Secretin

Mechanism of Action 12.1 Mechanism of Action The primary action of ChiRhoStim ® is to stimulate pancreatic ductal cells to secrete pancreas fluid in large volumes that contain bicarbonate. Secretin is a hormone that is normally released from the duodenum upon exposure of the proximal intestinal lumen to gastric acid, fatty acids and amino acids. Secretin is released from enterochromaffin cells in the intestinal mucosa. Secretin receptors have been identified in the pancreas, stomach, liver, colon and other tissues. When secretin binds to secretin receptors on pancreatic duct cells it opens cystic fibrosis transmembrane conductance regulator (CFTR) channels, leading to secretion of bicarbonate-rich-pancreatic fluid. Secretin may also work through vagal-vagal neural pathways since stimulation of the efferent vagus nerve stimulates bicarbonate secretion and atropine blocks secretin-stimulated pancreatic secretion.

INDICATIONS AND USAGE ChiRhoStim ® is indicated for the stimulation of: pancreatic secretions, including bicarbonate, to aid in the diagnosis of pancreatic exocrine dysfunction. gastrin secretion to aid in the diagnosis of gastrinoma, and pancreatic secretions to facilitate the identification of the ampulla of Vater and accessory papilla during endoscopic retrograde cholangiopancreatography (ERCP). ChiRhoStim® is a secretin class hormone indicated for stimulation of: pancreatic secretions, including bicarbonate, to aid in the diagnosis of exocrine pancreas dysfunction (1) gastrin secretion to aid in the diagnosis of gastrinoma (1) pancreatic secretions to facilitate the identification of the ampulla of Vater and the accessory papilla during endoscopic retrograde cholangiopancreatography (ERCP) (1)

DOSAGE AND ADMINISTRATION 2.2 Preparation and Dosage Regimen The recommended dosage regimen of ChiRhoStim® by indication is shown below in Table 1. TABLE 1: Dosage by Indication Indication Recommended Dosage Regimen Stimulation of pancreatic secretions, including bicarbonate, to aid in the diagnosis of exocrine pancreas dysfunction 0.2 mcg/kg by intravenous injection over 1 minute Stimulation of gastrin secretion to aid in diagnosis of gastrinoma 0.4 mcg/kg by intravenous injection over 1 minute Stimulation of pancreatic secretions to facilitate the identification of the ampulla of Vater and accessory papilla during endoscopic retrograde cholangiopancreatography (ERCP) 0.2 mcg/kg by intravenous injection over 1 minute Preparation of Recommended Dosage ChiRhoStim ® is a lyophilized powder, which requires reconstitution prior to intravenous administration. Determine the number of vials needed for the prescribed dosage based on the patient’s weight and recommended dosage. Follow these steps to determine the patient dose: Total dose (mcg) = patient’s weight (kg) x prescribed dose (mcg/kg). Total injection volume (mL) = total dose (mcg) divided by the concentration of the reconstituted solution (2 mcg/mL). Round the total injection volume to the nearest tenth of a mL. Total number of vials = total injection volume divided by the vial volume (8 mL). To reconstitute one 16 mcg vial: Dissolve the contents of the ChiRhoStim ® 16 mcg vial in 8 mL of 0.9% Sodium Chloride Injection, USP, to yield a concentration of 2 mcg/mL. Shake vigorously to ensure dissolution. Inspect the reconstituted solution visually for particulate matter and discoloration prior to administration. If particulate matter or discoloration is seen, discard the reconstituted solution. To reconstitute one 40 mcg vial: Dissolve the contents of the ChiRhoStim ® 40 mcg vial in 10 mL of 0.9% Sodium Chloride Injection, USP, to yield a concentration of 4 mcg/mL. Shake vigorously to ensure dissolution. Inspect the reconstituted solution visually for particulate matter and discoloration prior to administration. If particulate matter or discoloration is seen, discard the reconstituted solution. Repeat steps above to reconstitute additional vials, as needed, to administer the total dose. Use immediately after reconstitution and discard any unused portion. 2.3 Administration and Test Methods Stimulation testing with ChiRhoStim ® should only be performed by physicians with sufficient expertise. Ensure that the institution has established normative ranges for pancreatic exocrine response. Stimulation of Pancreatic Secretions, including Bicarbonate, to Aid in the Diagnosis of Exocrine Pancreas Dysfunction: Preparation: Instruct patients to fast for at least 12 to 15 hours prior to beginning the test. Sample Collection: [performed using either the gastroduodenal/Dreiling tube (fluoroscopic) or endoscopic collection method] Gastroduodenal (Dreiling) Tube Collection Method Pass a radiopaque, double-lumen gastroduodenal tube through the mouth using a guidewire. Under fluoroscopic guidance, place the opening of the proximal lumen in the gastric antrum and the opening of the distal lumen beyond the ampulla of Vater. Confirm the tube positioning and secure the tube. Connect both the proximal (gastric) and distal (duodenal) lumens to low intermittent suction, and apply negative pressure of 25 to 40 mmHg to both lumens. Collect a sample of the duodenal contents and check the pH of the aspirate to verify tube position. Proceed to next step if the duodenal aspirate has a pH of 6 or higher. If the pH is less than 6, reposition the tube. Collect a baseline sample of duodenal fluid for a 15-minute period. Administer ChiRhoStim ® at a dose of 0.2 mcg/kg body weight intravenously over 1 minute [see Dosage and Administration (2.2)] . For the 60-minute period following the injection, collect four consecutive 15-minute samples of duodenal fluid. Clear the duodenal lumen of the tube with an injection of air after each 15-minute sample collection. Note that wide variation in aspirate volumes is indicative of incomplete aspiration between samples. Endoscopic Collection Method: Endoscopic Pancreatic Function Test (ePFT) Administer a topical anesthetic spray to the posterior pharynx and place a bite block in the mouth. Perform a standard upper endoscopy by passing the endoscope into the stomach with the patient in the left lateral decubitus position. After gastric insufflation, aspirate all gastric fluid through the endoscope and discard. Pass the endoscope through the pylorus into small intestine and position the tip of the endoscope at the junction of the second and third portion of the duodenum. Aspirate duodenal fluid for several seconds to clear the residual gastric acid from the tube. Collect a baseline aspirate of duodenal fluid (3 to 5 mL) from the post-bulbar duodenum. Administer ChiRhoStim ® at a dose of 0.2 mcg/kg of body weight intravenously over 1 minute [see Dosage and Admi

ADVERSE REACTIONS 6.1 Clinical Trials Experience Because clinical trials are conducted under varying conditions, adverse reaction rates observed during the clinical trials of a drug cannot always be directly compared to the rates observed during the clinical trials of another drug and may not reflect the adverse reaction rates observed in practice. The data described below reflect exposure to ChiRhoStim® in 531 patients from an open-label clinical trial. The population consisted of patients aged 1 to 91 years, 185 males, 346 females, 480 Caucasians, 31 Blacks, 12 American Indians, 6 Hispanics, and 2 Asians with known or suspected diseases of the exocrine pancreas including chronic pancreatitis and pancreatic cancer. Most patients received a single dose of ChiRhoStim® in a dose range of 0.2 mcg/kg to 0.4 mcg/kg. The most common adverse reactions (reported in at least 2 patients in the trial) are listed in Table 2. TABLE 2 Adverse Reactions in at Least 2 Patients Treated with a Single-Dose of ChiRhoStim® in a Clinical Trial Adverse Reaction ChiRhoStim® Number of Patients N = 531 Nausea 9 Vomiting 3 Flushing 2 Upset stomach 2 Most common adverse reactions (≥2 patients) are nausea, vomiting, flushing, and upset stomach. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact ChiRhoClin, Inc. at 1-877-272-4888 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. See 17 for PATIENT COUNSELING INFORMATION. Revised: 07/2017

DRUG INTERACTIONS 7.1 Hyporesponse with Anticholinergics The concomitant use anticholinergic drugs may cause a hyporesponse to stimulation testing with ChiRhoStim ® . Discontinue anticholinergic drugs at least 5 half-lives before administering ChiRhoStim ® [see Dosage and Administration (2.1)] . 7.2 Hyperresponse of Gastrin Secretion with H 2 -Receptor Antagonists and PPIs The concomitant use of H 2 -receptor antagonists or PPIs may cause a hyperresponse in gastrin secretion in response to stimulation testing with ChiRhoStim ® , falsely suggesting gastrinoma. Discontinue H 2 -receptor antagonists at least 2 days before administering ChiRhoStim ® to aid in the diagnosis of gastrinoma. The time it takes for serum gastrin concentrations to return to baseline following discontinuation of PPIs is specific to the individual drug. Consult the prescribing information of each specific PPI before administering ChiRhoStim ® to aid in the diagnosis of gastrinoma.