Are generic antidpressants less effective?

I’ve been taking Wellbutrin (generic name Bupropion) for about seven years, minus the time I was pregnant with my son. I would say that overall it’s been very successful, except for during one period. All of a sudden, even though I was faithfully taking my medicine, it was as though I was taking sugar pills. I realized that the color and size of the pills in my most recent prescription refill were different from the ones that I had been taking. It turned out that the pharmacy had started stocking a different brand of Bupropion. When I explained what was happening they ordered a bottle from the company they had previously been stocking. Within a few days I was back to normal. From then on I made sure that they filled my prescriptions using that specific company until I ultimately went back to taking the brand name version.

I was not particularly surprised that the effectiveness of the generic version varied so widely between manufacturers. I know of someone who had a recurrence of seizures a couple of decades ago when she started taking a generic version of the medication prescribed for her epilepsy. Her doctor measured the amount of medication in her bloodstream and found that there was a much lower amount than there should have been. I haven’t been sanguine about the effectiveness of generics since then.

You can imagine that I wasn’t too surprised when a report came out recently that raised questions about the effectiveness of generic Wellbutrin. This report was not the result of a study, per se. The website ConsumerLab.com was approached by Joe and Terry Graedon, the authors of The People’s Pharmacy column. They had been receiving numerous complaints about generic Wellbutrin from consumers who saw a return of their depression while taking it, as well as an increase in side effects in some cases.

ConsumerLab.com ran their own tests on Bupropion from three different companies, comparing how the three stacked up against the brand name version. You can read a detailed account of the testing here, but in a nutshell, the generic Wellbutin released its active ingredient at a much quicker rate. There are two potential problems with this happening. One is that there is no active ingredient being released into the system during the latter four hours. The second problem is that too much active ingredient is being released into the bloodstream in the first four hours. Bupropion can cause anxiety and even has a potential for seizure if too much is released into the bloodstream at once. This over-dosage probably also accounts for the side effects people were experiencing when they used the generic Bupropion.

Generic versions of drugs go through a much less rigorous process to obtain FDA approval than their brand name counterparts did before them. Instead of testing their drug on hundreds or thousands of subjects, they need to only test on 24 to 36 subjects in order to prove that it behaves in the bloodstream in a similar manner to the brand name version. In addition, the frequency of quality control testing during production is left up to the company. They can test one in 1,000 pills or one in 100,000 pills.

With the bulk of prescription drugs, the generic version can vary slightly from how the brand name behaves without any ill effects to the patient. But there are some drugs that have what is called a “narrow therapeutic index.” This means that even a small variation in the way the drug behaves in the bloodstream can have ill effects. Bupropion may fall into this category.

Unfortunately, in many cases patients don’t actually have any choice in whether the drug they’re taking is generic or brand name. Insurance companies hate to pay for brand name medications. If a generic version exists, that’s what they want the patient to take, and they will almost always refuse to pay for a brand name drug in that situation. Even if the doctor writes “Brand Name Medically Necessary” on the prescription slip, chances are there’s still going to be a battle with the insurance company.

If you have switched from a brand name antidepressant that was working for you to a generic antidepressant that doesn’t seem to be working as well, it’s probably a good idea to keep a record not only of your moods, but also of any possible side effects. This will bolster your case when you and your doctor make your push to have your insurance company pay for the brand name.