February 21, 2011

Differing Brands of Generic Metformin Behave Differently

Dr. Bernstein has been preaching about this on his web telecasts for years, but it bears repeating: If you are having problems with generic metformin or not seeing it make much impact on your blood sugar, change brands before you assume it isn't working or that you can't tolerate it.

I just had this message brought home to me when my pharmacy (Walgreens) filled my prescription for metformin ER with tablets from SunPharma instead of the ones from Teva they'd given me for years.

The pills were about half the size of the ones I'd been getting, which suggested they contained less of a matrix substance to slow the release of the metformin. And sure enough, when I took the same dose I had been taking with no problems with the Teva brand metformin, I felt exhausted and semi-poisoned. It felt just like when I had taken an overdose of metformin some years ago, when my family doctor prescribed an overdose after confusing the dosage instructions for regular metformin--which can be taken in larger doses--with those of metformin ER.

Not only that, but my fasting blood sugars went up. Clearly the SunPharma metformin ER was not behaving like a true extended release should and releasing slowly through a 24 hour period but was hitting my blood stream all at once and then was done.

A quick visit to Google revealed that Sun Pharmaceuticals is an Indian company and that in the past the FDA has forced them to recall batches for quality issues.

When it was time to refill my prescription, I called my pharmacy and spoke with the pharmacist who shrugged off my concerns and told me I'd have to speak to the pharmacy manager (not available that day.) So I got on the phone and called other local pharmacies and asked them what brand they were dispensing. Two of them still carry the Teva brand, so I took my empty pill bottle to the closest one and they transferred the prescription and filled it with the Teva. I was very happy to find that it worked just the way I remembered, with no unpleasant side effects.

This experience made me wonder how many of the people who tell me they can't take metformin because of the side effects were victims of cheap versions like the SunPharma one.

If you try metformin and find the side effects overwhelming after a month's trial--typical problems would be dramatic digestive problems or a feeling of exhaustion and low grade toxicity--talk to your pharmacist about trying another brand or move your prescription to another pharmacy that carries another brand.

Dr. Bernstein says that the brand name version, Glucophage, is the best. I've never tried it so I can't verify that. If you can get it, go for it. I've heard that some pharmacies will order a specific brand for you if you ask, but before you do this, check how much the prescription will cost you as some insurers may not pay for your prescription if you specify the brand or they may make you to pay much more.

If you're taking metformin ER, which brand you are taking? How well does it work for you? Have you switched brands and seen a difference? Please cite the manufacturer name if you can. It would be nice to build up some expertise here as to how the different versions work. If I get enough feedback I'll add it to the page where I describe metformin on the Blood Sugar 101site.

NOTE: You should be able to find the name of the manufacturer somewhere on your label. I believe this is a legal requirement in the U.S..

GENERICS

by glasshospital

Later this year, the nation’s top selling drug–Lipitor–will lose its patent protection. Soon thereafter, generic drug manufacturers will compete to market a low cost version of the drug.

How low?

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The price will drop in the neighborhood of 90%. Makes you wonder why the cost is so high in the first place. Manufacturers justify it as the price of innovation. Patent exclusivity allows pharmaceutical firms to recoup their investments in research and development (and marketing).

To complicate matters, once the patent expires it’s not quite a free-for-all. For complicated legal reasons, a single generic manufacturer is given a six month window of exclusivity before the drug can be manufactured in the ‘public domain.’

This means that the price is certain to drop (if the generic manufacturer clears its legal hurdles), but not by the massive amount it will once there are lots of other manufacturers competing.

I mention this story for two reasons:

First, the company that makes brand-name Lipitor, Pfizer, is causing controversy by applying to sell its version of the drug over-the-counter (meaning available without a doctor’s prescription). Critics accuse the company of a naked cash grab, arguing that Pfizer is simply trying to extend their product’s market share dominance.

There’s a nice summary of the controversy from mega-medical blogger KevinMD. Link here.

No doubt many of you have opinions about generics–ranging from “I always choose them since it’s the most cost-effective strategy” to “Never. I don’t trust anything less than brand name. I don’t like being forced into generics by my insurer. Isn’t this why I have insurance in the first place?” [Patients have said that to me many times.]

The other reason I offer the story is to let you in on a secret of the medical profession. Get ready:

[sotto voce] Doctors like generics. We believe in them. In general, we find it ludicrous to pay the differential for brand name drugs. Claims about the superiority of brand name drugs are just so much smoke and mirrors. Don’t believe the hype.

Having said that, here are a couple of stories to keep us all on our toes:

Some drugs actually aren’t the same. For example, it’s been generally accepted that there are differences in the way brand name blood thinner Coumadin is metabolized versus it’s generic ‘equivalent,’ warfarin. So the absolute I just gave you about docs always favoring generics isn’t absolutely true.

Then try this on: Patients get confused when they’re on a generic and suddenly it switches. Happens all the time. Pharmacies get huge bulk discounts on the pills they sell. Next year, when you go for that refill on your amlodipine or metformin (the first a very common blood pressure medicine, the second the most common oral medicine for diabetes), the pill could easily change size, shape and color. But it’s for all intents and purposes the same thing. The only difference is the ‘inert’ stuff in the pills, what are called congeners.

But it is darn confusing when this happens. And even though the ‘active’ ingredient, the actual drug, is supposedly safe and effective, there are anecdotes of things going wrong. I had a patient on the blood pressure medicine lisinopril for years. She tolerated it well, and it worked to control her blood pressure. We were both happy.

Sure enough, her pharmacy changed her pills from round white ones to oblong pink ones. After the third dose, she had a major allergic reaction called angioedema. [Her face, tongue, and lips swelled up.] Luckily, with treatment, she got better and no further harm was done. Coincidence? We’ll never know. One thing we know: no more lisinopril for her.

So, that’s this week’s debate. Where do you fall on generics vs. brand name?

Apparently, it’s no contest. A vast majority of Americans prefer generics and believe that they are safe and effective. Scott Hensley at NPR’s Shots blog has a nice post about this trend.