PubMed · 14863742
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S LOSSIUS, G TOFT. 1951. [Xylocaine].. https://pubmed.ncbi.nlm.nih.gov/14863742/
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We investigated the effects of the rate of solvent removal by varying ambient pressure at a fixed temperature on the morphology, particle sizes, drug encapsulation efficiency and releases pattern of lidocaine loaded poly-L-lactatide (PLLA) and poly-D,L-lactatide (PDLLA) microspheres, prepared with O/W emulsion-solvent evaporation process. Prepared in the fast rate of solvent evaporation (FRSE) process by reducing ambient pressure, smoothly morphological surface of drug loaded PLLA and PDLLA microspheres was observed. While in the normal rate of solvent evaporation (NRSE) process, roughness or pinhole surface was only found at drug loaded PLLA microspheres. Fabricated in the FRSE process, both PLLA and PDLLA microspheres showed smaller particle sizes and lower drug encapsulation efficiencies than those prepared in NRSE process. In regard to two materials, PLLA microspheres had higher drug encapsulation efficiencies than PDLLA ones for both processes. Although initial burst releases of drug were observed for both PLLA and PDLLA microspheres prepared in whatever solvent removal process, drug release for PLLA microspheres was slightly less than that for PDLLA ones in the earlier stage of drug release. However, in the subsequent stage of drug release, there was no difference between two materials. In corporation with different crystalline characteristics of PLA polymer and its derivatives, FRSE process by reducing ambient pressure could be further applied to produce different characteristics of microspheres for drug delivery.
The interaction of lidocaine hydrochloride or lidocaine ester derivatives with lecithin vesicles was investigated by proton magnetic resonance (1H-NMR) spectroscopy. Signal broadening of drug indicated the incorporation of the drug into the vesicle membrane. Positively charged nitrogen of lidocaine hydrochloride interacted with polar part of the lecithin vesicles. On the other hand, lidocaine ester derivatives indicated interaction with lecithin vesicles not only by positive charge of nitrogen but also by electrostatic effect of ester carbonyl group. This may be related with the prolonged duration of lidocaine ester derivatives.
Tissue expansion has achieved a prominent role in soft-tissue reconstruction. Expansion-induced pain is often a limiting factor in this process and can affect patients for as long as 24 to 48 hours following each expansion session. Although lidocaine is known to be an effective analgesic, only anecdotal reports of its usefulness when placed within a tissue expander currently exist. This two-part study was designed first to determine if in fact silicone is readily permeable to lidocaine, and second to determine if the potential diffusion dynamics can be defined. In part 1 of the study, the silicone polymer was indeed found to be readily permeable to lidocaine as measured with fluorescence immunoassay technique. In part 2, two groups of Surgitek and Dow Corning expanders were filled with saline and lidocaine and placed in saline baths. At several intervals over a 48-hour period, aliquots of the surrounding saline were sampled and the lidocaine levels subsequently determined. A rather predictable and consistent diffusion curve was demonstrated. The significant difference in diffusion characteristics between the two expander types was apparently due to wall thickness differences inherent in the manufacturing. In this in vitro study, filler-valve leakage did not significantly contribute to lidocaine migration from within these tissue expanders. This basic in vitro work will now set the stage for further in vivo and clinical investigations to more precisely define the role of lidocaine in the tissue-expansion process.