Case Study: Pharmacoscintigraphy to compare fast acting aspirin to ibuprofen tablet formulations


The client wanted to assess site and time of tablet disintegration of their new disintegrating acetylsalicylic acid tablets and to compare this to commercially available OTC pain products. This was important to establish a clear advantage in disintegration rate and therefore absorption time. Gamma Scintigraphy gave the client clear answers and strong marketing data to support their product commercially.


To investigate the gastrointestinal disintegration and absorption of two fast disintegrating aspirin formulations compared with two commercial ibuprofen products (Nurofen and Dolormin).

Radiolabelling Validation

A drill and fill method was used to radiolabel tablets with Technetium-99m diethylenetriaminepentaacetic acid (99mTcDPTA). Validation of the radiolabelling procedure via scintigraphic monitoring of radiolabelled tablets during in vitro dissolution testing confirmed that the radiolabelling procedure did not impact tablet disintegration properties and the radiolabel acts as an appropriate marker for tablet disintegration.

Radiolabelled dissolution with images taken in front of the gamma camera.

Quality Control

In compliance with GMP, all tablets were radiolabelled within 24 hrs of dosing to contain 4MBq 99mTc at time of dosing. All work was completed according to approved Batch Manufacturing Records and QP released once confirmation of acceptance criteria was obtained.

Clinical Study

Healthy male subjects were dosed with one of the following treatments at each visit:

  • Treatment 1: 500mg Aspirin,
  • Treatment 2:1000mg Aspirin,
  • Treatment 3: 400mg Ibuprofen (Nurofen),
  • Treatment 4: 683 mg Ibuprofen DL-lysin = 400mg ibuprofen (Dolormin).

Following dosing, sequential anterior images were taken of the abdominal area at regular intervals until 240 mins, or until complete tablet disintegration was observed.

Pharmacokinetic samples were collected at regular intervals from pre-dose until 238 mins post dose.


Median time to complete disintegration was 9 min and 5 min for the 500mg and 1000mg aspirin formulations respectively. This was faster than for the ibuprofen formulations (37.5 min and 37.5 min respectively).

Fig 2: Representative scintigraphy images at selected time points showing tablet disintegration.

The aspirin formulations disintegrated between five and eight times faster than the ibuprofen formulation.

Plasma concentration vs time curves show a dose dependency present in the active ingredients of aspirin, whilst the ibuprofen containing products differ (Fig 3)

Fig 3: Plasma concentration vs time. Mean ± SD

Plasma aspirin concentrations were detectable within 5 min of administration, with peaks observed 20 mins post dose correlating well with previously reported in vivo data (ref Voelker, 2012).

Compared with aspirin products, there was high variability of Tmax in the ibuprofen containing products (Fig 4)

Fig 4: Time to maximum plasma concentration (Tmax)

Peak plasma salicyclic acid (SA) were attained within 1h following administration with an estimated elimination half-life of approximately 4h for both aspirin fast acting formulations (Table 1)

Pharmacokinetic parameters (Mean/SD for AUC, Cmax, t1/2 and MRT (mean residence time)); Median/Man, Max for Tmax)

Title: Pharmacokinetic parameters (Mean/SD for AUC, Cmax, t1/2 and MRT (mean residence time)); Median/Man, Max for Tmax)


This pharmacoscintigraphic study was sucessfully able to show that gastrointestinal disintegration and systemic absorption of the aspirin formulations was faster than that of the ibuprofen formulations.

The study conduct was completed by BDD from study initiation to final clinical report inside 12 weeks.


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