Leukocyte hydrogen peroxide production in a surgical wound in mice. The effects of an amide local anaesthetic

Long-acting local anesthetics and perioperative pain management

Although the use of long-acting local anesthetics has become a useful therapeutic approach for managing peri- and postoperative pain, recent evidence reveals unexpected outcomes. This article reviews the clinical use of long-acting local anesthetics, presents current clinical research findings, and makes recommendations for their use.

Effect of bupivacaine on cultured tenocytes

Proliferation of cultured human fibroblasts and other types of cells has been shown to be hindered by exposure to local anesthetics, which are widely used in musculoskeletal medicine for their use in regional anesthesia, selective nerve blocks, bursography, and brisement. We hypothesized that bupivacaine would decrease cell proliferation and production of extracellular matrix components collagen and proteoglycan in healthy human tenocytes in culture. Primary human tenocyte cultures were prepared from samples of normal tendons obtained from healthy tissue that would otherwise have been discarded during lower extremity tendon transfer surgery. Samples were obtained from 6 patients, 5 women and 1 man with an average age of 69 years (range, 17-73 years). Five flexor digitorum longus tendon samples and 1 peroneus longus tendon sample were used. Harvested tendon tissues (5 mm(3)) were used as explants for primary cell cultures. To measure the proliferative response to bupivacaine, seeded cells were exposed to saline control or to various concentrations of bupivacaine in 1% fetal bovine serum DMEM/F12 or 10% fetal bovine serum DMEM/F12. The 1% fetal bovine serum medium demonstrated the pure bupivacaine effect, and 10% fetal bovine serum more closely approximated the in vivo environment. Seeded cells were starved of fetal bovine serum for 12 hours before exposure to phosphate-buffered saline (control group) and 500 microM bupivacaine (experimental group). This concentration of bupivacaine was selected because it was found to significantly hinder proliferation in both the 1% and 10% fetal bovine serum groups in our proliferation assay. Tenocyte proliferation and extracellular matrix component production were significantly lower (P<or=.05) at >or=1 time points up to 6 days in bupivacaine-treated groups as compared with controls.

["Alternative" effects of local anesthetic agents]

The following article summarizes different aspects of local anesthetic effects that cannot be explained purely by a sodium channel blockade. Particularly remarkable is hereby their antiinflammatory activity, e.g. the inhibition of pathological changes such as excessive stimulation of the inflammatory system, without compromising the host defense system. In contrast to other immunosuppressive drugs commonly used for treating such conditions, local anesthetics look promising for the future as a new therapeutic option. Besides general anesthetic activity, local anesthetics exert cerebroprotective effects and are furthermore, in consideration of their cardiovascular stability, of interest during neuroanesthetic procedures. In addition, local anesthetics are known for their potency to minimize bronchial hyperreactivity, although details of the underlying mechanisms are not yet elucidated. These effects of local anesthetics may represent interesting prospects for which their relevance has to be determined.

Pharmacologic prevention of posterior capsule opacification: in vitro effects of preservative-free lidocaine 1% on lens epithelial cells

PURPOSE

To assess the in vitro effectiveness of preservative-free lidocaine 1% in removing lens epithelial cells (LECs) from the anterior capsule and to evaluate the effect of lidocaine on the LECs.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Eight rabbits (16 eyes) were used in the study. After the rabbits were killed, the eyes were enucleated and divided into 2 groups. In Group 1 (n = 8 eyes), LECs were exposed to preservative-free lidocaine 1% or balanced salt solution (BSS) for 1, 2, or 5 minutes. The anterior capsules were then stained with trypan blue and alizarin red. Photomicrographs of each capsule were taken and analyzed for LEC damage. In Group 2 (n = 8 eyes), hydrodissection was performed with 1 of the agents, followed by phacoemulsification and cortical cleanup. The LEC attachment to the anterior capsule was evaluated by histopathology.

RESULTS

Anterior capsule fragments irrigated with BSS showed no LEC nuclear staining; ie, no direct toxic effect. In those irrigated with preservative-free lidocaine 1%, the LECs showed mild toxicity; some cells showed blue nuclear staining. After hydrodissection with lidocaine, the capsules were almost free of LECs; after hydrodissection with BSS, the capsules showed a normal layer of LECs attached to the anterior capsule.

CONCLUSIONS

Preservative-free lidocaine 1% may help diminish the amount of live LECs by facilitating cortical cleanup, by loosening the desmosomal area of cell-cell adhesion with decreased cellular adherence, or by a direct toxic effect. The use of this agent may help prevent posterior capsule opacification.