Pain hurts..
Time to get it out there.. managing chronic pain is often the worst part of going to clinic. These medicines are scary, you are never sure if the patient is shooting straight with you, and at the end of the day nothing really works to make the pain better anyway. Not fun.
I won’t pretend that I can make this part of the job enjoyable or easy, but I can offer a few tools that I have used to make it a little more tolerable. Today,
Equianalgesic Dosing.
Many patients with chronic pain take a continuous supply of short acting pain medicines, like hydrocodone or oxycodone. Just like we use long acting diltiazem once we’ve gotten the a fib under control, it makes sense to switch stable patients on to a long acting pain medicine.
- It’s easier to take.
- It offers a more consistent level of pain control.
- There is potentially less risk for dependence and addiction because of less peaks and valleys with opiate levels.
Plus, the VA has a new policy limiting the number of doses of short acting pain medicine. So, you might be forced to do it anyway.
How to make the switch? Here’s an equianalgesic dose calculator:
Simple, right? Convert the Lortab to MS Contin, and send them on their way. You should know by now, nothing is that easy.
Here’s the trouble, no one really agrees on these doses. This calculator uses guidelines from the American Pain Society, and others, so is pretty good, but isn’t perfect. A few things to consider as you look at individual patients:
- Metabolites: Chronic administration of long acting medicines may cause a build up of metabolites. Methadone is particularly known for this, so be extra careful with that one.
- Cross-tolerance: Patients get tolerant to a particular opioid, and may not need as much medicine when switched to something new. Most references recommend reducing the dose to 25-50% when you make a switch.
- People are not airplanes: If you give X medicine to 50 different patients, 60 different things will happen. Pay particular attention to elderly patients, cirrhotics, and patients with renal disease.
Practically, the way that I deal with this uncertainty is that I aim low on the long acting, and leave the patient with their short acting medicine. I will figure out how much a low dose of long acting medicine SHOULD replace, and then try to drop the number of short acting pills that I provide.
For example, in a patient taking Lortab 10/325 6 times a day, whom I want to change to MS Contin:
- The calculator says, 60mg oral hydrocodone, converted to morphine, at 50% reduction is 30 mg of morphine. this is convenient because MS Contin comes in 15mg tabs, you can give this twice a day.
- I would pick 50% reduction in an older patient, one with liver or kidney disease, or one whose pain was fairly controlled on his current regimen. If he was out of control,I might decide to reduce only 25%-30%
- I would still give him some Lortab each month, maybe 45-60 pills (down from 120), to cover bad pain days, and the fact that you reduced his dose.
- I find that if I don’t actively reduce the dose of short acting medicine from the beginning, it never gets reduced.
I’m sure that’s clear as mud by now. Let me know if you have questions,and we can talk more in clinic if you have specific patients that you want to switch.
I Hate Rashes 
Just wanted to add an observation of my own from my experiences as a resident, about the special populations you mentioned above: 9 out of 10 overdoses requiring a physician's intervention (i.e. Narcan) I have seen were in renal patients. They are at increased risk for both excess of the active agent and of active toxic metabolites.Also, the agent switching effect (dose lowering) can be used to the patient's benefit in difficult to control pain requiring very high doses of a particular agent. Palliative docs use this strategy from time to time, deliberately cycling through different meds over time.