lecture 66

Question 1

primary causes of chronic constipation

Answer 1

normal transit functional symptomatic (most common)
slow transition
evacuation disorder

Question 2

secondary causes of chronic constipation

Answer 2

medications
obstruction (cancer, stricture)
metabolic (hypothyroid, hypercalcemia)
neurological (parkinsonism, MS)
systemic (scleroderma, amyloidosis)
psychiatric (depression, eating disorders)

Question 3

medications that cause constipation

Answer 3

Analgesics (opioids and NSAIDs)
antacids (aluminum, calcium)
agents with strong anticholinergic properties (antihistamines, antimuscarinics, and amitriptyline)
iron preparations
diueretics
chronic use of stimulant laxatives (mixed evidence, unlikely if normal dose is used)

Question 4

normal physiology of defectation

Answer 4

sensory perception of stool
rectal distension
contract diaphragm, abdomen, and rectal muscles
relax EAS (decrease LES pressure)
relax puborectallis muscle

Question 5

dyssynergic defecation

Answer 5

prolonged colonic transit time
discoordination of abdominal, rectonanal, and pelvic floor muscles
rectal hyposensitivity
paradoxical increase in sphincter pressure
under 20% relaxation of resting and sphincter pressure
inadequate abdomino-rectal propulsive forces

Question 6

acute constipation presentation

Answer 6

a noticeable change in normal BM pattern (less than 3 per week)
other features - stools are dry and hard; BM is painful and stools are difficult to pass; feelings that bowels have not been fully emptied

Question 7

acute treatment

Answer 7

based on relief being seen in
follow up in 1-2 days and check stool frequency, episodes of diarrhea, dietary changes, and SE from meds

Question 8

acute relief in 1 hour

Answer 8

use enema (saline, tap water, or soap suds)
bisacodyl or glycerin suppository

Question 9

acute relief in 3 to 6 hours

Answer 9

citrate of magnesia
larger doses of PEG (also used for GI preps)

Question 10

acute relief in 24 hours

Answer 10

bisacodyl tablets
senna tablets

Question 11

acute relief in 48 hours

Answer 11

milk of magnesia
PEG (miralax)

Question 12

chronic presentation

Answer 12

includes 2 or more of the following during at least 25% of defecations with symptoms lasting over 6 weeks
1. straining
2. lumpy or hard stools
3. sensation of incomplete evacuation
4. sensation of anorectal obstruction/blockage
manual naeuvers to facilitate defecation
under 3 defecations per week

Question 13

etiology of chronic constipation

Answer 13

dietary (poor fluid intake or decrease caloric intake)
failure to heed defecation reflex
impaired physical mobility
lack of privacy
increased psychological distress
disease states that slow down GI motility (diabetes, parkinson’s, CNS injury or disease, MS)

Question 14

treatment of chronic constipation

Answer 14

step therapy
follow up in 1-2 weeks and check stool frequency, episodes of diarrhea, dietary changes, and SE from meds

Question 15

step therapy for chronic constipation

Answer 15

1 - relieve acute constipation through dietary modifications
2 - bulk forming laxatives and fluids
3 - PEG, Lactulose, or sorbitol
4 - short term use of stimulant then maintenance agent
5 - lubiprostone, linaclotide, prucalopride, plecanatide ($$$, usually reserved for chronic idiopathic)

Question 16

referral required when the patient has

Answer 16

symptoms that have persistent (with appropriate intervention for greater than 2 weeks without significant relief)
black or tarry stools
marked abdominal pain or discomfort
a fever
severe NV
family history of IBD or colon cancer
drastic change in severity or nature of symptoms

Question 17

prep for GI procedure

Answer 17

hyperosmotic or saline laxatives (PEG, OsmoPrep, Visicol, Suprep, Suclear, Prepo)
clear liquid starts day prior to procedure in the afternoon/evening
drinking large quantities of fluid is key
use great caution in patients with heart failure, renal disease, electrolyte abnormalities

Question 18

promote regular bowel habits

Answer 18

include ample fluids and fiber in diet
do not ignore the urger to defecate
establish a regular, unhurried time for BM
encourage patients to defecate when colonic activity is greatest (first thing in the morning, within 30 minutes after meal)

Question 19

ample fluid and fiber diet

Answer 19

6-8 glasses of water per day
add in high fiber foods to diet slowly (20-30g per day; increase over 7-10 days to minimize gas and to promot natural fiber degradation)
eat prunes (high concentration of simple sugars)
alternative to prunes include fresh green kiwifruit, dried pitted prunes, power psyllium

Question 20

constipation in spinal cord injury pt

Answer 20

routine use of bowel stimulants
usually suppositories

Question 21

constipation in pregnancy

Answer 21

diet, fiber, docusate
senna in more severe cases

Question 22

constipation in diabetes

Answer 22

use prokinetic agents (metoclopramide, prucalopride)
stimulants

Question 23

constipation in patients on O

Answer 23

stimulants
then add docusate, lactulose, or PEG PRN
avoid bulk laxatives
Opiod receptor antagonist when other treatment doesn’t work (Methylnaltrexone, Naloxegol)

Question 24

Methylnaltrexone (Relistor)

Answer 24

treats OIC
8-12 mg SQ every other day
expect BM within 30 minutes
very expensive

Question 25

Naloxegol (Movantik)

Answer 25

25mg PO qd
1hr prior to 1st meal or 2hrs after meals (on empty stomach, high fat meal increased extent and rate of absorption)
very expensive

Question 26

bulk laxatives for constipation

Answer 26

drugs - psyllium, methylcellulose, calcium polycarbophil
mechanism - forms emollient gels which retain water, swells, and stimulates BM

Question 27

pros/con bulk laxatives

Answer 27

pros - soften stools better than docusate; well tolerated with fewer SE
cons - taste; must have adequate fluid intake; gas formation; impact on drug absorption; not ideal for bedridden patients

Question 28

surfactant/emollient in constipation

Answer 28

drug - docusate (doss)
mechanism - decrease fecal surface tension; stool softener
PROS - safe; helps prevent hard stools and hemorrhoids
CONS - unknown efficacy; not effective for active constipation

Question 29

lubricants in constipation

Answer 29

drug - mineral oil
mechanism - lubricates lumen of colon
pros - lubricates, softens
cons - poor patient acceptance due to oilness; only effective in prevention of constipation; may decrease absorption of fat-soluble vitamins

Question 30

saline laxative in constipation

Answer 30

drugs - milk of magnesia, magnesium citrate, fleet’s saline enema (rapid onset)
mechanism - draws fluid into colon which stimulates motility

Question 31

saline laxatives pros/cons

Answer 31

pros - used for acute management of constipation; quick onset; most economical
cons - taste; avoid in renal patients due to sodium and magnesium

Question 32

hyperosmotic agents in constipation

Answer 32

drugs- sorbitol, lactulose, peg 3350, glycerin suppositories
mechanism - draaws fluid into colon due to high concentration of sugar, peg, or glycerin

Question 33

hyperosmotic agents pros/con

Answer 33

pros - well tolerated; softens while stimulating BM; excellent for chronic constipation
cons - 1 to 3 day onset at usual doses; sweet taste of some agents; minor nausea, cramping

Question 34

stimulant laxatives in constipation

Answer 34

drugs - senna, bisacodyl (enteric coated and suppositories)
mechanism - locally stimulate enteric nerves which stimulates contractions and mobility; also increases fluid and Na secretion into the lumen

Question 35

stimulant laxatives pros/cons

Answer 35

pros - 6 to 12 hours onset; works in patients with motility disorders; DOC for OIC
cons - risk of nausea and cramping; avoid long-term continuous use in pts with normal GI motility