Nowadays, there is a growing interest for optimising topical formulations. The demands on topical formulations are very different. For any concentration-time profile desired, the composition can be selected from a number of usual recipes. Adding of ingredient of specific properties can influence the penetration behaviour. Because the drug delivery through the human skin is very complex and depends on many factors, using a mathematical model can only elucidate the influence of various components of the formulation on the penetration process. The present work is devoted to describe the release and penetration of a drug from a suspension based on a mathematical-physical model. Vaseline is used as basic component of the formulation. The influence of each particular component of the suspension was characterised. Changing the amount of paraffinum liquidum in the suspension the release and penetration behaviour were affected. Based on the appropriate mathematical model the relevant dependencies were quantitatively characterised. An artificial dodecanol-collodion membrane was used as acceptor. Propylene glycol was used as enhancer. The relationship between enhancer effect and enhancer concentration in the suspension is quantitatively described. The drug release and penetration from a suspension were simulated under in vivo conditions. The results of the simulation facilitate formulation design so that an optimal system could be developed. Because of the complexity, the mathematical model demands many parameters with high accuracy as input data, which cannot be obtained by using traditional methods like Franz's cell or multilayer membrane system. For that reason, non-invasive spectroscopic methods were applied to penetration studies, namely Fourier transform infrared attenuated total reflection (FTIR-ATR) and FTIR photoacoustic spectroscopy.