ChiRhoStim Dosage

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

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 Administration (2.2)].
  • Starting 15 minutes after administration of ChiRhoStim ®, collect 4 timed duodenal fluid aspirates (each 3 to 5 mL) at 15-minute intervals. Keep the patient in the left lateral decubitus position throughout the procedure.

Sample Handling and Interpretation:

• Place fluid specimens on ice for immediate measurement of bicarbonate concentration. If samples will not be analyzed immediately, store fluid at –80°C.
• Peak bicarbonate concentrations of 80 to 130 mEq/L after administration indicate normal pancreatic exocrine function.

Stimulation of Gastrin Secretion to Aid in the Diagnosis of Gastrinoma:

Preparation:

• Instruct patients to fast for at least 12 hours prior to beginning the test.

Sample Collection:

• Before administering ChiRhoStim ®, draw two blood samples for determination of fasting serum gastrin levels (baseline values).
• Administer ChiRhoStim ® at a dose of 0.4 mcg/kg of body weight intravenously over 1 minute [see Dosage and Administration (2.2)].

• Collect post-injection blood samples after 1, 2, 5, 10, and 30 minutes for determination of serum gastrin concentrations.

Sample Interpretation:

• Gastrinoma is strongly suspected in patients who show an increase in serum gastrin concentration of more than 110 picograms (pg) per mL over baseline levels on any of the post injection samples.

Stimulation of Pancreatic Secretions to Facilitate the Identification of the Ampulla of Vater and Accessory Papilla During Endoscopic Retrograde Cholangiopancreatography (ERCP):

When difficulty is encountered by the endoscopist in identifying the ampulla of Vater or in identifying the accessory papilla in patients with pancreas divisum:

• Administer ChiRhoStim ® at a dose of 0.2 mcg/kg of body weight intravenously over 1 minute [see Dosage and Administration (2.2)].
• Visible excretion of pancreatic fluid from the orifices of these papillae will enable their identification and facilitate cannulation.