Methylprednisolone shortens the effects of bupivacaine on sensory nerve fibers in vivo

Effect of Adding Perineural Methylprednisolone to Peripheral Nerve Blocks Combined With Intravenous Dexamethasone for Prolonged Postdischarge Analgesia After Fast-track Total Knee Arthroplasty: A Randomized Controlled Trial

OBJECTIVES

Patients undergoing total knee arthroplasty (TKA) may experience moderate-to-severe subacute pain after hospital discharge that may be undermanaged. We aimed to evaluate the effect of methylprednisolone added to ultrasound-guided peripheral nerve blocks (PNBs) combined with multimodal analgesia including intravenous dexamethasone for prolonged analgesia after early discharge.

MATERIALS AND METHODS

We randomized 80 patients who underwent fast-track TKA into 2 groups. All patients received a periarticular injection, PNBs, and multiple doses of intravenous dexamethasone. The methylprednisolone group received 140 mg methylprednisolone in PNBs, while the nonmethylprednisolone group did not. The primary outcome was the incidence of moderate-to-severe pain (Numerical Rating Scale ≥4) during the first 12 postdischarge days. The secondary outcomes included pain scores until 3 postoperative months, incidence of rebound pain, functional performances, patient satisfaction, and adverse events.

RESULTS

No significant between-group differences were noted in the incidence of moderate-to-severe pain during the first 12 postdischarge days (nonmethylprednisolone vs. methylprednisolone groups: 70% vs. 69.2%, P=0.941). However, this incidence was significantly higher in the methylprednisolone group between 2 weeks and 1 month (P=0.015) and between 1 and 3 months (P=0.004) postoperatively. No between-group differences in the Numerical Rating Scale scores at the postdischarge time points, incidence of rebound pain, and functional performance results were noted.

DISCUSSION

Adding perineural methylprednisolone to ultrasound-guided PNBs for multimodal analgesia with intravenous dexamethasone did not prolong analgesia and improved the functional ability after fast-track TKA within 12 postdischarge days. However, the incidence moderate-to-severe pain may increase between the 2-week and 3-month follow-up.

Effect of budesonide on the perception of induced airway narrowing in subjects with asthma

The perception of bronchoconstriction may be modulated by airway inflammation. However, the effect of inhaled corticosteroid (ICS) treatment on perception in subjects with asthma has received limited study. The aim of this study was to determine the effect of inhaled budesonide on the perception of breathlessness induced by histamine challenge. Thirty-five subjects with poorly controlled asthma were randomized to receive budesonide (1,600 or 3,200 microg/d) for 8 wk, followed by 8 wk at 1,600 microg/d and subsequent downtitration according to a clinical algorithm. Borg scores were recorded during histamine challenges performed at baseline and at 8, 16, 24, 48, and 72 wk. Perception was estimated as the slope of Borg/% fall FEV(1). The Borg/FEV(1) slope increased significantly after 8 wk of budesonide (0.09 [0.08-0.12] to 0.15 [0.11-0.19], p = 0.002), and remained increased compared with baseline values at all subsequent visits. There were no significant differences in Borg/ FEV(1) slope between subjects who were and were not taking ICS at study entry. The magnitude of change in the Borg/FEV(1) slope did not differ significantly between treatment groups and was not related to changes in baseline FEV(1), airway hyperresponsiveness, blood eosinophils, or serum eosinophil cationic protein (ECP). We conclude that treatment with budesonide enhances the perception of airway narrowing, but the effect is unrelated to budesonide dose, or to changes in circulating eosinophil markers.

Inclusion of lignocaine base into a polar lipid formulation--in vitro release, duration of peripheral nerve block and arterial blood concentrations in the rat

BACKGROUND

Slow-release formulations of local anaesthetics may produce nerve blocks of long duration. The present study aimed at investigating the in vitro and in vivo properties of a polar lipid formulation for slow release of lignocaine and the effects on nerve block duration by inclusion of dexamethasone into the system.

METHODS

In vitro release of lignocaine from the lipid formulation was studied in a US Pharmacopoeia rotating apparatus. Sciatic nerve blocks were induced in rats by 0.1 ml of test formulations containing lignocaine HCl 20 mg. ml-1 in aqueous solution, lignocaine base 20, 100 or 200 mg. ml-1 in lipid formulation or the last formulation with dexamethasone 0.05, 0.5 or 5 mg. ml-1. The durations of sensory and motor block and the arterial blood concentrations of lignocaine were investigated.

RESULTS

In vitro there was a sustained release of lignocaine from the lipid formulation, with 50% release at around 48 h. In vivo lignocaine base 20 mg. ml-1 in lipid formulation produced sciatic nerve blocks of significantly shorter duration than lignocaine HCl 20 mg. ml-1 in aqueous solution, while lignocaine base 100 and 200 mg. ml-1 in lipid formulation produced blocks lasting two and three times longer, respectively, than the lignocaine HCl solution. Addition of dexamethasone did not affect the duration of nerve block. Following administration of lignocaine base 200 mg. ml-1 in lipid formulation, as compared to lignocaine HCl 20 mg. ml-1 in aqueous solution, the maximal blood concentration of lignocaine was only three times higher in spite of the ten-fold difference in dose, and the mean terminal half-life was three times longer, reflecting the slow release from the formulation.

CONCLUSIONS

Our findings indicate that lignocaine base in polar lipids acts as a slow-release preparation of local anaesthetic both in vitro and in vivo.