Pharmacology · Mucosal protectants (sucralfate and bismuth)
Sucralfate !
A sucrose–aluminium complex that sticks to the ulcer base like a bandage and shields it from acid, pepsin and bile. It is barely absorbed.
Updated 2026-11-01
Mechanism of action
Sucralfate is sucrose octasulfate combined with aluminium hydroxide. In gastric acid it forms a viscous, negatively charged paste that binds the positively charged proteins of the ulcer base and covers it, protecting it from acid, pepsin and bile salts. It also inhibits pepsin, adsorbs bile salts and may stimulate local prostaglandins and concentrate growth factors at the ulcer. It does not reduce acid secretion or gastrin.
- Acid turns sucralfate into a sticky, negatively charged paste
- The paste binds the proteins of the ulcer base
- It shields the ulcer from acid, pepsin and bile salts
- The ulcer heals under the barrier, without less acid secretion
Pharmacokinetics
- Absorption
- Minimal; it acts locally in the stomach and duodenum. Small amounts of aluminium are absorbed.
- Elimination
- Most leaves in the faeces; the small absorbed part is excreted in the urine.
Indications
- Short-term treatment of active duodenal ulcer. Peptic ulcer disease →
- Maintenance after a duodenal ulcer heals. Peptic ulcer disease →
Adverse effects
Common
- Constipation (the most common)
- Allergic reactions: hives, rash, itching
Contraindications
- Hypersensitivity to sucralfate or its excipients
Key interactions
- Fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin), tetracycline, digoxin, levothyroxine, phenytoin, quinidine, theophylline, ketoconazole, cimetidine
- Sucralfate binds them in the gut and lowers their absorption; giving the other drug at least two hours before sucralfate avoids it.
- Warfarin
- Subtherapeutic prothrombin times have been reported.
- Aluminium-containing antacids
- More total aluminium in the body, a concern in kidney failure.
What is monitored
- Kidney function and signs of aluminium toxicity in kidney failure or dialysis
- Blood levels of drugs with a narrow margin (digoxin, phenytoin, INR) when sucralfate is started or stopped
- Swallowing in frail or recently intubated patients
Administration and safety
- Taken on an empty stomach, before meals and at bedtime
- Oral use only: the suspension must never be injected
- Antacids are separated from it by about half an hour, and other drugs are given at least two hours before
- In tube feeding it can form bezoars; the team decides whether it suits the patient
Nursing care
- Space other oral medicines at least two hours before sucralfate
- Ask about constipation and encourage fluids and fibre where appropriate
- Check that the patient can swallow tablets safely; liquid forms exist
- Label oral syringes clearly so the suspension is never given intravenously
Pregnancy and breastfeeding
Animal studies showed no fetal harm and it is barely absorbed; there are no well-controlled studies, so it is used in pregnancy only if clearly needed.
Test yourself
Think of the answer, then tap the question to see it.
Why is ciprofloxacin given at least two hours before sucralfate?
Sucralfate binds the antibiotic in the gut and markedly lowers its absorption.
Why is sucralfate used with caution in chronic kidney failure?
It releases a little absorbable aluminium, which the failing kidney cannot excrete; aluminium builds up and damages bone and brain.
Does sucralfate lower gastric acid secretion?
No. It acts as a physical barrier over the ulcer; in fact it needs acid to form its protective paste.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - SUCRALFATE tablet (DailyMed (U.S. National Library of Medicine), 2026); Sucralfate: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2017); Medications for the Treatment of Gastric Acidity - Gastroenterology - MSD Manual Professional Edition (MSD Manual Professional Edition, 2025).
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