What is the approach to intravenous (IV) opioid pain control?

From the Guidelines

Intravenous morphine is the opioid of first choice for moderate to severe cancer pain, with an initial dose of 2-4mg IV every 4 hours, and should be titrated based on pain response and side effects. For acute pain management, hydromorphone (0.5-1mg IV every 3-4 hours) or fentanyl (25-50mcg IV every 1-2 hours) are also recommended first-line options 1. Begin with the lower dose in elderly patients or those with respiratory concerns, then titrate based on pain response and side effects. Patient-controlled analgesia (PCA) offers superior pain control by allowing patients to self-administer small, frequent doses within preset limits (typical settings: morphine 1mg bolus with 6-minute lockout, maximum 10mg/hour). Always monitor respiratory rate, sedation level, and oxygen saturation during IV opiate administration, with naloxone (0.04-0.4mg IV) readily available for reversal of respiratory depression.

Key Considerations

• The average relative potency ratio of oral to i.v. morphine is between 1:2 and 1:3 1
• Fentanyl and buprenorphine (via the t.d. or i.v. route) are the safest opioids in patients with chronic kidney disease stages 4 or 5 (estimated GFR < 30 mL/min) 1
• A different opioid should be considered in the absence of adequate analgesia (despite opioid dose escalation) or in the presence of unacceptable opioid side effects 1
• Multimodal analgesia incorporating scheduled acetaminophen, NSAIDs when appropriate, and adjuvant medications like gabapentinoids can reduce opiate requirements and associated side effects.

Administration Routes

• The s.c. route is simple and effective for the administration of morphine, diamorphine and hydromorphone and it should be the first-choice alternative route for patients unable to receive opioids by oral or t.d. route 1
• i.v. infusion should be considered when s.c. administration is contraindicated (peripheral oedema, coagulation disorders, poor peripheral circulation and need for high volumes and doses) 1
• i.v. administration is an option for opioid titration when rapid pain control is needed 1

From the FDA Drug Label

Initiate treatment in a dosing range of 0.2 mg to 1 mg every 2 to 3 hours as necessary for pain control, and at the lowest dose necessary to achieve adequate analgesia. Intravenous administration should be given slowly, over at least 2 to 3 minutes, depending on the dose. Titrate the dose to achieve acceptable pain management and tolerable adverse events.

The approach to intravenous (IV) opioid pain control with hydromorphone is to:

• Start with a low dose (0.2 mg to 1 mg) every 2 to 3 hours as needed
• Administer IV doses slowly over 2 to 3 minutes
• Titrate the dose based on individual patient response to achieve adequate pain management and minimize adverse reactions 2
• Continually re-evaluate patients to assess pain control and potential adverse reactions
• Adjust the dosage to obtain an appropriate balance between management of pain and opioid-related adverse reactions. Key considerations include:
• Using the lowest effective dose for the shortest duration
• Reserving titration to higher doses for patients with insufficient response to lower doses
• Monitoring for signs of opioid withdrawal and adjusting the dose accordingly

From the Research

Approach to Intravenous (IV) Opioid Pain Control

• The approach to IV opioid pain control involves titrating the opioid dose to achieve adequate pain control, with the goal of minimizing adverse effects 3, 4.
• Morphine, hydromorphone, and fentanyl are commonly used IV opioids for acute pain management, with different pharmacokinetic and pharmacodynamic profiles 3.
• The effect delay, onset, and duration of these opioids vary, with morphine having an effect delay of 1.6 to 4.8 hours, hydromorphone having an effect delay of 18 to 38 minutes, and fentanyl having an effect delay of 16.4 minutes 3.
• IV patient-controlled analgesia (IV-PCA) using opioids such as morphine and fentanyl can be an effective analgesic method for post-operative pain, but may be associated with side effects such as respiratory and circulatory depression, and post-operative nausea and vomiting (PONV) 5.
• Opioid rotation from one opioid to another, such as from transdermal fentanyl to continuous subcutaneous hydromorphone, requires careful consideration of the equianalgesic dose and may require downward titration to avoid opioid toxicity 6.
• Institution-specific protocols for IV opioid administration in the emergency department (ED) may improve timely provision of appropriate analgesics and result in better pain reduction 4.
• Conversion of high-dose IV opioids to neuraxial opioids, such as epidural or intrathecal opioids, is a common clinical dilemma, with wide variation in conversion ratios applied by pain specialists 7.