PURPOSE: The aim of this study was to elucidate the potential use of the step-scan FT-IR photoacoustic spectroscopy (PAS) for the non-destructive determination of drug penetration into membranes. METHODS: The penetration of clotrimazole from a 10% (w/w) suspension in Vaseline into a dodecanol-collodion acceptor membrane was studied by three methods: the step-scan FT-IR PAS with a phase modulation, a multilayer membrane system, and a modified libration model. Based on Fick's second law, the diffusion coefficient of the drug in the membrane was derived by numerical fitting of the experimental data. RESULTS: The three methods applied provided almost the same diffusion coefficient D = 2.2 10(-9) cm2/s for clotrimazole in the membrane. Because of the non-destructive mode of operation, the accuracy of results obtained by FT-IR PAS is much better than that attainable by other two methods. CONCLUSIONS: Step-scan FT-IR photoacoustic spectroscopy in conjunction with a phase modulation is useful to determine the penetration of drug through membranes. The fact that samples can be investigated without elaborate preparation is an advantage of this spectroscopic technique.
PURPOSE: The aim of this study was to elucidate the potential use of the step-scan FT-IR photoacoustic spectroscopy (PAS) for the non-destructive determination of drug penetration into membranes. METHODS: The penetration of clotrimazole from a 10% (w/w) suspension in Vaseline into a dodecanol-collodion acceptor membrane was studied by three methods: the step-scan FT-IR PAS with a phase modulation, a multilayer membrane system, and a modified libration model. Based on Fick's second law, the diffusion coefficient of the drug in the membrane was derived by numerical fitting of the experimental data. RESULTS: The three methods applied provided almost the same diffusion coefficient D = 2.2 10(-9) cm2/s for clotrimazole in the membrane. Because of the non-destructive mode of operation, the accuracy of results obtained by FT-IR PAS is much better than that attainable by other two methods. CONCLUSIONS: Step-scan FT-IR photoacoustic spectroscopy in conjunction with a phase modulation is useful to determine the penetration of drug through membranes. The fact that samples can be investigated without elaborate preparation is an advantage of this spectroscopic technique.