Introduction:
Semi-solid dosage forms are very popular. Bases affect the release of active substances are the main component of this group of preparations. Among the dermal formulations a large percentage are those that contain non-steroidal anti-inflammatory drugs, including diclophenac sodium. Aim of the study was to assess the ointment bases impact on the release of diclophenac sodium from dermal semi-solid preparations. We have analyzed the following types of bases: gel-type, lipophilic, absorption and emulsion.

Materials and methods:
The study compared two commercial preparations: Veral and Diclac Lipogel, and five formulations prepared with blender. Pharmaceutical availability of diclophenac sodium was examined using Kerckhoffs and Huizing apparatus. Release of diclophenac sodium was carried out at 37°C and 32°C. Absorbance of the samples was measured spectrophotometrically.

Results:
Optimum pharmaceutical availability had ointment formulation based on glycerol, which showed a high percentage of released sodium diclofenac, a high velocity release constant (k) and a low half-time release (t1/2). Least suitable bases for diclophenac sodium were lipophilic vehicles - Vaseline and eucerine. The pharmacokinetic parameters derived from glycerol ointment were better than the parameters derived from the gels based on carbopol. The kinetics of other drugs turned out to be less favorable than for commercial gels. Faster release of diclophenac sodium was obtained at 37 ° C.

Conclusions:
The best release of the sodium diclofenac eleased was observed in case of recipe formulation (ointment formulation based on glycerol), as compared to the commercially available preparations. Temperature influenced the release of the amount of diclofenac sodium from the two analyzed gels.