Structural determination of testosterone esters in oil injectables by thermospray mass spectrometry.

In the absence of analytical reference standards, the combination of thermospray and collision-activated dissociation mass spectrometry has been utilized to separate and identify the presence of several esters of testosterone in imported oil injectables. Structural identifications were based on generic daughter ions considered diagnostic of the steroidal ring structure of these anabolic steroids as well as daughter ions representative of the ester alkyl or aryl side chains.

Automated sampling of in vitro dissolution medium: effect of sampling probes on dissolution rate of prednisone tablets.

The effect of sampling probe size and location on the in vitro dissolution rate of prednisone tablets was examined. Using USP XX Apparatus 2 with an automated sampling system, dissolution rates were determined using two types of large filter-tipped probes and a small capillary probe. Each probe was tested at three locations within the kettle. The large probes caused hydrodynamic changes which, when compared with results obtained through manual sampling, resulted in significant changes in dissolution rates at each location. These changes were less evident when the capillary probe was used, with an insignificant difference between results of automated and manual sampling when the capillary probe was placed midway between the paddle shaft and the kettle wall.

Systematic error associated with apparatus 2 of the USP dissolution test II: Effects of deviations in vessel curvature from that of a sphere.

Dissolution vessels made from glass or plastic are recognized by the USP as being suitable for dissolution testing. Glass vessels with a bottom inside curvature flatter than that of a sphere can cause a high bias in dissolution results; vessels with a steeper curvature can cause a low bias. The inside bottom curvature of plastic vessels adhered closely to the curvature of a sphere. The plastic vessels are preferable for use if the drug is not adsorbed and the vessel is not attacked by the dissolution medium. Bias in results between individual positions of a dissolution apparatus was traced to two shafts which were not vertical.