Chloroxazone

# Chloroxazone ## Overview - **Classification**: Centrally acting skeletal muscle relaxant - **Mechanism**: Acts at the spinal cord and subcortical areas of the brain to inhibit polysynaptic reflex arcs involved in muscle spasm, leading to muscle relaxation. ## Primary Indications 1. **Muscle Spasm** - Relief of discomfort associated with acute, painful musculoskeletal conditions. ## Adult Dosing ### Standard Dosing **Acute Painful Musculoskeletal Conditions** - **Dose**: **250 mg** to **750 mg** - **Frequency**: Three to four times daily (TID/QID) - **Route**: Oral - **Duration**: Short-term, as needed for acute spasm - **Maximum Dose**: **3000 mg** per day ### Dose Adjustments - **Renal Impairment**: No specific dose adjustments provided; use with caution. - **Hepatic Impairment**: **Contraindicated** in patients with known hepatic impairment. Use with extreme caution and reduce dose if mild impairment, monitoring LFTs closely. - **Elderly Patients**: Start with lower doses (e.g., **250 mg TID**) due to increased sensitivity to CNS effects and potential for decreased metabolism. Monitor closely for sedation and falls. ## Pediatric Dosing **Note**: Chloroxazone is generally **not recommended** for children under **12 years of age** due to lack of established safety and efficacy data. ### Neonates (0-28 days) - **Dose**: **Not recommended**. - **Special Notes**: Safety and efficacy have not been established. Avoid use. ### Infants (1-12 months) - **Dose**: **Not recommended**. - **Special Notes**: Safety and efficacy have not been established. Avoid use. ### Children (1-12 years) - **Dose**: **Not recommended**. - **Special Notes**: Safety and efficacy have not been established. Avoid use. ### Adolescents (13-18 years) - **Dose**: Limited data. Some sources suggest **125-250 mg TID-QID**; however, adult dosing is often approached with caution. - **Maximum**: Refer to adult maximum dose (**3000 mg/day**) if used, but generally start lower. - **Special Notes**: Closely monitor for sedation and other adverse effects. Consider alternative agents with better-established pediatric data. ## Safety Information ### Contraindications - **Absolute**: Known hypersensitivity to chloroxazone or any component. - **Absolute**: Pre-existing hepatic impairment or liver disease. ### Common Adverse Effects - **Very Common (>10%)**: Drowsiness, dizziness, lightheadedness. - **Common (1-10%)**: Nausea, vomiting, GI upset, heartburn. - **Serious but Rare**: Hepatotoxicity (jaundice, liver enzyme elevation), angioedema, GI bleeding, hypersensitivity reactions. ### Key Drug Interactions - **CNS Depressants (Alcohol, Benzodiazepines, Opioids)**: Increased risk of additive CNS depression (sedation, respiratory depression). Avoid concomitant use or reduce doses. - **Hepatotoxic Agents**: Increased risk of liver injury when co-administered. Monitor LFTs closely. - **CYP2E1 Inducers/Inhibitors**: Chloroxazone is metabolized by CYP2E1; interactions possible, but clinical significance often low for short-term use. ## Monitoring & Follow-up - **Before Treatment**: Obtain baseline liver function tests (LFTs) if prolonged use or risk factors for hepatic impairment exist. - **During Treatment**: Monitor for signs of CNS depression (sedation, dizziness). Observe for signs of hepatic dysfunction (jaundice, dark urine, abdominal pain). - **Clinical Signs**: Watch for persistent GI upset, unexplained fatigue, or allergic reactions. ## Clinical Pearls - 💡 **Tip 1**: Take with food or milk to minimize gastrointestinal upset. - 💡 **Tip 2**: Advise patients about potential drowsiness and dizziness; avoid driving or operating heavy machinery until effects are known. - 💡 **Tip 3**: Counsel patients to avoid alcohol and other CNS depressants due to additive sedative effects. - 💡 **Tip 4**: Discontinue chloroxazone if signs of liver dysfunction occur and consult a physician immediately. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.