What is the appropriate starting dose and administration protocol for a fentanyl (opioid) infusion in opioid-tolerant patients requiring continuous palliative care?

Fentanyl Drip Protocol for Palliative Care

For opioid-tolerant patients requiring continuous palliative care, a fentanyl drip should be prepared by mixing fentanyl with normal saline solution (NSS) at a starting dose equivalent to the patient's current 24-hour opioid requirement, using a 100:1 conversion ratio from IV morphine to IV fentanyl. 1

Determining the Starting Dose

1. Calculate the patient's current 24-hour opioid requirement
2. Convert to IV morphine equivalent if patient is on another opioid
3. Convert from IV morphine to IV fentanyl using a 100:1 ratio

Conversion Table for Common Opioids to IV Fentanyl

Current Opioid	Conversion Factor to IV Fentanyl
IV Morphine	100:1 (100 mg morphine = 1 mg fentanyl)
Oral Morphine	300:1 (300 mg oral morphine = 1 mg fentanyl)
Oral Oxycodone	200:1 (200 mg oral oxycodone = 1 mg fentanyl)
IV Hydromorphone	20:1 (20 mg hydromorphone = 1 mg fentanyl)

Preparation of Fentanyl Drip

1. Calculate the 24-hour fentanyl requirement in micrograms
2. Mix the calculated amount of fentanyl with NSS to create a 24-hour infusion
3. Program the infusion pump to deliver the solution over 24 hours

Example Calculation:

• Patient currently on 8 mg/hr IV morphine
• 24-hour morphine dose: 8 mg × 24 hr = 192 mg/day
• Converting to fentanyl: 192 mg morphine ÷ 100 = 1.92 mg fentanyl = 1,920 mcg fentanyl per 24 hours
• Hourly rate: 1,920 mcg ÷ 24 hours = 80 mcg/hour

Important Considerations

Dose Adjustments

• For patients with well-controlled pain, consider reducing the calculated dose by 25-50% to account for incomplete cross-tolerance 1
• For patients with poorly controlled pain, begin with 100% of the equianalgesic dose or increase by 25% 1

Breakthrough Pain Management

• Prescribe breakthrough doses of short-acting opioids at 10-20% of the 24-hour fentanyl dose 1
• Assess need for breakthrough medication after 24 hours and adjust continuous infusion accordingly

Monitoring

• Monitor respiratory rate, sedation level, and pain scores closely, especially during the first 24 hours
• Have naloxone readily available for reversal if respiratory depression occurs 2
• Adjust dose based on clinical response and side effects

Special Considerations

• Fentanyl is 50-100 times more potent than morphine with rapid onset (1-2 minutes IV) 2
• Stability: Fentanyl solutions remain stable (>95%) for at least 7 days at temperatures from 5°C to 38°C 3
• When combining with midazolam, be aware that midazolam stability decreases to 90% after 4 days at room temperature 3
• Avoid using fentanyl in opioid-naïve patients due to risk of respiratory depression 4
• For patients with hepatic impairment, reduce the initial dose due to fentanyl's hepatic metabolism 2

Common Pitfalls to Avoid

• Overestimating the initial dose can result in fatal overdose 4
• Combining fentanyl with other sedatives significantly increases respiratory depression risk 2
• Applying heat near the infusion site can increase absorption and lead to overdose
• Using fentanyl for unstable pain requiring frequent dose changes is not recommended 1

Remember that continuous clinical assessment is essential when administering fentanyl infusions, with dose adjustments based on the patient's response and breakthrough medication requirements.