1.Characterization of four crystal polymorphs and a monohydrate of s-bupivacaine hydrochloride (levobupivacaine hydrochloride).
Niederwanger V1, Gozzo F, Griesser UJ. J Pharm Sci. 2009 Mar;98(3):1064-74. doi: 10.1002/jps.21496.
Five crystal forms of the amide-type local anesthetic S-bupivacaine hydrochloride (levobupivacaine) were prepared and characterized by means of thermal analytical methods, FTIR- and Raman-spectroscopy, powder X-ray diffractometry, and moisture sorption analysis. Commercial lots of the substance may consist of form A degrees , the thermodynamically stable form at 20 degrees C, and/or the metastable form C. Form A degrees shows a highly reversible transformation into form B (T(trs): 85.3 degrees C) with a transition enthalpy of 4.6 kJ mol(-1). The hysteresis between the experimental transition temperatures is 3.5 K, indicating a very weak kinetic control. The hydrate shows a variable water content (0.71-1.14 mol/mol) between 10% and 90% relative humidity (RH) and dehydrates to form C under dry conditions or at elevated temperatures. All anhydrous forms transform to the hydrate at and above 90% RH (25 degrees C). Form C slowly converts to form A degrees on storage and is the polymorph with the highest hygroscopicity.
2.Effect of intravenous vasopressor on spread of spinal anaesthesia and fetal acid-base equilibrium.
Cooper DW1, Gibb SC, Meek T, Owen S, Kokri MS, Malik AT, Koneti KK. Br J Anaesth. 2007 May;98(5):649-56. Epub 2007 Mar 8.
BACKGROUND: We previously found rostral spread of spinal plain levobupivacaine to be less with prophylactic i.v. phenylephrine than with ephedrine during Caesarean delivery. This study investigated whether rostral spread of spinal hyperbaric bupivacaine is also less with phenylephrine than with ephedrine.
3.Tolerability of large-dose intravenous levobupivacaine in sheep.
Chang DH1, Ladd LA, Wilson KA, Gelgor L, Mather LE. Anesth Analg. 2000 Sep;91(3):671-9.
In preclinical pharmacological studies of levobupivacaine (S-bupivacaine), we determined its tolerability, cardiovascular actions, and pharmacokinetics, and we estimated its margin of safety compared with bupivacaine in conscious sheep. Levobupivacaine HCl. H(2)O was infused IV for 3 min into 10 previously instrumented ewes (approximately 50 kg). On subsequent days, the doses were increased by 50 mg from 200 or 250 mg until fatality occurred. All doses produced convulsions, QRS widening, and cardiac arrhythmias. With incremental doses, 4 of 4 animals survived 200 mg, 7 of 10 survived 250 mg, 3 of 7 survived 300 mg, but 0 of 3 survived 350 mg. Death resulted from sudden onset ventricular fibrillation (n = 3, within 2-3 min), electromechanical dissociation-pump failure (n = 5, within 4-5 min), or ventricular tachycardia-induced cardiac insufficiency (n = 2, >10 min). The estimated fatal dose (mean +/- SD) was 277 +/- 51 mg for levobupivacaine (compared with 156 +/- 31 mg found previously for bupivacaine).