Acute pancreatitis (AP) is one of the most common gastrointestinal causes of hospital admission, ranging from mild self-limited disease to severe necrotizing pancreatitis with multi-organ failure and mortality exceeding 30% in infected necrotizing disease. Pharmacological and supportive management is predominantly supportive, but the choice of resuscitation fluid, the approach to pain control, the disciplined restriction of antibiotics, and the route and timing of nutritional support each have measurable outcome impact based on high-quality trial evidence.
Intravenous fluid resuscitation is the cornerstone of early AP management. Aggressive early hydration counteracts the profound third-space fluid losses, microvascular leakage, and hypovolemia that drive pancreatic ischemia and progression to necrosis. The choice of resuscitation fluid matters: lactated Ringer's solution (LR) is preferred over 0.9% normal saline (NS) based on mechanistic and trial data. LR is mildly alkalotic (pH 6.5) and buffered by lactate metabolism in the liver to bicarbonate, which may reduce systemic inflammatory response syndrome (SIRS (systemic inflammatory response syndrome)) activation driven by the hyperchloremic acidosis associated with large-volume NS infusion. The WATERFALL (Water for Acute Pancreatitis with Lactated Ringer's and Lactated Ringer's) randomized controlled trial (RCT (randomized controlled trial)) demonstrated that LR significantly reduced the composite rate of moderately severe or severe pancreatitis compared to NS, with a lower rate of SIRS persistence at 24 hours.1 Goal-directed fluid resuscitation targeting improved clinical parameters (heart rate below 120 bpm, urine output above 0.5 mL/kg/hour, hematocrit reduction toward normal) is preferred over fixed-volume protocols, and over-resuscitation causing abdominal compartment syndrome should be avoided.
Pain management in AP requires a balanced approach that provides adequate analgesia without introducing paralytic ileus, respiratory depression, or masking clinical deterioration. Intravenous opioids remain the primary analgesic class for moderate-to-severe AP pain, with hydromorphone or morphine used most commonly; the earlier concern about sphincter of Oddi spasm with morphine has not been validated as clinically significant in adequately powered comparative studies. Epidural analgesia provides superior pain control in severe AP and is associated with improved splanchnic perfusion, but requires intensive care unit (ICU (intensive care unit)) monitoring and is not universally available. Non-opioid adjuncts including intravenous acetaminophen and NSAIDs may reduce opioid requirements but are typically insufficient as monotherapy in moderate-to-severe disease. ERCP (endoscopic retrograde cholangiopancreatography) with sphincterotomy is indicated emergently in AP complicated by cholangitis or persistent biliary obstruction, and within 72 hours in severe gallstone pancreatitis with biliary obstruction; it does not alter the course of mild gallstone AP without obstruction or cholangitis.2
Antibiotic use in AP must be restricted to evidence-based indications. Prophylactic antibiotics for sterile necrotizing pancreatitis – once widely practiced based on the hypothesis that gut bacterial translocation could be prevented – do not reduce mortality, infected necrosis rates, or need for intervention in multiple large RCTs and meta-analyses, and are explicitly discouraged in all current guidelines. The only validated indications for antibiotics in AP are confirmed infected necrosis (typically diagnosed by CT (computed tomography)-guided fine-needle aspiration with positive culture, or by clinical deterioration with gas in the necrotic collection on CT imaging) and concurrent cholangitis. For infected pancreatic necrosis, antibiotics that achieve adequate penetration into pancreatic and peripancreatic tissue are selected: imipenem-cilastatin, meropenem, and quinolones with metronidazole are commonly used. Fluconazole or echinocandin coverage is added if fungal colonization is demonstrated. Definitive management of walled-off pancreatic necrosis (WOPN (walled-off pancreatic necrosis)) is endoscopic or surgical drainage, not antibiotic-only therapy.3
Nutritional support in AP should be initiated early and via the enteral route whenever feasible. Enteral nutrition (EN (enteral nutrition)) maintains gut mucosal integrity, reduces bacterial translocation, supports immune function, and reduces infectious complications compared to total parenteral nutrition (TPN (total parenteral nutrition)) in multiple RCTs. Nasogastric (NG (nasogastric)) tube feeding is equivalent in efficacy and safety to nasojejunal (NJ (nasojejunal)) feeding in the majority of AP patients, despite earlier concerns about stimulating pancreatic secretion – clinical trials have not shown significant differences in pain, complications, or tolerance between routes. TPN is reserved for patients in whom enteral access cannot be established or enteral feeding is not tolerated. Oral feeding should be reintroduced as early as tolerated clinically, beginning with low-fat, soft solid foods rather than clear liquids, as the clear-liquid-to-solid progression does not reduce complications and prolongs hospitalization.4
The decision to prescribe antibiotics in AP should be based on documented evidence of infection, not on clinical deterioration alone (which can reflect SIRS without infection), CRP elevation, or fever. Prophylactic antibiotic use in sterile necrosis exposes patients to Clostridioides difficile infection risk, antibiotic resistance selection, and drug adverse effects without benefit. Repeat CT or clinical assessment at 7–10 days in deteriorating patients with necrotizing pancreatitis is appropriate; fine-needle aspiration is indicated when CT cannot distinguish infected from sterile necrosis and the result will change management.
Chronic pancreatitis (CP (chronic pancreatitis)) results in progressive, irreversible destruction of both exocrine and endocrine pancreatic tissue. Exocrine pancreatic insufficiency (EPI (exocrine pancreatic insufficiency)) – the inability to produce adequate digestive enzymes for luminal nutrient digestion – typically manifests when exocrine function falls below 10% of normal. It presents clinically with steatorrhea, fat-soluble vitamin deficiencies, malnutrition, and weight loss, and requires pharmacological replacement of pancreatic enzymes as the primary treatment.
Pancreatic enzyme replacement therapy (PERT (pancreatic enzyme replacement therapy)) is the definitive pharmacological treatment for EPI. The commercially available preparations contain lipase, protease, and amylase in defined ratios, but lipase is the critical therapeutic component because fat digestion is most severely impaired in EPI and because fat malabsorption drives the greatest nutritional morbidity. Standard dosing is 40,000–50,000 Ph. Eur. units of lipase per main meal and 20,000–25,000 units per snack, with titration upward (to a maximum of approximately 80,000 units/meal) if steatorrhea persists or fat absorption is inadequate by coefficient of fat absorption (CFA (coefficient of fat absorption)) testing. Formulation selection is essential: pH-sensitive enteric-coated microspheres (2 mm or smaller) empty from the stomach concurrently with nutrient chyme and dissolve in the duodenum when luminal pH rises above 5.5, releasing enzymes precisely when and where they are needed. Older large-particle or non-enteric-coated preparations are substantially less bioavailable.5
The timing of PERT administration is as important as the dose. Enzymes must be taken during the meal, not before or after, to achieve mixing with the food bolus in the stomach and synchronized duodenal release. Splitting the dose (half at the start, half midway through a large meal) improves mixing efficiency with large meals. A proton pump inhibitor (PPI (proton pump inhibitor)) is added as adjunctive therapy when response to PERT at adequate doses remains suboptimal, because pancreatic bicarbonate deficiency leads to low duodenal pH, which impairs enteric-coating dissolution and inactivates co-released pancreatic enzymes by acid denaturation. PPI co-administration raises duodenal pH above the dissolution threshold and substantially improves PERT efficacy in patients with documented poor response.6 Fat-soluble vitamin deficiencies – ADEK (vitamins A, D, E, and K) – are nearly universal in inadequately treated EPI due to impaired micellar fat absorption. Routine supplementation with multivitamins containing fat-soluble vitamins and monitoring of serum 25-hydroxyvitamin D, vitamin A, vitamin E, and INR (as a surrogate for vitamin K activity) are mandatory in established EPI. Zinc and selenium deficiency should also be screened given their co-dependence on fat-soluble nutrient absorption pathways.
Pain management in CP is one of the most clinically challenging aspects of the disease. The pain arises from multiple mechanisms including elevated ductal pressure from obstruction, perineural inflammation, and central sensitization, and therefore responds variably to any single intervention. The WHO analgesic ladder applies: non-opioid analgesics first (acetaminophen, NSAIDs), then weak opioids, then strong opioids, with the understanding that long-term opioid therapy in CP carries substantial risk of opioid use disorder in a population already predisposed by co-occurring alcohol use disorder. Pregabalin, by modulating central pain sensitization through voltage-gated calcium channel alpha-2-delta subunit blockade, has demonstrated modest benefit in CP pain in RCTs and is a useful opioid-sparing adjunct.7 Antioxidant supplementation (selenium, ascorbic acid, beta-carotene, alpha-tocopherol, methionine) has been investigated in small trials with inconsistent results. Endoscopic ductal decompression, extracorporeal shock wave lithotripsy, and celiac plexus block are procedural options for refractory pain. Alcohol cessation is the single most impactful intervention for slowing disease progression and pain trajectory in alcohol-related CP.
Step 1: Start at 40,000–50,000 lipase units per main meal; 20,000–25,000 per snack; administer during (not before) the meal.
Step 2: If steatorrhea persists at 4 weeks, increase to maximum ~80,000 units/meal. Verify timing compliance and formulation type (must be pH-sensitive microspheres).
Step 3: Add PPI if response remains suboptimal – targets duodenal pH above dissolution threshold. Omeprazole 20–40 mg once daily before breakfast is standard.
Step 4: Monitor: CFA on high-fat diet (normal >92%), fat-soluble vitamin levels annually, weight and BMI at each visit.
Note: Porcine-derived preparations are standard – inform patients for dietary or religious considerations. Pediatric dosing uses weight-based lipase units per kilogram per meal (max 2,500 units/kg/meal).
Pancreatic endocrine tumors – including insulinoma, VIPoma (vasoactive intestinal peptide-secreting tumor), glucagonoma, gastrinoma, and non-functioning pancreatic neuroendocrine tumors (NETs (neuroendocrine tumors)) – are managed through a combination of surgical resection when feasible and pharmacological control of hormone excess when surgery is not immediately possible or the tumor is metastatic. Somatostatin analogues are the pharmacological cornerstone of most functional pancreatic endocrine tumor syndromes.
Somatostatin analogues (SSAs (somatostatin analogues)) – specifically octreotide and lanreotide – are synthetic long-acting analogues of the endogenous peptide somatostatin, which acts through five G-protein-coupled somatostatin receptor subtypes (SSTR1–5) to suppress hormone secretion and inhibit cell proliferation. Most functional gastroenteropancreatic neuroendocrine tumors (GEP-NETs (gastroenteropancreatic neuroendocrine tumors)) express SSTR2 (somatostatin receptor subtype 2) and SSTR5 (somatostatin receptor subtype 5) at high density, making SSAs effective secretory inhibitors in the majority of cases. Octreotide is available as immediate-release subcutaneous injection (used for acute symptom control and initial titration) and as long-acting release (LAR) intramuscular depot formulation (monthly dosing for maintenance). Lanreotide autogel is a deep subcutaneous depot administered monthly or every 6–8 weeks at higher doses.8
VIPoma (Verner-Morrison syndrome) produces watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome) through VIP (vasoactive intestinal peptide)-mediated intestinal fluid and electrolyte hypersecretion. Octreotide at 100–600 micrograms per day in divided subcutaneous doses, or equivalent LAR formulation, suppresses VIP secretion and controls diarrhea in 80–90% of patients, enabling fluid and electrolyte stabilization before surgical resection. Glucagonoma produces the glucagonoma syndrome (migratory necrolytic erythema, glossitis, angular cheilitis, weight loss, and hyperglycemia) through glucagon excess-driven catabolism and fatty acid mobilization; SSAs reduce glucagon levels and improve the skin manifestations, though response is partial and nutritional support and insulin for hyperglycemia management are co-required. Carcinoid syndrome – flushing, diarrhea, and bronchospasm caused by serotonin, bradykinin, and other vasoactive mediators from intestinal carcinoid NETs with hepatic metastases – is controlled by SSAs (octreotide LAR 20–30 mg monthly) which suppress 5-HT (5-hydroxytryptamine) and other mediator secretion.8
Insulinoma is the most common functional pancreatic NET (neuroendocrine tumor), causing hypoglycemia through autonomous insulin secretion independent of blood glucose. The pharmacological goal before surgical resection – or in inoperable cases – is suppression of insulin release and prevention of hypoglycemia. Diazoxide, a non-diuretic benzothiadiazine derivative, activates ATP-sensitive potassium (KATP (ATP-sensitive potassium)) channels in pancreatic beta cells, hyperpolarizing the cell membrane and suppressing voltage-gated calcium channel opening, thereby inhibiting calcium-triggered insulin exocytosis. Diazoxide is dosed at 150–400 mg per day orally in divided doses, with frequent glucose monitoring. Its principal adverse effects are sodium and fluid retention (managed with co-prescribed diuretics, typically hydrochlorothiazide), hirsutism with long-term use, and hyperglycemia if dosed too aggressively. SSAs are less reliable for insulinoma than for VIPoma/glucagonoma because insulinoma commonly expresses SSTR3 (somatostatin receptor subtype 3) and SSTR5 without SSTR2, and paradoxical hypoglycemia worsening can occur through suppression of glucagon counter-regulation; SSAs should be used for insulinoma only under careful glucose monitoring.9
Beyond hormonal control, SSAs have antiproliferative effects on NETs mediated through SSTR2-induced cell cycle arrest, promotion of apoptosis, and inhibition of angiogenic growth factor secretion. The PROMID (Placebo-controlled, Prospective, Randomized study on the effect of Octreotide LAR in the control of tumor growth In patients with metastatic neuroendocrine midgut tumors) trial demonstrated that octreotide LAR significantly prolonged time to tumor progression in midgut NETs compared to placebo,8 and the CLARINET (Controlled study of Lanreotide Antiproliferative Response In NETs) trial confirmed lanreotide depot similarly delayed progression in non-functioning GEP-NETs.10 For progressive or refractory GEP-NETs, additional systemic options include everolimus (mTOR (mechanistic target of rapamycin) inhibitor), sunitinib (a multi-targeted tyrosine kinase inhibitor active in pancreatic NETs), and peptide receptor radionuclide therapy (PRRT (peptide receptor radionuclide therapy)) with lutetium-177-DOTATATE, which binds SSTR2 on tumor cells and delivers targeted radiation. These agents are typically reserved for disease progression on SSA (somatostatin analogue) therapy.
Patients with carcinoid syndrome undergoing surgery, anesthesia induction, or hepatic artery embolization are at risk for carcinoid crisis – a life-threatening surge of vasoactive mediators producing severe flushing, bronchospasm, and hemodynamic collapse. High-dose octreotide (500 micrograms intravenous bolus before induction, followed by 50–100 micrograms/hour infusion during the procedure) is the standard prophylactic protocol. All procedural teams treating carcinoid patients must have octreotide immediately available. Octreotide is also the treatment of choice for acute carcinoid crisis.
Nutritional pharmacology in gastroenterology encompasses the clinical management of patients who cannot meet their energy and micronutrient needs by oral intake alone, and those whose gastrointestinal diseases produce specific nutritional deficiencies requiring targeted supplementation. The pharmacological principles governing parenteral nutrition (PN (parenteral nutrition)) composition and delivery, the pathophysiology and management of refeeding syndrome, the selection of enteral nutrition formulations, and the correction of disease-specific micronutrient deficits all demand precise pharmacological understanding for safe and effective implementation.
Parenteral nutrition, also termed total parenteral nutrition (TPN (total parenteral nutrition)) when all nutritional requirements are delivered intravenously, provides macronutrients (dextrose 3.4 kcal/g, amino acids 4 kcal/g, and intravenous lipid emulsions 9–10 kcal/g), electrolytes, trace elements, and vitamins through a central venous catheter. Standard macronutrient targets for PN in acutely ill adult patients are 20–25 kcal/kg/day total energy and 1.2–2.0 g/kg/day protein. IV lipid emulsions historically used soybean oil-based formulations (rich in n-6 polyunsaturated fatty acids with pro-inflammatory potential); newer mixed-oil emulsions incorporating fish oil (providing n-3 fatty acids with anti-inflammatory properties), olive oil, and medium-chain triglycerides have been associated with improved metabolic and hepatic outcomes. PN-associated liver disease (PNALD (PN-associated liver disease)) – ranging from cholestasis and hepatic steatosis to cirrhosis with long-term use – is the most serious hepatic complication, driven by the absence of enteral stimulation, bile acid accumulation, and lipid composition; fish oil-enriched lipid emulsions substantially reduce PNALD incidence and can reverse established cholestasis.11
Refeeding syndrome (RFS (refeeding syndrome)) is a potentially fatal metabolic complication occurring when nutritional support is introduced too rapidly in severely malnourished patients – including those with anorexia nervosa, malabsorptive GI (gastrointestinal) disease, chronic alcoholism, or prolonged starvation. Pathophysiology centers on insulin-mediated intracellular shifts of phosphate (PO4 (phosphate)), potassium (K (potassium)), and magnesium (Mg (magnesium)) as glucose and amino acids stimulate anabolism. Cellular uptake depletes already-reduced serum concentrations, producing severe hypophosphatemia, hypokalemia, and hypomagnesemia. Hypophosphatemia is the hallmark and most dangerous element of RFS: serum phosphate below 0.5 mmol/L causes impaired ATP (adenosine triphosphate) production, 2,3-diphosphoglycerate depletion (causing hemolytic anemia and impaired oxygen delivery), rhabdomyolysis, respiratory muscle failure, and cardiac arrhythmias. Management protocol: identify patients at high risk before initiation of feeding, correct electrolytes to safe levels first, initiate feeding at 10 kcal/kg/day (50% of estimated needs) for the first 2 days, advance cautiously by 33% every 2 days while monitoring electrolytes twice daily, and supplement thiamine 200–300 mg IV daily for the first 3 days (Wernicke encephalopathy prevention).12
Enteral nutrition formulations are categorized by protein source and degree of hydrolysis, caloric density, fiber content, and disease-specific adaptation. Polymeric formulas (intact protein, typically 1 kcal/mL) are appropriate for patients with functional gut absorptive capacity. Semi-elemental formulas (partially hydrolyzed protein, medium-chain triglycerides) are used for moderate malabsorption. Elemental formulas (free amino acids, minimal fat as MCT (medium-chain triglycerides)) are reserved for severe malabsorption, short bowel syndrome, or post-surgical bowel with minimal residual absorptive surface. Disease-specific formulations exist but have limited high-quality evidence: renal disease formulas reduce phosphate and potassium; hepatic formulas enrich BCAA (branched-chain amino acids); diabetic formulas reduce carbohydrate load and glycemic impact. Immune-modulating formulas enriching arginine, glutamine, and omega-3 fatty acids (pharmaconutrition) showed early promise in surgical ICU patients but subsequent large RCTs found heterogeneous or null results; current consensus supports standard EN (enteral nutrition) over immune-modulating formulas in most non-surgical ICU patients.13
Micronutrient deficiencies in GI disease follow predictable anatomical and pathophysiological patterns. Iron, folate, and calcium are absorbed primarily in the proximal small intestine (duodenum and proximal jejunum), making them vulnerable in celiac disease, Crohn's ileitis, and after Roux-en-Y gastric bypass or duodenal exclusion procedures. Vitamin B12 (cobalamin) requires intrinsic factor secreted by gastric parietal cells and terminal ileal cubilin receptors for absorption; B12 deficiency arises after total or near-total gastrectomy, pernicious anemia, chronic PPI (proton pump inhibitor) use (reducing intrinsic factor secretion marginally at high doses), ileal resection, or Crohn's ileitis involving the terminal ileum. Fat-soluble vitamins (ADEK) require bile acid micelles and adequate intestinal lymphatic function; deficiency occurs in cholestatic liver disease, EPI (exocrine pancreatic insufficiency), Crohn's disease with fat malabsorption, and after ileal resection destroying the enterohepatic circulation of bile acids. Zinc deficiency, prevalent in inflammatory bowel disease and cirrhosis, impairs wound healing, immune function, taste acuity, and urea cycle enzymes. Selenium deficiency in prolonged TPN or severe malabsorption causes cardiomyopathy and skeletal myopathy. Systematic monitoring and targeted supplementation tailored to the specific GI diagnosis are essential components of comprehensive disease management.
NICE criteria for high RFS risk (any one of): BMI below 16 kg/m2; unintentional weight loss >15% in 3–6 months; little or no nutritional intake for >10 days; low levels of K, Mg, or PO4 before feeding. Protocol: correct electrolytes before feeding, supplement thiamine 200–300 mg IV/day, start at ≤10 kcal/kg/day, advance 33% every 2 days if electrolytes stable, monitor K/Mg/PO4 twice daily for first 72 hours. Goal: restore nutrition without precipitating the electrolyte shifts that cause cardiac, respiratory, and neurological failure.
de-Madaria E, Buxbaum JL, Maisonneuve P, et al. Aggressive or moderate fluid resuscitation in acute pancreatitis. N Engl J Med. 2022;387(11):989–1000.
doi:10.1056/NEJMoa2202884Tenner S, Vege SS, Sheth SG, et al. American College of Gastroenterology Guidelines: Management of acute pancreatitis. Am J Gastroenterol. 2024;119(3):419–437.
doi:10.14309/ajg.0000000000002645van Santvoort HC, Besselink MG, Bakker OJ, et al. A step-up approach or open necrosectomy for necrotizing pancreatitis. N Engl J Med. 2010;362(16):1491–1502.
doi:10.1056/NEJMoa0908821Petrov MS, Pylypchuk RD, Emelyanov NV. Systematic review: nutritional support in acute pancreatitis. Aliment Pharmacol Ther. 2008;28(6):704–712.
doi:10.1111/j.1365-2036.2008.03786.xWhitcomb DC, Lehman GA, Vasileva G, et al. Pancrelipase delayed-release capsules (CREON) for exocrine pancreatic insufficiency due to chronic pancreatitis or pancreatic surgery: a double-blind randomized trial. Am J Gastroenterol. 2010;105(10):2276–2286.
doi:10.1038/ajg.2010.201Bruno MJ, Haverkort EB, Tytgat GN, van Leeuwen DJ. Maldigestion associated with exocrine pancreatic insufficiency: implications of gastrointestinal physiology and properties of enzyme preparations for a cause-related and patient-tailored treatment. Am J Gastroenterol. 1995;90(9):1383–1393.
doi:10.1111/j.1572-0241.1995.tb08029.xOlesen SS, Bouwense SA, Wilder-Smith OH, van Goor H, Drewes AM. Pregabalin reduces pain in patients with chronic pancreatitis in a randomized, controlled trial. Gastroenterology. 2011;141(2):536–543.
doi:10.1053/j.gastro.2011.04.003Rinke A, Müller HH, Schade-Brittinger C, et al. Placebo-controlled, double-blind, prospective, randomized study on the effect of octreotide LAR in the control of tumor growth in patients with metastatic neuroendocrine midgut tumors: a report from the PROMID Study Group. J Clin Oncol. 2009;27(28):4656–4663.
doi:10.1200/JCO.2009.22.8510Vezzosi D, Bennet A, Rochaix P, et al. Octreotide in insulinoma patients: efficacy on hypoglycemia, relationships with Octreoscan scintigraphy and immunostaining with anti-sst2A and anti-sst5 antibodies. Eur J Endocrinol. 2005;152(5):757–767.
doi:10.1530/eje.1.01901Caplin ME, Pavel M, Cížková D, et al. Lanreotide in metastatic enteropancreatic neuroendocrine tumors. N Engl J Med. 2014;371(3):224–233.
doi:10.1056/NEJMoa1316158Nehra D, Fallon EM, Puder M. The prevention and treatment of intestinal failure-associated liver disease in neonates and children. Surg Clin North Am. 2011;91(3):543–563.
doi:10.1016/j.suc.2011.02.003Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. BMJ. 2008;336(7659):1495–1498.
doi:10.1136/bmj.a301Calder PC. Immunonutrition in surgical and critically ill patients. Br J Nutr. 2007;98(Suppl 1):S133–S139.
doi:10.1017/S0007114507832909