Sucralfate

Sucralfate is a basic aluminium salt of sucrose octasulphate that protects the ulcer base without altering gastric acid output. It is minimally absorbed, so its effects are local, but the absorbed aluminium accumulates in kidney failure.

Classification. Mucosal protectant; cytoprotective agent.

Mechanism. At gastric pH under 4, sucralfate cross-links into a viscous, adherent paste that binds preferentially to proteins at the ulcer crater, forming a barrier against acid, pepsin and bile salts. It also binds pepsin and bile acids and stimulates local prostaglandin, mucus and bicarbonate production.

Pharmacodynamics. Adherence to the ulcer lasts up to 6 hours. It has no systemic antisecretory effect, and its activity falls if gastric pH is raised by a PPI or H2 receptor antagonist.

Pharmacokinetics. Less than 5% of the sucrose octasulphate is absorbed and is excreted unchanged in urine. Most of the dose is excreted in faeces. About 3% to 5% of the aluminium is absorbed.

Adult oral doses unless stated. Take on an empty stomach.

Duodenal ulcer.

• Healing: 1 g four times daily (1 hour before meals and at bedtime) or 2 g twice daily (on waking and at bedtime) for 4 to 8 weeks; up to 12 weeks if not healed.

• Maintenance after healing: 1 g twice daily.

• Maximum 8 g daily.

Benign gastric ulcer. 1 g four times daily or 2 g twice daily for 6 to 8 weeks, with endoscopic confirmation of healing.

Reflux oesophagitis. 1 g four times daily for 8 to 12 weeks; a PPI is more effective and is preferred. Sucralfate is an option when a PPI is unavailable or declined.

Stress ulcer prophylaxis. 1 g every 6 hours by mouth or nasogastric tube. A PPI or H2 receptor antagonist is preferred because sucralfate blocks feeding tubes, reduces enteral drug absorption and does not reduce clinically important bleeding more than acid suppression.

Radiation or chemotherapy oesophagitis and stomatitis. 1 g in 10 mL suspension swished and swallowed four times daily. Evidence is limited and results are inconsistent.

Children. Safety and efficacy are not established; avoid because of aluminium exposure.

Contraindications. Hypersensitivity to sucralfate or aluminium; avoid in dialysis patients and in prolonged use with CrCl under 30 mL/min.

Common adverse effects. Constipation (about 2%), dry mouth, nausea, rash, back pain and dizziness.

Serious adverse effects.

• Aluminium accumulation in kidney impairment: encephalopathy, osteomalacia, microcytic anaemia and proximal myopathy.

• Hypophosphataemia with prolonged use.

• Hyperglycaemia has been reported in diabetes; monitor glucose when starting.

• Bezoar formation, particularly in critically ill patients on enteral feeding, with delayed gastric emptying, or after crushed tablets or suspension are given through feeding tubes.

• Aspiration of the suspension in patients with swallowing problems.

• Rare anaphylaxis and hypersensitivity reactions.

Major interactions. Sucralfate adsorbs and chelates many drugs.

• Fluoroquinolones, tetracyclines, ketoconazole, itraconazole, digoxin, phenytoin, theophylline, quinidine and warfarin: reduced absorption. Give the other drug at least 2 hours before sucralfate and monitor INR, phenytoin levels and theophylline levels.

• Levothyroxine: give at least 4 hours apart.

• Antacids: separate by at least 30 minutes, since sucralfate needs acid to activate.

• Citrate-containing medicines increase aluminium absorption.

Special groups.

• Pregnancy: minimal systemic absorption and animal data are reassuring; acceptable when needed.

• Breastfeeding: not expected to enter milk in meaningful amounts; compatible.

• Older adults: constipation and impaction risk; check kidney function before regular use.

• Kidney impairment: avoid prolonged use, particularly when CrCl is under 30 mL/min; if used, restrict to short courses and check aluminium.

• Liver impairment: no dose adjustment.

Formulations. Tablets 1 g; oral suspension 1 g in 5 mL.

Administration. Take 1 hour before meals and at bedtime. Swallow tablets whole with water, or dissolve in water before giving. Shake the suspension. Do not give with antacids within 30 minutes.

Enteral tubes. Use the suspension, flush thoroughly with at least 30 mL of water before and after, and stop if tube blockage occurs.

Baseline. Creatinine and calculated CrCl in older adults and anyone with suspected kidney disease. Glucose in diabetes.

Monitoring.

• Review ulcer healing at 4 to 8 weeks; confirm gastric ulcer healing endoscopically.

• Phosphate with prolonged use.

• Serum aluminium in kidney impairment on prolonged therapy.

• INR, phenytoin levels and theophylline levels when coprescribed.

• Bowel habit in older adults and on enteral feeding.

Therapeutic drug monitoring. Not applicable; serum aluminium is a toxicity measure only.

Stopping. No taper is needed. Stop for suspected aluminium toxicity, bezoar, severe constipation or hypophosphataemia.

Referral and escalation. Endoscopy for alarm features or failure to heal at 8 weeks. Nephrology input for suspected aluminium toxicity.