Evaluation of Efficacy of Combination of Pregabalin and Antioxidant in Reducing Pain in Chronic Pancreatitis: a Randomized Control Trial

Study hypothesis: Combination of antioxidants and pregabalin results in better pain relief than placebo in patients with chronic pancreatitis.

Chronic pancreatitis (CP) is a clinical enigma, with pain being the most distressing symptom that brings the patient to clinical attention. Pain in chronic pancreatitis is multifactorial, and may be related to pancreatic ductal hypertension, tissue hypertension, inflammatory cytokines, oxidative stress and neuropathic mechanisms like mechanical allodynia, inflammatory hyperalgesia and temporal summation. The mainstay of treatment for pain in CP due to pancreatic ductal stone is endotherapy (ESWL and ERCP). Recent randomized controlled trials have shown that antioxidant cocktail and pregabalin (a presynaptic voltage gated calcium channel blocking agent) can result in significant reduction of pain in CP.

In this study, the investigators will study the efficacy of the combination of antioxidants and pregabalin in reducing pain and compare that with placebo. The investigators will randomize patients with documented chronic pancreatitis with recurrent/persistent pain after undergoing endotherapy and ductal clearance into three groups: Group A- antioxidants + pregabalin; Group B- Placebo. The primary outcome will be change in pain score and the secondary outcomes will be change in the number of painful days, analgesic requirements, quality of life and depression scale. Pain score will be quantified by the Izbicki pain score and visual analog scale; while quality of life and depression will be measured by the EORTC QLQ-C30/PAN26 and Beck depression inventory respectively. Comparison between Group A vs B will be made by the Chi square test/Fischer Exact and the Student's 't' tests respectively and analysis will be done on a intention to treat and per protocol basis. With an expected improvement of pain by 40% (at 80% power and alpha of 0.05) and adjusting for a presumed 10% drop out rate, the required sample size in each group will be at least 40.