Experimental arthritis in the rat does not alter the analgesic potency of intrathecal or intraarticular morphine

Omega-3-carboxylic acids provide efficacious anti-inflammatory activity in models of crystal-mediated inflammation

This study assesses the efficacy and exposure–response relationship of omega-3-carboxylic acids (OM-3 CA) in models of crystal-based inflammation. Human THP-1 macrophages and primary peripheral blood mononuclear cells exposed to multiple inflammatory crystal types were used to determine the anti-inflammatory potential of omega-3 (OM-3) fatty acids in vitro. Anti-inflammatory effects of OM-3 CA in vivo were tested in rat monosodium urate (MSU) crystal air pouch and rat knee intra-articular MSU injection models. Acute treatment with the OM-3 fatty acid docosahexaenoic acid suppressed MSU-, cholesterol crystal-, and calcium pyrophosphate crystal-mediated interleukin-1β (IL-1β) production in vitro. In vivo, OM-3 CA dose-dependently reduced crystal-mediated cell migration, exudate volume, and levels of IL-1β and prostaglandin E₂. Following intra-articular injection of MSU, treatment with OM-3-CA (1 mL/kg) and indomethacin (1 mg/kg) resulted in similar mean reductions in pain (23% and 41%, respectively) and swelling (58% and 50%, respectively), compared with controls. Additionally, in complex formulations of OM-3 fatty acids, high levels of palmitic acid could reduce the in vivo effect on crystal-mediated IL-1β elevation. OM-3 CA has a broadly efficacious anti-inflammatory effect with a strong exposure–response relationship that could be beneficial in prevention and treatment of crystal arthritis, with potential applications in other IL-1β-mediated diseases.

Does the type of arthroscopic surgery modify the analgesic effect of intraarticular morphine and bupivacaine? A preliminary study

OBJECTIVE

To analyze the different analgesic response to intraarticular morphine and bupivacaine in different types of arthroscopic surgery.

DESIGN

Prospective, randomized and double-blinded. Fifty-three consecutive patients undergoing an arthroscopic knee procedure under general anesthesia. They were studied separately in 2 groups (types of surgery): (1) "Low inflammatory surgery": diagnostic arthroscopy, partial meniscectomy; and (2) "High inflammatory surgery": ACL (anterior cruciate ligament) reconstruction, lateral release, patellar shaving and plicae removal. At the end of the procedure, patients were randomized to receive 25 mL of bupivacaine 0.25% with epinephrine (1/200,000), 5 mg of morphine, or saline (placebo) into the knee joint. Postoperative pain was determined through the visual analog scale (VAS). Supplemental analgesia (ketorolac) was administered via intravenous patient-controlled analgesia (i.v. PCA). Pain and requirements of analgesia were compared between bupivacaine, morphine, and placebo in each group of surgery.

RESULTS

When considering only the "Low inflammatory" group of patients, those who received bupivacaine showed a lower postoperative pain score at 4 and 8 hours (P < 0.05). When considering only the "High inflammatory" group, the patients who received morphine showed a lower postoperative pain score at 24 hours and less requirements of ketorolac (P < 0.05).

CONCLUSIONS

The analgesic effect of morphine and bupivacaine is different depending on the type of arthroscopic surgery. Intraarticular bupivacaine is effective in surgeries with a low inflammatory response. For surgeries with a higher inflammatory response, morphine has a better analgesic effect. Postoperative intraarticular analgesic therapy should be indicated according to the performed arthroscopic procedure.