Racemic Bupivacaine Research Articles

There is no place in modern obstetrics for racemic bupivacaine

There is no place in modern obstetrics for racemic bupivacaine

A comparative study of the safety of 0.25% levobupivacaine and 0.25% racemic bupivacaine for paracervical block in the first stage of labor

The objective of the study was to evaluate and compare the safety of levobupivacaine and racemic bupivacaine for paracervical block (PCB) in the first stage of labor after uncomplicated pregnancy. Forty women in an open pilot study and 397 women in a double-blind randomized study received PCB for pain relief in the first stage of labor, either with 25 mg of levobupivacaine or with 25 mg of racemic bupivacaine. The incidence of cardiotocographic pathology was compared between the groups using Fisher's exact test. The 95% confidence intervals for the between-group difference were calculated by Newcombe's method. In the randomized double-blind study, the incidence of any pathological result in cardiotocography (CTG) was 10.4% in the levobupivacaine group and 12.8% in the racemic bupivacaine group. The incidence of fetal bradycardia in the groups was 2.6 and 3.8%, respectively. All the cardiotocographic changes were transient, and no operative intervention was indicated because of CTG. No difference in the analgesic effect between the drugs was found. Most of the parturients in the levobupivacaine group (97%) and in the racemic bupivacaine group (96%) had spontaneous vaginal delivery. Neonatal outcome was good in both groups. No difference in cardiotocographic pathology was found between PCB with levobupivacaine compared with PCB with racemic bupivacaine. The incidence of bradycardia was low. PCB was found to be a safe pain-relief method for low-risk parturients.

What determines the analgesic effect of paracervical block?

The objective of the study was to evaluate the analgesic effect of paracervical block (PCB) in labor pain relief and to discover the determinants associated with good analgesia. In a prospective trial, 341 women received PCB for pain relief in the first stage of labor, with 10 ml of 0.25% levobupivacaine or racemic bupivacaine. All these pregnancies were uncomplicated and the progress of labor was normal. The analgesic effect of PCB was measured by using a visual analog scale (VAS). The factors associated with good pain relief (>50% decrease in the VAS score within 30 min) were analyzed statistically by Student's t-test or the Mann-Whitney test (continuous variables), Fisher's exact test (categorial variables) and after univariate analysis by logistic regression analysis. For pairwise comparisons, Wilcoxon's signed ranks test was used. Good pain relief was achieved in 47.2% of the cases. 12.3% of the parturients needed subsequent epidural or spinal analgesia. In logistic regression analysis, primiparity, a high pain score before PCB, and PCB given by a specialized obstetrician were found to affect the level of pain relief 30 min after PCB. The best pain relief after PCB was achieved among primiparas. Good pain relief was connected with a high pain score before PCB and an experienced obstetrician.

Long QT syndrome: anaesthetic management at delivery

We describe the anaesthetic management of a spontaneous vaginal delivery at 39 weeks' gestation in a 22-year-old patient with congenital long QT syndrome. With a strong family history of sudden deaths, the patient had an initial QT interval corrected for rate (QTc) of >600 ms. Following a once-daily 50-mg dose of atenolol over the previous 11 months, her QTc remained prolonged at 560 ms. To minimise any increase in catecholamine levels and consequent risk of malignant ventricular arrhythmias, a combined spinal-epidural technique was selected using intrathecal diamorphine and levobupivacaine, with intravenous and oral magnesium and potassium supplementation. Levobupivacaine was substituted for routine racemic bupivacaine to decrease the risk of drug-induced cardiotoxicity. Delivery outcome was successful and uneventful. We outline the pathophysiology, risks and treatments of long QT syndrome, and discuss the analgesic management of this patient in labour with congenital long QT syndrome.

Levobupivacaine Versus Ropivacaine Infiltration Analgesia for Mastopexy

A prospective double-blind study was conducted to compare the analgesic properties of levobupivacaine and ropivacaine in a bilaterally symmetrical mastopexy model. Both of these 2 long-acting local anesthetic amides are associated with lower cardiac and central nervous system toxicity than racemic bupivacaine, a widely used agent for long-lasting perioperative analgesia in esthetic procedures. In this study, each of the 18 patients undergoing bilateral mastopexy under conscious sedation received preoperative infiltration with levobupivacaine in 1 breast and equal volume of ropivacaine in the other. Patients were requested to assess their pain separately in each side every 2 hours and for 12 hours postoperatively on a visual analog scale. Overall analgesia achieved up to 12 hours postoperatively was found to be statistically different between the 2 local anesthetic factors in favor of levobupivacaine. At 2 hours postoperatively, no difference was found between the 2 local anesthetic agents in terms of analgesic efficacy (P = 0.298). However, postoperative pain scores recorded after infiltration with levobupivacaine were significantly lower than pain scores for the ropivacaine-infiltrated sides (P<0.001) at all other timeframes. Both anesthetics provided satisfactory analgesia for at least 10 hours, but constantly low pain scores were recorded for levobupivacaine for 10 hours postoperatively, whereas for ropivacaine only for 6 hours. At 12 hours, 66% of patients needed oral analgesia for pain in the ropivacaine-infiltrated breast. It is concluded that levobupivacaine is more effective for local infiltrative analgesia in mastopexy than ropivacaine, providing longer-lasting postoperative analgesia.

Comparative effects of levobupivacaine and racemic bupivacaine on excitotoxic neuronal death in culture and N-methyl-d-aspartate-induced seizures in mice

We compared the neurotoxic profile of racemic bupivacaine and levobupivacaine in: (i) a mouse model of N-methyl-d-aspartate (NMDA)-induced seizures and (ii) in an in vitro model of excitotoxic cell death. When used at high doses (36 mg/kg) both bupivacaine and levobupivacaine reduced the latency to NMDA-induced seizures and increased seizure severity. However, levobupivacaine-treated animals underwent less severe seizures as compared with bupivacaine-treated animals. Lower doses of levobupivacaine and bupivacaine had opposite effects on NMDA-induced seizures. At doses of 5 mg/kg, levobupivacaine increased the latency to partial seizures and prevented the occurrence of generalized seizures, whereas bupivacaine decreased the latency to partial seizures and did not influence the development of generalized seizures. In in vitro experiments, we exposed primary cultures of mouse cortical cells, containing both neurons and astrocytes, to 100 μM NMDA for 10 min for the induction of excitotoxic neuronal death. This treatment killed 70–80% of the neuronal population, as assessed 24 h after the excitotoxic pulse. In this particular model, both levobupivacaine and bupivacaine were neuroprotective against NMDA toxicity. However, neuroprotection by levobupivacaine was seen at lower concentrations (with respect to bupivacaine) and was maintained at concentrations of 3 mM, which are much higher than the plasma security threshold for the drug in vivo. In contrast, no protection against NMDA toxicity was detected when 3 mM concentrations of bupivacaine were applied to the cultures. Our data show a better neurotoxic profile of levobupivacaine as compared to racemic bupivacaine, and are indicative of a safer profile of levobupivacaine in clinical practice.

L‐Bupivacaine 0.5% vs. racemic 0.5% bupivacaine for caudal epidural analgesia in horses

Bupivacaine is available as a racemic mixture of its enantiomers, d-bupivacaine and l-bupivacaine (LB). The aim of this randomized, double-blind study was to investigate the clinical efficacy and safety of S(-)-bupivacaine compared with standard racemic bupivacaine (RB) in horses under caudal epidural analgesia. Two treatments were administered to each horse, with a 2-week interval between subsequent treatments. Treatment 1 consisted of 0.5% LB at a dose of 0.06 mg/kg of body weight, and treatment 2 consisted of 0.5% RB at a dose of 0.06 mg/kg of body weight. Epidural injections were given in all animals between the first and second coccygeal vertebra. Heart rate (HR), arterial pressures, respiratory rate (RR), rectal temperature (RT), analgesia, and motor blocking were determined before drug administration (basal) and 5, 10, 15 and 30 min after drug administration, and at 30 min intervals thereafter. There were no significant differences between the two treatments in the quality of sensory and motor block. The duration of analgesia was 320 +/- 30 min (mean +/- SD) for RB and 360 +/- 42 min for LB. HRs and RRs, arterial pressures and RT did not change (P < 0.05) significantly from basal values after epidural administration of LB or RB. This study supports that 0.5% LB is an effective alternative to RB in caudal epidural analgesia in conscious, standing horses. The use of LB vs. RB warrants further investigation, particularly for long-lasting surgery in the perineal region.

Volume anestésico mínimo para bloqueio retrobulbar extraconal: comparação entre soluções a 0,5% de bupivacaína racêmica, de levobupivacaína e da mistura enantiomérica S75/R25 de bupivacaína

Minimum anesthetic volume (MAV) of local anesthetics corresponds to the effective volume for regional anesthesia in 50% of patients. In this study, MAV of 0.5% racemic bupivacaine, 0.5% levobupivacaine and enantiomeric S75/R25 bupivacaine were calculated and compared. This study involved two series of patients undergoing cataract extraction. Series 1 patients received either 0.5% racemic bupivacaine (n = 9) or 0.5% levobupivacaine (n = 11). Series 2 patients received either 0.5% racemic bupivacaine (n = 11) or 0.5% enantiomeric S75/R25 bupivacaine (n = 10). Blockades were achieved by single-injection and inferior-lateral approach. Motility of each rectus muscle was assessed 10 minutes later as: 0 (absent), 1 (decreased) or 2 (normal). Total muscle scores represented total eye motility score (TMS). Local anesthetic volume administered to the first patient of each group was 7.4 mL. Subsequent patients received volumes corresponding to 0.1 higher natural logarithm unit (if TME > 2) or lower (if TME < 2) as compared to natural logarithm of preceding volume. Massey and Dixon's formulae were used for MAV calculations. MAVs of bupivacaine in both series were 6 mL and 6.2 mL, respectively. MAVs of levobupivacaine and enantiomeric S75/R25 bupivacaine were 5.7 mL and 5.8 mL, respectively. There were no differences between groups in effective anesthetic volumes. Similar volumes of 0.5% racemic bupivacaine, 0.5% levobupivacaine and enantiomeric S75/R25 bupivacaine are needed for extraconal retrobulbar anesthesia.

Sistemas de liberação controlada com bupivacaína racêmica (S50-R50) e mistura enantiomérica de bupivacaína (S75-R25): efeitos da complexação com ciclodextrinas no bloqueio do nervo ciático em camundongos

Bupivacaine-induced side effects have led to the search for new local anesthetics (LA) with similar potency and lower toxicity, such as bupivacaine enantiomeric mixture (S75-R25). Drug-delivery systems for LA in carriers, such as cyclodextrins (CD), have been developed to improve anesthetic potency and therapeutic index of those drugs. This study aimed at preparing, characterizing and evaluating the anesthetic efficacy of inclusion complexes of bupivacaine enantiomeric mixture (S75-R25) and racemic bupivacaine (S50-R50) with hydroxypropylb- cyclodextrin (HPb-CD) comparing them to clinically available preparations.Inclusion complexes were obtained by mixing appropriate volumes of HPb-CD and S50-R50 or S75-R25 to final 1:1 or 1:2 molar ratios and were characterized by phase solubility experiments. Affinity constants (K) were determined between HPb-CD and each LA. Motor and sensory blocks induced by plain or complexed LA formulations were evaluated in mice by sciatic nerve block. Three LA concentrations were used during the experiment: 0.125, 0.25 and 0.5%.Solubility experiments results were indicative of S50-R50:HPb-CD and S75-R25:HPb-CD complexation, with similar affinity constant (K) values: 14.7 M-1 and 14,3 M-1, respectively. In vivo experiments have shown that complexation has enhanced differential nerve blockade induced by LA: i) motor blockade duration induced by S75-R25 was similar, to the induced by but less intense S50-R50 ( p < 0.001). S50-R50HPb-CD and S75-R25HPb-CD complexes have decreased onset (p < 0.01 and p < 0.05, respectively), without changing motor block intensity (Emax) as compared to plain drugs; ii) sensory block evaluation has revealed higher analgesic intensity with S50-R50HPb-CD (2-fold, p < 0.001) and S75-R25HPb-CD (1.5-1.8-fold, p < 0.01 and p < 0.001, respectively) with both molar ratios (1:1 and 1:2, LA:CD), in addition to prolonging analgesic effect as compared to S50-R50 and S75-R25.More pronounced analgesic effects obtained by complexation with HPb-CD have shown that both formulations, S50-R50HPb-CD and S75-R25HPb-CD, are very useful for postoperative pain relief, requiring lower LA concentrations. Nevertheless, it is worth noticing that S75-R25 - being less toxic than racemic bupivacaine - is an interesting alternative for the development of more effective and safe drug-delivery systems as compared to racemic bupivacaine (S50-R50).

Plasma levobupivacaine concentrations following scalp block in patients undergoing awake craniotomy

Levobupivacaine is an effective local anaesthetic agent for nerve blockade with less systemic toxicity than racemic bupivacaine. The safety and efficacy of levobupivacaine for scalp blockade during awake craniotomy have not been addressed previously. Serial arterial plasma levobupivacaine concentrations following scalp blockade were measured to 2 h in 10 patients booked for awake craniotomy for epilepsy or tumour surgery. Bilateral scalp blockade providing surgical anaesthesia was achieved with a mean dose of 177 mg (2.5 mg kg(-1), range 1.6-3.2 mg kg(-1)) of levobupivacaine (0.5%, 5 mg ml(-1)) with epinephrine (5 microg ml(-1)) added immediately before the block insertion. The maximum measured plasma levobupivacaine concentration was 1.58 (0.44) microg ml(-1) [mean (SD)] with a mean time to peak plasma concentration of 12 (4) min. There were no episodes in any of the 10 patients of symptoms or signs suggestive of either CNS or CVS toxicity. This study demonstrated a relatively rapid rise of plasma levobupivacaine concentration without evidence of cardiovascular or central nervous system sequelae in a sample population of patients who may be particularly prone to perioperative seizures.

Differential Effects of Bupivacaine and Ropivacaine Enantiomers on Intracellular Ca2+Regulation in Murine Skeletal Muscle Fibers

Increased intracellular Ca concentrations are considered to be a major pathomechanism in local anesthetic myotoxicity. Racemic bupivacaine and S-ropivacaine cause Ca release from the sarcoplasmic reticulum of skeletal muscle fibers and simultaneously inhibit Ca reuptake. Examining the optical isomers of both agents, the authors investigated stereoselective effects on muscular Ca regulation to get a closer insight in subcellular mechanisms of local anesthetic myotoxicity. R- and S-enantiomers as well as racemic mixtures of both agents were tested in concentrations of 1, 5, 10, and 15 mm. Saponin-skinned muscle fibers from the extensor digitorum longus muscle of BALB/c mice were examined according to a standardized procedure. For the assessment of effects on Ca uptake and release from the sarcoplasmic reticulum, agents were added to the loading solution and the release solution, respectively, and force and Ca transients were monitored. The effects of S-enantiomers on both Ca release and reuptake were significantly more pronounced than those of racemic mixtures and R-enantiomers, respectively. In addition, the effects of racemates were markedly stronger than those of R-enantiomers. With regard to Ca release, the effects of bupivacaine isomers were more pronounced than the isomers of ropivacaine. These data show that stereoselectivity is involved in alterations of intracellular Ca regulation by bupivacaine and ropivacaine. S-enantiomers seem to be more potent than R-enantiomers, with intermediate effects of racemic mixtures. In addition, lipophilicity also seems to determine the extent of Ca release by local anesthetics.

Enantioselective Actions of Bupivacaine and Ropivacaine on Coronary Vascular Resistance at Cardiotoxic Concentrations

The main concern with the use of the long-acting local anesthetics bupivacaine and ropivacaine is inadvertent IV injection, which exposes the heart to toxic drug concentrations. We tested the hypothesis that these chiral anesthetics exert enantioselective actions on coronary vascular tone, the regulation of which does not involve voltage-gated Na(+) channels. Coronary perfusion pressure (CPP) was continuously measured in isolated hearts perfused via the aorta at a constant flow rate. This method provides a sensitive assay of coronary vascular resistance in the intact heart. In parallel experiments, we examined the effects of bupivacaine and ropivacaine on intracellular [Ca(2+)] in coronary endothelial cells. In addition, the effect of bupivacaine on mitochondrial membrane potential was assessed using isolated ventricular myocytes. Racemic bupivacaine and R(+)-bupivacaine produced similar dose-dependent decreases in CPP. However, S(-)-bupivacaine, S(-)-ropivacaine and R(+)-ropivacaine increased CPP. In contrast to adenosine triphosphate, neither racemic bupivacaine nor S(-)-ropivacaine changed endothelial intracellular [Ca(2+)], suggesting that these clinically used drugs do not modulate endothelial nitric oxide synthase. We also showed that the putative uncoupler bupivacaine did not depolarize mitochondria in intact ventricular myocytes. In conclusion, the long-acting local anesthetics have enantioselective actions on coronary resistance vessels. Racemic bupivacaine and R(+)-bupivacaine are coronary vasodilators, whereas S(-)-bupivacaine, S(-)-ropivacaine and, to a lesser extent, R(+)-ropivacaine all induce coronary vasoconstriction.

Bupivacaine versus l-bupivacaine for labor analgesia via combined spinal-epidural: A randomized, double-blinded study

Study objective To compare the intensity and duration of motor block and the duration of sensory block with racemic bupivacaine and l-bupivacaine for combined spinal-epidural analgesia, as previous studies have shown contradictory results. Design A prospective, randomized, double-blinded study. Setting Birth Center at Magee-Womens Hospital, Pittsburgh, Pa. Patients Multiparous American Society of Anesthesiologists physical status I and II patients requesting labor analgesia. There were 2 groups: group A with 34 patients and group B with 33. Interventions Group A received a mixture of 2.5 mg of racemic bupivacaine and 25 μg of fentanyl into the subarachnoid space. Group B received 2.5 mg of intrathecal l-bupivacaine and 25 μg of fentanyl. Pain verbal analog score (VAS, 0-10) scores and Bromage scores were recorded at 5, 15, 30, and every 30 minutes thereafter until the VAS increased to 3 or higher, at which time the epidural block was activated with 0.125% bupivacaine and fentanyl. Patients' vital signs and fetal heart rate were monitored for 30 minutes after the block. Main results None of the patients in both groups had any demonstrable motor block. The median VAS decreased from 7 to 0 in 5 minutes in group A and from 7.5 to 0 in group B. The average durations of sensory block in groups A and B were 114.85 ± 26.27 and 101.9 ± 35.20 minutes ( P = NS), respectively. Conclusion Contrary to earlier studies, we did not find any difference in the intensity and duration of sensory or motor blocks between racemic bupivacaine and l-bupivacaine. Based on our findings in the parturient population studied, we conclude that l-bupivacaine does not offer any advantages over racemic bupivacaine when used for combined spinal-epidural for labor analgesia.

Randomized, double-blind, phase III, controlled trial comparing levobupivacaine 0.25%, ropivacaine 0.25% and bupivacaine 0.25% by the caudal route in children

The rationale for replacing racemic bupivacaine with the s-enantiomers levobupivacaine and ropivacaine is to provide a wider margin of safety with the same analgesic efficacy and less postoperative motor block. In a randomized, double-blind, phase III, controlled trial we compared the caudal administration of levobupivacaine 0.25% and ropivacaine 0.25% with bupivacaine 0.25% in children. Ninety-nine ASA I-II children less than 10 yr old scheduled for elective sub-umbilical surgery were randomized to receive caudal block with bupivacaine 0.25%, ropivacaine 0.25% or levobupivacaine 0.25%. The primary outcome of the study was the clinical efficacy of the caudal block during the operation. Secondary outcome measures were analgesic onset time, pain relief after the operation and residual motor blockade. The proportion of children with effective analgesia during the operation was similar among groups. There were no significant differences in the analgesic onset time of the caudal block. Bupivacaine produced a significant incidence of residual motor block compared with levobupivacaine or ropivacaine at wake-up (P<0.01). There were no significant differences in the number of patients receiving rescue analgesia after surgery. However, analgesic block lasted significantly longer in patients receiving bupivacaine (P=0.03). During sub-umbilical surgery, caudal levobupivacaine, ropivacaine and bupivacaine provided comparable analgesic efficacy. Bupivacaine produced a higher incidence of residual motor blockade and a longer analgesic block than ropivacaine and levobupivacaine.

Dexmedetomidine Decreases the Convulsive Potency of Bupivacaine and Levobupivacaine in Rats: Involvement of α2-Adrenoceptor for Controlling Convulsions

Dexmedetomidine, a highly selective alpha(2)-adrenoceptor agonist, is used in combination with local anesthetics for sedation and analgesia. We tested the hypothesis that dexmedetomidine used for sedation alters the convulsive potency of racemic bupivacaine and levobupivacaine in awake, spontaneously breathing rats. In the first experiments, male Sprague-Dawley rats were randomly divided into six groups: bupivacaine with no dexmedetomidine (bupivacaine control; BC), bupivacaine with small-dose dexmedetomidine (BS), bupivacaine with large-dose dexmedetomidine (BL), levobupivacaine with no dexmedetomidine (levobupivacaine control; LC), levobupivacaine with small-dose dexmedetomidine (LS), and levobupivacaine with large-dose dexmedetomidine (LL) (n = 10 for each group). Continuous infusion of dexmedetomidine (Groups BC and LC, 0 microg x kg(-1) x h(-1); Groups BS and LS, 3.6 microg x kg(-1) x h(-1); and Groups BL and LL, 10.8 microg x kg(-1) x h(-1)) was started after bolus injection (Groups BC and LC, 0 microg/kg; Groups BS and LS, 0.5 microg/kg; and Groups BL and LL, 1.5 microg/kg). Fifteen minutes after the start of the dexmedetomidine infusion, continuous infusion of bupivacaine (Groups BC, BS, and BL) or levobupivacaine (Groups LC, LS, and LL) at 1 mg x kg(-1) x min(-1) was started and continued until tonic/clonic convulsions occurred. Dexmedetomidine achieved significantly different sedation levels both in Groups BC, BS, and BL and in Groups LC, LS, and LL (P < 0.05). Convulsive doses of bupivacaine and levobupivacaine were significantly larger in Groups BL and LL than in Groups BC and LC, respectively (P < 0.01 for both). Concentrations of bupivacaine and levobupivacaine in plasma and in brain at the onset of convulsions were also larger in Groups BL and LL than in Groups BC and LC (P < 0.01 for both). In the second experiment, yohimbine (1 mg/kg) administered 10 min before and 5 min after the start of dexmedetomidine infusion completely reversed the sedative effect of dexmedetomidine (bolus 1.5 microg/kg, followed by 10.8 microg x kg(-1) x h(-1)). Convulsive doses and plasma and brain concentrations of bupivacaine and levobupivacaine at the onset of convulsions in rats receiving yohimbine and dexmedetomidine were significantly smaller than in those receiving only dexmedetomidine (P < 0.05 for all) and were similar to those without dexmedetomidine or yohimbine. We conclude that dexmedetomidine used for sedation decreases the convulsive potency of both bupivacaine and levobupivacaine in rats. Alpha(2)-adrenoceptor agonism may be involved in this anticonvulsant potency.

Anaesthetic Agents for Advanced Regional Anaesthesia

Interest in the use of regional anaesthesia, particularly peripheral nerve blocks (PNBs) and continuous PNBs, has increased in recent years. Accompanying this resurgence in interest has been the development of new local anaesthetics and additives designed to enhance block duration and quality. This manuscript provides a literature-based review on accepted uses of local anaesthetics and adjuncts for a variety of regional anaesthesia techniques. A brief review of local anaesthetic pharmacodynamics describes the action of these drugs in preventing nerve depolarisation, thus blocking nerve impulses. Toxic adverse effects of local anaesthetics, specifically CNS and cardiac manifestations of excessive local anaesthetic blood concentrations and the direct neurotoxic properties of local anaesthetics, are discussed generally and specifically for many commonly used local anaesthetics. Clinically useful ester and amide local anaesthetics are evaluated individually in terms of their physical properties and toxic potential. How these properties impact on the clinical uses of each local anaesthetic is explored. Particular emphasis is placed on the long-acting local anaesthetic toxic potential of racemic bupivacaine compared with levobupivacaine and ropivacaine, which are both levorotatory stereoisomers. Guidelines for using ropivacaine and mepivacaine, based on the authors' experience using advanced regional anaesthesia in a busy practice, is provided. Finally, epinephrine (adrenaline), clonidine and other local anaesthetic additives and their rationale for use is covered along with other future possibilities.

A comparative study of the safety of 0.25% levobupivacaine and 0.25% racemic bupivacaine for paracervical block in the first stage of labor

A comparative study of the safety of 0.25% levobupivacaine and 0.25% racemic bupivacaine for paracervical block in the first stage of labor

Effects of bupivacaine enantiomers and ropivacaine on vasorelaxation mediated by adenosine triphosphate-sensitive K(+) channels in the rat aorta.

Effects of bupivacaine enantiomers and ropivacaine on vasorelaxation mediated by adenosine triphosphate-sensitive K(+) channels in the rat aorta.

Chromatographic separation of bupivacaine racemate by mathematical model with competitive langmuir isotherm

HPLC (High Performance Liquid Chromatography) was utilized for the chiral separation of racemic bupivacaine, and mathematical modeling with competitive Langmuir isotherm was performed to determine the opti- mum feed condition. For each racemic compound, the isotherm parameters a, b and mass transfer coefficients k were obtained by parameter estimation and maximum likelihood method. The agreement of elution profiles between the experimental data and the calculated values was fairly good. In order to find the optimum separation condition, simulations were carried out to determine the feed conditions such as concentration and injection volume. To preparatively separate racemic bupivacaine, the desirable injection volumes were 0.05 ml at 2.0 mg/ml of the con- centration of racemic mixture or 0.01 ml at 20 mg/ml.

Levobupivacaine in obstetric analgesia and anaesthesia. Where is its place?

Levobupivacaine, the S-enantiomer of racemic bupivacaine, will be available in Germany in mid-2004. Pharmacological studies demonstrated that, compared to bupivacaine, levobupivacaine has equal local anaesthetic potency with reduced potential for cardiac and CNS toxicity. This review introduces the new long-acting amide local anaesthetic levobupivacaine to the reader and evaluates its place in obstetric analgesia and anaesthesia compared to bupivacaine and ropivacaine.