Sterility Test Volume

The sampling quantities defined in USP <71> Sterility Tests are determined based upon statistical probabilities of identifying contamination, should it be present, given various article and batch sizes. The specific direction to follow is found in tables 2 and 3 in the chapter. Table 2 defines the minimum volume per test article to be inoculated into each sterility media type. Since there are two types of media used during a USP <71> sterility test, tryptic soy broth (TSB) and fluid thioglycolate medium (FTG or FTM), the quantity noted in the table represents half of the per-article test volume needed to complete a USP <71> compliant sterility test. Table 3 defines the minimum number of articles of a final product to be tested based on the batch size of the lot being assessed. Complying with the sampling guidelines in USP <71> provides the recommended level of stringency for sterility testing of compounded pharmaceutical products and is the minimum acceptable quantity to test to ensure confidence in a “Sterile” result.


Mycoplasmas are a fascinating group of extremely small bacteria with unique characteristics and growth habits. There are over 120 species of Mycoplasmas found in and on a variety of animal and plant hosts. They possess no cell walls, are fastidious in their growth requirements, and are the smallest type of self-replicating prokaryotic organism. Their lack of a cell wall makes them resistant to antibiotics like Penicillin, which target cell wall synthesis in other bacterial organisms. Mycoplasmas are parasitic and commensal bacteria that commonly colonize cell lines and tissue cultures in the lab environment, and the epithelial lining of the respiratory and urogenital tracts in humans. Their parasitic nature is a result of their inability to produce a number of factors required for growth, hence their association with living cells and tissues.

Compounding Errors

In 2022, Compounding Today ran a series of articles on pharmaceutical compounding errors. These articles are captured in an 11 part series. See the links below for access to content.

Atomic Absorption

Aaron Thompson, MS Forensic Technology Leader

Aaron Thompson, MS

Forensic Technology Leader

Water Activity

In compounded preparations, water activity refers to the water in a drug product freely available to participate in reactions such as hydrolysis or provide an environment that supports microbiological growth. Measuring water activity is important because many drug products include water in their formulations and are sensitive to water exchanges with the environment.

Stability failures

Quality assurance programs are essential to establishing standards for compounded preparations. One of the most important elements in a QA program is identifying the root cause of a failure and implementing a corrective action to prevent a future failure, also known as CAPA (Corrective and Preventative Action).

USP <795> states that compounders shall adhere to general principals of compounding which includes adequate procedures and records exist for investigating and correcting failures or problems in compounding, testing, or the preparation itself. 

Stability Factors

Stability measures the extent to which a product retains, within specified limits, and throughout its period of storage and use, the same properties and characteristics it possessed at the time of compounding. According to USP <1191>, pharmacists should establish and maintain compounding conditions that ensure drug stability to help prevent therapeutic failure and adverse responses.

National Drug Codes

According to the Food and Drug Administration (FDA), drugs are identified and reported using a unique, three-segment number called the National Drug Code (NDC) which serves as the FDA’s identifier for drugs. FDA publishes the listed NDC numbers in the NDC Directory which is updated daily.

Particulate Matter Testing

What is particulate matter and why is testing performed?

Particulate matter is unwanted solid material in solutions for injection. Particle counts that exceed USP limits in intravenous drug products could block blood flow inside the patient's body causing paralysis or death.  


Particulate matter testing is a good indicator of the quality of a manufacturing process and the containers used. 

OOS Investigation Part 2

ARL’s out-of-specification investigations use a hybrid approach to review data, formulations, and tests. Our data reviewers consult with ARL’s scientific directors and clients to ensure we provide a 360-view investigation and evaluate all aspects of the laboratory, data, and client and analyst trends. Typical investigations are concluded within one week or within 4 business days after the due date.