is a manmade sugar that is broken down in the bowel so very little gets into the bloodstream. Hence, it may be used short term in diabetic patients.

  • However, if you have diabetes and need to take high doses of lactulose for many months, it may affect your blood sugar levels and you should monitor blood sugar levels carefully.



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