Conversion of Gabapentin to Pregabalin
In a previous post, I discussed the rare situation of patients being on both gabapentin and pregabalin and some possible explanations for this scenario. That prompted someone to ask me how to do a conversion of gabapentin to pregabalin.
Let’s set up the scenario; your patient is on pregabalin 150 mg BID and Gabapentin 300 mg three times per day for neuropathic pain. The first question I would ask the patient and/or provider is “How well is the pain managed?”
The question of where their pain is at would help me decide the route of attack in getting them off of one and onto the other. If the patient’s pain is well managed, I would simply recommend tapering down on one of these agents. My preference would be the pregabalin because I know how expensive it is (at least at this time). The patient may have a strong opinion about which one they feel is working better and that has to be a consideration before developing the taper down plan.
If the patient’s pain is not under control, I would likely go up on one of them at the same time I reduce the other. Unfortunately there is no perfect dose equivalent of gabapentin to pregabalin. Some have suggested 300mg of gabapentin to 50 mg of pregabalin, but I also want to remind you of the dose dependent kinetics of gabapentin. No conversion is going to be perfect or at least we won’t know the perfect conversion.
In the scenario above (gabapentin 300 TID and pregabalin 150 mg BID), if the patient’s pain was not under control, as an initial step, I would probably go up on the gabapentin by 600-900 mg (total daily dose) and reduce the pregabalin by 100-150 mg (total daily dose).
There are definitely a lot of different variables that go into this conversion, but the nice thing with this conversion is that we can likely be pretty conservative (i.e. we don’t need to do it all at once.
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