My local CVS pharmacy sucks. Sure, it was close by, but it seemed like they never had medications ready when promised, or they dispensed a generic instead of the brand name as the prescription stated, or they put all the prescriptions on auto refill without your consent and then called you multiple times a day to come pick up a prescription you didn’t need yet. About a month ago I finally got so fed up with the local CVS that I changed all my prescriptions to the local Walgreens. I picked up my first refill on my Metformin ER and started taking it about a week later. I keep a food diary and test four times a day (fasting and after every meal). After about a week of taking the new batch of pills, my glucose readings started to go haywire. Meals which had been safe for over a year were suddenly giving me really high readings (160s instead of the usual 120s). My first thought was that I was one of those few people every year whose medication stops working for them, but that didn’t make sense because some of the readings were still good. If the medication wasn’t working, it should be consistently not working. Not seeming to work sometimes, but not others. I kept taking the pills, eating, and testing and it seemed to me that it wasn’t me, but the medication I got from the Walgreens. My fasting levels had gone from 90-100 range up to 110-120. One morning it was 147 which really freaked me out! The readings after breakfast (and my morning medication) were usually okay, but the readings after lunch were high again around 145-165+ instead of the usual 120s. Dinner seemed to be hit or miss until I noticed that if I had taken my evening pills before I ate, the reading was what I expected, but if I didn’t take the pills until after dinner (I normally take a dose at 8am and one at 8pm) the reading was high again.
I got one of my old CVS bottles and compared the labels, thinking that maybe I was accidentally given the wrong form of Metformin. They were both Metformin ER but the one from Walgreens was from Tagi and the Metformin I got from the CVS was from Granules Pharma. I took both bottles and went to the Walgreens to see if they could get the same ones I was getting from the CVS. I explained to the pharmacist what was happening. She said she could order the ones from Granules Pharma for me and she would try to override the protocols and get me a refill of the brand I had been taking so I could switch back to them right away (instead of having to use the rest of the 90 day supply of the other one). I should be able to pick them up today.
In the meantime, I started taking the Metformin from Tagi as if it were an immediate release instead of an extended release. I took one before eating breakfast, one before lunch and one before dinner, and the last one before bed. Early results with this dosing schedule look good. My post prandial levels are consistently below 145. But what a pain to have to remember to take the pill about thirty minutes before every meal instead of just popping two in the morning and two before bed. I will be going soon to have my A1c. I’m hoping this snafu with the medication hasn’t caused too much of a rise. I look forward to being back on the brand of Metformin I was used to and having predictable results again.
Let’s pretend for a minute or two that I wasn’t so diligent about testing and didn’t keep a food diary. I would have continued to take the Metformin from Tagi on the same schedule as before and when I went to the doctor again in a few months to have my A1c done, it would have been way up. We would have wondered why and added on more medication thinking that my diabetes had progressed instead of knowing that my body just wasn’t reacting the same way to the medication from the new manufacturer.
Nearly 80% of the prescriptions filled in the U.S. are for generic drugs. The FDA requires generic drugs to have the same active ingredient, strength, dosage form, and route of administration as the brand-name drug. The generic manufacturer must prove its drug is the same (bioequivalent) as the brand-name drug. This doesn’t mean there are no differences between brand name and generic drugs. Most often the differences lie in the inert or inactive ingredients. The inactive ingredients such as coatings, stabilizers, fillers, binders, flavorings, diluents, and others are necessary to turn a chemical into a usable drug product. Usually, these differences do not change the effectiveness of the medicine. These ingredients may be used to
- Provide bulk so that a tablet is large enough to handle
- Keep a tablet from crumbling between the time it is manufactured and the time it is used
- Help a tablet dissolve in the stomach or intestine
- Provide a pleasant taste and color
Inactive ingredients are usually harmless substances that do not affect the body. However, because inactive ingredients can cause unusual and sometimes severe allergic reactions in a few people, one version, or brand, of a drug may be preferable to another.
Even though the generic must have the same active ingredients and in the same amount as the original, the other ingredients in the medication, such as fillers, can be different and can affect how quickly the medication gets absorbed by your body.
These small changes can have a big impact in how your body responds and how well the drug works. What matters isn't necessarily the dose of the medication, but how much of it and how quickly your body can use it. Several different companies may make the same generic drug, but they might use different filler ingredients so their medications could have slightly different rates of absorption or cause different side effects. Patients who do well on one generic may not do as well on another generic and the same goes for the brand-name medication vs. the generic.
With some conditions, even a slight difference can have serious consequences. This is most often seen by people taking anti-seizure medication.
If you're happy with how a generic drug works for you, find out who the manufacturer is. Depending on the state you live in, this information might be on the prescription bottle. If it's not, ask your pharmacist. Check your medication each time you get it refilled. If you notice a difference in appearance, check the label or ask the pharmacist if it was made by a different company than you are used to. If so, monitor your condition carefully until you can see how the new prescription works for you. If you start to have symptoms or side effects that are unusual for you, see if the pharmacist can still get the medication from the manufacturer you used to get it from. If not, try switching to a different manufacturer before going to a completely different medication or adding additional medications.
Update: I haven’t yet been able to get the Metformin from Granules Pharma so have been limping along on the Tagi brand. I had my A1c done on May 17 and it was hanging steady at 5.7. My official fasting glucose however, has gone from a 98 to 107. I’ve noticed that all my fasting levels at home have been higher since I switched medications. I’m hoping that when I switch back it will go back down to where it was before. I’ll keep you posted.