Skip to content

What’s the Difference Between 503A vs. 503B Compounding Pharmacies?

503b compounding pharmacy

In the nuanced world of animal health care, compounding pharmacies play a vital role in personalizing the patient experience. Unlike traditional pharmacies, compounding facilities have the unique ability to tailor medications, addressing the diverse and complex health needs of each animal. This responsibility is overseen and regulated by the Food and Drug Administration (FDA).

Passed in the wake of several high-profile compounding mishaps, the Drug Quality and Security Act was enacted in 2013 to reinforce the quality and safety of compounded medications through FDA oversight. This legislation comprises two key components: the Compounding Quality Act, which updates regulations for 503A compounding pharmacies that produce medications for individual patients and introduces 503B outsourcing facilities that produce medications in bulk, and the Drug Supply Chain Security Act, which establishes a framework for tracking prescription drug products throughout the supply chain to ensure their safety and integrity.  In this article, we compare and contrast 503A vs. 503B compounding pharmacies. Plus, we’ll explore how 503A pharmacies—including Mixlab—partner with vets for high-quality, tailored prescriptions.

Ensuring Safety and Quality in Compounding Pharmacies

State boards of pharmacy (BOP) provide primary oversight for compounding pharmacies. Additionally, the Food and Drug Administration (FDA) holds compounding pharmacies to distinct standards whether they are 503A traditional compounding pharmacies or 503B outsourcing facilities.

Compounding pharmacies adhering to section 503A are mainly regulated by the BOP in the state in which they reside as well as in the states to which they ship medication. They must comply with the United States Pharmacopeia (USP) compounding standards adopted by their respective states. 503B outsourcing facilities are subject to federal FDA oversight and have to meet certain regulations, including Current Good Manufacturing Practice (CGMP) requirements, which outline quality assurance and control measures. 

This oversight ensures 503A and 503B pharmacies maintain cleanliness, proper labeling and accuracy. It also prevents contaminated or improperly formulated medications. Both 503A and 503B pharmacies are subject to inspections by oversight agencies to show compliance. 

Let’s Dive into 503A Compounding Pharmacies

503A compounding pharmacies are primarily focused on creating customized medications for individual animals based on prescriptions from health care practitioners. Let’s break down the specific roles and regulations for Mixlab and other 503A pharmacies.

What is a 503A Compounding Pharmacy?

A 503A compounding pharmacy can address unique patient needs that cannot be met by 503B pharmacies and commercially available medications. Oftentimes, this means altering the strength, dosage, form, flavor, or excluding certain ingredients due to allergies or other sensitivities. These customizations ensure pets can take medications they need. Prescribers can feel confident knowing that medications from 503A pharmacies will meet each animal’s specific health needs. 

At Mixlab, we offer a wide range of alternative medication types that animals will not only take, but  may even enjoy! We provide 30+ flavor options, along with customizable forms, to ensure medications are tailored to each pet’s taste. This level of specification is unique to 503A pharmacies. 503B pharmacies typically do not offer pet-specific compounding; instead, they produce in bulk.    

503A pharmacies engage in both sterile and non-sterile compounding. Sterile compounding is necessary for products that will be introduced into sterile areas of the body, such as injections or eye drops. Adherence to stringent aseptic processing standards is paramount to prevent infections. Non-sterile compounding involves medications that are ingested orally or applied topically.

What Quality Standards Apply to a 503A Pharmacy?

To ensure quality and safety, 503A pharmacies must comply with United States Pharmacopeia guidelines, specifically USP 795 for non-sterile compounding and USP 797 for sterile compounding. Mixlab brings an added level of quality assurance by aligning with the Pharmacy Compounding Accreditation Board (PCAB) standards in our commitment to the safety and quality of our compounded products.

503A pharmacies can also voluntarily adopt the CGMP measures required for 503B pharmacies. Mixlab incorporates many of these elements into our processes for both non-sterile and sterile operations. For example, Mixlab’s dedicated Quality Department ensures the quality of our sterile products with comprehensive batch release testing, including sterility and endotoxin assessments. Our labs also ensure proper environmental monitoring, cleanliness, and documentation for all products. By adhering to the highest quality standards, Mixlab offers veterinarians and animal owners the ultimate confidence in our products.

Are There Limits to Office Use Compounding for 503As?

It’s a common misconception that 503A pharmacies cannot compound office-use medications, meaning for use in a prescriber’s office without specific patient names, while 503B pharmacies can. The reality is that it’s actually based on state regulations. There are state-specific restrictions on the amount of medicine that 503A pharmacies can compound for office use. However, this is not inherently a limitation. Instead, it emphasizes the patient-specific nature of 503A compounding. It allows pharmacies to focus on small-batch, high-quality preparations rather than mass production.

Exploring 503B Outsourcing Facilities

As the pharmaceutical landscape evolves, 503B outsourcing facilities continually emerge as key elements in the compounding ecosystem. They offer a unique service by compounding drugs in bulk for the broad market. This approach contrasts with highly personalized 503A pharmacies. Given the nature of 503B, the customization of medication offerings, strengths, and flavorings are generally limited. 503B pharmacies have set product catalogs due to the testing required to manufacture products.

What CGMP and FDA Regulations Apply to 503B Pharmacies?

503B facilities must adhere to the CGMP regulations overseen by the FDA, including requirements for the manufacturing facility, processing, packing, and storing large quantities of medications. Other 503B requirements include environmental monitoring programs, biannual registration of their product list with the BOP and FDA, and a recall notice program. However, their focus on mass production limits their ability to tailor products to individual pet needs. 503A pharmacies can operate at or above 503B standards while also providing customized products. At Mixlab specifically, our tolerance standards are over 3x more stringent than industry standards. Our commitment to excellence earned us a PCAB® accreditation, provided to compounding pharmacies with the highest quality assurance practices.

A Final Take on 503A vs. 503B Compounding Pharmacies

While subject to different regulations, both 503A traditional compounding pharmacies and 503B outsourcing pharmacies must adhere to state and federal oversight to ensure animal safety. The products available at 503A pharmacies, including Mixlab, offer tailored solutions to veterinarians and pet parents that are not available from bulk 503B pharmacies. At Mixlab, we believe that each individual animal should receive the personalized care they deserve. Ready to customize your pet’s prescriptions? Contact us to get started.