Pancreatic Enzyme Replacement Therapy in CF Patients

Cystic fibrosis is the most common fatal genetic disorder in North America. CF affects the epithelial transport in exocrine tissues. The disorder produces thick, sticky mucus secretions that may seriously impair the function of various organ systems. The organ systems that are affected include the respiratory tract, the gastrointestinal tract, the liver, the genitourinary system, and the sweat glands.

CF has three major consequences: chronic lung disease, pancreatic insufficiency, and abnormally high electrolyte concentrations in the sweat.

Cystic fibrosis causes pancreatic insufficiency in most cases, causing 85-90% of serious cases to require pancreatic enzyme replacement therapy (PERT). With age, damage to the pancreas becomes worse. The thick mucus obstructs the small pancreatic ducts and interferes with the secretion of digestive enzymes, pancreatic juices, and pancreatic hormones. Eventually, the pancreatic cells are surrounded by mucus and are gradually replaced by fibrous tissues. Malabsorption of many nutrients including fat, protein, vitamins, and minerals often leads to malnutrition. Additionally, the secretion of insulin may be affected resulting in glucose intolerance and diabetes.

With high energy needs, fat restrictions are inappropriate. Instead, pancreatic enzyme replacements are used to control Steatorrhea, relieve abdominal pain, and reduce the mass and frequency of stools passed. To improve the effectiveness of the enzyme replacements, H2-blockers are often provided as well. Even with enzyme replacements, from 10-20% of food energy is lost in the stools.

Pancreatic insufficiency has a strong influence on nutrition status and is a predictor of long-term outcome. The thickened secretions obstruct the pancreatic ducts and prevent the secretions of lipase, amylase, proteases, and bicarbonate. When pancreatic insufficiency is present, individuals are treated with pancreatic enzyme extracts. All enzyme products contain the various enzymes synthesized by the pancreas, including amylase, proteases and lipase in varying amounts. Commercial enzyme products vary in lipase activity from 4,000-25,000 U lipase/capsule. They are available in powder form as tablets that are acid labile or as enteric-coated microspheres- the enteric coating is designed to protect the enzyme from destruction by the acidic environment of the stomach.

Pancreatic enzymes are always taken when food or beverages are consumed. The dosage for enzymes in individualized based on the patient’s diet, nutritional status, degree of pancreatic insufficiency, intestinal pH, and GI anatomy and physiology. Because of inconsistencies in enzyme formulations, the Food and Drug Administration (FDA) has issued a rule requiring manufacturers of pancreatic enzyme supplements to obtain approval for their products. Prior to obtaining approval, manufacturers will need to test the enzymes in clinical trials and demonstrate that they are safe and effective. This rule means that the FDA now requires pancreatic enzymes to meet the same standards of testing as any other new drug.