Karen asked
I had the same situation I was taking Microgestin and the pharmacy changed it to Junel which I didnt like, I feel I am bleeding more and longer periods of time. Is this normal?
Answer
The article referenced for this question is the following:
As discussed in the article, your pharmacy may switch between different brands of birth control pills, as long as they are considered bio-equivalent per FDA requirements (1). If two products are classified as bio-equivalent to one another, they are legally substitutable in most situations (2) .
The risk of side effects occurring more often on one brand of birth control than another is relatively unlikely based on how the FDA establishes generic equivalence (more on this below) but all it takes is a simple Google search (3) to see you are not alone in experiencing issues!
Below we discuss the differeneces between Junel, Microgestin and generic brands of birth control pills in general.
Different Birth Control Brands
While the same active ingredients in two different 'substitutable' birth control products will be same (and in the same amounts), the inactive ingredients are likely to be different. To illustrate this, below are the different ingredients for Junel 1.5/30 and Microgestin 1.5/30.
Junel 1.5/30
- Ethinyl Estradiol 0.03 mg
- Norethindrone Acetate 1.5 mg
- Acacia Senegal
- FD&C Red No. 40
- Lactose
- Magnesium Stearate
- Pregelatinized Starch
Microgestin 1.5/30
- Ethinyl Estradiol 0.03 mg
- Norethindrone Acetate 1.5 mg
- Acacia Senegal
- Confectioners sugar
- D&C Yellow No. 10
- FD&C Blue No. 1
- FD&C Yellow No. 6
- Lactose
- Magnesium Stearate
- Starch
- Talc
Clearly, the inactive ingredient list is different between the two products. Inactive ingredients are not supposed to cause any difference in effect for a certain product. From the FDA (4):
"Generic medicines and brand-name medicines share the same active ingredient, but other characteristics, such as colors and flavorings, that do not affect the performance, safety, or effectiveness of the generic medicine, may be different."
Nevertheless, there certainly is a chance that you won't tolerate a specific inactive ingredient or an ingredient you are sensitive to is in higher quantities in one of the products. For example, it isn't uncommon for certain individuals to be allergic to specific dyes (5).
Another thing we have to consider is whether or not generically substituable products actually contain the exact same amount of active ingredients.
What Is Bioequivalence?
As a broad definition, the term 'bioequivalent' means that two products have the same rate and extent of absorption. In other words, in relation to Junel and Microgestin, studies need to show they are both absorbed into our bodies at the same rate and the overall absorption needs to be the same. When these characteristics are met, theoretically, you will have the same therapeutic effect.
The statistical methods used to determine bioequivalence are a bit beyond the scope of this article but it is important to note that when we say two products need to have the same rate and extent of absorption, it is within a statistical interval (specifically the pharmacokinetic values of the test product need to be within 80% and 125% of the reference product with a 90% confidence interval) (6).
All of this boils down to this...generic equivalents need to be nearly the same as one another, but there is variability.
One study released by the FDA reported that the average difference in AUC (a pharmacokinetic term known as 'area under the curve' which measures drug concentrations over time) between products considered bioequivalent was around 3.5% (7).
Switching Generic Birth Control Brands
So, as discussed above, there are two issues that could occur when you are switched to a different birth control pill product:
- The inactive ingredients are different (which could cause differences in how you tolerate the medication).
- Although 'bioequivalent', there are likely small differences in how fast each is absorbed and to what extent.
In the vast majority of cases, individuals will not experience differences in efficacy or side effects with different generic drugs. Generic drugs often get a bad rap but are extremely important to keep medical costs down and drive new drug development (8).
Nevertheless, a small difference in your birth control pill could certainly be the potential culprit in the side effects you are experiencing (e.g. spotting, bleeding more than normal). Minor changes, such as missing a dose or changing the time you take your pill, are well known to cause adverse bleeding effects in many (9).
It is important to let you pharmacy and doctor know about the side effects you are experiencing. If possible, ask your pharamcist if they are able to order and dispense the same birth control pill for you, although there may be challenges such as drug availability and insurance coverage.
If the pharmacy can order and dispense your desired product but won't for whatever reason, ask your doctor to write your prescription as 'DAW', meaning 'dispensed as written'. Your pharmacy will legally need to dispense it (assuming they can order it in). See more about 'DAW' laws in your state here: DAW Guide By State.
