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Reviewed by Firstly, it is essential to identify what an opioid is. Simply put, they are drugs that act on specific receptors in the body, causing morphine-like effects that help to reduce pain. They can also be used for anesthesia.
When a patient is going through an opioid treatment process where dosing on a particular drug is resulting in little to no effect, physicians may begin to consider the option of employing a rotation therapy with another one. What this means is that the patient begins to switch between opioids of different chemical classes in order to find the perfect dose for the condition of the patient. Opioid dose conversion in this manner helps to increase the efficiency of treatment and improve overall outcomes with analgesic benefits, adverse event profile, and patient adherence.
Table Of Contents:
How Opioid Conversion Works?
There are no universally specified approaches to converting opioids. The common go-to for people seeking a quick answer is online calculators, but the information contained in these will vary in terms of the opioid equianalgesic dosing among the specified drugs.
Bearing this in mind, professional assistance is highly recommended because doctors, pharmacists, and other medical professionals can add their blend of scientific knowledge and situational experience to the math involved in calculating these conversions. This will ensure that the results of the process are as accurate and safe as can be.
Opioid conversion should be done only by qualified medical personnel. Patients shouldn’t substitute the prescribed medication or change the dosage on their own. If a patient suggests that their prescription has to be cached a call to the doctor is required as an initial step.
Factors That Can Affect Opioid Conversion
An important point to note in the course of opioid conversion is that results can vary by patient. Also, the opioid withdrawal period can occur during the process of switching or substituting the current medication. If the result of a specific opioid replacement therapy works well for one patient, it may not necessarily work the same way for another. This may be down to one or more of the following factors:
- Drug interactions
- Pharmacogenetics
- Drug and food interactions
- Diseases, especially liver and renal diseases
- Diet
- Physical attributes
- Opioid allergy, etc.
Additionally, if a patient has exhibited a form of response or lack of response to a particular opioid, conversion to another one of a similar pharmacological class may prove abortive – even if both share different indications. For instance, tramadol and SNRIs have different indications, but they function similarly by blocking the reuptake of serotonin and norepinephrine. This opioid pharmacology similarity among both means that an opioid conversion involving them may not yield the results that are hoped for.
Reasons To Ask For Opioid Conversion
Before moving on to the opioid conversion table, note that this process should only be considered if one or more of the following situations occur:
- The patient stops responding to a specific medication
- The patient has never responded to a prescribed drug
- The patient is approaching doses where side effects become more prevalent than treatment effects
- Other major risks associated with the current drug.
Mismanagement of the process of conversion can lead to complications such as opioid toxicity or overdose. These situations will require admission to the rehab facility as soon as possible.
Opioid Conversion Table
The table below is by no means a hundred percent set in stone. The figures shown are equivalents, rather than exact numbers, so the sense of judgment of the prescriber is still required.
For easy reference, all the other opioids listed in the table will be converted into morphine equivalents. The prescriber can use the method of calculation to find the appropriate doses when converting other medications among each other.
The second column contains the doses that are to be converted (10mg morphine equivalents), and the third column contains doses that are to be converted into 30mg equivalents. The fourth column of bioavailability is used to calculate the actual amount of the drug that goes into the bloodstream. To get this number, you have to multiply the dose of each drug by its figure for bioavailability. The resulting figure will always be a smaller number. For instance, if the dose for codeine is 100mg, the actual amount that goes into the bloodstream would be 30mg. If any mistakes are made with these numbers for an extended period of time, the patient must undergo detox as soon as it is found out.
The final column shows what the average dosing intervals for each drug should be each day.
| Drug | Parental Dose (MG) Equivalent to 10 MG IV Morphine | Oral Dose Equivalent to 30 MG Oral Morphine | Bioavailability of Oral Dosage Form | Dosing Interval (HRS) |
|---|---|---|---|---|
| Morphine | 10 | 30 | 0.3 | 3 |
| Anileridine (Leritine) | 25 | 75 | 0.3 | 3 |
| Codeine | 100 | 300 | 0.3 | 3 |
| Diamorphine | 8 | 12.5 | 0.4 | 3 |
| Fentanyl | 0.1 | – | – | 1 |
| Hydromorphone (Dilaudid) | 2 | 3 | 0.6 | 3 |
| Levorphanol | 2 | 4 | 0.5 | 6-12 |
| Meperidine (Demerol) | 80 | 250 | 0.3 | 3 |
| Methadone | 2-10 | 2-10 | 1.0 | 8-12 |
| Oxycodone (Percocet, Oxycontin) | 10 | 12 | 0.8 | 3 |
| Propoxyphene | 50 | 100 | 0.5 | 4 |
| Sustained Release Morphine (MS Contin) | – | 30 | 0.5 | 8-12 |
The table above is provided for educational use only. Self-medication or any changes to prescribed dosage aren’t allowed.
Practical Tips On Opioid Conversion
The following tips will be helpful for one dealing with opioid conversion guidelines:
- As suggested earlier, the figures on the conversion table are equivalents and not exact numbers. If calculations result in fractions, then the figure should be rounded down.
- Doses should be adjusted and monitored as appropriate, especially when dealing with special patients – such as old people or people with health impairments that impact the drug effects in the system.
- When dealing with bunepropine, measurements are made in micrograms, not milligrams, and this can then be converted.
- As a prescriber dealing with converting opioid prescriptions of rapid fentanyl preparations must always seek the advice of specialists.
In case one have noticed any signs of opioid abuse or addiction in themselves or a loved one, they must seek professional help not to become a part of the Opioid Crisis victims.
Health professional can always advise the safest and the most effective ways to overcome this disorder, detox procedures to ease the withdrawals, and guide through the addiction treatment process.
Page Sources
- Agency Medical Directors Group, Opioid Dose Calculator, https://amdg.wa.gov/Calculator/DoseCalculator.htm
- World Health Organization, Pharmacological Profiles and Opioid Conversion Tables, https://www.ncbi.nlm.nih.gov/books/NBK537482/
- Center for Disease Control and Prevention, Calculating Total Daily Dose of Opioids for Safer Dosage, https://www.cdc.gov/drugoverdose/pdf/calculating_total_daily_dose-a.pdf
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