Nefopam but not physostigmine affects the thermoregulatory response in mice via alpha(2)-adrenoceptors

Nefopam hydrochloride as a component of multimodal analgesia in the postoperative period

The modern approach to the multimodal scheme of postoperative analgesia includes the mandatory use of drugs that have a small number of side effects and at the same time have a polymodal effect on the pathogenetic links of pain development. Nefopam hydrochloride is able to prevent the development of: opioid hyperalgesia, stop pain stimuli without respiratory depression, affect platelet aggregation and the condition of the mucous membrane and motility of the gastrointestinal tract, which distinguishes it from classical NSAIDs. Nefopam hydrochloride is characterized by a low risk of addiction with prolonged use, a pronounced anti-sensory effect, especially significant at the stage of awakening and in the early postoperative period. Postoperative analgesia based on nefopam hydrochloride as a component of multimodal analgesia is effective and safe in the absence of absolute contraindications. The planned use of nefopam hydrochloride for the correction of pain reduces complications in the postoperative period and improves the quality of life of patients. Nefopam hydrochloride is one of the most effective drugs for the correction of postoperative tremor syndrome. The use of nefopam hydrochloride as a drug, which is a part of premedication before surgical interventions and a component of multimodal analgesia, improves the quality of the postoperative period due to: reduction of pain syndrome, planned correction of postoperative tremor syndrome and correction of complications arising from inadequate treatment of pain syndrome.

Evidence that the multiflorine-derived substituted quinazolidine 55P0251 augments insulin secretion and lowers blood glucose via antagonism at α2 -adrenoceptors in mice

AIMS

To investigate the mechanism of action of 55P0251, a novel multiflorine-derived substituted quinazolidine that augments insulin release and lowers blood glucose in rodents, but does not act via mechanisms addressed by any antidiabetic agent in clinical use.

MATERIALS AND METHODS

Using male mice, we determined the effects of 55P0251 on glucose tolerance, insulin secretion from isolated islets and blood oxygen saturation, including head-to-head comparison of 55P0251 to its inverted enantiomer 55P0250, as well as to other anti-hyperglycaemic multiflorine derivatives discovered in our programme.

RESULTS

55P0251 was clearly superior to its inverted enantiomer in the glucose tolerance test (area under the curve: 11.3 mg/kg 55P0251, 1.19 ± 0.04 min*mol/L vs 55P0250, 1.80 ± 0.04 min*mol/L; P < .0001). For insulin release in vitro, this superiority became visible only under concomitant adrenergic background stimulation (glucose-stimulated insulin release, fmol*islet^-1 *30 min^-1 : without α₂ -adrenoceptor agonist: 500 μmol/L 55P0251, 390 ± 34, vs 55P0250, 459 ± 40, nonsignificant; with α₂ -adrenoceptor agonist: 250 μmol/L 55P0251, 138 ± 9, vs 55P0250, 21 ± 6; P < .0001). Since receptor binding assays suggested antagonism at α_2A -adrenoceptors as a potential mechanism of action, we measured oxygen saturation in capillary blood from the tail as a surrogate of vasoconstriction, which supported α₂ -antagonistic action in vivo (90 mg/kg 55P0251, 83 ± 3%, vs 55P0250, 57 ± 3%; P < .0001). Lack of association between glucose-lowering activities and α_2A -adrenoceptor binding affinity arising from comparison of multiflorine derivatives was attributed to differences in their pharmacokinetic properties.

CONCLUSIONS

Our findings suggest that 55P0251 and related multiflorine derivatives are to be categorized as α₂ -adrenoceptor antagonists with potential to lower blood glucose by blocking α_2A -adrenoceptors on pancreatic β cells.

Nefopam for the prevention of perioperative shivering: a meta-analysis of randomized controlled trials

BACKGROUND

Shivering is a frequent complication following surgery and anaesthesia. A large variety of studies have been reported that nefopam may be efficacious for the prevention and treatment of perioperative shivering. Regrettably, there is still no conclusion of the efficacy and safety of nefopam for the prevention of perioperative shivering. The aim of this analysis is to evaluate the efficacy of nefopam for the prevention of perioperative shivering in patients undergoing different types of anaesthesia compared with placebo group and other active interventions.

METHODS

PubMed, EMBASE, Cochrane Central Register of Control Trials were systematically searched for potentially relevant trials. Trial quality and extracted data were evaluated by two authors independently. Dichotomous data on the absence of shivering was extracted and analysed by using relative risk (RR) with 95% confidence interval (CI). Continuous outcome was abstracted and analysed by using weighted mean difference (WMD) with 95% confidence interval (CI). Outcome data was analysed by using random effect model or fixed effect model in accordance with heterogeneity.

RESULTS

Compared with placebo, prophylactic administration of nefopam significantly reduced the risk of perioperative shivering not only in the patients under general anaesthesia but also neuraxial anaesthesia (RR 0.08; 95% CI 0.05-0.13). As compared with clonidine, nefopam was more efficacious in the prevention of perioperative shivering (RR 0.34; 95% CI 0.17-0.70). Nefopam has no influence on the extubation time (WMD 0.92; 95% CI -0.15-1.99).

CONCLUSION

Our analysis has demonstrated that nefopam is associated with the decrease of risk of perioperative shivering following anaesthesia without influencing the extubation time.

Spinal noradrenergic modulation and the role of the alpha-2 receptor in the antinociceptive effect of intrathecal nefopam in the formalin test

BACKGROUND

Nefopam has shown an analgesic effect on acute pain including postoperative pain. The reuptake of monoamines including serotonin and noradrenaline has been proposed as the mechanism of the analgesic action of nefopam, but it remains unclear. Although alpha-adrenergic agents are being widely used in the perioperative period, the role of noradrenergic modulation in the analgesic effect of nefopam has not been fully addressed.

METHODS

Changes in the antinociceptive effect of intrathecal (i.t.) nefopam against formalin-elicited flinching responses were explored in Sprague-Dawley rats pretreated with i.t. 6-hydroxydopamine (6-OHDA), which depletes spinal noradrenaline. In addition, antagonism to the effect of nefopam by prazosin and yohimbine was evaluated to further elucidate the antinociceptive mechanism of i.t. nefopam.

RESULTS

Pretreatment with i.t. 6-OHDA alone did not alter the flinching responses in either phase of the formalin test, while it attenuated the antinociceptive effect of i.t. nefopam significantly during phase 1, but not phase 2. The antagonist of the alpha-2 receptor, but not the alpha-1 receptor, reduced partially, but significantly, the antinociceptive effect of i.t. nefopam during phase 1, but not during phase 2.

CONCLUSIONS

This study demonstrates that spinal noradrenergic modulation plays an important role in the antinociceptive effect of i.t. nefopam against formalin-elicited acute initial pain, but not facilitated pain, and this action involves the spinal alpha-2 but not the alpha-1 receptor.