USP and - The ABCs of E&L

Extraction Efficiency

How efficient are your extractions?

As an industry-recognized medical device testing provider and an experienced conductor of extractables and leachables studies on a wide variety of pharmaceutical products, EKG Labs has encountered a number of unique extraction challenges.

EKG’s Extraction Methods

In order to ensure we are providing our clients with the highest quality data that meets the ever-updating industry expectations for extractables/leachables (you can read more about these changing guidances on our Industry Updates page), EKG has been continually developing and improving our in-house extractable and leachable methods, both for assessment of medical devices and for pharmaceutical products.

EKG now has a small assortment of go-to standards, with a range of molecular features, polarities, etc. used to verify our methods, when necessary. We have demonstrated good recovery (95% +) of these standards through the extraction process itself (both exhaustive and exaggerated), through pooling and solvent reduction of extraction solvents, and through additional preparation of the extraction solvents for instrumental assessment. For example, EKG has assessed our methods for solvent exchange of non-polar extraction solvents (commonly hexane) into LC/MS-compatible solvents as well as our methods for solvent evaporation of polar extraction solvents (nominally water) and reconstitution into GC/MS-compatible solvents.

With the data we have been obtaining over time, we remain confident that our extractable/leachable analytical screening methods are more than sufficient to support biological safety of a medical device (ISO 10993) or pharmaceutical safety (USP 1663 and 1664).

Following analytical screening methods and toxicological assessment, some clients may decide to run analytical targeting methods for potential leachable compounds of concern. EKG has partnered with many clients who have brought us unique target leachables in complex sample matrices.

Leachable Targets: Two Case Studies

For example, in a previously published case study, EKG worked to extract extremely low level PAHs from a liposomal drug formulation. After developing an instrumental method for detection of the target PAHs at the required limits, we analyzed recovery from spikes into the drug formulation across a wide variety of extraction solvents and liquid-liquid extraction techniques. Extraction efficiency was heavily dependent on a precise extraction solvent ratio and extraction volume ratio.

In a different project, EKG worked to develop methods of extraction for a target leachable of concern in a cream. Initial development at a different lab had involved dissolving cream in acetonitrile, generating partially solubilized samples and poor analytical results. In order to target the analytes of interest with less matrix interference, we evaluated a number of organic solvents and sample dissolution techniques. EKG found that adding pentane to the extraction worked best to remove cream excipients.

However, in EKG’s initial method validation, we noticed that preparations of spiked placebo cream had an average percent recovery of ~78%. It was possible that the low recoveries were sample-related, but given the consistency of recovery, we continued to pursue assessment and optimization of the extraction efficiency. EKG then prepared standards of the leachable target in a matrix mimicking the composition of the client’s drug product. By following the same sample preparation procedure, the standard was consistently recovered at 79%.

EKG had noted during this work that when acetonitrile and pentane where added in a known ratio, the total volume of the organic layers would still be as expected, but the ‘acetonitrile’ layer had an increased volume, close to the observed extraction efficiency. The working theory was certain steps of the extraction process increased the otherwise low miscibility of the two solvents. It was found that allowing the pentane to evaporate from the acetonitrile resulted in assay results that stabilized between 100-101%.

EKG’s Vision

While some of our work is straightforward sample preparation, default extractions per our standard internal methods for optimization of extractable identification, EKG continues to thrive on tackling projects of this nature, enjoying the challenge. We want to meet the uniqueness of our clients’ products with development, when appropriate, of an individualized extraction method.

About EKG Labs

EKG Labs is an analytical service provider for the medical device and pharmaceutical industries. Our analytical services support regulatory filings, product development, and analytical chemistry investigations. EKG regularly conducts assays and impurity investigations in challenging matrices, developing and validating methods to monitor APIs or any chemicals of potential concern.

Additional specialty analytical services include: extractables, leachables, a variety of USP testing, biocompatibility (ISO 10993), characterization, deformulation, and other investigational activities.

If you are experiencing a challenge with development and validation of a method or need analytical services to support your product development, please contact us at 810-354-5229.