Lot Release Testing Analytics for Small-Molecule Drugs

Published on: 
Pharmaceutical Technology, Pharmaceutical Technology-10-02-2018, Volume 42, Issue 10
Pages: 46, 50–51

Experts weigh in on up-to-date analytical procedures for the lot release testing of small-molecule pharmaceuticals.

Successful lot release testing for small-molecule drugs is dependent on efficient analytical tools and practices. This article explores the analytics of this testing process with Natalia Belikova, PhD, Analytical Services director, and Gayla Velez, general manager, both at SGS Life Sciences in Lincolnshire, IL; and Mark Shapiro, director, Analytical Research & Development, and Daniel M. Bowles, PhD, senior director, Chemical Development, both at Cambrex in High Point, NC.

Methodology advancements

PharmTech: What are some common analytical methods used for the lot release testing of small-molecule pharmaceuticals? Have there been any recent advances to these methods?

Belikova and Velez (SGS): First, we have to distinguish whether we are talking about small molecules as active pharmaceutical ingredients (APIs) or small molecules as finished drug products (tablets, capsules, injectables, etc.). 

Most common panels for the testing of APIs will include basic tests such as loss on drying (LOD), residue on ignition (ROI), water content, identification, assay/purity, residual solvents, heavy metals, and microbial tests. Pharmaceutical manufacturing companies have to be absolutely sure that they are dealing with APIs with sufficient quality. If a contaminated or adulterated batch of API is used in production, it can result in a big financial loss, production delays, and a loss of reputation. 

There has not been much advancement in traditional basic wet chemistry tests, which are very conservative and have not changed for the past several decades. Recently, heavy metals testing has moved from non-specific wet chemistry color reaction to inductively coupled plasma (ICP) technology that distinguishes between specific elemental impurities, and can quantify them at very low levels down to parts per billion depending on the element. That change was officially accepted by the United States and European pharmacopeias. Many assays are traditionally done by titration or using high-performance liquid chromatography (HPLC), and there is a trend of moving from titration to chromatographic techniques as HPLC is more specific. Additionally, there is a trend of moving from traditional HPLC to high-throughput ultra-high performance liquid chromatography (UHPLC), although that is still not common in compendial methods. 

Another methodology that is used to confirm polymorphic structure (ID test) for small molecules uses X-ray powder diffraction. This allows an analyst to distinguish between small-molecule batches with the same molecular structure but different crystallinity. For the small molecules in drug product form, the most common test panel will include assay, related substances, water test (for lyophilized products), container-integrity test (for individually packaged products), dissolution (if applicable), and particulate matter (for injectable products).

Shapiro and Bowles (Cambrex): As a manufacturer of small-molecule APIs, all the batches of products we make undergo rigorous analytical protocols to ensure their quality. Depending on the type of molecule, we would generally use either HPLC or capillary gas chromatography (GC). Each method gives us the option to use various detection modes: for HPLC, there are ultraviolet, charged aerosol detection (CAD), a mass spectrometer or a triple quadrupole mass spectrometer (TQMS); and for GC, there are flame ionization detector (FID), electron capture detector (ECD), thermal conductivity detector (TCD), or again, a mass spectrometer. 

We would also use other techniques such as inductively coupled plasma-mass spectrometry (ICP-MS) to ensure there were no elemental metal or inorganic impurities, as well as infrared spectroscopy and nuclear magnetic resonance (NMR). Additionally, we would test water content using Karl Fischer (KF) titration, and undertake any appropriate United States Pharmacopeia (USP) tests, as well as analyzing particle size distribution, while also using X-ray powder diffraction to confirm that we have produced the correct polymorph. 

In terms of advances, developments in HPLC in terms of porous shell columns and shorter columns, as well as the introduction of UHPLC across our sites, have shortened method times, and increased the efficiency of the analysis we undertake. The greater sensitivity that is also possible with modern mass spectrometers, as well as the increased use of CAD for non-UV active components, has also improved the ability and speed of analytical departments to both develop methods and undertake quality control (QC) analysis.

Procedure walk-through

PharmTech: Can you walk us through your small-molecule lot release testing procedures?

Shapiro and Bowles (Cambrex): For any molecule we manufacture, there will be a predefined procedure that contains all the information pertinent to its release, including specifications, methods, and any outsourced testing necessary. Once a batch is made, a sample is submitted to the QC team along with a material release form which tracks the data associated with the sample throughout the analytical process. An analyst is assigned the sample who will ensure the testing is carried out in accordance with its needs, and when completed the data are reviewed and verified to ensure compliance with all specifications. A certificate of analysis is then generated by the quality analysis (QA) department which then releases the material to the customer.


Belikova and Velez (SGS): As a contract lab, we rely on our individual clients’ needs, and usually they will provide us with a list of tests and specifications. If the small molecule is known and has a compendial monograph for it, we will follow procedures described in the monograph, but if the small molecule is new and not yet published in a compendium, our lab will offer to develop and validate methods for release testing. 

All results generated in the laboratory have a thorough QC data review. Our quality assurance department also independently verifies all data packages prior to releasing the results, and our final ‘product’ is the certificate of analysis (CoA) that lists all tests performed and the results of each test.


New technology

PharmTech: What are some products/instruments that have been recently incorporated into your small-molecule lot release testing procedures? How are these products improving testing quality and analytical capabilities?

Belikova and Velez (SGS): For the past five years, our laboratory in Lincolnshire,

IL has extensively used Pinnacle PCX, a post-column derivatization system from Pickering Laboratories that allows us to perform analysis of amino acids for individual raw materials and small peptides. This instrument replaced thin layer chromatography (TLC) tests used in the past to monitor ninhydrin positive substances. HPLC technology is more specific than TLC, has better sensitivity, is faster, and costs less. Additionally, our laboratory has an X-ray powder diffractogram D2-phaser from Bruker that is used extensively for the identification of polymorphic form of small molecules. It also allows us to evaluate the purity of an API (qualitatively) and confirm that the polymorphic structure of API does not change when an API is incorporated into the final drug product during the manufacturing process. This methodology is very useful when clients ask us to evaluate if extensive storage (under International Council for Harmonization conditions or accelerated studies) affects the polymorphic form of an API as well. We also use Acquity H-Class UPLC systems from Waters for method development/validation and release testing of various client products. The use of UHPLC technology results in much shorter runs/higher throughput, better resolution between peaks, and higher sensitivity than traditional HPLC. 

Other analytical equipment that we extensively utilize for routine small-molecule testing are: differential scanning calorimeter (DSC) for melting point (ID test); thermogravimetric analyzer (TGA) for ID and water test; elemental analyzer (CHNS/O) to confirm carbon/hydrogen/nitrogen/sulfur composition; and a Malvern Mastersizer 2000 to evaluate particle size distribution.

Shapiro and Bowles(Cambrex): The use of a TQMS alongside HPLC allows the sensitive and specific analysis of potential genotoxic impurities (PGIs) to sub-1 ppm level. ICP-MS allows us to test for elemental impurities as per the new USP <233> inhouse, and we have an autosampler on this instrument to allow us to undertake efficient method development and validation. Our use of coulometric oven KF reagents removes the dependence on the solubility parameter with the traditional direct KF. This can be critical in early-phase molecules where a small change in production parameters can result in large changes in solubility, resulting in the inability to perform direct KF in the qualified solvent.

Best practices

PharmTech: What are some best practices for conducting small-molecule testing?

Shapiro and Bowles(Cambrex): The pharmaceutical industry is highly regulated, and so as analysts we must adhere to these regulations by using appropriate, qualified, and verified or validated methods to ensure product and patient safety at all times. At Cambrex, we have clear and effective standard operating procedures laid out to ensure we can maintain a proper compliance stance at all stages, in line with good manufacturing, distribution, and laboratory practices.

Internally, these include the development and writing of clear, safe procedures that can be easily and effectively executed by all QC staff, and we encourage open communication between disciplines (manufacturing, QC, and QA) throughout the process of method development. Our testing procedures are passed from the analytical R&D team to the QC department through an intermediary validation stage to provide enhanced method robustness. During the QC stage of lot release, we parse the testing across a number of colleagues to enhance the throughput and efficiency of the process.

Belikova and Velez (SGS): Our facility in Lincolnshire, IL has recently been expanded to accommodate the increasing demand in both chemistry and microbiology/sterility testing. If a client sends us a sample for both (chemistry and microbiology/sterility) release testing, then we often ask clients to send samples in multiple vials, so that each department can work with its own sample to run tests concurrently. Otherwise, the microbiology/sterility department will work with a sample first under aseptic conditions and then all chemistry tests will be performed. 

For hygroscopic materials, our standard practice is to perform a water test first (in a low humidity-controlled environment), so the sample is not compromised with possible moisture uptake. For the tests that require a relatively long test procedure (for example, loss on drying for constant weight or residue on ignition to constant weight), we coordinate between different analysts on different shifts so we have workflow continuation and can deliver results to the clients in a timely manner. 

Highly toxic, potent compounds and controlled substances require special handling and safe disposal, which SGS offers to its clients as a service.

Article Details

Pharmaceutical Technology
Vol. 42, No. 10
October 2018
Pages: 46, 50–51


When referring to this article, please cite it as A. Lowry, "Lot Release Testing Analytics for Small-Molecule Drugs," Pharmaceutical Technology 42 (10) 2018.