Compounded versus proprietary sincalide for evaluation of gallbladder ejection fraction

OBJECTIVE: To report a comparison of compounded and proprietary sincalide in the evaluation of gallbladder ejection fraction during hepatobiliary scintigraphy. CASE SUMMARIES: Two patients were referred to nuclear medicine with symptoms consistent with hepatobiliary dysfunction. Both underwent hepatobiliary scintigraphy to evaluate anatomic and physiologic tract patency of the hepatobiliary system. Compounded sincalide, an adjuvant pharmaceutical used to evaluate gallbladder ejection fraction, was infused during hepatobiliary scintigraphy, and gallbladder ejection fractions were 11% and 24%, respectively. Hepatobiliary scintigraphy was repeated on both patients 72 hours later with proprietary sincalide used as the adjuvant pharmaceutical. The gallbladder ejection fractions were 32% and 72%, respectively. DISCUSSION: The use of sincalide to evaluate gallbladder ejection fraction in hepatobiliary scintigraphy is widely accepted in the surgical and nuclear medicine community. In late 2001, the sole manufacturer of sincalide announced indefinite unavailability of the product. Following the announcement, several compounding pharmacies began selling extemporaneously compounded sincalide as a replacement. Use of the compounded product has assumed therapeutic equivalence. CONCLUSIONS: Significant differences in gallbladder ejection fraction between compounded sincalide and sincalide in our patients are likely due to the intrinsic variability in response to sincalide. Clinicians should be aware of this variability, as well as the potential effect of concomitant medications.