PubMed · 3388265
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1988. [Ortofen (ortophenum)].. https://pubmed.ncbi.nlm.nih.gov/3388265/
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The aim of this work was to study the release mechanisms of drugs having different solubility (buflomedil pyridoxalphosphate 65%, sodium diclofenac 3.1%, nitrofutantoin 0.02% w/v,) from hydroxypropyl methylcellulose (HPMC) matrices by concomitantly studying swelling, diffusion and erosion fronts movement and drug delivery. The main goal was to clarify the role played by polymer swelling in drug transport. The results showed that the rate and amount of drug released from swellable matrices was dependent not only from drug dissolution and diffusion but also from solid drug translocation in the gel due to polymer swelling. In fact, as drug solubility decreased, the slower drug dissolution rate in the gel layer allowed drug particles to be transported close to the matrix erosion front. The presence of solid particles in the gel reduced the swelling and the entanglement of polymer chains and affected the resistance of gel towards erosion. As a consequence, the matrix became more erodible. The erosive delivery accelerated after the matrix had been completely transformed into the rubbery state, particularly when a considerable amount of solid drug particles remained in the gel phase.
AIM: To predict skin permeability of drugs with theoretical parameters. METHODS: The semiempirical self-consistent field molecular calculation AM1 method is utilized to obtain the structural parameters of drug molecules. Stepwise multiple regression analysis or BP network is then utilized to establish the correlation between skin permeability of drugs and their structural parameters. RESULTS: The calculated human skin permeability coefficients (kp) of 22 model drugs in vitro or the R values (R = absorbed/unabsorbed) of 17 drugs in vivo are in good agreement with their observed values. CONCLUSION: Theoretical parameters can be used to predict skin permeability of drugs.