Pathophysiology
Clinical meaning
Sucralfate's mechanism involves acid-catalyzed hydrolysis of the aluminum hydroxide moiety followed by cross-linking of sucrose octasulfate polymers through aluminum coordination bonds, creating a viscous polyanion gel with strong electrostatic affinity for positively charged proteins (fibrinogen, albumin, fibronectin) exposed at the ulcer base. The binding energy (approximately 6.5 kcal/mol) exceeds that of normal mucosa (2.1 kcal/mol), explaining selective ulcer adherence. Cytoprotective mechanisms operate through parallel pathways: direct stimulation of constitutive cyclooxygenase-1 (COX-1) increasing prostaglandin E2 and I2 synthesis (enhancing mucosal blood flow by 30% and bicarbonate secretion by 50%), sequestration of epidermal growth factor (EGF) from saliva and gastric juice at the ulcer surface (concentrating it 7-fold compared to surrounding mucosa), and adsorption of bile acids (primarily chenodeoxycholic acid and deoxycholic acid) that cause mucosal injury through solubilization of membrane phospholipids. The pepsin inhibition (32% reduction) occurs via both direct binding and pH-mediated conformational change of the enzyme. Aluminum absorption is minimal (0.005-0.1% of administered dose) in patients with normal renal function, with clearance via glomerular filtration. In CKD stage 4-5 (GFR below 30), aluminum clearance decreases proportionally, with accumulation in...