1. what is the most common cause of constipation? a.pelvic floor dyssynergia b.slow transit...
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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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