Small molecule somatostatin receptor subtype 4 (sst4) agonists are novel anti-inflammatory and analgesic drug candidates

We provided strong proof of concept evidence that somatostatin mediates potent analgesic and anti-inflammatory actions via its receptor subtype 4 (sst₄) located both at the periphery and the central nervous system. Therefore, sst₄ agonists are promising novel drug candidates for neuropathic pain and neurogenic inflammation, but rational drug design was not possible due to the lack of knowledge about its 3-dimensional structure. We modeled the sst₄ receptor structure, described its agonist binding properties, and characterized the binding of our novel small molecule sst₄ agonists (4-phenetylamino-7H-pyrrolo[2,3-d]pyrimidine derivatives) using an in silico platform. In addition to the in silico binding data, somatostatin displacement by Compound 1 was demonstrated in the competitive binding assay on sst₄-expressing cells. In vivo effects were investigated in rat models of neurogenic inflammation and chronic traumatic neuropathic pain. We defined high- and low-affinity binding pockets of sst₄ for our ligands, binding of the highest affinity compounds were similar to that of the reference ligand J-2156. We showed potent G-protein activation with the highest potency of 10 nM EC₅₀ value and highest efficacy of 342%. Oral administration of 100 μg/kg of 5 compounds significantly inhibited acute neurogenic plasma protein extravasation in the paw skin by 40-60%, one candidate abolished and 3 others diminished sciatic nerve-ligation induced neuropathic hyperalgesia by 28-62%. The in silico predictions on sst₄-ligands were tested in biological systems. Low oral dose of our novel agonists inhibit neurogenic inflammation and neuropathic pain, which opens promising drug developmental perspectives for these unmet medical need conditions.

Predictors of the use of analgesic drugs 1 year after joint replacement: a single-center analysis of 13,000 hip and knee replacements

Background

Pain persists in a moderate number of patients following hip or knee replacement surgery. Persistent pain may subsequently lead to the prolonged consumption of analgesics after surgery and expose patients to the adverse drug events of opioids and NSAIDs, especially in older patients and patients with comorbidities. This study aimed to identify risk factors for the increased use of opioids and other analgesics 1 year after surgery and focused on comorbidities and surgery-related factors.

Methods

All patients who underwent a primary hip or knee replacement for osteoarthritis from 2002 to 2013 were identified. Redeemed prescriptions for acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), and opioids (mild and strong) were collected from a nationwide Drug Prescription Register. The user rates of analgesics and the adjusted risks ratios for analgesic use 1 year after joint replacement were calculated.

Results

Of the 6238 hip replacement and 7501 knee replacement recipients, 3591 (26.1%) were still using analgesics 1 year after surgery. Significant predictors of overall analgesic use (acetaminophen, NSAID, or opioid) were (risk ratio (95% CI)) age 65–74.9 years (reference < 65), 1.1 (1.03–1.2); age > 75 years, 1.2 (1.1–1.3); female gender, 1.2 (1.1–1.3); BMI 30–34.9 kg/m² (reference < 25 kg/m²), 1.1 (1.04–1.2); BMI > 35 kg/m², 1.4 (1.3–1.6); and a higher number of comorbidities (according to the modified Charlson Comorbidity Index score), 1.2 (1.1–1.4). Diabetes and other comorbidities were not significant independent predictors. Of the other clinical factors, the preoperative use of analgesics, 2.6 (2.5–2.8), and knee surgery, 1.2 (1.1–1.3), predicted the use of analgesics, whereas simultaneous bilateral knee replacement (compared to unilateral procedure) was a protective factor, 0.86 (0.77–0.96). Opioid use was associated with obesity, higher CCI score, epilepsy, knee vs hip surgery, unilateral vs bilateral knee operation, total vs unicompartmental knee replacement, and the preoperative use of analgesics/opioids.

Conclusions

Obesity (especially BMI > 35 kg/m²) and the preoperative use of analgesics were the strongest predictors of an increased postoperative use of analgesics. It is remarkable that also older age and higher number of comorbidities predicted analgesic use despite these patients being the most vulnerable to adverse drug events.

Postoperative Outcomes in Cold Dissection Versus Bipolar Electrocautery Tonsillectomy: A Randomized Double-Blind Controlled Study

Tonsillectomy is one of the oldest and most common procedures worldwide. This surgery is performed by different methods include cold dissection technique (CDT) and bipolar electrocautery technique (BET). Assessment and comparison of postoperative outcomes in cold dissection and bipolar electrocautery is the aim of present study. This randomized controlled clinical trial study was conducted as double-blind on 534 patients. The enrolled patients underwent tonsillectomy in Vali-e-Asr Hospital of Birjand city from Oct. 2013-Oct. 2015. Al patients systematically allocated into two groups treated with cold dissection or bipolar electrocautery methods. Intensity of throat pain scores, Otalgia, analgesic consumption, resume normal diet, body temperature and also wound healing on 10th day after operation were measured and compared between the two groups. The gathered data were analyzed by SPSS software (Ver-22) and using necessary tests. The differences between studied groups less than 0.5 (p < 0.05) considered significant statically. 51.7 and 50.6% in the CDT and the BET groups were male respectively. In comparison between the groups the mean of pain scores 4 and 24 h after operation in the BET group were higher significantly (p < 0.001). Otalgia only 4 h after surgery was higher significantly in the BET group (p = 0.008). All the other studied parameters were significantly more desirable in the CDT group (p < 0.001). According to the findings of present study it seems that the CDT is safer and more favorable than the BET in tonsillectomy.

Effects of Extracorporeal Shock Wave-Mediated Transdermal Local Anesthetic Drug Delivery on Rat Caudal Nerves

Cavitation plays a substantial role in the clinical effects of extracorporeal shock wave therapy (ESWT). It is also generally accepted as a major mechanism in sonophoresis. To identify the enhancing effect of extracorporeal shock wave-mediated transdermal drug delivery, 24 Wistar rats were randomly assigned to four groups: (i) topical application of a eutectic mixture of local anesthetics (EMLA); (ii) 1-MHz ultrasound; (iii) ESWT pre-treatment combined with EMLA application; (iv) ESWT concurrent with EMLA application on rat tails. The degree of anesthesia was assessed using the amplitude and latency of sensory nerve action potentials within 5 min after a 60-min EMLA application. The results indicated that ESWT pre-treatment and concurrent ESWT accelerated the anesthetic effects of the EMLA cream on the tail nerve (p < 0.05). This finding might indicate that shock wave-mediated transdermal drug delivery is possible during the ESWT period.

Synthesis of resveratrol derivatives as new analgesic drugs through desensitization of the TRPA1 receptor

A series of 31 resveratrol derivatives was designed, synthesized and evaluated for activation and inhibition of the TRPA1 channel. Most acted as activators and desensitizers of TRPA1 channels like resveratrol or allyl isothiocyanate (AITC). Compound 4z (HUHS029) exhibited higher inhibitory activity than resveratrol with an IC₅₀ value of 16.1μM. The activity of 4z on TRPA1 was confirmed in TRPA1-expressing HEK293 cells, as well as in rat dorsal root ganglia neurons by a whole cell patch clamp recording. Furthermore, pretreatment with 4z exhibited an analgesic effect on AITC-evoked TRPA1-related pain behavior in vivo.