The pharmacokinetics of ropivacaine in hepatic and renal insufficiency

Effect of ropivacaine on peripheral neuropathy in streptozocin diabetes-induced rats through TRPV1-CGRP pathway

Objective To determine the effect of ropivacaine on peripheral neuropathy in diabetic rats and its possible mechanism.

Methods Forty-eight Sprague–Dawley rats were randomly divided into six groups: nondiabetic control group, nondiabetic group A (0.25% ropivacaine), nondiabetic group B (0.75% ropivacaine), diabetic control group (diabetic peripheral neuropathy (DPN) +artificial cerebrospinal fluid), diabetic group A (DPN+0.25% ropivacaine), and diabetic group B (DPN + 0.75% ropivacaine), with eight rats in each group. Within an hour of the last administration, the sciatic motor nerve conduction velocity (MNCV) of each group was measured, and the morphological changes of rat sciatic nerve were observed by HE, Weil’s staining and electron microscopy. The expression of transient receptor potential vanilloid (TRPV1) in the spinal cord dorsal horn of rats was analyzed by immunohistochemistry, and the expression of Calcitonin gene-related peptide (CGRP) protein in the spinal cord was analyzed by Western blot.

Results Compared with the nondiabetic control group, elevated blood glucose, decreased weight and reduced average mechanical withdrawal threshold (MWT), additionally, the sciatic nerves showed significantly slowed conduction velocity (both P<0.001) and damaged pathological structure, the expression of TRPV1 and CGRP were decreased (both P<0.001) in the diabetic groups. Compared with the diabetic control group, down-regulation of TRPV1 and CGRP in spinal cord was significant for the diabetic groups A and B treated with 0.25 and 0.75% ropivacaine, the higher concentration of ropivacaine correlated with a greater change.

Conclusion Ropivacaine can significantly block sciatic nerve conduction velocity in DPN rats in a concentration-dependent manner, which may be related to the expression of the TRPV1-CGRP pathway.

Intraperitoneal Local Anesthetic Instillation and Postoperative Infusion Improves Functional Recovery Following Colectomy: A Randomized Controlled Trial

BACKGROUND

Intraperitoneal local anesthetic is an analgesic technique for inclusion in the polypharmacy approach to postoperative pain management in enhanced recovery after surgery programs. Previously, augmentation of epidural analgesia with intraperitoneal local anesthetic was shown to improve functional postoperative recovery following colectomy.

OBJECTIVE

This study determines whether intraperitoneal local anesthetic improves postoperative recovery in patients undergoing colectomy, in the absence of epidural analgesia, with standardized enhanced recovery after surgery perioperative care.

DESIGN

This is a multisite, double-blinded, randomized, placebo-controlled trial (ClinicalTrials.gov Identifier NCT02449720).

SETTINGS

This study was conducted at 3 hospital sites in South Australia.

PATIENTS

Eighty-six adults undergoing colectomy were stratified by approach (35 open; 51 laparoscopic), then randomly assigned to intraperitoneal local anesthetic (n = 44) and control (n = 42) groups.

INTERVENTIONS

Patients in the intraperitoneal local anesthetic group received an intraoperative intraperitoneal ropivacaine 100-mg bolus both pre- and postdissection and 20 mg/h continuous postoperative infusion for 48 hours. Patients in the control group received a normal saline equivalent.

MAIN OUTCOME MEASURES

Functional postoperative recovery was assessed by using the surgical recovery scale for 45 days; postoperative pain was assessed by using a visual analog scale; and opioid consumption, use of rescue ketamine, recovery of bowel function, time to readiness for discharge, and perioperative complications were recorded.

RESULTS

The intraperitoneal local anesthetic group reported improved surgical recovery scale scores at day 1 and 7, lower pain scores, required less rescue ketamine, and passed flatus earlier than the control group (p < 0.05). The improvement in surgical recovery scale at day 7 and pain scores remained when laparoscopic colectomy was considered separately. Opioid consumption and time to readiness for discharge were equivalent.

LIMITATIONS

This study was powered to detect a difference in surgical recovery scale, but not the other domains of recovery, when the intraperitoneal local anesthetic group was compared with control.

CONCLUSIONS

We conclude that instillation and infusion of intraperitoneal ropivacaine for patients undergoing colectomy, including by the laparoscopic approach, decreases postoperative pain and improves functional postoperative recovery. We recommend routine inclusion of intraperitoneal local anesthetic into the multimodal analgesia component of enhanced recovery after surgery programs for laparoscopic colectomy. See Video Abstract at http://links.lww.com/DCR/A698.

Flip-flop pharmacokinetics--delivering a reversal of disposition: challenges and opportunities during drug development

Flip-flop pharmacokinetics is a phenomenon often encountered with extravascularly administered drugs. Occurrence of flip-flop spans preclinical to human studies. The purpose of this article is to analyze both the pharmacokinetic interpretation errors and opportunities underlying the presence of flip-flop pharmacokinetics during drug development. Flip-flop occurs when the rate of absorption is slower than the rate of elimination. If it is not recognized, it can create difficulties in the acquisition and interpretation of pharmacokinetic parameters. When flip-flop is expected or discovered, a longer duration of sampling may be necessary in order to avoid overestimation of fraction of dose absorbed. Common culprits of flip-flop disposition are modified dosage formulations; however, formulation characteristics such as the drug chemical entities themselves or the incorporated excipients can also cause the phenomenon. Yet another contributing factor is the physiological makeup of the extravascular site of administration. In this article, these causes of flip-flop pharmacokinetics are discussed with incorporation of relevant examples and the implications for drug development outlined.

Pharmacology in the elderly and newer anaesthesia drugs

In developed countries, a growing proportion of patients presenting for anesthesia and surgery are elderly. Despite this, and the fact that aging is known to be associated with alterations in drug pharmacokinetics and dynamics, there is little detailed information about the impact of aging on the pharmacology of commonly used anesthetic agents. In this review, we discuss existing current knowledge on the physiological changes that occur with age and the way these changes affect the pharmacokinetics and dynamics of anesthetic agents. Also, an overview of up-to-date PK-PD modeling concepts and their usefulness and limitations in modern anesthesiologic practice with respect to the elderly population is given. Finally, newer agents such as sugammadex, remifentanyl, ropivacaine and desflurane are discussed in detail with emphasis on current evidence concerning dosing, safety and efficacy of their use in the elderly.

[Cardiac arrest after axillary plexic anaesthesia with ropivacaine in a chronic kidney failure dialysis patient]

The local anaesthetics are responsible for an important part of morbidity and mortality during conduction anaesthesia. We describe fatal accident plexic anaesthesia with ropivacaine in spite of a classical reanimation measure in a dialysis patient.

Liquid chromatography–electrospray mass spectrometry determination of free and total concentrations of ropivacaine in human plasma

A specific and sensitive liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method was developed for the determination of free and total ropivacaine in human plasma. The work-up procedure involved a simple precipitation of plasma proteins with methanol. Etidocaine served as the internal standard. After microscale equilibrium-dialysis, measurement of free ropivacaine levels was performed after direct injection of the dialysate into the chromatograph. The system used a Zorbax eclipse XD8 C8 analytical column packed with 5 microm diameter particles as the stationary phase. The mobile phase consisted of a 15-min gradient (mobile phase A: 0.05% (v/v) trimethylamine in acetonitrile, mobile phase B: 2mM ammonium formate buffer (pH 3)). Mass spectrometric data were acquired in single ion monitoring mode at m/z 275 for ropivacaine and m/z 277 for etidocaine. The drug/internal standard peak area ratios (plasma) or peak areas (dialysate) were linked via a quadratic relationship to concentrations. Precision ranged from 1 to 7.6% accuracy was between 92.6 and 109%. The lower limits of quantitation were 1 microg/l in plasma and 2 microg/l in the dialysate. This method was found suitable for the analysis of plasma samples collected during a clinical trial performed in 30 infants undergoing epidural anaesthesia or continuous psoas compartment block.