In a recent clinical study, researchers have harnessed the power of pharmacoscintigraphy to explore the permeation of radiolabeled Nimesulide in a topical formulation. According to the findings, topical delivery of Nimesulide, assessed through gamma scintigraphy with the radiolabeled drug complex (Technetium99m Nimesiulide [99mTc-NSD]) in a gel, demonstrated mean percentage permeation of 0.32%–36.37% at 5 and 240 minutes on human volunteers, indicating the technique's reliability for noninvasive evaluation of drug permeation.

The topical route presents an alternative to oral delivery for therapeutic substances, often exhibiting similar effectiveness but with a potentially improved tolerability profile. Hence, this study utilized gamma scintigraphy, a nonintrusive method involving radioactive substances application, to carry out biodistribution studies. Technetium pertechnetate 99mTc was used to radiolabel NSD, creating a radiolabeled drug complex (99mTc-NSD) that was then incorporated into a topical gel formulation. Human volunteers were subjected to gamma scintigraphy to determine the permeation of the radiolabeled drug from the topical gel.

The topical gel was formulated using 99mTc-NSD as a tracing agent and carbomer 940 as the gelling agent. The pH of the resulting gel was determined to be slightly acidic at 5.3 – 0.063, aligning with the pH requirements for topical products. Additionally, the viscosity of the prepared gel was found to be optimal. The efficiency of radiolabeling for the 99mTc-NSD complex was enhanced through the optimization of different conditions, including variations in temperature and the pH of the solvent. The most favorable radiolabeling results were achieved at a temperature of 30°C and a pH of 7.

An in vitro study on the stability of the 99mTc-NSD complex in both saline and serum was conducted for a duration of 24 hours. The data revealed that, following a 24-hour incubation period, the 99mTc-NSD exhibited labeling efficiencies of 92.95% ± 1.09% in saline and 91.49% ± 2.58% in serum.
A topical gel based on 99mTc-NSD was administered on the backs of human volunteers. The gamma scintigraphy instrument was employed to identify the region of interest and subsequently measure the corresponding quantity of the permeated drug.

99mTc-NSD mean percentage permeation was observed to range from 0.32+0.22 to 36.37+  2.86 at 5 and 240 minutes, respectively. This data underscores the potential of gamma scintigraphy as a noninvasive and reliable technique for exploring drug permeation via topical routes of administration. These findings not only contribute valuable insights into the field of drug delivery but also pave the way for further exploration of topical formulations as a viable and effective means of administering therapeutic substances. The study's outcomes hold promise for advancing the development of pharmaceuticals with better tolerability and enhanced patient outcomes.