Application Of TDS-1012 Fully Automatic Sampling Transdermal Diffusion System in Creams

In vitro release (IVRT) testing is a key experiment in pharmaceutical research, particularly in transdermal drug delivery systems and sustained-release formulations. It is primarily used to evaluate the release characteristics of drugs from a formulation. Semisolid formulations are typical candidates for transdermal drug delivery systems. Vertical diffusion cells can be used to simulate the in vivo environment. The formulation is placed in a suitable release medium and the rate and extent of drug release from the formulation are measured. This serves as a tool for formulation optimization, quality assessment, and prediction of in vivo behavior. Therefore, finding the right release medium is crucial. Below, we conducted IVRT experiments on a cream in different release media to observe differences in drug release rates from the formulation.

Experimental Methods

Fully Automated Diffusion Sampling System Parameters (TDS-1012)

Sample Volume: Approximately 100 mg

Dosage Form: Cream (domestic)

Temperature: 32°C ± 0.5°C

Speed: 600 rpm

Artificial Membrane: 0.2 μm PES Membrane (Merck)

Sampling Time: 1, 2, 3, 4, 5, 6, 7, 8 hours

Diffusion Cell: 15 mm inner pore diameter; 9 ml diffusion cell volume

Release Media: 30% ethanol/normal saline, normal saline, phosphate buffer (pH 7.4)

Chromatographic Conditions (Aglient 1260 Infinity II)

Detector: UV 254 nm

Flow Rate: 1.0 mL/min

Mobile phase: Methanol/water solution

Column: Extend-C18 column

Experimental Results

The drug release rate from the sample was expressed as the cumulative drug release (μg/cm²) and the square root of time (t) (i.e., the Higuch formula: M = kt1/2). The k value in the formula represents the release rate. The results are as follows: The drug release amount from the cream varied under different release media conditions. The 30% ethanol/normal saline group had the highest drug release rate (61.254), indicating that the addition of ethanol to the release medium effectively promoted drug release. The release rates of the normal saline and phosphate buffer groups were 39.565 and 39.096, respectively, which were similar but lower than those of the 30% ethanol/normal saline group.

Experimental Results

Experimental Conclusion

The above results demonstrate that, while satisfying the sink conditions, different release media significantly influence the drug release rate from creams. This suggests that selecting the right release medium can effectively help us obtain more reliable and effective data. Specifically, 30% ethanol/normal saline significantly increased the drug release rate, providing an important reference for drug formulation optimization and quality evaluation. Therefore, validation of the release medium selection is essential when conducting in vitro drug release experiments.