1. Liquid Chromatographic Analysis of Local Anesthetics in Human Plasma after Sample Preparation by On-Line Dialysis. Optimization by Use of Experimental Design
P. Chiap, B. BoulangeP, L. Fotsing 1, Ph. Hubert, J. Crommen*. Chromatographia 2001, 53, June (No. 11/12)
Stock solutions of bupivacaine, mepivacaine, and prilocaine hydrochloride, prepared by dissolving each compound (25 mg) in methanol (25 mL), were stored under refrigeration at 4℃ when not in use. During method development a mixed solution of the three analytes was prepared by diluting each stock solution (1.0 mL) to 10 μgmL-1 (each compound) with water. This intermediate solution was stored under refrigeration at 4℃ and was found to remain stable for at least one week. It was then diluted with water or plasma to a final concentration of ca 750 ngmL-1 for each analyte. These solutions were prepared daily.
2. The effect of local anaesthetic infiltration on urethral function during the tension-free vaginal tape (TVT) procedure
Jonathan R. A. Duckett & Nick S. Papanikolaou & Maria Eaton. Int Urogynecol J (2008) 19:839–841
Urodynamic stress incontinence (USI) affects a great number of adult women and is associated with a significant impact on quality of life. Several different surgical procedures have been reported for the treatment of USI. The tension-free vaginal tape (TVT) operation has become a widely accepted surgical treatment for USI. Cure rates of between 80 and 86% have been described. The original technique described placement of the tape under the mid-urethra using local anaesthesia and sedation. Forty millilitres of prilocaine hydrochloride 1% and adrenaline 0.5% was injected suprapubically, and another 40 ml was infiltrated sub- and paraurethrally. The tension was adjusted by asking the patient to cough during the procedure, and the tension was adjusted to reduce urinary incontinence. Using this technique resulted in high long-term cure rates with low complications such as voiding dysfunction. The operation can also be performed under regional anaesthesia. Previous work assessing the effect of spinal anaesthesia on urethral function has demonstrated that cough pressures are not significantly reduced, but urethral relaxation causes an increased tendency to leak after the spinal anaesthetic. Spinal anaesthesia alters the bladder neck position and urethral closure function, shortening the anatomical and functional urethral length and reducing the maximum urethral closure pressure and pressure transmission ratio in the urethra. If the cough test is used, there may be a tendency to overtighten the tape to abolish leakage. This would result in an increased risk of voiding dysfunction.
3. Microemulsion Microstructure Influences the Skin Delivery of an Hydrophilic Drug
Wafa Naoui & Marie-Alexandrine Bolzinger & Bernard Fenet & Jocelyne Pelletier & Jean-Pierre Valour & Rafik Kalfat & Yves Chevalier. Pharm Res (2011) 28:1683–1695
The reverse effect has been observed in one instance, however. Accordingly, particular attention should be paid to the mass fractions of ingredients in the microemulsion before comparing drug release. The study by Kreilgaard et al. is very instructive to illustrate this point. The permeations of a lipophilic and a hydrophilic drug (lidocaine and prilocaine hydrochloride) were compared from o/w, bicontinuous, and w/o micro- emulsions. The microemulsions differed by their respective water, oil and surfactant mass fractions, but also by their cosurfactant/surfactant mass ratio. For both drugs the highest fluxes were obtained with the o/w microemulsion containing the highest amount of water (50 to 65%). The authors did not suggest the microstructure as a relevant enhancement parameter, but pointed out the influence of the mobility of the drug in the microemulsion. In the present study, the caffeine transdermal flux enhancement due to the o/w microstructure was not very high; a two-fold increase of the caffeine flux was observed only for the o/w microemulsion comparatively to the solution (Table 3). This result is far less than the 6-fold or 10-fold increase in prilocaine hydrochloride flux generated by o/w microemulsions (loaded at 13 or 14%) comparatively to a 2% Xylocain hydrogel.