Treatments for Constipation

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Treatments for constipationCJ Lau 26 Aug 2009


Definition of constipation Etiology and pathophysiology of constipation Rationale for drug use Pharmacological and non pharmacological treatments Patient education/counselling


1. 2. 3. 4.

Constipation has varied meaning for different people Rome II criteria define constipation as >2 of the following in a 12 weeks period: Straining at defecation at least a quarter of the time Lumpy or hard stools at least a quarter of the time Sensation of incomplete evacuation at least a quarter of the time 3 or fewer bowel movements/week

Types of constipation 1. 2. 1.

Acute constipation Use suppositories or enema to clear the rectum and followed by simple non drug measure Use lactulose or sorbitol if dietary fibre cannot be adequately increased Fecal impaction Occurs when dry hard stool become compacted into large hard stool which cannot be expelled from rectum

Fecal impaction continues..2. 3. 4. 5.

Should initially be disimpacted by manual disimpaction An enema with mineral oil can then be used to soften the stool Sometimes impacted fecal must be accomplished using sigmoidoscopy with instrumentation Regular laxative use in addition to lifestyle and diet changes

Types of constipation 1.



Chronic constipation Normal colonic transit- exhibit psychosocial distress Colonic inertia/slow colonic transit- have delayed passage of radiopaque markers through proximal colon, have little or no increase in motor activity following a meal Dyssynergic defecation- inappropriate contraction of pelvic floor muscle, can be only diagnosed with anorectal manometry


The slowing of colonic transit may be idiopathic or due to motor disorders associated with many diseases Due to side effects of many drugs- opiods, calcium supplements, verapamil, anticholinergics, aluminium antacids Medical conditions (secondary causes)hypothyroidism, pregnancy, irritable bowel syndrome, Parkinson disease, colon cancer & Hirschprungs disease


Defecation involves the coordinated relaxation of puborectalis and external anal sphincter muscles, together with increased in intraabdominal pressure and inhibition of colonic segmenting activity. Slow transit constipation- possibly related to decreased numbers of high-amplitude propagated contractions Pelvic floor dysfunction- features normal or slightly slowed colonic transit, leads to inability to evacuate adequately the content from the rectum.

Hirschsprungs disease

Incidence of 1 in 5000 patients, commonly due to trisomy 21 A rare cause of intractable constipation in toddler and children Absence of ganglion cells in the myenteric & subcutaneous plexures of the distal colon resulting sustained contraction of the aganglionic segment. Bowel above the constricted area dilates (megacolon) due to stool trapping Commonly occurs near rectum region May require surgery to remove the aganglion segment


Careful history taking- defining the nature and duration of constipation and identify secondary causes Physical examination- rectal examination may be helpful. It can identify fissures and heamorrhoids Endoscopy/colonoscopy Radiography/imaging

Dietary and lifestyle changes

Is the mainstay treatment for constipation, it should be continued even when laxatives are used Ensure adequate dietary fibre intake (25-30g/daily). Increase intake gradually to avoid bloating & flatulence Ensure adequate fluid intake Increase exercise, avoid sedentary lifestyle Behaviour changes- do not hold urge to defecate

When to start treatment

Symptoms do not resolve after treating reversible causes (eg. Hypothyroidism, depression etc) Dietary changes are ineffective Fecal impaction When starting on opioid analgesia

Onset of effect of laxatives Group of Examples Onset oflaxatives Bulking agents Osmotic laxatives action pysllium Glycerol, lactulose, sorbitol Oral: 4872hours Oral: 2472hours Rectal: 530min

Polyethylene Oral: 0.5glycol, saline 3hours laxatives Rectal: 230min Stool softener Docusate, Oral: 24-

Bulking agent (eg. psyllium)

Useful for mild constipation,small hard stool and long term control Not to be used in acute constipation Absorb water into colon to increase fecal bulk which stimulates peristaltic activity Ensure adequate fluid intake to avoid intestinal obstruction Pregnancy risk factor B & excretion in breast milk unknown S/E: flatulence, bloating, abdominal discomfort

Osmotic laxatives 1. 1. 2. 3. 4. 5. 6.

Glycerol (suppository)- can be used for acute relief of constipation, onset of action (5-30minutes) Ravin enema (List C item) is available in hospital, contains glycerin 25% and NaCl 15% Lactulose (List B item, available as 3.35g/5ml in hospital) not suitable for acute relief (onset of action-1 to 3 days), need to be taken regularly Poorly absorbed, metabolised by colonic bacteria, exert osmotic effect on colon CI- lactose and galactose intolerance Dose- adult: 15-30ml/day, increase to 60ml/day in 1-2 divided dose, paed: 0.5ml/kg 12-24hourly Pregnancy risk factor B and excretion in breast milk unknown Can be mixed with water, fruit juice or milk for better taste

Osmotic laxatives 1. 2. 3.


Sorbitol 70% non absorbable sugar, produce osmotic effect at the colon Dose: 2-11yo 2ml/kg , >12yo- 30-150ml Precaution- use with caution with patients with severe cardiopulmonary or renal impairment, large volume may cause fluid overload or electrolytes imbalance S/E: oedema, abdominal discomfort, diarrhea, fluid and electrolytes disturbances

Osmotic laxatives 1.


3. 4.

Polyethylene glycol Used for bowel cleansing prior to GI examination or occasional treatment of constipation Dose for constipation: adult- 17g of powder dissolves in 8oz(240ml) of water for Miralax, not to be used for > 2 weeks Do not add flavouring agent to the solution, chilled solution is more palatable Many commercial dosage forms available, dose depends on each product (eg. Movicol, Movicol half, Colonlytelly)

Osmotic laxatives 1.

2. 3. 4. 5. 6.

Saline laxatives Contains poorly absorbed irons eg magnesium sulfate, phosphate, and citrate which retain water in colon by osmotic effect and stimulates peristalsis Onset of action- 30min to 3hours Sodium phosphate laxatives are CI in heart failure and renal impairment Dosage- depending on each product S/E: nausea, bloating, electrolyte imbalance Eg- Fleet Ready-to-use Enema, Micolette, Microlax,

Stool softener 1. 2. 3. 4. 5.

Have little value used as single agent in chronic constipation or opiod induced constipation Liquid paraffin (List C item) Lubricates fecal material to facilitate passage CI in children 10yo, 10mg at night children 4-10yo, 5mg at night Dose (supp): 10yo, 10mg morning Senna Onset of action- 6-12hr S/E: discolouration of urine to yellowish brown or red. Dose: 7.5-30mg at bedtime for adults Available in market as tablet, granule

Non pharmacological treatment 1.


3. 4.

Biofeedback Behavioral approach that is used to correct inappropriate contraction of the pelvic floor muscles and external anal sphincter during defecation Train patients to relax pelvic floor muscles during straining and to correlate relaxation and pushing during defecation Does not appear to benefit patients with slow transit constipation Evidence quality is moderate

Overall Management

Normal or slow transit constipationpatient education, dietary changes, drug therapy, behavioral therapy Severe intractable slow transit constipation- surgery in extreme condition Dyssynergic defecation- biofeedback

Tramonte, SM, Brand, MB, Mulrow, CD, et al. The treatment of chronic constipation in adults. A systematic review. J Gen Intern Med 1997; 12:15. Floch, MH, Wald, A. Clinical evaluation and treatment of constipation. Gastroenterologist 1994; 2:50 Longstreth, GF, Thompson, G, Chey, WD, et al. Functional bowel disorders Gastroenterology 2006; 130:1480 An Evidence-Based Approach to the Management of Chronic Constipation in North America. Am J Gastroenterol 2005; 100:S1 Chiarioni, G, Whitehead, WE, Pezza, V, et al. Biofeedback is superior to laxatives for normal transit constipation due to pelvic floor dyssynergia. Gastroenterology 2006; 130:657. Lexi-comps drug information handbook 13th ed Australian medicine handbook 2008 BNF and BNF for children online Frank Shann 14th ed