What Is an Active Pharmaceutical Ingredient (API)?

An active pharmaceutical ingredient (API) is the component of an over-the-counter (OTC) or prescription medication that produces its intended health effects. If a prescription drug has a generic, its name is the same as its API. Combination therapies have more than one active ingredient, each of which may act differently or treat different symptoms.

It's a good idea to know the APIs of medications that you take. (For example, acetaminophen—the active ingredient in Tylenol—is a well-known API.) This can help you better communicate with your healthcare providers, recognize which generics and brand name versions are the same, and avoid harmful interactions and accidental overdoses.

This article discusses APIs, what they are, why they're important, and how to find them on a drug label.

drug manufacturing
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APIs and Other Medication Components

Drugs are manufactured under stringent conditions to maintain consistency and minimize the risk of contamination.

All drugs are made up of two core components:

  • The API is the central ingredient. APIs are produced from raw materials with a specified strength and chemical concentration.
  • The excipient includes substances other than the drug that help deliver the medication to your system.

Excipients are chemically inactive substances, such as lactose or mineral oil in the pill. These materials are used to help the medication remain stable and to control absorption when you take the drug. Excipients can cause allergic reactions.

The Food and Drug Administration (FDA) requires equivalency testing for generic drugs to ensure that they are of the same potency as the brand versions. Some generic drugs may contain different excipients than the brand versions, but many generics are identical to them.

Examples of Active Pharmaceutical Ingredients

Some common OTC and prescription medications and their active pharmaceutical ingredients include:

Active Ingredients in Common OTC Medications
Brand Name Active Pharmaceutical Ingredient 
Advil ibuprofen
Benadryl diphenhydramine
Claritin loratadine
Mucinex guaifenesin
Neosporin bacitracin
Pepcid AC famotidine
Prilosec omeprazole
Tylenol acetaminophen
Active Ingredients in Common Prescription Medications
Brand Name Active Pharmaceutical Ingredient
Amoxil amoxicillin
Glucophage metformin
Levoxyl levothyroxine
Lipitor atorvastatin
Neurontin gabapentin
Norvasc amlodipine
Prozac fluoxetine
Ventolin albuterol

Why You Should Look For APIs

There are many situations when you will benefit from knowing the APIs of medications you are taking.

Here are a few examples:

  • Duexis is a prescription medication used for treating arthritis. It contains ibuprofen (an anti-inflammatory) and famotidine (which protects against ulcers). Ibuprofen is also available in OTC form as Advil, Motrin, and as a generic. Famotidine is available In OTC form as Pepcid.
  • Robitussin DM is an OTC medication that's commonly used for treating symptoms of a common cold. This medication contains dextromethorphan, a cough suppressant, and guaifenesin, an expectorant. Guaifenesin is also the API In Mucinex, and dextromethorphan is the API In Delsym.

You could end up taking too much of any of these APIs if you aren't aware that they are available In different medications and brands. Furthermore, if a medication that you're taking isn't working or is causing side effects, then you can avoid jumping to the same API by a different name in a potentially futile attempt to try something that you think is different.

How to Find an API on a Drug Label

For OTC drugs, the API and the amount each dose contains are listed at the top of the Drug Facts label under the heading "Active Ingredient." The health effect is listed to the right of that information.

Prescription drug labels list the brand name of the drug (if applicable) above the generic name. The generic name is also the API of that drug. If you received the generic version of the drug, the label may also tell you what brand name the drug is usually sold under. For example: "Amphetamine 10MG: Generic for Adderall 10MG."

The generic name of a drug is typically a derivative of the chemical name, which is used less often. For example, the chemical name for aspirin is acetylsalicylic acid.

Where Are APIs Made?

Other than the U.S., the largest API manufacturers are located in Asia, particularly in India and China, according to the FDA. Typically, the pharmaceutical company that produces a medication will use its own country's safety measures when producing the final product.

If you want to be sure that your medication is approved in your home country, it's important that you obtain your medications from a reputable retailer.

A Word From Verywell

Pharmacists are often an untapped resource. They can provide you with a wealth of information on both OTC and prescription drugs, including potential interactions, contraindications, and substitutes.

If you have any questions or concerns about the medications you are taking or plan to take, it's worth requesting a consultation.

1 Source
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  1. Food and Drug Administration. Generic drugs: Questions and answers.