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  1. Randall Stevens1,
  2. Kimberly Guedes1,
  3. Nilam Mistry1,
  4. Duncan Lascelles1,
  5. David Ball2
  1. 1Centrexion Therapeutics Corp, Boston, United States of America
  2. 2MAC Clinical Research, Manchester, United Kingdom


Background CNTX-4975 is a long-acting, trans-capsaicin injection in phase 3 trials for treatment of moderate to severe pain associated with knee osteoarthritis (OA). Intra-articular (IA) CNTX-4975 injection produces short-lived procedural pain that can be ameliorated with joint cooling. A prior analysis (Cohort 2) demonstrated that a circumferential circulating ice water wrap (CCIWW) more effectively lowered IA knee temperature and reduced procedural pain than an ice pack on top of the knee (3.4 vs 7.3, respectively, on a numeric pain rating scale [NPRS] 10 minutes post-CNTX-4975).

Objectives Subjects were enrolled in 2 separate cohorts (C3/C4) to: compare effects of 2 circumferential cooling methods on IA and skin knee temperature and procedural pain (C3); and assess procedural pain with an abbreviated cooling schedule and with vs without post-CNTX-4975 cooling (C4).

Methods Eligible subjects were adults aged 45–75 yrs with ≥3 months of bilateral moderate to severe OA knee pain. All subjects received each cooling device on opposite knees; IA CNTX-4975 injections and other procedures on the left and right knees were separated by 7 (±2) days. See Figure for study design. IA and skin temperatures were recorded throughout the procedures. Subjects rated procedural pain at prespecified times using NPRS (0=no pain; 10=worst possible pain).

Results Five subjects enrolled in and completed each cohort (mean age, yrs: C3, 57.6; C4, 59.6; each 80% male). In C3, mean IA temperatures decreased with both methods; mean temperatures at baseline and 105 minutes were 33.7°C and 26.7°C for ice-gel pack cooling and 32.4°C and 28.2°C for CCIWW. Skin temperature reductions between cohorts were similar; mean temperatures were 28.8°C and 14.3°C (ice-gel pack) and 28.7°C and 15.2°C (CCIWW). Mean IA temperatures in C4 at baseline and 55 minutes (15 minutes post-CNTX-4975 and/or end of last cooling period [CCIWW only]) were 33.6°C and 29.0°C for ice-gel pack cooling and 32.1°C and 27.7°C for CCIWW. Mean skin temperatures were 28.5°C and 22.8°C for ice-gel pack and 27.8°C and 18.8°C for CCIWW. Pain levels before CNTX-4975 were low. Procedural pain peaked 10–20 minutes after CNTX-4975 injection in both cohorts. While mean pain levels were similar across cohorts (Table), pain was reduced more effectively by CCIWW in C3 and ice-gel pack in C4. Procedural pain was not increased in the absence of post-injection cooling in C4.

Conclusion The ice-gel pack and CCIWW effectively reduced IA knee joint temperatures and procedural pain in both cohorts. Shorter cooling time and low pain levels observed with IA CNTX-4975 and ice-gel pack cooling in C4 suggest that this strategy may be feasible in clinical practice.

Disclosure of Interests Randall Stevens Shareholder of: Centrexion Therapeutics Corp, Employee of: Centrexion Therapeutics Corp, Kimberly Guedes Employee of: Centrexion Therapeutics Corp, Nilam Mistry Employee of: Centrexion Therapeutics Corp, Duncan Lascelles Consultant for: Centrexion Therapeutics Corp, David Ball: None declared

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