There are two methods of calculating the equivalent dose when converting from oral morphine
to transdermal method. By the commonly used Physician's Desk Reference Table, this figure would have been just 75 mcg/hour fentanyl
release system to be worn for 72 hours, and then gradually titrated upwards for proper analgesia. By the Brietbart method, this would be around 120 mcg/hour patch. Therefore, your doctor has correctly advised the use of a 125 mcg/hour release patch. The release rate is calculated per hour for all fentanyl patches, though these are to be worn for 72 hours. You must also keep in mind that these are just equivalent dosages, calculated conservatively to avoid overdose. So it may be possible that this dose is not adequate for you. You can discuss this with your doctor who, in my opinion, will gradually hike up the dose to provide you with adequate relief.
Hope this helps you. Best wishes.