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Many medications can be changed from brand name to generic, or vice versa, with no problems. But sometimes even tiny changes in a medication formula can make a big difference in how a medication affects your body. Here are nine types of medications you need to talk to your doctor about before switching.
Medications for underactive thyroid
Because the thyroid is such a sensitive gland, even a small change in the dose of your thyroid medication may have a major effect on the amount of thyroid hormone in your blood. “Generic products do not have to contain the same inactive ingredients as the comparable brand-name products,” explains Susan W. Miller, professor and chair of the Department of Pharmacy Practice at Mercer University College of Pharmacy in Atlanta. “For any patient, levothyroxine — whether brand names Synthroid, Levoxyl or Levothroid, or generic — should ideally not be switched,” Miller says. If a switch is necessary, “the patient’s thyroid levels should be closely monitored to detect changes in the blood levels of the hormone,” she cautions.
There are several different forms of albuterol inhalers (Ventolin, Proventil HFA, ProAir HFA, ProAir RespiClick) and levalbuterol (Xopenex HFA). Miller says it’s hard to get the exact same response when using different albuterol inhalers because they are “rescue therapy” for asthma attacks. To play it safe, don’t change the brand of your albuterol inhaler without your doctor’s supervision and monitoring. Also, you might want to double-check your prescription before you leave the pharmacy in order to make sure your new inhaler matches the one you had picked up the last time.
Digoxin for heart failure
In 1984, Congress passed a law that made it faster and easier to get generic medications approved. However, since both brand name Lanoxin and its generic version digoxin were already on the market before this law was passed, makers of the generic version didn’t have to prove whether digoxin worked similarly enough to Lanoxin for the two to be swapped. Since the differences between digoxin and Lanoxin haven’t been studied, Miller says it’s best not to switch.
Theophylline for asthma and COPD
According to Mercer University’s Miller, the inactive ingredients used in generic theophylline products vary per manufacturer, and this affects how quickly the medication is absorbed inside your body. Also, theophylline products come in controlled- release or extended-release forms — which release the active ingredient at different rates than brand-name versions. This can affect blood levels of the drug. Unless you are under the care of the doctor for monitoring and follow-up, you shouldn’t switch between theophylline products, Miller says.
Certain diabetes medications
For many years, insulin was the only type of diabetes medication that came as an injection, but that’s no longer the case. Today, liraglutide (Saxenda or Victoza), exenatide (Byetta, Bydureon), dulaglutide (Trulicity), albiglutide (Tanzeum) and pramlinitide (Symlin) are all injectable diabetes medications that aren’t insulin. Unfortunately, some people confuse these medications with insulin, and that can lead to problems. Not only do these drugs work differently than insulin, but some of the side effects are different, too. Your doctor may prescribe both insulin and one of the other non-insulin injectable drugs. But understand that the non-insulin injectables can’t be swapped for insulin.
Eyedrops for glaucoma
Generic eyedrops approved after 1962 are considered similar to the brand-name version as long as they contain the same amounts of the same active ingredient found in the brand version. However, the inactive ingredients may be different, which can affect how these medications behave — especially when it comes to shelf life, temperature changes and effectiveness. This is especially a concern with Xalatan and its generic form latanoprost. Bottom line: If you are taking brand-name or generic eyedrops for glaucoma, ask your doctor what to expect before swapping one for the other.
Eyedrops for Dry Eyes
You can buy many different eyedrops over the counter (OTC) for dry eyes. These products often contain ingredients that soothe and lubricate the eye. In addition, two prescription eyedrops are currently approved for treating dry eyes: Restasis (cyclosporine) and a new drug called Xiidra (lifitegrast). Unlike OTC products, Restasis works by encouraging tear production. Nobody’s quite sure how Xiidra works yet. Prescription and OTC products have been reviewed for safety, but you may notice some differences in how the drops work: Some may provide more relief, while the effects of other eyedrops may not seem to last as long. Because the many combinations of ingredients in drops for treating dry eyes vary, Miller says it’s hard to get consistent results. Most eyedrops, regardless of their indication, can cause stinging, blurred vision, and similar symptoms.
Studies haven’t shown a major difference between the brands Coumadin and Jantoven, and generic warfarin. However, finding the right warfarin dose can depend on many things, such as the condition being treated and your genes. Since warfarin interacts with many different drugs and foods, your doctor has to run a test to help figure this out. Any changes to your diet or medications can affect how warfarin responds, so you’ll need to get retested and your dose may change. Miller warns against switching to any different warfarin products without first talking to your doctor and being monitored.
Both extended-release and controlled-release versions of seizure medications are specially designed to release a specific amount of drug over a period of time in order to reduce risk of seizure by keeping drug levels steady. However, different inactive ingredients alter drug levels in your body when changing between brand names and generics or when taking generic versions made by different manufacturers — which makes you more prone to seizures. Unless your doctor tells you otherwise, you’re better off sticking with the same version of the same seizure medication made by the same manufacturer.