The effect of combination of Gabapentin (GABIX®) with Dextromethorphan (DexAlone®) for reducing CRPS in old patients with distal radius fracture

Abstract Background: Complex regional pain syndrome (CRPS) is a debilitating complication following fractures, particularly prevalent in elderly patients with distal radius fractures. Gabapentin and NMDA antagonists like Dextromethorphan have shown potential in pain modulation and central sensitization reduction, but their combined efficacy in CRPS prevention remains unclear. Objective: To evaluate the effect of combining Gabapentin (GABIX®) with Dextromethorphan (DexAlone®) versus Gabapentin alone on CRPS incidence, postoperative pain, and functional outcomes in elderly patients undergoing closed reduction and K-wire fixation for distal radius fractures. Methods: This prospective randomized clinical trial included 78 patients aged ≥50 years with AO/OTA type C distal radius fractures treated at Akhtar Hospital (Tehran, 2025–2026). Patients were randomized to receive either GABIX® alone (Group B) or in combination with DexAlone® (Group A) for 10 days postoperatively. CRPS diagnosis was assessed using the Modified Research Diagnostic Criteria at 3 and 6 months. Pain scores (VAS) were recorded weekly until 12 weeks. Functional outcomes were assessed using DASH and Mayo Wrist Score at 3 and 6 months. Results: Both groups were demographically comparable. While Group A showed a lower incidence of CRPS (5% vs 13%), the difference was not statistically significant (P > 0.05). Pain scores (VAS) were significantly lower in Group A during the 6th, 10th, and 12th weeks (P6: 0.004, P10: 0.026, P12: 0.014). No significant difference was observed in DASH scores, but the Mayo Wrist Score significantly improved in Group A at 6 months (P = 0.001). Conclusion: The combination of Gabapentin and Dextromethorphan demonstrated superior pain reduction in the subacute phase following distal radius fracture surgery in elderly patients, though CRPS incidence reduction was not statistically significant. This combination may offer a promising strategy for improving postoperative recovery and quality of life.