Antinociceptive effects of dezocine on complete Freund's adjuvant-induced inflammatory pain in rats

Topiramate inhibits adjuvant-induced chronic orofacial inflammatory allodynia in the rat

Chronic orofacial pain disorders are common debilitating conditions, affecting the trigeminal system. Its underlying pathophysiological mechanisms are still unclear and the therapy is often unsatisfactory, therefore, preclinical models are crucial to identify the key mediators and novel treatment options. Complete Freund's adjuvant (CFA)-induced orofacial inflammatory allodynia/hyperalgesia is commonly used in rodents, but it has not been validated with currently used drugs. Here we tested the effects of the adjuvant analgesic/antiepileptic voltage-gated Na+ channel blocker complex mechanism of action topiramate in comparison with the gold standard antimigraine serotonin 5-HT1B/D receptor agonist sumatriptan in this model. CFA was injected subcutaneously into the right whisker pad of male Sprague-Dawley rats (250-300 g), then mechanonociceptive threshold values were investigated with von Frey filaments (3, 5, and 7 days after CFA injection). Effects of topiramate (30 mg/kg per os) and sumatriptan (1 mg/kg subcutaneous) on the adjuvant-induced chronic inflammatory orofacial allodynia were investigated 60, 120, and 180 min after the treatments each day. To determine the optimal concentration for drug effect analysis, we tested the effects of two different CFA-concentrations (1 and 0.5 mg/mL) on mechanonociceptive thresholds. Both concentrations of CFA induced a chronic orofacial allodynia in 60% of all rats. Although, higher CFA concentration induced greater allodynia, much more stable threshold reduction was observed with the lower CFA concentration: on day 3 the thresholds decreased from 18.30 g to approximately 11 g (low) and 5 g (high), respectively, however a slight increase was observed in the case of higher CFA concentration (on days 5, 7, and 11). In all investigation days, topiramate showed significant anti-allodynic effect comparing the pre and post drug dose and comparing the vehicle treated to the drug treated groups. Sumatriptan also caused a significant threshold increase compared to pre dose thresholds (day 3) and also showed a slight anti-allodynic effect compared to the vehicle-treated group (day 3 and 5). In the present study CFA-induced chronic orofacial allodynia was reversed by topiramate in rats validating the model with the adjuvant analgesic. Other than establishing a validated orofacial pain-related syndrome model in rats, new ways are opened for the repurposing of topiramate.

Dezocine as a potent analgesic: overview of its pharmacological characterization

Dezocine, a synthetic opioid, introduced in 1970s as an analgesic, was redeveloped for relieving moderate to severe pain by Yangtze River Pharmaceutical Group in China in 2009. To date, dezocine occupies 45% of China's opioid analgesic market. Along with dezocine being a dominated painkiller, a certain amount of research was conducted to elucidate dezocine's action. In this review we summarize the current knowledge on the receptor, preclinical and clinical pharmacology of dezocine. Briefly, preclinical data show that dezocine is effective under varying pain conditions, particularly chronic neuropathic pain and cancer pain, through activation of opioid receptors, and inhibition of norepinephrine reuptake. Clinical data establish the effectiveness of dezocine either as a primary analgesic for postoperative pain management or a supplement for balanced analgesia. The receptor profile of dezocine is different from known pure μ agonists, and allows it to be used in combination with other opioids for additivity in efficacy or lower incidence of adverse effects.

Dezocine relieves the postoperative hyperalgesia in rats through suppressing the hyper-action of Akt1/GSK-3β pathway

The relieving role of dezocine in pain after surgery was previously reported, while the potential mechanism was not completely clear. Therefore, the current research probed into the regulatory mechanism of dezocine in pain after surgery. A postoperative pain model was established by performing plantar incision surgery on the juvenile Sprague-Dawley rats. After the rats were treated with dezocine or SC79 (Akt1 activator), the paw withdrawal threshold and paw withdrawal latency of rats were detected to evaluate the mechanical allodynia and thermal hyperalgesia. After the plantar tissue, dorsal root ganglions, and spinal cord of rats were collected, the expressions of Akt1, p-Akt1, GSK-3β, and p-GSK-3β in the tissues were determined by western blot to evaluate the activation state of the Akt1/GSK-3β pathway. After surgery, the paw withdrawal threshold and paw withdrawal latency of rats were lessened, whereas the ratios of p-Akt1/Akt1 and p-GSK-3β/GSK-3β were augmented in rat plantar tissue, dorsal root ganglions, and spinal cord. After treatment with dezocine alone, the paw withdrawal threshold and paw withdrawal latency of postoperative rats were elevated, but ratios of p-Akt1/Akt1 and p-GSK-3β/GSK-3β were reduced. After co-treatment with dezocine and SC79, SC79 reversed the effects of dezocine on elevating the paw withdrawal threshold and paw withdrawal latency, and reducing the ratios of p-Akt1/Akt1 and p-GSK-3β/GSK-3β in postoperative rats. Dezocine ameliorated the postoperative hyperalgesia in rats via repressing the hyper-action of Akt1/GSK-3β pathway.

Effects of Dezocine and Sufentanil on Th1/Th2 Balance in Breast Cancer Patients Undergoing Surgery

BACKGROUND

It is very important for breast cancer patients undergoing surgery to choose an opioid that has little effect on the immune system. The aim of this study is to compare the effects of dezocine or sufentanil on postoperative pain and Th1/Th2 balance in patients undergoing breast cancer surgery.

METHODS

Data from 92 breast cancer patients from January 2019 to July 2020 at Foshan Second People's Hospital (Guangdong, China) were analyzed. Sufentanil (SF) was used in group SF (n = 44) and dezocine (DE) in group DE (n = 48). The Visual Analog Scale (VAS) scores were assessed, and the percentages of Th1 cells and Th2 cells in peripheral blood were detected before anesthesia and at 2, 12, 24, and 48 hours after surgery.

RESULTS

There was no significant difference in the VAS scores between the two groups at 2, 24, and 48 hours after surgery (P > 0.05). The VAS scores at 12 hours after surgery in group DE were significantly lower than those in group SF with a statistically significant difference (P < 0.05). The percentage of Th1 cells in group DE at 2, 12, 24, and 48 hours after surgery was significantly lower than that in group SF (P < 0.05). The percentage of Th2 cells in group DE at 2, 12, 24, and 48 hours after surgery was significantly lower than that in group SF (P < 0.05). The Th1/Th2 ratio at 2, 12, 24, and 48 hours after surgery was significantly higher in group DE than that in group SF (P < 0.05).

CONCLUSION

Dezocine for anesthesia induction and postoperative analgesia can maintain the balance of Th1/Th2 more stable than, with the same analgesia efficacy as, sufentanil during the early postoperative period in breast cancer patients undergoing surgery.