What is the appropriate next step in managing a patient with sacral pain who is currently being treated with diclofenac (NSAID) injection and chlorzoxazone (muscle relaxant) tablets twice daily?

Management of Sacral Pain with Current Diclofenac and Chlorzoxazone Therapy

The current regimen of diclofenac injection and chlorzoxazone tablets twice daily is appropriate for acute sacral pain, but treatment should be limited to 3-5 days maximum (not exceeding 7 days), and if pain persists beyond 3 days, add acetaminophen rather than continuing diclofenac alone. 1

Immediate Management Approach

Duration and Monitoring of Current Therapy

• Limit diclofenac use to 3-5 days maximum for acute musculoskeletal pain conditions, as most resolve within this timeframe and prolonged NSAID use increases risk of gastrointestinal, cardiovascular, and renal complications 1

• The combination of acetaminophen plus chlorzoxazone has demonstrated pain reduction (WMD -2.92 cm on 10-cm VAS) at 1-7 days compared to placebo, supporting the current use of chlorzoxazone 2

• Always administer diclofenac with food to minimize gastrointestinal side effects 1

• Monitor specifically for: epigastric pain, dyspepsia, melena, hematemesis (GI bleeding signs), unexplained weight gain or edema (fluid retention), and signs of hepatotoxicity including nausea, fatigue, right upper quadrant tenderness 3

If Pain Inadequately Controlled After 3 Days

• Add acetaminophen 3-4g daily rather than extending diclofenac duration to minimize cumulative NSAID toxicity 1

• The combination of acetaminophen plus oral diclofenac provides symptom relief (OR 3.72, CI 1.02-13.52) and is among the most effective interventions for acute musculoskeletal pain 2

• Acetaminophen alone reduces pain at 1-7 days (WMD -1.07 cm) with moderate-certainty evidence 2

Adjunctive Non-Pharmacological Interventions

Immediate Implementation

• Apply heat or cold therapy to the sacral area for 15-20 minutes several times daily, as this provides additional pain relief without medication risks 1

• Practice gentle range-of-motion exercises when pain allows to maintain mobility and prevent stiffness 1

• Use relaxation techniques including deep breathing exercises and guided imagery to help manage pain perception 1

Critical Safety Considerations

Gastrointestinal Protection

• If treatment extends beyond 5 days or patient has GI risk factors, add gastroprotective treatment (proton pump inhibitor or H2-blocker) 2

• Diclofenac carries risk of serious GI ulceration and bleeding that can occur without warning symptoms 3

Contraindications and High-Risk Situations

• Do not use in patients with aspirin-sensitive asthma due to risk of severe bronchospasm 3

• Exercise extreme caution in patients with coagulation disorders or on anticoagulants, as diclofenac inhibits platelet aggregation and prolongs bleeding time 3

• Monitor renal function in elderly patients or those with pre-existing renal impairment 3

• Avoid in late pregnancy as diclofenac causes premature closure of ductus arteriosus 3

Drug Interactions

• Do not combine with aspirin, as this reduces diclofenac protein binding and increases risk of adverse effects without clear benefit 3

• Use caution with methotrexate, as NSAIDs competitively inhibit methotrexate accumulation and increase toxicity risk 3

When to Reassess or Escalate

Mandatory Reassessment Points

• If pain persists beyond 7 days of treatment, discontinue diclofenac and reassess for alternative diagnoses or need for imaging studies 1

• Consider that sacral pain may represent serious underlying pathology (fracture, infection, malignancy, cauda equina syndrome) if accompanied by red flags: fever, trauma history, neurological deficits, bowel/bladder dysfunction, or progressive weakness

• For chronic or recurrent sacral pain, the current acute treatment approach is insufficient and requires comprehensive evaluation for underlying structural or inflammatory conditions

Mechanism Supporting Current Therapy

• Diclofenac has unique spinal antinflammatory action through multiple mechanisms: PPAR-γ activation, COX-2 inhibition, suppression of neuronal hyperexcitability via K+ channel blockage, and ability to cross the blood-brain barrier 4, 5

• Chlorzoxazone acts centrally at the spinal cord and subcortical brain areas to inhibit multisynaptic reflex arcs, reducing skeletal muscle spasm with peak levels reached 1-2 hours after oral administration 6

• This combination addresses both inflammatory pain (diclofenac) and muscle spasm (chlorzoxazone) components of sacral pain 6, 4