Influence of Iodine-131 Solution Volume and Storage Time on In Vitro Dissolution

Abstract

Objective: This investigation was conducted to determine the influence of ¹³¹I solution volume and storage time on the in vitro release of radioiodide from capsules.

Methods: In vitro dissolution profiles for ¹³¹I sodium iodide capsules compounded in a centralized nuclear pharmacy were determined using the USP XXIII Dissolution Test. Iodine-131 solution volumes of 0.05, 0.15 and 0.25 ml and storage times of 2, 5, 7 and 9 days were considered.

Results: By 80 min after initiation of the dissolution test, more than 95% of the ¹³¹I was released from capsules prepared with 0.15 and 0.25 ml of the ¹³¹I solution. The 0.05-ml capsules reached 95% at 55 min. Capsules prepared with 0.05 ml of solution and stored 2, 5, 7 or 9 days released over 95% of the radioactivity within 65 min. Capsules prepared with 0.25 ml of solution and stored for 2, 5, 7 or 9 days released over 95% of the ¹³¹I by 55 min after initiation of the dissolution test.

Conclusion: Neither the different volume of radioactive sodium iodide solution used in the preparation of capsules nor the time of storage greatly influenced the release of ¹³¹I from the capsules. Based on dissolution profiles, it appears that the bioavailability of ¹³¹I would not be influenced by factors studied in this investigation.