Don’t Be Fooled By The Packaging . . . Or The Marketing!!!

I fielded a call from a patient, complaining that I wrote XL instead of SR after my prescription for Wellbutrin.  My bad.  She is on the SR and not the XL.  A quick call to the pharmacy and the problem was solved.  But, was it a problem in the first place? For a small minority of patients it can be.  For most, however, the use of one of the varieties of extended release medicines is more about convenience than anything else.  Wellbutrin (buproprion HCL) presents a unique situation where there is not only one but TWO varieties of extended release tablets.  Lets look at the difference . . .

Wellbutrin immediate release tablets (75 and 100 mg tablets) has been in a generic form for ages.  Not coincidentally,  a “sustained release” formulation of Wellbutrin . . . Wellbutrin SR . . . became available shortly before the immediate release preparation went generic.  This did represent a significant advantage over the immediate release tablets, because it allowed us to push the dose up without requiring more than two doses per day (three doses per day is impossible to remember consistently).  It also spread the peak blood level out so that side effects were less for many people.  But drug patents don’t last forever . . . and shortly before the SR version went generic . . . lo and behold . . . the extended release version . . . Wellbutrin XL . . . came out.

In some ways, the XL version does represent a step forward.  For someone on a higher dose, it allows once a day dosing (highly desirable).  The maximum dose allowable for the SR was 200  mg at a time.  If I prescribed more than 200 mg at a time, it would have to be in a split dose to minimize the risk of seizures. With the XL version, I could prescribe up to 45o mg to be taken at one time.  So the XL does represent a step forward . . . in certain circumstances.  Does it represent something more than convenience?  Not really.  For ALL sustained release products, the difference is in the packaging of the product . . . not in the product itself.  By packaging, I mean the coating or other technological advances that allow the active ingredient to be released more slowly than in a standard immediate release version.  “Regular” Wellbutrin dissolves and enters your system fairly quickly.  The dissolution of the SR and XL preparations happens more slowly, so absorption takes place over time.  You theoretically get the same amount of medicine (and the same amount of benefit) but with a slower and more gentle peak to the blood level.  This theoretically results in fewer side effects and greater tolerability.  This can be very important on the higher end of the dosing spectrum . . . and much less important at the lower and middle parts of the dosing spectrum.  Does it matter if someone gets Wellbutrin SR 150 verses Wellbutrin XL 150?  For the vast, vast majority of patients . . . no.  A rare patient will experience more sleep difficulties taking 150 XL compared with 150 SR.  The buproprion that is in both, however, is equivalent, and the form of delivery is so similar, there is little chance that one will result in a outcome different than the other.

Now is the generic Wellbutrin comparable to the brand only Wellbutrin?

That has been the source of much angst and will need to be explored in another discussion . . .

–Dan Hartman, MD

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