Opioids
First, as an aside: remember opiate refers to a substance derived from opium (from the poppy) while opioids are synthetic/semi-synthetic versions of opiates.
- PO codeine to PO morphine: divide by ten
- PO tramadol to PO morphine: divide by five
- PO morphine to PO oxycodone: divide by two
- PO morphine to S/C morphine: divide by two
- PO morphine to S/C diamorphine: divide by three
- PO morphine to S/C oxycodone: divide by three
- morphine to fentyl: divide by 100
Other misc notes:
- codeine relies on conversion to an active form by the P450 enzyme group. Not all patients are able to do this (roughly 10% of the population struggle), and other drugs (such as SSRIs) may interfere with the effectiveness of conversion so the same amount of codeine may have a very variable analgesic effect on different people.
- doses of all opioids should be reduced in renal failure except fentanyl
- if asked to prescribe a breakthrough dose this is usually 1/6th of the total 24hr dose.
Benzos (and derivative)
Rough conversions are:
Chlordiazepoxide 15mg = Temazepam 10mg = Diazepam 5mg = Lorazepam 0.5mg
Decrease by 1/8th every 2 weeks.
Now for a little pyrexia of unknown origin...
