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Therapeutic Equivalence: Pharmaceutical and Bioequivalence

Anne Kamiya, Megan Gilbert
  • Author
    Anne Kamiya

    Anne has experience in science research and creative writing. She has a graduate degree in nutritional microbiology and undergraduate degrees in microbiology and English (myth & folklore). She has also worked as an ocean and Earth science educator.

  • Instructor
    Megan Gilbert

    Megan has a master's degree in nursing and is a board certified Women's Health Nurse Practitioner. Her area of clinical focus is the impact of infectious disease on pregnancy. She has experience teaching college allied health classes. She is also a certified EMT and holds a certificate of added qualification in electronic fetal monitoring.

Learn about therapeutic equivalence. Study the difference between pharmaceutical equivalence and bioequivalence, and identify therapeutic equivalence codes. Updated: 03/17/2022

What Is Therapeutic Equivalence?

Montelukast is the generic version of a medication prescribed for asthma, but it is also known by its brand name, Singulair. Several versions of generic montelukast are made by different pharmaceutical companies and each of these generic versions are considered therapeutically equivalent by the Food and Drug Administration (FDA).

Therapeutically equivalent drugs can be safely substituted for each other according to the FDA. Whether someone takes Singulair or one of the many generic versions of montelukast, the medications are, in lay terms, essentially the same. The same can be said for many other medications, both prescription and over the counter. From antidepressants to antibiotics to heart medications, many therapeutically equivalent versions of a medication are available in the average pharmacy or supermarket shelf.

Therapeutically equivalent drugs are especially important because of the exorbitant cost of prescription medications, both with and without health insurance. Generic medications are often a less costly alternative to brand name drugs; at least 75% of all prescription medications purchased in the United States are generic.

Therapeutic equivalence (TE) is specifically defined by the FDA and has very strict criteria for a drug to meet. In order to be therapeutically equivalent, two or more FDA approved drugs must be pharmaceutically equivalent, bioequivalent, and officially recognized by the FDA in their Orange Book. Let's define these three criteria now:

Pharmaceutical Equivalence

Pharmaceutical equivalence is a drug that has the same active ingredient, dosage, concentration/strength and route of delivery as the brand drug. As long as the inactive ingredients do not impact the required criteria, they do not make a difference in whether or not a medication is pharmaceutically equivalent. The following table outlines some examples of pharmaceutical equivalents:

Drug Function Active Ingredient Proprietary Name
Birth Control Ethinyl Estradiol-Norethindrone acetate Gemmily, Merzee, Taytulla,
Aurovela 24 FE, Larin 24 FE, Leribane
Over the Counter Pain Medication Ibuprofen Advil, Motrin
Migraines Acetaminophen + Butalbital Butapap, Allzital
Muscle Relaxant Baclofen Lioresal, Gablofen

Bioequivalence

Bioequivalence is when two things are metabolized and processed by the body in the same way; the rate of their metabolism by the body and the extent of their availability to the body are biologically equivalent. In a bioequivalent drug, the active ingredient is either similar or the same, and behaves the same way in the body as would the comparable drug.

Orange Book

In order to qualify as therapeutically equivalent, drugs must be FDA approved, have the same active ingredients, and meet very specific criteria set by the FDA. All therapeutically equivalent drugs are listed in an FDA database called the Approved Drug Products with Therapeutic Equivalence Evaluations called the Orange Book, which names drug products that meet the safety effectiveness requirements of the FDA, their patent and some other information.

Therapeutic Equivalence: Definition

Your head is pounding and the nurse from your doctor's office has suggested you try a pain reliever, so you walk into the drug store. You make your way to the pain reliever aisle and you're confronted with row after row of options. Why are there so many brands? What's the difference between Tylenol® with an active ingredient of acetaminophen and the store brand acetaminophen?

According to the U.S. Food and Drug Administration (FDA), two medicines that have the same clinical effect and safety profile are said to have therapeutic equivalence. These two drugs, each from a different manufacturer, are known to have nearly identical properties and can be interchanged as needed.

These medicines are sometimes referred to as brand name medications and generic medications. According to the FDA, there should be no clinical difference between them, although patients often notice a difference in cost. This is what you're most likely to notice while you're in the pharmacy trying to find something to stop your headache.

The purpose of establishing if two medications are therapeutic equivalents is to allow the generic drug to go through a shorter, more cost-effective, approval process while still protecting public safety.

For a drug to be approved as a therapeutic equivalent it must:

  1. Be safe and effective
  2. Contain the same active ingredient as the original medication
  3. Utilize the same route of administration
  4. Be the same dosage
  5. Meet the same standards for strength, quality, purity, and identity
  6. Be bioequivalent (with bioequivalent meaning the body is able to process it in the same way that the original drug was processed)
  7. Be correctly labeled
  8. Be manufactured in accordance with the FDA's Current Good Manufacturing Practice regulations

Testing can be performed in vitro or in vivo. In vitro refers to when a test is done outside the living environment, sometimes referred to as test tube studies. In vivo refers to when a test is done on the entire living organism, such as when a drug trial is conducted on human participants.

Of note, these drugs do not need to have the same:

  1. Appearance (scoring, color, shape)
  2. Flavor
  3. Packaging
  4. Preservatives
  5. Release mechanisms
  6. Minor aspects of labeling

Sometimes, one of these will be of particular importance to a patient, and a physician may prescribe a brand-specific product.

The most important part of this is that the drugs have the same active ingredient. So, therefore, both Tylenol® and the store brand drug must contain acetaminophen, even though they will be produced by different companies. While acetaminophen and ibuprofen can both be used to treat your headache, because they are different medications they would never be considered therapeutic equivalents.

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Criteria for Therapeutic Equivalence.

If a medication is not FDA approved, like some specialty formulation diet pills, for instance, then it will not have a therapeutic equivalent.

Definition of active and inactive ingredients

  • Active ingredients are the pharmaceutical components of a medication - the FDA-regulated medication itself. In the Singulair example, montelukast sodium is the active ingredient.
  • Inactive ingredients are filler ingredients that give a medication its color, shape, consistency, or texture. Examples include cornstarch, food coloring, cellulose, gelatin, emulsifiers, or flavorings. They do not impact the pharmaceutical strength or quality of the active ingredient.

A therapeutically equivalent drug must by thoroughly evaluated before it can be listed in the Orange Book. Firstly, the drug must be safe, effective and have the same quality and purity as the generic drug. Verification of these criteria are done by both in vitro (test tubes in a lab) and in vivo (in the body) studies. Therapeutic equivalence intersects pharmaceutical equivalence and bioequivalence. Part of the certification process also ensures that the therapeutically equivalent drug is as safe and effective as the brand drug.

To be therapeutically equivalent, the drug must be pharmaceutically equivalent to the brand drug (same active ingredient, dosage, concentration/strength and route of delivery), have the same form (e.g., tablet, capsule, injection), and be FDA approved, listed in the Orange Book, correctly labeled, and given a therapeutic equivalence "A" code by the FDA

Factors that do not impact therapeutic equivalence include:

  • Shape or aesthetics of the medication. The generic tablet can be an orange triangle, while the brand tablet is a blue circle.
  • Physical packaging and labeling details. The generic drug's packaging may be styled differently and lists a different manufacturer and inactive ingredients.
  • Release mechanism - each medication may use a different method or mechanism to deliver the drug to target cells in the body. For example, one capsule may release its active ingredient via osmosis, while another may erode.
  • Cost. The generic medication may be ten times cheaper than the brand medication without health insurance.
  • Flavor. For example, the generic tablet is cherry flavored, while the brand tablet is lemon flavored.

Therapeutic Equivalence Codes

Therapeutic equivalence codes, or TE codes, are a coding system used by the FDA to identify therapeutically equivalent drugs. All therapeutically equivalent drugs are listed in the FDA Orange Book database, labeled with two letters (and sometimes a number), and always starts with code letter A. The A indicates a drug is therapeutically equivalent. If the drug starts with the code letter B this means it is not therapeutically equivalent. The second letter after the A or B gives more information about the drug, like its form for example.

Therapeutic Equivalence: Examples

The FDA keeps a list (known as the Orange Book) of every approved therapeutic equivalent.

One prescription example would be combined oral contraception, also known as the birth control pill. While there are many formulations of oral contraception, the combination of desogestrel 0.15mg and ethinyl estradiol 0.03mg is available under the following names from different companies:

  • Desogen
  • Emoquette
  • Enskyce
  • Isibloom
  • Reclipsen
  • Apri
  • Ortho-Cept
  • Solia
  • Cyred
  • Juleber

These various brands may come in different colors and packaging. But the expectation is that they can be substituted for one another with little difficulty.

Another example is the oral diazepam tablets (brand name Valium), often used for muscle spasms and anxiety. The tablets are available from the following companies:

  • Barr: 2mg, 10mg
  • Ivax Sub Teva Pharmaceuticals: 2mg, 5mg, 10mg
  • Mayne Pharmaceuticals: 2mg, 5mg, 10mg
  • Mylan: 2mg, 5mg, 10mg
  • Vintage Pharmaceuticals: 2mg, 5mg, 10mg
  • Roche Pharmaceuticals: 2mg, 5mg, 10mg (the original holders of the patent)
  • Dava Pharmaceuticals Inc: 2mg, 5mg

As you can notice, not every company produces every approved dosage. The only requirement for therapeutic equivalence is that the dosages are the same as the original approved medication.

Several examples apply to treating your pounding headache. If you wanted an over-the-counter medication (OTC), meaning an option available without prescription, here are a few choices:

  1. The active ingredient in Tylenol (acetaminophen) is available from various brands.
  2. The active ingredient in Motrin and Advil (ibuprofen) is available from various makers.
  3. The active ingredient in Excedrin and Bayer's (aspirin) is available from various makers.

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Video Transcript

Therapeutic Equivalence: Definition

Your head is pounding and the nurse from your doctor's office has suggested you try a pain reliever, so you walk into the drug store. You make your way to the pain reliever aisle and you're confronted with row after row of options. Why are there so many brands? What's the difference between Tylenol® with an active ingredient of acetaminophen and the store brand acetaminophen?

According to the U.S. Food and Drug Administration (FDA), two medicines that have the same clinical effect and safety profile are said to have therapeutic equivalence. These two drugs, each from a different manufacturer, are known to have nearly identical properties and can be interchanged as needed.

These medicines are sometimes referred to as brand name medications and generic medications. According to the FDA, there should be no clinical difference between them, although patients often notice a difference in cost. This is what you're most likely to notice while you're in the pharmacy trying to find something to stop your headache.

The purpose of establishing if two medications are therapeutic equivalents is to allow the generic drug to go through a shorter, more cost-effective, approval process while still protecting public safety.

For a drug to be approved as a therapeutic equivalent it must:

  1. Be safe and effective
  2. Contain the same active ingredient as the original medication
  3. Utilize the same route of administration
  4. Be the same dosage
  5. Meet the same standards for strength, quality, purity, and identity
  6. Be bioequivalent (with bioequivalent meaning the body is able to process it in the same way that the original drug was processed)
  7. Be correctly labeled
  8. Be manufactured in accordance with the FDA's Current Good Manufacturing Practice regulations

Testing can be performed in vitro or in vivo. In vitro refers to when a test is done outside the living environment, sometimes referred to as test tube studies. In vivo refers to when a test is done on the entire living organism, such as when a drug trial is conducted on human participants.

Of note, these drugs do not need to have the same:

  1. Appearance (scoring, color, shape)
  2. Flavor
  3. Packaging
  4. Preservatives
  5. Release mechanisms
  6. Minor aspects of labeling

Sometimes, one of these will be of particular importance to a patient, and a physician may prescribe a brand-specific product.

The most important part of this is that the drugs have the same active ingredient. So, therefore, both Tylenol® and the store brand drug must contain acetaminophen, even though they will be produced by different companies. While acetaminophen and ibuprofen can both be used to treat your headache, because they are different medications they would never be considered therapeutic equivalents.

Therapeutic Equivalence: Examples

The FDA keeps a list (known as the Orange Book) of every approved therapeutic equivalent.

One prescription example would be combined oral contraception, also known as the birth control pill. While there are many formulations of oral contraception, the combination of desogestrel 0.15mg and ethinyl estradiol 0.03mg is available under the following names from different companies:

  • Desogen
  • Emoquette
  • Enskyce
  • Isibloom
  • Reclipsen
  • Apri
  • Ortho-Cept
  • Solia
  • Cyred
  • Juleber

These various brands may come in different colors and packaging. But the expectation is that they can be substituted for one another with little difficulty.

Another example is the oral diazepam tablets (brand name Valium), often used for muscle spasms and anxiety. The tablets are available from the following companies:

  • Barr: 2mg, 10mg
  • Ivax Sub Teva Pharmaceuticals: 2mg, 5mg, 10mg
  • Mayne Pharmaceuticals: 2mg, 5mg, 10mg
  • Mylan: 2mg, 5mg, 10mg
  • Vintage Pharmaceuticals: 2mg, 5mg, 10mg
  • Roche Pharmaceuticals: 2mg, 5mg, 10mg (the original holders of the patent)
  • Dava Pharmaceuticals Inc: 2mg, 5mg

As you can notice, not every company produces every approved dosage. The only requirement for therapeutic equivalence is that the dosages are the same as the original approved medication.

Several examples apply to treating your pounding headache. If you wanted an over-the-counter medication (OTC), meaning an option available without prescription, here are a few choices:

  1. The active ingredient in Tylenol (acetaminophen) is available from various brands.
  2. The active ingredient in Motrin and Advil (ibuprofen) is available from various makers.
  3. The active ingredient in Excedrin and Bayer's (aspirin) is available from various makers.

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Frequently Asked Questions

What is the difference between pharmaceutical equivalent and therapeutic equivalence?

Both pharmaceutical equivalent and therapeutic equivalence are terms defined by the FDA. However, the criteria for a drug to be therapeutically equivalent is stricter. A therapeutically equivalent drug must meet all the criteria of pharmaceutically equivalent drugs (same active ingredient, same dosage/concentration/strength, same route of delivery) and also have the same form/identity (e.g., tablet or capsule) as the brand drug. Additionally, it must also be tested for bioequivalence, FDA approved, and listed in their Orange Book with a code starting with the letter A.

What does te code AB mean?

"AB" is a therapeutic equivalence code designated by the FDA. "A" means the drug is considered therapeutically equivalent by the FDA. "AB" together means this drug previously wasn't thought to be therapeutically equivalent because of bioequivalence issues but was shown in subsequent scientific studies to be therapeutically equivalent.

What is bioequivalence and therapeutic equivalence?

Drugs that are bioequivalent are processed and metabolized by the body in the same way. All therapeutically equivalent drugs are bioequivalent, but not all bioequivalent drugs are therapeutically equivalent. Therapeutically equivalent drugs must be bioequivalent, FDA approved, and have strict FDA criteria to meet.

What is therapeutic equivalence code?

The therapeutic equivalence code is a way to identify therapeutically equivalent drugs. The code was developed by the FDA so drugs could be cataloged in their Orange Book. All drugs are assigned codes based on their therapeutic equivalence.

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