(20) Mucosal protective agents: sucralfate, misoprostol & bismuth

MUCOSAL PROTECTIVE AGENTS

main idea

• These drugs mainly: ↑ stomach protection

• Normal stomach defenses include:

  • mucus

  • bicarbonate

  • blood flow

  • prostaglandins

  • tissue repair

 How mucosal protection differs from acid suppression?

• PPIs/H2 blockers mainly: ↓ the aggressive factor = acid

• GI injury happens when: aggressive factors > protective factors

MASTER CHART

SAVE

MY
BELLY

STOP HERE

Mucosal protective drugs

• Sucralfate

• Misoprostol

• Bismuth

Sucralfate

topics discussed

• Main idea

• Mechanism

• Use

• ADR

• Admin

• DDI

Sucralfate

Main idea

• Band-Aid over an ulcer

• Sucralfate does NOT mainly suppress acid. It covers and protects the injured area.

Sucralfate

Mechanism

• In acidic/watery environment: sucralfate

→ becomes a gel

→ attaches to proteins in the ulcer

→ physically covers the ulcer

→ protects it from acid + pepsin

Sucralfate

administration

• Empty stomach

• 1 g QID

• ≥1 hour before meals

Sucralfate

use

• stress-related bleeding prophylaxis in ICU

• Can also be used as an adjunct to acid-suppressing drugs.

Sucralfate

ADR

• Constipation

• Avoid prolonged use in renal insufficiency because of concern with aluminum.

Sucralfate

DDI

Sucralfate forms a gel

→ can bind other medications

→ ↓ their absorption

→ separate dosing

MISOPROSTOL

topic overview

• Main Idea

• Mechanism

• Use

• ADR

• MISOPROSTOL + PREGNANCY

MISOPROSTOL

Main Idea

• Misoprostol = PGE₁ analog

• Think: “Replace the prostaglandin protection that NSAIDs removed,” and restores GI protection.

MISOPROSTOL

mechanism

Misoprostol

→ ↑ mucus

→ ↑ bicarbonate

→ ↑ mucosal blood flow

AND

→ ↓ acid secretion

→ protects stomach

MISOPROSTOL

Main use

Prevent NSAID-induced ulcers

MISOPROSTOL

ADRs

• diarrhea

• abdominal pain

• needs frequent dosing. Why?

  • Half-life <30 minutes → usually 3–4 doses/day

MISOPROSTOL

+ PREGNANCY

• → prostaglandin receptors in uterus → uterine contraction → can cause abortion

• contraindicated in pregnancy because can cause abortion.

BISMUTH

Topics Covered

• main idea/mechanism

• use

• ADR

BISMUTH

main idea/mechanism

• Think Pepto-Bismol.

• In stomach: bismuth subsalicylate → separates into:

  • Bismuth → mainly local GI action

  • Salicylate → absorbed/systemic component

BISMUTH

use - overview

1. Dyspepsia

2. H. pylori

3. Acute / traveler's diarrhea

BISMUTH

use - Dyspepsia

Bismuth

→ coats ulcers/erosions

→ protects against acid/pepsin.

BISMUTH

use - H. pylori

Bismuth has activity against H. pylori

BISMUTH

use - Acute / traveler's diarrhea

Bismuth subsalicylate

→ ↓ prostaglandin/chloride secretion

→ ↓ stool frequency and liquidity

BISMUTH

ADRs/Cautions

• Very important to know difference

  • Bismuth → black stool and dark tongue that is harmless

  • Melena → black stool from digested blood / upper GI bleeding

• Other cautions

  • use short-term

  • avoid in renal insufficiency

  • prolonged use can rarely cause neurotoxicity/encephalopathy

  • high doses of subsalicylate → salicylate toxicity