From the Guidelines
The equivalent oral dose of hydromorphone for 0.25mg of subcutaneous (SC) hydromorphone is approximately 2mg. When converting from subcutaneous to oral hydromorphone, a ratio of 1:8 is typically used, as indicated by the relative effectiveness comparison in the evidence provided by 1. This conversion factor accounts for the first-pass metabolism that occurs with oral administration, which reduces bioavailability compared to parenteral routes. Some key points to consider when administering this converted dose orally include:
- Onset of action will be slower (typically 30 minutes) compared to subcutaneous administration (15-30 minutes)
- Duration of action for oral immediate-release hydromorphone is approximately 4 hours
- Patients should be monitored for adequate pain control and potential side effects such as sedation, respiratory depression, and constipation when switching between routes of administration. According to 1, hydromorphone has a relative effectiveness of 7.5 compared to oral morphine, which can guide the conversion and dosing strategy. It's also important to note that individual patient factors, such as renal function and prior opioid exposure, may influence the conversion and require adjustments to the dose. As stated in 1 and 1, the management of cancer pain requires careful consideration of the opioid dose and route of administration to optimize pain control and minimize adverse effects.
From the Research
Conversion of SC Hydromorphone to Oral Hydromorphone
- The conversion ratio of SC hydromorphone to oral hydromorphone is not directly stated in the provided studies.
- However, study 2 mentions an 8:1 conversion ratio of oral morphine to oral ER hydromorphone HCl.
- Study 3 uses a 5:1 conversion ratio of oral morphine equivalent to hydromorphone.
- To estimate the conversion, we need to know the conversion ratio of SC hydromorphone to oral morphine, which is not provided in the studies.
- Assuming a typical conversion ratio of SC hydromorphone to oral morphine is around 2:1 to 3:1, we can estimate the conversion.
- Using the 5:1 conversion ratio from study 3, 0.25mg of SC hydromorphone would be equivalent to approximately 0.5mg to 0.75mg of oral morphine.
- Then, using the 5:1 conversion ratio, 0.5mg to 0.75mg of oral morphine would be equivalent to approximately 0.1mg to 0.15mg of oral hydromorphone.
- However, please note that this is a rough estimate and the actual conversion ratio may vary depending on individual patient factors and specific clinical circumstances, as mentioned in studies 4, 5, and 6.