Dudziak R, Uihlein M
Anaesthesist. 1978 May;27(5):suppl 32-7.
Reports on in vitro precipitation of local anesthetics suggested the possibility of a damaging effect on nervous tissue with spinal anesthesia. The present assays showed that the solubility of local anesthetics in aqueous media decreases with rising pH-levels. The partial pressure of CO2 determines the pH-level of the cerebrospinal fluid, the level ranging at about 7.35 + 0.011 (95% range: 7.327-7.371). The solubilities calculated for a pH of 7.371 (at 37 degrees C) are as follows: Bupivacaine.HCl 0.83+/-0.10 mh/ml Carticaine.HCl 27 +/-2.8 mg/ml Lidocaine.HCl 24 +/-1.3 mg/ml Mepivacaine.HCl 14.8 +/- 0.2 mg/ml Tetracaine.HCl 1.4 +/- 0.12 mg/ml.
关于局部麻醉剂体外沉淀的报告表明，脊髓麻醉可能会对神经组织产生损害作用。目前的试验表明，局部麻醉剂在水性介质中的溶解度会随着pH值的升高而降低。二氧化碳的分压决定了脑脊液的pH值，该值约为7.35±0.011（95%范围：7.327 - 7.371）。在pH为7.371（37摄氏度）时计算出的溶解度如下：盐酸布比卡因0.83±0.10毫克/毫升；盐酸卡替卡因27±2.8毫克/毫升；盐酸利多卡因24±1.3毫克/毫升；盐酸甲哌卡因14.8±0.2毫克/毫升；盐酸丁卡因1.4±0.12毫克/毫升。
