Are generic and brand name drugs exactly the same?
June 13, 2007 1:05 PM   Subscribe

Is it possible for me to experience different side effects on a generic drug vs. its brand name equivalent? The drug in question is neurological.

I take Tegretol for epilepisy (siezure control), 200mg twice a day. Yesterday my doctor gave me a new writ, and I took it to a new pharmacy. I didn't realize they gave me the genetic Carbamazepine until I got home. Figuring it was exactly the same, I didn't worry about it.

Now I feel tired, somewhat out of it, and most humorously, I am slightly slurring my words. It's like I'm on a bit of cold medication. None of these side effects are uncommon for the drug. But I've been taking Tegretol for 20 years -- I'm very familiar with it. I didn't experience these effects (or experience them to this degree) on the brand name. That said, I could just be tired, sick, stressed, etc.

Is it possible that Carbamazepine is the culprit? Shouldn't the two drugs be exactly the same? I mean, a chemical is a chemical...right?
posted by samh23 to Health & Fitness (30 answers total) 1 user marked this as a favorite
They should be the same. However if the name-brand is some special formulation (e.g. time release, etc) there may not be a generic in that formulation, and the pharmacist may have given you the regular generic formulation. However, there are control in place for this not to happen, so it's unlikely.
posted by Pastabagel at 1:17 PM on June 13, 2007

They should be the same, but they aren't necessarily. Quality control at different factories can vary widely. If you continue to experience the symptoms, switch back to the name brand.
posted by milarepa at 1:20 PM on June 13, 2007

That kind of thing is controlled very, very carefully. If the generic is truly a replacement for the brand-name drug they should be identical in all important ways except price.
posted by Steven C. Den Beste at 1:20 PM on June 13, 2007

Of course, it depends on where the generic came from. If it came from China, all bets are off.
posted by Steven C. Den Beste at 1:21 PM on June 13, 2007

Upon further googling, there is a tegretol-XR (extended release). Is that what you used to get, but now you got generic regular tegretol?

On this site, you notice there are two Carbamazepines listed, one is XR the other isn't, however there are pictures of the pills, and it appears that there may be no generic XR formulation (note the 'T' on the pill), though I could be wrong about this. Does this help? Which one does your pill look like?
posted by Pastabagel at 1:22 PM on June 13, 2007

I remember experiencing that lethargy when I was on Tegretol way back in the day, but if I recall, it was only at the beginning and one time when they upped my dose. Are you sure they didn't up the mgs/pill on you as well, perhaps even by accident?

But yeah, generics are supposed to be the same as brand name drugs. That's why pharmas get worried whenever a blockbuster drug falls out of patent protection.
posted by epugachev at 1:24 PM on June 13, 2007

There is a slim but not impossible chance the pharmacist gave you the wrong pills. You might want to check.
posted by chairface at 1:26 PM on June 13, 2007

Personal experience: Was on the brand name of a drug. My insurance ended and I switched to the generic for cost reasons. Doctor wanted me to stay on the generic because his patients had better success with it than the generic. I didn't notice a difference in the result of the drugs, but had more severe side effects from the generic, which did not subside after time. This was with SSRIs, so YMMV.
posted by meerkatty at 1:30 PM on June 13, 2007

A drug is a drug, yes, but the fillers might make a wee difference. Wee, but noticeable.
posted by kmennie at 1:41 PM on June 13, 2007

Best answer: I'm just trying to get my neuro to write me off my generic anticonvulsant (Zonegran, not Tegretol, but similar drill) because I have read from almost every source that the side effects (notably the stupids, which you are describing) are much worse on the generic than on the brand. Medically the drugs should be the same, but binders and such can be different and some people believe that can affect absorption. Many, many people believe that generic XR drugs don't work as well as the brands. All of this is anecdotal and your Doctor will swear up and down that the brand and the generic are legally required to be identical, but the experience of man of us on anticonvulsants is to the contrary. Talk to you neuro about the stupids -- you may well want to switch back.
posted by The Bellman at 1:44 PM on June 13, 2007

"They should be the same, but they aren't necessarily. Quality control at different factories can vary widely. If you continue to experience the symptoms, switch back to the name brand."

"Of course, it depends on where the generic came from. If it came from China, all bets are off."

These comments are completely wrong for drugs sold in the United States. FDA regulations and inspections will apply to any such facilities and the regulatory process is extremely stringent.
posted by jcwagner at 1:50 PM on June 13, 2007

The binders/fillers or artificial coloring would be the only difference between the generic and the brand.
posted by pieoverdone at 1:59 PM on June 13, 2007

Best answer: This is from my sister who has been taking tegretol for a long time for TLE seizure control

"There is a different range of effectiveness for name brand drugs versus the generic equivalent. One of the things that keeps generic medication cheap is that they are not held to the same rigorous standards as name brand medications are.

My own neurologist will not prescribe generic epilepsy medication to control seizures. While generic Tegretol might be fine for headaches or migraines, there is often too wide a range of strength from pill to pill. This can cause blood levels to vary, which in epilepsy medication will mean that you have a greater chance of side effects and a lowered chance of efficacy for seizure control.

Seizure control relies on a steady, constant, medication level. Generic pills simply can not offer this. The Epilepsy Foundation of America backed me up on this a few years ago when I querried them on the topic. I would suggest having your doctor correct the mistake a.s.a.p. Your body seems to be telling you the same thing through it's experience of different and stronger side-effects.

Best of luck!"
posted by jessamyn at 1:59 PM on June 13, 2007

There are certainly differences between the fillers, binders, release mechanisms, etc., that could affect the manner in which your body reacts to a generic prescription instead of the patent-protected version of that drug. It's not just the active pharmaceutical ingredient(s) that determine how the drug works, it's the manner in which they are delivered, especially for neurological and psychoactive drugs, and the manner varies in some cases between patent-protected drugs and the generic versions

This whole line of discussion about quality and standards and factories and generic pills being unable to deliver medication in the same way is just wrong, though.
posted by jcwagner at 2:15 PM on June 13, 2007 [1 favorite]

I was taking a medication that became available as a generic. When I renewed the prescription, it was for the generic version. Within 12 hours of taking the first dose, I broke out in hives on my neck and arms. Once I switched back to the namebrand there were no problems. My doctor said it was likely I was allergic to one of the binders/fillers in the generic version.
posted by notme at 2:27 PM on June 13, 2007

Like jessamyn, my neurologist refuses to write prescriptions for generic anti-seizures medicines. I am not a doctor, but before I found my current dr. I was on generic Dilantin. And I still had seizures.
posted by mitzyjalapeno at 2:28 PM on June 13, 2007

edit: like jessamyn's sister
posted by mitzyjalapeno at 2:28 PM on June 13, 2007

These comments are completely wrong for drugs sold in the United States. FDA regulations and inspections will apply to any such facilities and the regulatory process is extremely stringent.

Right. Pills are always legit and pharmacists never make mistakes.
posted by backupjesus at 2:47 PM on June 13, 2007

I know of someone whose neurologist had generic provigil (modafinil) tested, and said it was quite different than the brand name, which he therefore insisted on prescribing.
posted by StickyCarpet at 2:51 PM on June 13, 2007

I stopped taking one SSRI after relocating from one health district in London to another. Both prescriptions were generics, just different ones. The first one worked as described. The second had no effect on me whatsoever.
posted by genghis at 3:05 PM on June 13, 2007

My limited understanding, contrary to what people have written above, is that generic drugs do not have to contain the exact same drug formulation as the original drug. I was told by a doctor friend that in fact generics are required to have the same effect as the original drug, but my contain a reduced amount or different formulation of the active ingredient. He suggested that many drug companies liked generics because they could reduce the amount of perhaps costly effective ingredient in their medications. Wikipedia seems to back this up.

I would think that there is a good chance the changes you see are due to differences between the generic and brand name drug.
posted by procrastination at 3:12 PM on June 13, 2007

I don't think you're reading the Wikipedia info correctly: it says "Bioequivalence, however, does not mean that generic drugs are exactly the same as their innovator product counterparts, as chemical differences do exist." That, I believe, is refering to the binders, etc. - not to the medicine.

There is a lot of caution in prescribing generics when it comes to seizure meds. In my case (I'm on Lamictal) my doctor says that with these kinds of meds, you don't want to take chances that a generic might contain more or less of the active ingredient per pill (though the same amount on average) because of the risk involved - not just for bad episodes, but also because many of these drugs need to be titrated (tapered) when starting or finishing on them in order to avoid dangerous side-effects. Once you're on a steady dose, there might be some small risk of those side-effects if the generic's active ingredient varies a bit.

My doc says that this is rare, or even unlikely. He is OK with prescribing generics if I ask for them, as long as I monitor myself for changes in effectiveness and side-effects. I've had excellent luck with generics, which is good, because it is hard to afford these very expensive meds otherwise.

If you can afford the brand-name and you feel more comfortable with it, you should probably switch back. Otherwise, I'd report the effects to my doc, stay on the generic for a while, and see what happens.
posted by soulbarn at 3:52 PM on June 13, 2007

Best answer: Yes, actually, this happens all the time in my epilepsy clinic. The content of the medication is probably the same, to the milligram, but due to the way the pill is constructed, the absorption - what we call the pharmacokinetics and bioavailability - is different. In general generics usually dissolve more quickly, are absorbed more quickly, and produce a higher peak level. Since side effects are usually related to the height and duration of the peak, the result is that side effects are more pronounced.

If the trough level becomes lower than it otherwise would be, which it can because of these variances, you can also experience breakthrough seizures due to this.

For years I took the position "A chemical is a chemical, I won't be doing any shilling for the big name drug companies, I can't believe these effects are big enough to make a difference that a patient can detect." But eventually I came to change my mind about this with regard to certain of the anticonvulsants that I prescribe, based on what my patients were telling me. Carbamazepine is definitely one of the drugs on that short list.

So to sum up: yes, what you observed happens all the time.
posted by ikkyu2 at 4:04 PM on June 13, 2007 [4 favorites]

Best answer: I should point out that I continue to believe that for most medications, generics are absolutely equivalent in their potency and efficacy to their branded counterparts.

The reason that phenytoin and carbamazepine are exceptions to this rule has to do, to my mind, with the idea of the therapeutic index. That idea suggests that at a certain blood level of a drug, A, the drug has its benefical therapeutic effect; and at a different level, B, the drug shows its toxic or side effects.

For example, lets say you're taking lorazepam for anxiety. At a dose of 2 to 4 mg per day, you might experience an anti-anxiety effect. At a dose of 80 mg a day, you might lapse into a coma and stop breathing. In between there is a large territory where you might experience the therapeutic effect without ever getting the toxic effect. That is the 'therapeutic window'. If you reformulate your 4mg Ativan tablet so that instead of being 95% absorbed it is 98% absorbed, you still are nowhere near the toxic level.

But with the anticonvulsants, the therapeutic window is very small. In fact, most people start experiencing side effects from anticonvulsants at doses lower than the dose necessary to control their seizures. In that situation, any alteration of the drug that is going to push the peak level up is going to increase the manifestation of the side effects.

Anticonvulsants represent a specific class of drug which have a lot of side effects at their therapeutic doses, so this is one reason why consistency in the formulation can be more important for patients who have become stable while taking them.
posted by ikkyu2 at 4:11 PM on June 13, 2007 [4 favorites]

I can't speak to side effects, but I believe the subtle differences between brand and generics can have a distinct impact. I'd have to poke around a bit to refresh my recollection, but I believe the FDA considers a generic drug (filing an Abbreviated New Drug Application) bioequivalent to the brand name if they're bioavailability is within a particular range. Don't know the reg off-hand, but wikipedia summarizes the regulatory definition here.

I'm not a doctor, but a lawyer who once read a bunch of transcripts of meetings of neurologists sponsored by a company who's anti-epilepsy drug was nearing the end of it's exclusivity period. Generally speaking, all the neurologists agreed that there were special problems associated with switching from a brand to a generic (or vice versa, one assumes). I can't recall how much was anecdotal, but the concern was that some patients who were controlled on a brand-name drug might suffer breakthrough seizures on the generic version.

I can't remember more, but about the best I can tell you is I read a lot of meeting transcripts where most or all the neuros in attendance seemed to think that it could be a real problem - but only seemed concerned about it for these sorts of drugs.

On preview - ikkyu2 said it much better.
posted by averyoldworld at 4:16 PM on June 13, 2007

I'm so glad to hear you say that ikkyu2. I feel much better about asking for Zonegran (brand) now. We'll see what my doc says.
posted by The Bellman at 4:17 PM on June 13, 2007

Here's a report study that talks about (and seems to confirm) variability in anti-seizure generics (in this case, Lamictal/Lamotrigine.)
posted by soulbarn at 4:31 PM on June 13, 2007

Binding agents may change how the drug is released.
posted by devilsbrigade at 7:07 PM on June 13, 2007

I'm not in the camp, incidentally, of docs who will never prescribe generic anticonvulsants. My feeling though, is that if patients get on a certain formulation of generic drug, that they should know the manufacturer; and both the doc and the patient have to realize that changing over from one formulation to another is not a guarantee of bioequivalence.

Mylan Bertek makes a generic phenytoin, for instance, which is perfectly fine. Mylan also makes Phenytek extended release phenytoin under a different label. Parke-Davis makes branded Dilantin. I have patients stable on all three of these formulations; but if for some reason they have to switch from one to another, I warn them to expect these issues. It is annoying to have to know about this - it'd be nice if there was just one kind of phenytoin - but in the long run knowing about it makes my job easier.

I also find that these problems are greatly mitigated when patients can take medicines more frequently. Twice a day carbamazepine for epilepsy is really stretching it; usually when I go to a twice a day regimen on that drug, I use either Tegretol XR or Carbatrol, both of which are extended release. Three times a day carbamazepine (with the same overall daily dose) is much better for smoothing out these peaks and valleys in the drug level; if the original poster can't get back to what he's used to, changing to a three-times-a-day regimen might be something to suggest to the prescribing doc.
posted by ikkyu2 at 7:59 PM on June 13, 2007 [1 favorite]

Response by poster: Thanks very much to everyone who answered. Both the personal and clinical accounts were very helpful to me. I called my pharmacy and they'll switch out my pills tomorrow for the brand name, and hopefully, that will be the end of the stupids (as The Bellman accurarely described it).

For those who were wondering, they did fill my prescription with the correct medication and dosage, just in generic form. Never been on extended release so that wasn't the issue either.
posted by samh23 at 9:56 PM on June 13, 2007

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