What analgesic regimen should be ordered?

Analgesic Regimen for Total Hip Replacement

For postoperative pain management after total hip replacement, order a multimodal regimen based on pain intensity: for high-intensity pain (VAS >50), prescribe COX-2 selective inhibitors or conventional NSAIDs combined with IV strong opioids via PCA or scheduled dosing, plus paracetamol as baseline therapy; for low-to-moderate intensity pain (VAS <50), prescribe COX-2 selective inhibitors or NSAIDs combined with paracetamol, with weak opioids added if needed. 1

Pain Assessment and Stratification

• Assess pain intensity immediately using visual analogue scale (VAS), numerical rating scale (NRS), or verbal rating scale (VRS) to determine treatment tier 1
• High-intensity pain is defined as VAS >50 on a 0-100 scale 1
• Low-to-moderate intensity pain is VAS <50 1

For High-Intensity Pain (VAS >50)

First-Line Regimen

• Order COX-2 selective inhibitors OR conventional NSAIDs as the anti-inflammatory foundation 1
• Add IV strong opioids administered either by patient-controlled analgesia (PCA) or by fixed-interval IV administration titrated to pain intensity 1
• Include paracetamol (acetaminophen) as baseline therapy because it decreases supplementary analgesic requirements, though only in combination with other analgesics 1

Dosing Specifics

• Paracetamol: 1000 mg every 4-6 hours (maximum 4000 mg/24 hours in adults) 1, 2
• Strong opioids should be minimized by combining them with non-opioid analgesics 1
• Avoid intramuscular administration of strong opioids due to injection-associated pain 1

Critical Prescribing Details

• Prescribe analgesics on a scheduled basis, not "as needed" or "PRN" only 1
• Administer intra-operative strong long-acting opioids to secure analgesia when the patient awakens 1
• Do NOT use weak opioids for high-intensity pain in the early postoperative period (<6 hours) as they are ineffective 1

For Low-to-Moderate Intensity Pain (VAS <50)

First-Line Regimen

• Order COX-2 selective inhibitors OR conventional NSAIDs 1
• Add paracetamol as combination therapy 1
• Consider weak opioids (such as codeine, tramadol, or dihydrocodeine) if NSAIDs and paracetamol are insufficient or contraindicated 1

Timing Considerations

• Weak opioids are appropriate later in the postoperative period (>6 hours), in combination with paracetamol, when NSAIDs are contraindicated or insufficient 1

Rescue Medication for Breakthrough Pain

• Prescribe rescue doses of immediate-release strong opioids separate from the regular basal therapy for breakthrough pain episodes 1
• Allow rescue dosing up to hourly during individual titration 1
• Adjust the regular dose of sustained-release opioids based on total rescue medication used 1

Route of Administration

• Prioritize oral route as first choice when feasible 1
• Use IV route for immediate postoperative period when oral intake is limited 1

Mandatory Adjunctive Orders

• Prescribe laxatives routinely for prophylaxis and management of opioid-induced constipation 1
• Order antiemetics (metoclopramide or antidopaminergic drugs) for opioid-related nausea/vomiting 1

Important Caveats

• Avoid combining two products of the same pharmacological class with the same kinetics (e.g., two sustained-release opioids) 1
• Exercise caution with COX-2 inhibitors and NSAIDs in patients with known cardiovascular disease until cardiovascular safety is established 1
• Monitor for hepatotoxicity with paracetamol if daily dose exceeds 4000 mg, particularly in patients with liver disease 1, 2
• Avoid combination products (opioid + acetaminophen) in patients requiring large opioid doses to prevent acetaminophen-induced hepatotoxicity 1
• Re-evaluate pain and treatment regularly, anticipating breakthrough pain and side effects 1