Development of polymer film dosage forms of lidocaine for buccal administration: II. Comparison of preparation methods

In previous studies, we prepared film dosage forms of lidocaine (LC) with hydroxypropylcellulose (HPC) as a film base using the solvent evaporation (SE) method. However, from the viewpoint of environmental issues, a reduction in organic solvent use in pharmaceutical and other industries is required. In this study, we prepared the LC films by direct compression of the physical mixture (DCPM method) and direct compression of the spray dried powder (DCSD method). Magnesium stearate, which was required as a lubricant for direct compression, showed no effect on the LC release rate. The LC release rate (%/h) was independent of the compression pressure, but a higher pressure was preferable to easily remove the film from the punches. An increase in the film weight decreased the LC release rate expressed in %/h, whereas no significant effect of film weight was observed on the LC release rate from unit surface area expressed in mg/h/cm(2). The LC release rate (%/h) was independent of the LC content, suggesting that the LC release rate (mg/h) can be quantitatively controlled by changing the LC content in the formulation. The LC release rate and penetration rate were affected by the preparation method; that is, DCPM method < DCSD method < SE method. The LC penetration rates through excised hamster oral mucosa were linearly correlated to the release rate of un-ionized LC, which was estimated by the LC release rate multiplied by the un-ionized fraction of LC for the HPC film dosage form.