Naltrexone

Naltrexone is a synthetic, long-acting **pure opioid antagonist**. While structurally similar to naloxone, it has significantly higher oral bioavailability and a longer duration of action. In veterinary medicine, it is primarily utilized off-label as an adjunctive treatment for **compulsive behavior disorders**, such as: - Acral lick dermatitis (lick granulomas) - Tail chasing - Flank sucking - Other self-mutilating or stereotypic behaviors **Clinical Pearl**: The rationale for its use in behavior medicine stems from the hypothesis that stereotypic behaviors stimulate the release of endogenous opioids (endorphins), which reinforce the behavior. By blocking these receptors, naltrexone removes the internal "reward," helping to extinguish the compulsive action.

กลไกการออกฤทธิ์: Naltrexone acts as a **competitive antagonist** at opioid receptors, with the highest affinity for **μ (mu)** receptors, followed by **κ (kappa)** and **δ (delta)** receptors. - **Mechanism in Behavior Disorders**: Compulsive behaviors → Release of endogenous endorphins → Binding to μ-receptors → Reinforcement/Analgesia. - Naltrexone **blocks** these receptors → Prevents endorphin binding → Eliminates the auto-reinforcing reward loop of the stereotypic behavior.

ข้อมูลอ้างอิงยาของ VetSheet มีไว้สำหรับสัตวแพทย์ผู้มีใบอนุญาตเพื่อช่วยในการตัดสินใจทางคลินิก ไม่ใช่สิ่งทดแทนการวินิจฉัยของผู้เชี่ยวชาญหรือฉลากล่าสุดของผู้ผลิต