How to convert subcutaneous (SC) morphine 2.5-5.0 mg every 6 hours (q6h) to oral Dilaudid (hydromorphone)?

From the Guidelines

To convert subcutaneous morphine 2.5-5.0 mg every 6 hours to oral hydromorphone (Dilaudid), the equivalent oral hydromorphone dose would be 0.5-1.0 mg every 6 hours, based on the most recent and highest quality study available 1. This conversion is based on two key factors: first, the potency ratio between morphine and hydromorphone, and second, the change from subcutaneous to oral route.

When converting from subcutaneous morphine to oral hydromorphone, you must first consider the relative potency ratio of oral morphine to subcutaneous morphine, which is between 1:2 and 1:3 1. Then, you must consider the potency ratio between morphine and hydromorphone, with hydromorphone being approximately 5 times more potent than morphine 1.

Given the subcutaneous morphine dose of 2.5-5.0 mg every 6 hours, the equivalent oral morphine dose would be 5-10 mg every 6 hours, considering the route change. Then, converting this to hydromorphone, the dose would be 1-2 mg every 6 hours, considering the potency ratio between morphine and hydromorphone. However, since hydromorphone is more potent, it's safer to start at the lower end of this calculation, hence 0.5-1.0 mg every 6 hours.

Some key points to consider when converting opioids include:

• The average relative potency ratio of oral morphine to subcutaneous morphine is between 1:2 and 1:3 1
• Hydromorphone is approximately 5 times more potent than morphine 1
• When converting opioids, the new opioid is typically dosed at a substantially lower dose than the calculated dose to avoid overdose due to incomplete cross-tolerance and individual variability in opioid pharmacokinetics 1

Monitor the patient closely for pain control and side effects like respiratory depression, sedation, and constipation, and adjust the dose as needed. Provide appropriate breakthrough pain medication, typically 10-15% of the total daily dose, and implement a bowel regimen to prevent opioid-induced constipation.

From the FDA Drug Label

Conversion from Other Opioids to Hydromorphone Hydrochloride Tablets There is inter-patient variability in the potency of opioid drugs and opioid formulations Therefore, a conservative approach is advised when determining the total daily dosage of hydromorphone hydrochloride tablets. It is safer to underestimate a patient’s 24-hour hydromorphone hydrochloride dosage than to overestimate the 24-hour dosage and manage an adverse reaction due to overdose In general, it is safest to start hydromorphone hydrochloride therapy by administering half of the usual starting dose every 4 to 6 hours for hydromorphone hydrochloride tablets.

To convert subcutaneous morphine 2.5-5.0 mg every 6 hours to oral Dilaudid (hydromorphone), a conservative approach is advised due to inter-patient variability in opioid potency.

• The usual starting dose for hydromorphone is 2-4 mg orally every 4-6 hours.
• It is recommended to start with half of the usual starting dose every 4-6 hours.
• The dose can be gradually adjusted until adequate pain relief and acceptable side effects have been achieved.
• Close monitoring is necessary to avoid overdose and manage adverse reactions. 2

From the Research

Conversion of Subcutaneous Morphine to Oral Dilaudid

To convert subcutaneous morphine 2.5-5.0 mg every 6 hours (q6h) to oral Dilaudid (hydromorphone), the following steps can be taken:

• Determine the total daily dose of morphine: 2.5-5.0 mg q6h is equivalent to 10-20 mg per day (assuming 4 doses in 24 hours) 3, 4.
• Use the morphine to hydromorphone equivalence ratio: a commonly cited ratio is 7:1, but a study suggests a ratio of 3:1 may be more accurate for prolonged use 5.
• Calculate the equivalent daily dose of hydromorphone: using the 3:1 ratio, 10-20 mg of morphine per day is equivalent to 3.33-6.67 mg of hydromorphone per day.
• Convert to oral hydromorphone: oral hydromorphone is approximately 2-3 times more potent than subcutaneous hydromorphone, so the dose may need to be adjusted accordingly 6.
• Example calculation: 3.33-6.67 mg of hydromorphone per day orally is equivalent to 1.11-2.22 mg of oral hydromorphone per dose, assuming 4 doses in 24 hours.

Important Considerations

• The conversion ratio may vary depending on individual patient factors and the specific clinical context 5.
• Close monitoring of the patient's pain and adverse effects is necessary to adjust the dose as needed 3, 4, 7.
• The use of oral hydromorphone requires careful consideration of the patient's ability to swallow and absorb the medication 6.