The Ontario Pharmacists Association recognizes the complexity of the management of chronic pain and the issues surrounding it. As medication experts, pharmacists have an especially critical role to play where opioids are concerned, with regards to safe and responsible dispensing and patient education in order to prevent misuse.
In this section, we have collected resources to inform and assist pharmacists who dispense opioids:
Opioid Conversion for Chronic Non-cancer Pain
Close collaboration between all health care professionals involved in opioid prescribing and dispensing is essential.
Providers are reminded that opioid conversion charts refer to the analgesic strength of oral opioids and not to the psychoactive effects or effectiveness in relieving withdrawal symptoms.
Pharmacists should refrain from making any dose conversion recommendations in instances where opioid prescribing is primarily for addiction maintenance and not for purposes of chronic pain management, and particularly where there is no guarantee that the medication is being administered in the form it was intended.
Prescribers and pharmacists are strongly advised to utilize the information provided through the conversion chart, and to collaborate, agree upon, and document any medication conversion necessary so as to identify real or potential factors that are unique to the patient and/or the alternate drug.
Addendum regarding OxyContin substitution
The Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain, above, is quite comprehensive and pharmacists are encouraged to take the time to review the recommendations. One such recommendation in particular (R13 of the Canadian Guideline for Safe and Effective Use of Opioids for CNCP — Part B), should be considered when making a recommendation to switch an opioid and suggest an appropriate dose conversion.
Because of unpredictable and incomplete cross-tolerance from one opioid to another, suggested initial doses of the new opioid are as follows:
|If PREVIOUS opiod dose was:||The SUGGESTED new opioid dose is:|
|High||50% or less of previous opioid (converted to morphine equivalent)|
|Moderate or Low||60% to 75% of the previous opioid (converted to morphine equivalent)|
If switching to fentanyl, see Appendix B-8.1: Oral Opioid Analgesic Conversion Table (Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain). There is no evidence to support the practice of combining different types of opioids.