Ch 70: Constipation and Diarrhea

Question 1

med conditions that cause constipation

Answer 1

IBS-C, anal disorders, MS, cerebrovascular events, PD, spinal cord tumors, DM, hypothyroid

Question 2

lifestyle measures for constipation

Answer 2

64 oz water daily, limit caffeine/etoh d/t dehydration, inc physical activity. replace refined foods with whole grains and foods high in fiber.

Question 3

drugs that cause diarrhea

Answer 3

antacids with Mg, abx or CDAD, antineoplastics, colchicine, laxatives, metoclopramide, misoprostol, quinidine

Question 4

diarrhea common causes

Answer 4

bacterial - e. coli. r/o lactose intolerance. viral resolves in few days without tx. food poisoning or eating/drinking contamination

Question 5

drug tx diarrhea

Answer 5

short term bismuth subsalicylate (pepto bismol) has antisecretory and antibacterial effects, or loperamide (antimotility agent that slow GI and prolong water absorption)

Question 6

non drug tx diarrhea

Answer 6

fluid and ‘lyte replacement. replace fuids with PO rehydration solns (pedialyte, infalyte, etc) or gatorade as alt.

Question 7

diarrhea assoc with IBS

Answer 7

imodium usually acceptable. rifaximin (xifaxan) is abx approved for IBS-D but costly and relapse usually within several mo of tx. alosetron (lotronex) useful for women only, restricted d/t risk of ischemic colitis. pain/abd discomfort managed with antispasmodics and antidepressants.

Question 8

peripherally acting mu opioid agonist - example, schedule, indication

Answer 8

eluxadoline (Viberzi), CIV, REMS. indication: IBS-D where D is difficult to treat with usual tx. acts like opioid to induce constipation, but does not cross CNS.

Question 9

pepto-bismol - generic, contraindications, ADRs.

Answer 9

bismuth subsalicylate. contraindications: salicylate allergy, use with other salicylates (ASA, NSAIDs), coagulopathy, black/tarry stool. ADRs: black tongue/stool. caution in children d/t reye syndrome.

Question 10

imodium - generic, dosing, notes

Answer 10

loperamide. 4 mg PO after 1st loos stoll then 2 mg after each subsequent loose stool. max 16 mg/d. self tx should not be >48 h

Question 11

lomotil - generic, schedule, max dose

Answer 11

diphenoxylate/atropine. max 20 mg/d. subtx amt of atropine included to discourage abuse. CV

Question 12

dicyclomine - brand, warnings, ADRs, MOA, indication

Answer 12

bentyl. antispasmotic. warnings: AntiACh. ADRs: dizziness, dry mouth, nausea, blurred vision. indication: abd discomfort in diarrhea or constipation with IBS

Question 13

AGA guidelines for constipation

Answer 13

inc fiber intake via diet or supplement (1st line and for preg), add osmotic agent or stool softener which is OTC.

Question 14

bowel prep

Answer 14

prior to colonoscopy. sodium phosphates (fleet enema, osmoprep) can cause fluid/lyte abnormalities, risk with renal or cardiac disease. PEG formulations. use extra caution with CVD, renal insufficiency, and with concomitant diuretics.

Question 15

bulk forming agents - examples, MOA, notes

Answer 15

psyllium (metamucil), calcium polycarbophil (fibercon), methylcellulose (citrucel). create gel like matrix in stool to soak up fluid in loose stool and add bulk to stool. take 2 h before/after other drugs. requires adequate fluid.

Question 16

osmotics - examples, MOA, ADRs, notes

Answer 16

Mg hydroxide (MOM), PEG 3350 (miralax), glycerin (pedia-lax). ADR: lyte imbalance. MOA: cause fluid to retain in bowel wiht net inc of fluid secretions in small intestines to distend colon and inc peristalsis. Caution with Mg in renal impairment. onset is 30 min PO. suppository used for children who need to defecate.

Question 17

stimulants - examples, MOA, notes

Answer 17

senna (senokot), bisacodyl (dulcolax). MOA: stimulates the colonic neurons for peristaltic activity. give 30 min after meal. onset is 6-12 h oral. usually needed with chronic opioids. “push”

Question 18

emollients - example, MOA, notes

Answer 18

docusate (colace). MOA: soften fecal mass by reducing surface tension of oil-water interface of stool to allow more water and fat to mix with stool and make defecation easier. preferred when straining should be avoided (postpartum, post-MI, anal fissures, hemorrhois). use when stool is hard/dry. “mush”

Question 19

lubricants - example, MOA, notes

Answer 19

mineral oil. MOA: coat bowel and stool mass with water proof film to keep moisture in stool to defecate easier. onset 6-8 h. generally not rec d/t safety like aspiration (lipid pneumonitis)

Question 20

osmotics for whole bowel irrigation

Answer 20

PEG (colyte, gavilyte, golytely, etc). contraindications: acute phosphate nephropathy, gastric bypass or stapling surgery. consume prior to colonoscopy along with “clear liquid diet”. counsel to not consume red/blue/purple food coloring, solid or semi solid foods. some brands need medguide.

Question 21

lubiprostone - brand, MOA, ADRs, indication

Answer 21

amitiza. activates Cl channels in GI to inc fluid in GI and peristalsis. ADRs: ND, HA. consider alt if pt on methadone. indicated in CIC, opioid induced constipation, IBS-C in women.

Question 22

linaclotide - brand, MOA, BBW, ADRs, notes, indication

Answer 22

linzess. agonist of guanylate cyclase C to inc Cl and bicarb secretion into GI to dec GI transit time. BBW: death d/t dehydration in animals, avoid in peds. ADRs: diarrhea. keep in original container, medguide. indication: CIC in adults, IBS-C in adults

Question 23

alvimopan - brand, MOA, BBW, contraindications, indication

Answer 23

entereg. peripherally acting mu opioid antagonist to dec constipation. BBW: potential risk of MI with long-term use. contraindications: pts who have taken tx dose of opioids for 7+ days before use. indications: post-surgical pts to dec risk of post-op ileus. inpt only. REMS drug.

Question 24

plecanatide - brand, indication, BBW, ADRs, notes

Answer 24

trulance. agonist of guanylate cyclase C to inc Cl and bicarb secretion into GI to dec GI transit time. BBW: death d/t dehydration in animals, avoid in peds. ADRs: diarrhea. indication: CIC in adults.