Based on the tablet imprints specified you specified, it appears as though you have been switched to a different generic manufacturer of Suboxone sublingual tablets (buprenorphine hydrochloride, naloxone hydrochloride).
Buprenorphine hydrochloride 8 mg, naloxone hydrochloride 2 mg
Side 1: Half moon logo
Side 2: 155
Manufacturer Amneal or Mallinckrodt
Side 1: AN 415
Side 2: No imprint
This is a common scenario in pharmacy that is understandably concerning for patients: taking a prescription drug, then being required to switch from brand to generic or from one generic manufacturer to another. If the switch is brand to generic, the person is generally notified at the pharmacy. But that frequently doesn’t happen when the switch is one generic manufacturer to another.
Sometimes the person will contact the pharmacy after
noticing their pills look different. There are many times, whether the patient
knows about the switch or not, where the concern is that their medication’s
effects are suddenly not the same as they had been. Let’s examine why, but
first, some quick definitions:
Brand Drug: An FDA-approved drug product sold by the company who developed and manufactures it under a specific brand name product. Companies receive a certain number of years of patent protection that allows them to sell the drug exclusively. The approval process is extensive and costly.
Generic Drug: These are products manufactured by other pharmaceutical companies using drugs that have come “off-patent.” This means the company can take the drug molecule and create their own product with it. The approval process is much shorter and cheaper, because it’s based off the studies done on the brand drug.
Formulation: The recipe for a drug product. Imagine the drug is chocolate, and the drug product is chocolate cake. The formulation is a recipe for chocolate cake.
Dosage Form: The type of product the active ingredient is formulated into. Examples are tablets, capsules, and in this case, sublingual tablets.
Bioavailability: Briefly, the amount of drug that makes it to the place in the body where it is intended to act. In the case of Suboxone, this would be the brain. A lot of factors determine bioavailability, including dosage form, inactive ingredients, your body’s metabolism, and more.
If you call a retail pharmacy asking about brand and generic drugs, the response you’ll likely receive is, “They’re exactly the same, the FDA requires all generics to be the same as the brand name drug.” But let’s be real: nothing is that cut and dry, and unless you’re machining precision parts for aircraft engines or something, all manufacturing processes have variations.
Not only that, but competition between generic drug manufacturers in the US market is fierce, meaning each company that wants to produce a generic drug product is going to have to come up with their own formulation that they don’t intend to share. Generic drugs, therefore, often have slightly different ingredients between manufacturers. In the case of these two products you mentioned, there are some differences in the ingredients that allow the tablet to quickly dissolve under your tongue, as well as in flavoring, sweetening, and coloring. These can affect how fast or slow the tablet dissolves, how long you keep the tablet/drug solution under your tongue, and the amount of drug you end up swallowing (which inactivates it).
To get a generic drug product approved by the FDA, a manufacturer must establish that their product is bioequivalent to the reference (brand) product. Bioequivalent products are products that contain the same active ingredient, in the same quantity and dosage form, and that don’t significantly differ in bioavailability – that is, the rate and amount they are absorbed by the body and reach the site of action.
This is where things can get dicey. The FDA operates under the assumption that bioequivalence means identical effects. However, to account for variations in manufacturing, the FDA allows a range of 80%-125% in the average bioavailability of the generic product compared to the brand (which would be 100%). Further, the FDA does not assess or compare differences between generic drug products…only between generics and the brand. There exists a real potential for two generic forms of the same drug to differ in bioavailability by 40% if one were to have tested at 80% of the brand and the other at 120% of the brand.
This is a cause for concern in the pharmaceutical field, and your type of situation is why. So long as nothing else in your routine, diet, or medication regimen has changed, it is very possible that in switching from one generic to another, the amount of drug or the rate at which it reaches your brain may have changed enough for you to notice.
Buprenorphine is an opioid, and produces noticeable effects like drowsiness, euphoria, dry mouth, or if the amount is reduced, mild withdrawal symptoms. With this drug, the difference is not a dangerous one, and the altered effects should go away once your body has adjusted to the new product (a week at most).
However, it is important that you discuss this with the doctor who prescribes this medication for you, and continue to take your medication as prescribed, in the same way you were taking it before. You may also ask the doctor to indicate on the prescription to avoid switching generics, although this won’t be much help if your insurance requires a change.
If you experience any difficulty breathing, excessive drowsiness, or significant withdrawal symptoms, or if the altered effects worsen or persist for more than a week, seek medical attention right away.
Finally, this should not interfere with any drug screening – urine or otherwise. It will, of course, cause you to test positive for buprenorphine/naloxone, but will not cause you to test positive for any other drug.
Shein-Chung Chow, PhD. Bioavailability and Bioequivalence in Drug Development. Wiley Interdiscip Rev Comput Stat. July-August; 6(4): 304–312. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157693. Published online June 10, 2014. Accessed online December 3, 2017.
Actavis Elizabeth, LLC. Buprenorphine/Naloxone Sublingual Tablet Prescribing Information. Archived on https://dailymed.nlm.nih.gov. Accessed December 3, 2017.
Amneal Pharmaceuticals. Buprenorphine/Naloxone Sublingual Tablet Prescribing Information. Archived on https://dailymed.nlm.nih.gov. Accessed December 3, 2017.