Susan Haigney

The safety of a drug product is as important as its effectiveness. Testing a drug for potential impurities that may impact the lives of the patients who use these medicines before and after the drug hits the market is integral in the development and manufacture of these products.

® spoke with Magdalena Pringgoadimuljo, department manager, Metals at Element, and Sarayu Rao, PhD, supervisor, Trace Metals at Element, to find out how drug manufacturers can best go about testing their products for elemental impurities.

 How are drugs tested for elemental impurities? Is there a difference between testing of dosage forms?

 Advanced spectroscopy techniques are used to test for elemental impurities in drugs. Some of these techniques are commonly used, such as inductively coupled plasma mass spectrometry (ICP–MS), inductively coupled plasma optical emission spectrometry (ICP–OES), and atomic absorption spectrometry (AAS). The choice of technique depends primarily on the sample matrix and permitted daily exposure (PDE) limits of the elemental impurities of interest.

] General Chapter <233> recommends the use of ICP–MS or ICP–OES to measure elemental impurities concentrations in pharmaceutical products (1). While both techniques can measure multiple elements simultaneously, ICP–MS has lower detection limits than ICP–OES for most elements. AAS can measure only one element at a time and is commonly used for assay tests, limit tests, and identification tests following individual monographs (e.g., 

The potential toxicity of the elemental impurities varies depending on the route of administration. Three main dosage forms for which PDE limits are enumerated by ICH [International Council for Harmonisation] Q3D(R2) (2) and 

 <232>/<233>, parenteral, inhalation, and oral. Since the limits are different for each dosage form, the sample preparation and analysis technique may vary accordingly.

 Are there best approaches for testing for elemental impurities?

 There are a variety of approaches for testing elemental impurities, depending on goals and resources. However, the entire drug product lifecycle should be factored in—including manufacturing equipment, container closure system, drug substance, excipients, and the water used for processing.

A proper risk assessment is key to ensuring the safety of a drug product while avoiding performing unnecessary extra work. For instance, identifying which elements need to be tested for a product can result in testing only seven elements instead of 24. Risk assessments can be based on a variety of factors, including findings from published literature, data from similar processes, supplier data, data from tests of components and/or drug product, and prior knowledge.

 At what stage of development/manufacturing should testing be performed?

 There are multiple potential sources of elemental impurities during the development and manufacturing of a drug product. All potential sources of elemental impurities should be considered in the product risk assessment, including elements intentionally added (e.g., catalysts, inorganic reagents); elements not intentionally added but could be present in the API, excipient, raw material, or water used in the preparation of the drug product; elemental impurities that could be potentially introduced from the manufacturing equipment used in the production of the drug product; and elemental impurities that may be introduced from container closure systems (for liquid and semi-solid dosage forms).

Manufacturers should assess each elemental impurity expected to be present in the drug product by determining the observed or predicted level and compare it with the established PDE for that specific dosage form. If the risk assessment data demonstrates [that] results can be expected to be less than 30% of the PDE, no additional controls are necessary, provided the manufacturer has properly assessed the data and demonstrated that adequate controls have been applied.

 Are there any innovations in testing equipment or procedures that the industry should be implementing but are not currently for the detection of elemental impurities?

 ICP–MS and ICP–OES are the most used instrumental techniques for the determination of elemental impurities in pharmaceutical products due to their low detection limit capabilities (sub-ppt and ppb levels) and wide linear dynamic range. Depending on the sample matrix, the sample may require simple dilution with a solvent or acid digestion. For difficult-to-digest samples, one modern tool that pharmaceutical labs should have at their disposal is a microwave capable of performing high-pressure/high-temperature closed-vessel digestion. Furthermore, for difficult organic matrices, ICP–MS systems can be configured to withstand direct analysis of organic solvents.

Though ICP–MS is a highly specific technique, polyatomic interferences can become an issue unless effectively addressed. Many polyatomic interferences can be effectively mitigated by using a reaction/collision cell on the ICP–MS. Common examples include ArCl+ interference on arsenic (75As), ArAr+ interference on selenium (78Se), and ArNa+ interference on copper (63Cu). Another common issue is the response enhancement that can be observed with certain elements (e.g., arsenic, selenium, and phosphorus) in the presence of a highly organic matrix, which may cause a high bias on the response for these elements. This effect can be mitigated by [having the] matrix match the nebulizer stream with organic material.

The latest technology in interference removal is the triple quadrupole ICP–MS (ICP–MS/MS), which can resolve spectral interferences for the analysis of complex matrices and can also provide lower detection limits for challenging analytes (e.g., selenium, chromium, sulfur, phosphorus, and silicon) by reducing background interferences with the use of its MS/MS operation. Lower detection limits offer more flexibility with sample preparation techniques, enabling measurements at lower target concentrations.

Finally, for matrices where the limits of arsenic or mercury are exceeded, USP <232> provides speciation analysis as an option for evaluating the compliance of the materials to specifications. This is due to the differing toxicities of mercury and arsenic in their inorganic and complexed organic forms. Using ICP–MS in conjunction with liquid chromatography (LC), the hyphenated technique LC–ICP–MS can provide an alternate approach for demonstrating a material is safe.

 Which elemental impurities are most common in solid-dosage drugs?

 Class 1 elements (arsenic [As], cadmium [Cd], mercury [Hg], and lead [Pb]) and class 2A elements (vanadium [V], cobalt [Co], and nickel [Ni]) are highly toxic and have a high probability of occurrence in drug products. These elements should be included in risk assessments for all routes of administration, whether it is intentionally added during the
manufacturing process.

 What are the acceptable limits for such impurities?

 ICH Q3D has established PDE values for elemental impurities based on safety data and individual safety assessments (information recorded in monographs found in Appendix 3 of ICH Q3D [R2]). The elements of concern are classified into three classes based on their toxicity—Class 1, Class 2A, 2B, and Class 3. Based on the dosage form, and individual safety assessments, different PDE limits have been established for different routes of administration. For example, oral and parenteral routes have the same PDE (15 µg/day) for arsenic, however, a lower PDE limit for inhalation (2 µg/day).

 How have updated regulatory guidelines (e.g., ICH Q3D) impacted analysis for elemental impurities?

 Previously, the guideline for elemental impurities was based on a colorimetric ‘heavy metals limit’ test. This test was limited to 10 elements (lead, mercury, bismuth, arsenic, antimony, tin, cadmium, silver, copper, and
molybdenum), provided no information about the individual concentrations of each element, and could not be used for many other potential elemental impurities (e.g., platinum group elements). Therefore, the guideline was not specific or sensitive.

ICH Q3D replaced the flawed 100-year-old colorimetric test with modern instrumentation such as ICP–MS and ICP–OES techniques. The ICH Q3D guideline identifies and provides PDE limits for the highest risk elements across different dosage forms and provides a framework for the risk assessment and control of elemental impurities across a product lifecycle. USP <233> illustrates analytical procedures that possess characteristics, such as accuracy, precision, and specificity, that help manufacturers be certain measurements are reliable.

USP. USP General Chapter <233>, Elemental Impurities—Procedures. 

Articles

When evaluating a drug’s risk assessment for elemental impurities, one must consider all aspects of its lifecycle.

Drug Product Impurities Testing

microbes and viruses to study their structure and evolution Generative AI | Image Credit: ©Лилия Захарчук - stock.adobe.com

Manufacture of medicines is most often required to be performed in a sterile environment to ensure the quality and safety of these products. Microorganisms lurking in the air or on surfaces may degrade APIs and impact their effectiveness, according to Anne-Grit Klees, PhD, BioMonitoring Portfolio Manager for The Life Science business of Merck KGaA, Darmstadt, Germany. “Furthermore, pathogenic and even many non-pathogenic microorganisms can cause serious and life-threatening infections in patients, especially if immunodeficient. For this reason, particularly injectable drugs must be sterile. This can be achieved by final sterilization of the drug or, if not possible, by aseptic manufacturing.”

It is recommended by regulators that microbial monitoring of cleanrooms and isolators is performed by a combination of methods, says Klees. “Air monitoring is performed with a combination of volumetric microbial air samplers (active air monitoring) and settle plates (continuous passive air monitoring). Surfaces and personnel should be monitored with contact plates or swabs. Using alternative methods is also permissible if these have been validated and show comparable or superior efficacies.”

® spoke with Anne-Grit Klees to find out some environmental monitoring (EM) best practices manufacturers can follow to ensure the safety of their products.

What are the differences between environmental monitoring in aseptic versus non-aseptic manufacturing?

Anne-Grit Klees (The Life Science business of Merck KGaA, Darmstadt, Germany):

 The environmental monitoring methods are usually the same for both. The higher the cleanroom grade, the higher the monitoring frequency and number of sample locations. The monitoring equipment and culture media should possess features to match the cleanroom-grade requirements. For air samplers, features such as cleanability, resistance towards disinfectants, emission of particles, and disturbance of the unidirectional air flow are important to consider and should match the cleanroom concept. For culture media, there is a choice between single bagged ones for lower risk areas and irradiated, double, or triple bagged ones for the different manufacturing lines.

 What are some best practices for air monitoring?

Anne-Grit Klees (The Life Science business of Merck KGaA, Darmstadt, Germany): 

When selecting an air sampler, important features to consider are sampling volume accuracy, a good efficiency of the method to collect small particles, and whether damage to microorganisms is avoided during the sampling process. The recovery efficiency should be validated by the supplier according to ISO [International Organization for Standardization] 14698. What also matters is ease-of-use to minimize the risk of human errors, low particle emissions to prevent contamination of the cleanroom, good cleanability, and minimal disturbances of the unidirectional air flow. If the air sampler can be integrated into external tracking software systems, all data can be handled. This helps to observe trends.

What are some best practices for surface monitoring?

Surface monitoring is usually performed either with contact plates or swabs, depending on the accessibility of the sample location. Culture medium selection should be based on the ability over the complete shelf-life to detect a broad range of microorganisms. Furthermore, the media formulation should ensure that any potential growth-inhibiting substances such as disinfectant residues or antibiotics are inactivated. To maintain the cleanliness of the sampled surface any culture media residues should be removed after sampling.

 What are some best practices for personnel monitoring?

Personnel monitoring is always performed on the gloves, but also on gowning. The growth promotion properties of the selected media must [often] allow in-house skin flora of the personnel to grow. It is important that contact plate samples are taken of the personnel’s gowning or gloves before leaving the cleanroom. If glove tests are performed after critical interventions, the outer gloves should be replaced before continuing manual work.

 What are the latest advancements in processes and workflows for environmental monitoring?

 These are stated in the current 2022 version of the EU [European Union] CGMP [current good manufacturing practice] Annex 1. While the well-established volumetric air samplers, settle plates, contact plates, and swabs are still recommended to be used frequently, a new focus is on the importance of a contamination control strategy of the pharmaceutical company. This should include a risk-based sample plan that states the frequency and sample locations for those methods. There are additions about using validated rapid or automated technologies, also for continuous volumetric air sampling. These need to be equal to or superior to the above-described methods.

What are some of the best tools for performing environmental monitoring of cleanrooms?

Some portable microbial air samplers (e.g., the MAS-100 NT) offer high accuracy and excellent sampling efficiency. It is small enough to sample close to critical sample locations, can take up to 30 samples in one cleanroom, is easy to disinfect and available with an exhaust filter. It minimizes disturbance of the unidirectional air flow and is compatible with several EM software systems. Triple-bagged and gamma-irradiated ICR or ICR+ culture media for grade A and B cleanrooms reduce the contamination risk because outer bags can be removed in the material lock. Plate versions with locks allow safe transportation for incubation after sampling.

 What are some of the best tools for performing environmental monitoring of a restricted-access barrier system (RABS)?

In a RABS the same environmental monitoring tools can be used as in a cleanroom. However, if a RABS system is decontaminated with vaporized hydrogen peroxide (VHP), it must be ensured that the culture media within the RABS during decontamination are protected by VHP-impermeable bags. These can be hung up during decontamination. To prevent false negative results, all ICR settle plates, contact plates and ICR swabs are formulated to neutralize VHP residues. The MAS-100 NT can also withstand VHP decontamination if in switched-off mode. Alternatively, MAS-100 air samplers specially designed for isolators can be used.

 What are some of the best tools for performing environmental monitoring of isolators?

 In isolators, space is limited, so the control unit of the dedicated air samplers (e.g., MAS-100 Iso line) for isolators are positioned on the outside, saving space inside. The distance can be up to 10 m. A double-valve system prevents cross-contamination and the air tubing can be decontaminated with VHP (e.g., with the MAS-100 Iso MH, one control unit can handle up to four sampling locations.)

Certain packaging designs (e.g., IsoBag rapid transfer bags) save space in isolators. They readily provide ICR settle or contact plates in a DPTE [differential pressure transmitter for air] beta bag. Plates can be safely transferred via rapid transfer alpha ports whenever needed.

How are data obtained from environmental monitoring? How are these data used in pharma manufacturing?

 The data are usually obtained as colony forming units from the culture media used in active and passive air sampling as well as surface and personnel sampling. The new EU GMP Annex 1 suggests using the data both for batch release decisions and for trending analyses. It is possible to detect adverse trends by increasing excursions from action limits or consecutive excursions from alert levels. Also, noticing changes in the microbial flora is important. This helps to maintain the level of cleanliness and address issues by corrective and preventive actions.

Are there specific analytical tools that work best for different types of environmental
monitoring?

As the amount of data generated by environmental monitoring is huge, the PDA [Parenteral Drug Association] Technical Report No. 13 outlines computer-based tracking tools as essential. Specific software systems designed for environmental monitoring help to find adverse trends, and the stored data may allow conclusions as to what the root cause is. One important feature of the sampling equipment is that it should allow data transfer into such software systems, so that all tracked data are handled in a single database. This helps to stay compliant with the standard rules for data integrity.

When referring to this article, please cite it as Haigney, S. Monitoring for Microbes. 

Data from environmental monitoring can assist in keeping sterile environments sterile.

Monitoring for Microbes

FDA announced on June 22, 2023 the approval of Elevidys (delandistrogene moxeparvovec-rokl), the first gene therapy for the treatment of children ages four through five years that have Duchenne muscular dystrophy (DMD) and do not have a pre-existing medical reason that would prevent this kind of treatment. DMD is a rare genetic condition that leads to weakness and “wasting away” of the body’s muscles due to a defective gene, which creates an absence of a protein that keeps muscles intact.

Elevidys was approved through FDA’s accelerated approval pathway based on an evaluation of sponsor-submitted data. According to the agency, a randomized clinical trial showed Elevidys increased the expression of the Elvidys micro-dystrophin protein in children ages four to five years with DMD “who do not have significant pre-existing antibody titers against the AAV [adeno-associated virus] rh74 vector or have other contraindications based on the inclusion criteria of the clinical trials.” The approval was granted to Sarepta Therapeutics.

“Today’s approval addresses an urgent unmet medical need and is an important advancement in the treatment of Duchenne muscular dystrophy, a devastating condition with limited treatment options that leads to a progressive deterioration of an individual’s health over time,” said Peter Marks, MD, PhD, director of FDA’s Center for Biologics Evaluation and Research. “The FDA remains committed to facilitating the development of innovative new therapies to reduce the impact of debilitating diseases and to improve outcomes and quality of life for those affected.”

The agency approved Elevidys to treat pediatric patients four through five years of age with Duchenne muscular dystrophy.

Gene Therapy for Duchenne Muscular Dystrophy Approved by FDA

When referring to this article, please cite it as Haigney, S. Impurities Testing of Drug Products. 

All aspects of a drug’s lifecycle should be considered when evaluating risk assessment for elemental impurities.

Impurities Testing of Drug Products

FDA sent a warning letter, dated April 28, 2023, to Pharmedica USA, after an inspection of the company’s Phoenix facility found drug products meant to be sterile being prepared, packed, or held under insanitary conditions. The company also lacked International Organization for Standardization (ISO) classified areas for sterile drug manufacturing.

In addition, a variety of current good manufacturing practice violations were found, including failure to establish and follow written procedures to prevent microbiological contamination. “During the inspection, you informed us that you were unaware that ophthalmic drug products are required to be sterile and acknowledged that your facility is not designed and equipped to handle or manufacture sterile drug products, even though your drug products are intended for use as ‘eye drops,’” the agency stated in the letter.

The company also failed to establish adequate procedures for production and process control. “You failed to adequately qualify the equipment and validate the processes used to manufacture your drug products. You have not performed process performance qualification (PPQ) studies, nor do you have an ongoing program for monitoring process control, to ensure stable manufacturing operations and consistent drug quality for products in US distribution,” the agency stated.

These and other quality control problems led to a product recall and a cease of production at the Phoenix facility.

The agency found insanity conditions and CGMP violations at Pharmedica USA, LLC’s Phoenix facility during an inspection.

FDA Sends Warning Letter to Arizona Facility

FDA published two draft guidance documents on May 17, 2023 that provide recommendations to support pediatric drug approvals under the Pediatric Research Equity Act (PREA) and/or the Best Pharmaceuticals for Children Act (BPCA). The documents replace the draft guidance, 

How to Comply with the Pediatric Research Equity Act

Regulatory Considerations–Complying With the Pediatric Research Equity Act and Qualifying for Pediatric Exclusivity Under the Best Pharmaceuticals for Children Act 

was written to assist sponsors in complying with pediatric study requirements under the PREA. It also describes how to qualify for pediatric exclusivity and protections under BPCA. Provisions in the BPCA were extended to biologics in 2010.

Pediatric Drug Development Under the Pediatric Research Equity Act and the Best Pharmaceuticals for Children Act: Scientific Considerations 

helps sponsors develop data and information to support pediatric drug approvals. Selected clinical, scientific, and ethical issues are addressed.

The two draft guidance documents provide recommendations for the approval of pediatric drugs, biologics, and vaccines under the Pediatric Research Equity Act and the Best Pharmaceuticals for Children Act.