Bupropion IR is usually taken 2 or 3 times per day with 4-6 hours between doses. Wellbutrin SR means that the dose of Bupropion is slowly released into the body throughout the day with the goal of maintaining a constant drug concentration in the bloodstream. Wellbutrin XL releases the dose for an extended period of time in a day. The SR formulation is slowly released in 12 hours while the XL doses are released for a period of 24 hours.
The dosing recommendations for both Wellbutrin formulations also differ since both drug delivery systems are controlled by time. Wellbutrin SR is initially given as 150mg once daily, and after 4 days the dose can be increased to twice daily to achieve a constant drug concentration in the blood. On the other hand, the extended release form is usually given once a day since the dose is being released in a 24-hour time frame.
Personally, I have had more success with Wellbutrin SR. Several times I tried Wellbutrin XL, both at 150mgs and 300mgs, but I got agitated, irritable, and headachy, and would lose my temper more easily. Some people tend to get anxiety when taking Wellbutrin, so my doctor prescribes Buspar, which I take with each dose of Wellbutrin SR, and this combination has been very successful for me to alleviate both anxiety and depression. When taking it I feel more focused, and it also gives me energy and motivation.
Wellbutrin IR is the only formulation that works for me. I cannot tolerate the side effects of the SR and XL versions. Both make me so fatigued I'm tired after walking up a flight of stairs (and I am otherwise very healthy). The IR version does not cause this side effect. I do take a low dose of only 75 mg/ day (split in two 37.5 doses) so that may be why the difference in side effects. I am unusual in that I don't like the XR or SR versions of any meds. I took adderall XR and has the same side effects as with Wellbutrin. With the IR version, I felt great. It must be something with my body chemistry as I know that isn't typical. I also like the idea of having control how much of a stimulant my body is getting at one time, since it really doesn't always need to be the same (some days I might need more than others). That said, I think the twice per day dosing of the IR is an issue for some people and is why more people seem to take the longer acting versions.
If they don't give you intolerable side effects then the XL or SR versions would probably work just as well and be more convenient.
- Wellbutrin Information for Consumers
- Wellbutrin Information for Healthcare Professionals (includes dosage details)
- Side Effects of Wellbutrin (detailed)
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Anxiety from Wellbutrin? My psych changed me from Wellbutrin XL 150 mgs to Wellbutrin SR 100 mg BID?
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