GI: Anti-diarrheals

Question 1

Types of diarrhea

Answer 1

Osmotic diarrhea

Secretory Diarrhea

Motility Diarrhea

Inflammatory Diarrhea

Question 2

Cause osmotic diarrhea

Answer 2

Lactose malabsorption

Question 3

cause secretory diarrhea

Answer 3

cholera

Question 4

cause motility diarrhea

Answer 4

Colonic hypo or hypermotility

Question 5

cause inflammatory diarrhea

Answer 5

Infection, IBD

Question 6

Diarrhea: Primary treatment goal

Answer 6

Usually self-limited illness
Primary Tx goal: rehydration & maintenance of water/electrolytes

Question 7

Diarrhea: when to administer / avoid antidiarrheals

Answer 7

• Mild to moderate acute diarrhea pharmacotherapy can be safely administered
• Avoid antidiarrheals in bloody diarrhea, high fever, or systemic toxicity

Question 8

Types of antidiarrheals

Answer 8

Opiod agonists

Colloidal Bismuth

Question 9

Opioid agonists: agents

Answer 9

Loperamide (Immodium)

Diphenoxylate/Atropine (Lomotil)

Question 10

Opioid agonists: MOA

Answer 10

Affect intestinal motility (mu receptors), secretion (delta receptors) and absorption (mu and delta receptors)

Question 11

Loperamide (Immodium): potency

Answer 11

40-50x more potent than morphine as an antidiarrheal agent

(Opioid agonist)

Question 12

Loperamide (Immodium): PK

Answer 12

• Poor penetration to brain = no analgesic effects, nonaddictive
• Half life: 11h
• Extensive hepatic metabolism

(Opioid agonist)

Question 13

Loperamide (Immodium): Formulation and dosing

Answer 13

• Formulation: Capsule, tablet, liquid, suspension
• Dose initially then after each loose stool
• OTC, Adults and pedi

(opioid agonist)

Question 14

Loperamide (Immodium): ADRs

Answer 14

Overdose may result in CNS depression (especially kids) and paralytic ileus

(opioid agonist)

Question 15

Diphenoxylate/Atropine (Lomotil): PK

Answer 15

• A: rapid, onset of action in 45min
• ½ life: 2.5h, difenoxin (active metabolite) = 12h
• M: extensive hepatic

(opioid agonist)

Question 16

Diphenoxylate/Atropine (Lomotil): formulation and dosing

Answer 16

Formulation: tablet, liquid

Dose 4x daily prn

Prescription

(opioid agonist)

Question 17

Lomotil: addiction potential

Answer 17

Diphenoxylate/Atropine

Atropine is a potent anticholinergic. Not well tolerated at high doses –> prevents abuse

(opioid agonist)

Question 18

Colloidal Bismuth: Agents

Answer 18

Bismuth subsalicylate (Pepto-Bismol)

Question 19

Bismuth subsalicylate (Pepto-Bismol): MOA

Answer 19

Not well understood. Bismuth clay contains anti-secretory, anti-inflammatory, and anti-microbial action

(Colloidal Bismuth)

Question 20

Bismuth subsalicylate (Pepto-Bismol): PK

Answer 20

• A: bismuth <1%, subsalicylate >90%
• M: stomach acid converts bismuth subsalicylate to insoluble bismuth salts and salicylic acid

(Colloidal Bismuth)

Question 21

Bismuth subsalicylate (Pepto-Bismol): formulations and dosing

Answer 21

• suspension, chewable, caplet
• Dose: q30-60 min, up to 8/day
• OTC
• Adults & pedi

(Colloidal Bismuth)

Question 22

Bismuth subsalicylate (Pepto-Bismol): ADRs

Answer 22

• Discoloration of tongue (darkening)
• Grayish black stools
• Stool impaction (infants, debilitated pts)

(Colloidal Bismuth)

Question 23

Bismuth subsalicylate (Pepto-Bismol): Pedi

Answer 23

Caution in kids d/t risk of Reye’s syndrome (pedi pepto often does not contain bismuth subsalicylate)

(Colloidal Bismuth)