Case Presentation: A 21-year-old female recently started on doxycycline for acne presented to our institution with epigastric pain. On the third day of doxycycline initiation, the patient began feeling nauseous with progressively worsening pain. The pain was localized to the epigastrium, described as sharp, stabbing, radiating to her back, and rated as severe. The patient was non-ill appearing and hemodynamically stable. Physical examination was notable for tenderness to palpation of the epigastrium and left flank with hypoactive bowel sounds. Laboratory evaluation was notable for serum lipase of 11,561 U/L. Liver function tests, electrolytes, and lipid panel were within normal limits. A computed tomography scan of her abdomen revealed an acute interstitial edematous pancreas. Ultrasound of the abdomen was negative for cholelithiasis. Drug-induced pancreatitis diagnosis was made by excluding all common etiologies of acute pancreatitis, including alcohol, gallstones, hypertriglyceridemia, hypercalcemia, infection, autoimmune, or trauma. The doxycycline was discontinued as the suspected culprit of AP.
Discussion: Doxycycline is a broad-spectrum bacteriostatic tetracycline antibiotic commonly used to treat many bacterial infections, including acne vulgaris, soft tissue infections, respiratory infections, and sexually transmitted infections. It is a relatively safe medication with reported side effects, including gastrointestinal upset, photosensitivity, and renal toxicity. Acute pancreatitis is a rare side effect of doxycycline, with only a few cases reported in the literature. Drug-induced pancreatitis has no clinical features distinguishing it from other forms of pancreatitis, making it challenging for clinicians to diagnose. More than 70% of pancreatitis is due to gallstones or alcohol use. In our patient, imaging ruled out biliary disease, there was no history of alcohol use, and laboratory tests were within normal limits. There are 525 drugs listed in the World Health Organization database, with acute pancreatitis listed as an adverse reaction. For only 31 drugs has a definite causality been established. To date, there have been only six reported cases of doxycycline-induced pancreatitis. In addition, antibiotic-associated acute pancreatitis has been reported to occur immediately after drug administration or after one month of drug use. Our case is unique, as our patient had no underlying medical conditions; therefore, we attribute doxycycline resulting in an idiosyncratic drug reaction leading to acute pancreatitis. In addition, our patient presented after three days of doxycycline initiation, which is unique regarding the timeline of presentation of prior reported cases.
Conclusions: Though rare, doxycycline administration leading to acute pancreatitis is a severe adverse effect for clinicians to be aware of. The pathophysiology of drug-induced pancreatitis remains a mystery and is based on theories extracted from case reports. Potential mechanisms include pancreatic duct constriction, cytotoxic effects, and direct cellular injury. We highlight the importance of thorough history taking and medication reconciliation on admission. Furthermore, clinicians should maintain a high index of suspicion for drug-induced pancreatitis when a patient presents with gastrointestinal symptoms after recently starting doxycycline.