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What is the most common cause of constipation?

A. Pelvic floor dyssynergia

B. Slow transit

C. Functional

D. Mechanical obstruction

Constipation

• Symptom based disorder– Bloating– Hard stools– Difficult stool passage– Sensation of incomplete evacuation– Frequent straining

Constipation

• Common condition with 15% prevalence in North America and female to male ratio 2.2:1

• Symptoms increase with age > 65• Primary causes

– Functional (most common) include IBS-C– Defecation disorders

• Pelvic floor dyssynergia• Excessive perineal descent• Mechanical obstruction

– Slow transit (least common)

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Initial Testing

• CBC • TSH if there are other symptoms consistent

with hypothyroidism• Colonoscopy if any alarm features present

- blood in stool, anemia, weight loss, or if age appropriate screening has not already been performed

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Functional• IBS-C

– Recurrent abdominal pain at least 3 days/month during the last 3 months with onset ≥ 6 months prior

– Improvement with defecation, change in stool frequency or change in stool appearance or form

• Chronic constipation– Straining during at least 25% of defecations– Sensation of incomplete emptying for at least 25% defecations– Sensation of anorectal obstruction for at least 25% of

defecations– Need to use manual maneuvers to facilitate evacuation for at

least 25% of defecations– < 3 defecations per week

Functional

• Treatment options– Fiber supplementation, exercise, healthy diet, osmotic

laxative– May use stimulant laxative no more than 2-3 times per

week– Rx medications

• Lubiprostone- chloride channel activator • increases intestinal fluid secretion thereby increasing motility in

the intestine• Linaclotide-guanylate cyclase agonist

• Increases cGMP which stimulates secretion of chloride and bicarbonate which increases intestinal fluid, accelerates transit and reduces intestinal pain

Lubiprostone

• Take with food and water• Chronic idiopathic constipation

- 24mcg BID• IBS-C (women)

- 8mcg BID• Opioid induced constipation (non-cancer)

- 24mcg BID

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Lubiprostone

• Adverse reactions- Nausea- Diarrhea- Headache- Dyspnea

• Pregnancy category C• Unknown if excreted in human breast milk; not

in animals- Infants should be monitored for diarrhea

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Linaclotide

• Take on empty stomach at least 30 minutes prior to a meal

• Chronic idiopathic constipation- 145mcg daily

• IBS-C- 290mcg daily

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Linaclotide

• Adverse reactions- Diarrhea- Abdominal pain- Flatulence

• Pregnancy category C• Unknown if excreted in human breast milk

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Pelvic Floor Dyssynergia

• Accounts for 1/3 of constipation in the community• Likely acquired behavior disorder

- Increased muscle tension from anxiety or stress- Sexual abuse is reported in 22% of women with defecation

disorders• Puborectalis muscles and external anal sphincter must

relax• Diagnosed with anorectal manometry and balloon

expulsion test- evidence that pelvic floor retraining is superior to

laxatives for defecatory disorders- ~70% have improvement

• Biofeedback therapy

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There is currently only one prescription medication available to treat opioid induced

constipation.

A True

B False

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Opioid Induced Constipation• Most common reported side effect of opioid use in 41%

of patients• Mu-opioid receptors

- inhibition of propulsive activity of intestine and slow intestinal transit

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Methylnaltrexone Bromide (Relistor)

• Inhibits opioids from binding to mu-receptors in GI tract

• Does not cross blood brain barrier- Doesn’t interfere with centrally located receptors

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Methylnaltrexone Bromide

• Dosing• Single vial dosing (12mg) and pre-filled syringe

(8mg and 12mg)- Chronic non-cancer pain

- 12mg SQ daily (0.6mL)- Advanced illness

- weight based and every other day dosing prn- no studies past 4 months

• Cut dose in half for creatine clearance <30mL/min 20

Methylnaltrexone Bromide

• Category C• Unsure if passes into breast milk• Can cause opioid withdrawal in fetus due to

immature BBB• ADRs

- abdominal pain, nausea, diarrhea, hyperhidrosis

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Naloxegol (Movantik)

• Peripherally acting mu-opioid receptor antagonist; for use in chronic non-cancer pain

• Take on empty stomach 1 hour prior to first meal or 2 hours after

• 25mg PO daily; also comes in 12.5mg• First BM within 6-12 hours• Same ADRs as SQ injection• Category C

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Summary

• Many different causes of constipation and treatment is based on underlying cause

• Know when to move on from fiber and OTC medications

• Pelvic floor dyssynergia is extremely common in up to 1/3 of those with constipation in the community and can be treated with biofeedback

Summary

• Opioid induced constipation is managed differently than other forms of constipation

• Refer if any alarm features or if not comfortable moving beyond OTC medications

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