Upon completion of the chapter, the reader will be able to:
Describe the pathophysiology of acute pancreatitis and chronic pancreatitis.
Differentiate acute pancreatitis from chronic pancreatitis.
Formulate care plans for managing acute and chronic pancreatitis.
Choose appropriate pancreatic enzyme supplementation for patients with chronic pancreatitis.
The pancreas is a gland in the abdomen lying in the curvature of the stomach as it empties into the duodenum. It functions primarily as an exocrine gland but also has endocrine function. The exocrine cells of the pancreas are called acinar cells that produce and store digestive enzymes that mix with a bicarbonate-rich solution released from duct cells to produce pancreatic juice. This juice is released through the ampulla of Vater into the duodenum to aid in digestion and buffer acidic fluid released from the stomach (Figure 23–1).1
Anatomical structure of the pancreas and biliary tract. (From Bolesta S, Montgomery PA. Pancreatitis. In: DiPiro JT, Talbert RL, Yee GC, et al., eds. Pharmacotherapy: A Pathophysiologic Approach, 10th ed. New York, NY: McGraw-Hill; 2017; Figure 39–1, with permission. www.accesspharmacy.com.)
Pancreatic enzymes are produced and stored as inactive proenzymes within zymogen granules to prevent autolysis and digestion of the pancreas. Amylase and lipase are released from the zymogen granules in the active form, whereas the proteolytic enzymes are activated in the duodenum by enterokinase. Enterokinase triggers the conversion of trypsinogen to the active protease trypsin, which then activates the other proenzymes to their active enzymes. The pancreas contains a trypsin inhibitor to prevent autolysis.
EPIDEMIOLOGY AND ETIOLOGY
In the Western Hemisphere, acute pancreatitis (AP) is caused mainly by ethanol use/abuse and gallstones (cholelithiasis). Ethanol use accounts for about 30% of AP cases and gallstones about 30% to 40% of cases. Other common causes include hypertriglyceridemia, endoscopic retrograde cholangiopancreatography (ERCP), pregnancy, and autodigestion due to early activation of pancreatic enzymes. Numerous medications have been implicated as causes of AP, but other causes should be ruled out before discontinuing a medication indefinitely (Table 23–1).2
Table 23–1Selected Medications Associated with Acute Pancreatitis |Favorite Table|Download (.pdf) Table 23–1 Selected Medications Associated with Acute Pancreatitis
Cardiovascular: Enalapril, lisinopril, ramipril, losartan, furosemide, hydrochlorothiazide, amiodarone, statins
Anti-infectives: Metronidazole, sulfonamides, tetracycline, tigecycline, pentamidine, isoniazid, lamivudine, didanosine, nelfinavir, interferon/ribavirin
Gastrointestinal: Omeprazole, mesalamine
Neurologic: Valproic acid, clozapine
Hormonal: Conjugated estrogens, tamoxifen
Oncologic: Ifosfamide, cytarabine
Analgesics: Sulindac, salicylates
Other: Propofol, mercaptopurine, azathioprine, corticosteroids, marijuana
Ethanol abuse may cause precipitation of pancreatic enzymes in pancreatic ducts, leading to chronic inflammation and fibrosis resulting in loss of exocrine function. Ethanol may be directly toxic to the pancreatic cells ...