PubMed · 9609196
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F M Hall. 1998. MR arthrography.. https://doi.org/10.2214/ajr.170.6.9609196
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Our research on topical application of lidocaine-loaded non-ionic surfactant vesicles (NSVs) was prompted by the great interest on new delivery systems for local anaesthetics. This study is focused on a novel formulation of NSVs entrapping lidocaine in the form of a free base (LID) and a hydrochloride (LIDHCl). NSVs were prepared from polyoxyethylene sorbitan monolaurate (Tween20) and cholesterol. The effect of vesicle composition and environmental pH condition (8.6-5.5) on drug encapsulation efficiency (e.e.) was investigated. Experimental strategies involved: freeze-fracture, microscopy technique, dynamic light scattering, permeation through Silastic and mouse abdominal skin, in vitro release kinetics of vesicle-entrapped drugs, fluorescence quenching analyses. Diffusion experiments showed that the flux of charged lidocaine through Silastic membrane was possible only after the vesicle encapsulation. Permeation through mouse abdominal skin of LIDHCl loaded vesicles showed a higher flux and a shorter lag time with respect to classical liposome formulations, while LID permeation rate was quite similar for NSV and liposome formulations. Vesicles were also prepared in the presence of dicetylphosphate (DCP) and N-cetylpyridinium chloride (CP) to obtain negatively and positively charged vesicles respectively, but in this case the e.e. of the drug was negligible. The possible reason of the remarkable lower e.e. observed with charged vesicles was investigated by means of fluorescence quenching experiments.
UNLABELLED: Lidocaine, phenytoin, and bupivacaine are sodium channel blockers. Lidocaine displaces bupivacaine from its receptor on the sodium channel. However, lidocaine does not seem to decrease bupivacaine toxicity. Phenytoin also has been used to treat bupivacaine cardiotoxicity. To test the hypothesis that lidocaine or phenytoin might be used for the treatment of bupivacaine overdose, we compared the effects of bupivacaine on intraventricular conduction in the isolated heart of rabbits with bupivacaine and with either phenytoin or lidocaine added to bupivacaine. Twenty-four rabbit hearts were retrogradely perfused in a nonrecirculating Langendorff apparatus. The duration of QRS was measured without any drug and 10 min after infusion of 3 microM bupivacaine. Saline (control group) or increasing concentrations of either lidocaine or phenytoin was then added by 10-min-step increments. QRS duration was measured for each concentration at the end of a 10-min step. It was also determined 10 min after discontinuation of bupivacaine and after a period of washout for all drugs. QRS duration was significantly increased by adding phenytoin or lidocaine to bupivacaine. These drugs should not be used to treat the manifestations of bupivacaine toxicity. IMPLICATIONS: The effects of lidocaine and phenytoin on bupivacaine-related increases in cardiac conduction time have been studied in an isolated heart preparation. Both drugs increased the QRS widening induced by bupivacaine. We conclude that none of these drugs should be used for treating bupivacaine intoxication.
PURPOSE: We evaluated the effectiveness of a single injection of lidocaine on patient tolerance of multiple needle biopsies of the prostate. MATERIALS AND METHODS: In 100 consecutive group 1 patients local anesthesia was achieved by a single bolus injection of 10 ml. lidocaine and multiple prostatic needle biopsies was performed under ultrasound guidance. At the end of the procedure patients were asked to complete a questionnaire regarding the level of pain. Answers were compared with those of 100 group 2 patients who underwent prostatic biopsy before the introduction of local anesthesia. RESULTS: Of the group 1 patients 93% had only slight discomfort during the procedure and 7% required a further 1 cc bolus of lidocaine. In 55% of group 2 patients the level of pain during the procedure was significant but bearable, in 35% it was considered unbearable and in 10% sedation with midazolam was necessary. There was no significant difference in complications in the 2 groups. CONCLUSIONS: A single injection of local anesthesia for prostatic biopsy proved to be efficient, well tolerated by patients and effective for decreasing the pain associated with the procedure.