Skip to content



E&L Whitepaper

Guide to E&L Studies for Drug Manufacturing and Packaging Components

Extractables and leachables analyses (also known as E&L studies) are widely used in the pharmaceutical industry. The goal of these analyses is to ensure that there are no potentially harmful chemicals or compounds being absorbed into a drug product when it is manufactured, packaged, or stored.

Extraction studies are the first part of any E&L analysis. During this phase, chemists must identify and characterize all chemicals that could be extracted from manufacturing or packaging components under any laboratory conditions. Tests are conducted under exaggerated conditions, such as raised temperature and pH. This testing can be used to develop analytical methods for leachable studies.

Leachable studies are designed to detect the chemicals that could migrate into a drug product over its shelf-life, under conditions of normal use. In most cases, leachable studies can be considered a subset of extraction studies. At this point, there should be no chemicals leaching into the drug product that weren’t already seen in the extraction studies.

Why Does Extractable and Leachable Testing Matter?

If all drug products were stored in glass containers with natural corks, the risk of chemicals from the packaging leaching into the drug would be much lower. However, manufacturing costs and practicality concerns have driven most pharmaceutical companies to use plastic and rubber container and closure systems instead. These systems may allow organic or inorganic leachants to contaminate the drug product.

Rubber stoppers, for example, may contain antioxidants, oligomers, or curing agents that can leach into the drug product and impact that product’s efficacy. Plastic packaging or manufacturing components may contain potentially harmful compounds like bisphenol A (BPA). Additionally, chemicals in the adhesives and inks used in product labels can pass through plastic packaging and into the drug formulation.

There are many leachable species that drug manufacturers and their research teams must consider as part of their E&L studies, including:

  • Dyes and colorants
  • Lubricants, emulsifiers, and slip agents
  • Vulcanizing agents
  • Anti-static coatings
  • Residual monomer, oligomer, and polymer species
  • Phthalates, polyaromatic hydrocarbons, and nitrosamines
  • Silicone oils
  • Antioxidants
  • Toxic elements such as mercury and lead

When leachants enter a drug product, they can cause many potential safety issues, such as:

  • Reducing the drug’s stability
  • Altering the impurity profiles
  • Inactivating the active ingredient
  • Altering the taste, smell, or color of the drug
  • Causing the drug to become toxic
  • Increasing the carcinogenic risk associated with the drug

Pharmaceutical manufacturers must conduct E&L studies to evaluate the potential risks posed by leachants. Extractables and leachables testing can be included in a quality by design (QbD) approach and used to limit the risk of contamination before drug products go to market. If potentially harmful chemicals are detected at a level that poses a significant risk to patients, manufacturers may need to switch material suppliers or reformulate the component from which the offending chemicals are migrating.

Potential Sources of E&L Contamination in Drug Packaging

Any container-closure system or other packaging that interacts with a drug must be studied to obtain regulatory approval. Even secondary packaging should be evaluated, as chemicals can migrate through semi-permeable primary containers. Components that can be sources for extractables and leachables include:

  • Vials
  • Caps or Lids
  • Foil Seals
  • Single-Use Syringes
  • Intravenous Bags
  • Plastic Bottles and Tubes
  • Plastic Inhalers
  • Rubber Droppers
  • Papers, Inks, and Adhesives Used for Labels

Potential Sources of E&L Contamination in Drug Manufacturing

While container-closure systems are the most obvious source of leachants, manufacturing components should also be subjected to E&L studies. Chemicals can migrate into a drug formulation from any surface with which the product or its ingredients come into contact. Manufacturing components that may release leachants include:

  • Gaskets
  • Valves
  • Connectors
  • Tubing
  • Filters
  • Vats
  • Process Containers

Every manufacturing component with which a drug product has contact must be individually tested for extractables and leachables.

E&L Testing Guidelines

In the interest of patient safety, the US Food and Drug Administration (FDA) and the Product Quality Research Institute (PQRI) have developed guidelines for extractables and leachables testing. These organizations take a proactive, risk-based approach to E&L studies, factoring in the drug’s route of administration, the patient population, the dosage, and the potential for interaction between the drug product and its packaging or manufacturing components.

The PQRI has established safety thresholds based on the carcinogenic risk posed by contaminants. The threshold varies by product, delivery method, and dosing. For example, oral drugs have a higher threshold for leachants than inhaled drugs, as the body will filter out some of the contaminants. Typically, short-term drugs also have a higher safety threshold than long-term drugs because the carcinogenic risk is cumulative.

The E&L Testing Process

E&L testing requires multiple analytical techniques because no one technique can detect all potential leachants. And unfortunately, there’s no “one-size-fits-all” process for every test because there are so many variables (e.g., drug format, patient population, dose) to consider. However, E&L studies follow a basic structure:

  1. Extractables testing: Identifying and defining all extractables (e., potential leachants)
  2. Leachables testing: Developing methods to determine which extractables migrate to the drug product under realistic storage conditions

Extractables Testing

The goal of an extraction study is to uncover all possible extractables that could come from a manufacturing or packaging component under any circumstances. An extraction study represents the “worst-case scenario.” Not every chemical identified in the study will be a leachant, but because trace leachants can be easily masked, it’s important for chemists to collect comprehensive data so that they’ll know what to look for in a leachables study.

For controlled extraction studies, chemists use solvents of varying polarity—hexane, isopropanol, and water—to extract chemical compounds under exaggerated conditions. The resulting extracts can then be analyzed using multiple techniques, such as GC-MS, LC-MS, and HPLC, to identify the potential leachants.

After the potential leachants have been identified and quantified, a toxicologist should use that data to determine which compounds should be monitored in leachables testing.

Leachables Testing

Because leachants are identified under conditions of normal use, leachables testing should take place during stability testing, which tracks changes in the drug product over time. If this isn’t possible, chemists can also conduct leachables testing on end-of-shelf-life samples. Chromatograms from leachables studies should show the same peaks found in extractables studies, but those peaks should be smaller because realistic storage conditions are being used.

After quantifying and qualifying leachants, chemists must establish acceptance limits. Essentially, a red line is drawn on a chromatogram, and peaks at or above the line represent leachants that exceed the safety threshold.

Appropriate acceptance levels will vary by product, but the FDA has established the Threshold of Toxicological Concern (TTC) as a benchmark for any unstudied chemical that will not pose a significant risk of toxicity or carcinogenicity. The TTC estimates that exposure to a chemical at less than 1.5 micrograms per day poses a negligible risk. However, for higher-risk compounds, the TTC may be 0.50 micrograms. Alternatively, the TTC may be set higher than 1.5 micrograms per day for drug products that are used short-term or are the safest treatment for life-threatening conditions.

Leachants that exceed the TTC or a scientifically-established safety concern threshold (SCT) should be reported for toxicological assessment. If the toxicological assessment reveals that the leachant poses an unacceptable risk to patients, the manufacturer will have to replace the manufacturing or packaging component from which the leachant is migrating.        

The Challenges of Extractables and Leachables

When creating a pharmaceutical product, the onus is always on the manufacturer to identify potential leachants and prove that they don’t pose a risk to patients. In addition to shouldering the burden of proof, manufacturers may face specific challenges related to the specific drug format or the manufacturing and packaging materials they choose. Factors that manufacturers need to consider include:

Susceptible Drug Formats. Certain drug formats, including inhalation aerosols and injectable suspensions, have a lower safety threshold than oral drugs. Because inhaled and injected drugs enter the bloodstream more rapidly than oral drugs, they leave patients more vulnerable to impurities from packaging and manufacturing components. It’s not uncommon for E&L studies to reveal leachants that are above the recommended safety concern thresholds for these medications, and pharmaceutical companies may need to take extra precautions to prevent contamination.

Biologic Drugs. While certain leachants aren’t harmful on their own, they may change the way biologic drug products work. Biopharmaceutical manufacturers must determine how identified leachants interact with their products to ensure the products’ safety and efficacy aren’t compromised.

Single-Use Equipment. In the past, drug manufacturing facilities commonly used stainless steel equipment, and leachants weren’t a significant concern. Now, however, facilities often rely on single-use equipment, which is disposed of after use rather than cleaned. These single-use systems are typically made from multiple materials and exposed to gamma radiation that can create trace-level leachables. Due to the complexities of single-use systems, regulatory bodies require more E&L data for this equipment than they do for stainless steel components.

Packaging Labels. The labels often applied to plastic pharmaceutical bottles may contain potential leachants from their ink, paper, or glue. These leachants can easily pass through the primary plastic packaging and contaminate the drug product.

Difficult Matrices. In some cases, the greatest challenges of E&L studies involve identifying unknown compounds. Drug manufacturers must use a wide range of analytical techniques to ensure they’re detecting every extractable and leachant down to trace levels (parts per billion).

Supply Chain Complexities. Pharmaceutical supply chains typically involve many different material suppliers, and it can be difficult for manufacturers to manage chemical entities at every stage of their supply chain. However, when drug companies detect a potentially harmful leachant in a packaging or manufacturing component, they must trace the material back to its source and, if they can’t resolve the issue, switch to a new supplier.

Reducing the Risk of E&L Contamination

It’s impossible to eliminate the risk of E&L contamination completely, but drug manufacturers can take a proactive approach to managing risk. Conducting E&L studies early in the drug development process will help products obtain FDA approval, avoid recalls, and keep patients safe. Manufacturers should ensure that their chemical analysis team is following PQRI guidelines and reviewing data with an experienced toxicologist to determine when action must be taken to protect patients from contaminants.

Pharmaceutical manufacturers who lack the resources to perform E&L studies in-house must partner with a reliable chemical analysis lab that can develop customized testing protocol while still adhering to PQRI guidelines and regulatory requirements. Avomeen is that lab: we conduct controlled extraction testing and validated leachable studies to help our clients identify potential contaminants and their source.

Let’s work together to achieve your vision

Ready to get started? Click Get a Quote, or talk to an expert first if you’d like help in defining your project scope.