Tag Archives: active pharmaceutical ingredients

A Survey of Material Science and Physical Characterization Techniques and Equipment for Small Molecules – Part I 

Material science and physical characterization are crucial to ensure drug products’ or drug substances’ identities with measurements and analysis. There are many types of techniques and equipment to do this, each with its own features and qualities. In this blog, the first part of a series, we will review the advantages of a range of techniques and equipment. 

We’ll begin with X-Ray Powder Diffraction (XRPD) or XRD analysis. It is a powerful, non-destructive, and rapid technique for analyzing a wide range of materials (1 µm to 100 mm), including metals, polymers, catalysts, plastics, pharmaceuticals, and other materials. It is used for identification, crystal form characterization, and crystalline content in amorphous products.  

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) is useful for the detection of elemental content and elemental impurities. ICP-MS is also 

efficient as it is a multi-element technique. Ions are directly detected by an MS detector rather than by emission of light, as in the case of ICP-OES (Inductively Coupled Plasma-Optical Emission Spectroscopy). The ions are separated by a Quadrupole based on the mass-to-charge ratio. The best detection limits are available for most of the elements in ICP-MS as the number of ions produced is high, and although some spectral interference is seen, these are defined and limited.   

Dynamic Vapor Sorption (DVS) is a gravimetric technique used to measure the change in

 mass of a material in response to changes to surrounding conditions such as temperature or humidity. DVS is primarily used with water vapor but can be applied to other organic solvents as well for the physicochemical characterization of solids.  Some of the most common uses of DVS include:  

  • To determine the sorption isotherm;   
  • To evaluate the hygroscopicity of an API powder;   
  • To compare the hygroscopicity of different solid-state forms: solvates, polymorphs, salts, amorphicity, and cocrystals;  
  • To determine the deliquescence point of a material;  
  • To quantify and qualify the amorphous content in drug substance or excipient, and 
  • To evaluate the efficacy of packaging materials. 

We will wrap up with Differential Scanning Calorimetry (DSC). It is one of the most used thermoanalytical techniques for determining freezing and melting points and phase transitions. Specifically, it measures the heat flow produced by a sample when it is either heated, cooled, or held isothermally at an unchanging temperature. Crystallization behavior and chemical reactions are some other characteristics that can be measured by this technique. 

Our next entry will conclude with a look at Thermogravimetric Analysis (TGA), Fourier-Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), and, of course, the definitive analytical technique, Mass Spectroscopy (both GCMS and LCMS). 

Resources 

Setting the Standard with Reference Standard Qualifications

The term Reference Standard Qualifications (RSQ) “is defined as a list of tests, references to analytical procedures, and appropriate acceptance criteria,”1 and incorporate these quantitative reference standards to do so: purity, potency, identification, impurities content, and generally full characterization 

Identity Testing

There are a range of tests to ensure the identity of the drug product or drug substance. These can be done by a variety of equipment, including LC-MS, 1H NMR, 13C NMR, FTIR (Fourier Transform Infrared Spectroscopy), TGA (Thermal Gravimetric Analysis)/DSC (Differential Scanning Calorimetry), and UV-Vis. Appearance testing can be achieved by chiral or ion chromatography, elemental analysis (identifying C, H, and N), TGA/DSC, and XRPD.  

Quantitative Testing
For quantitative reference standards, there is a standard formula that should utilized (HPLC Purity) x (100% − % Residual Solvents − % Inorganic Impurities) = The Determination and Confirmation of the Assay Value % (i.e., weight %).  These component values can be quantified by using HPLC for the purity analysis, residual solvents by LOD or KF Water Content and HSGC, and inorganic impurities by ROI (Residue on Ignition), ICP-MS/OES ((Inductively Coupled Plasma Mass Spectrometry or Inductively Coupled Plasma Optical Emission Spectroscopy). (For a limited number of sample quantities of both residual solvent or inorganic impurities, they can alternatively be tested by TGA.) Finally, to access the weight percentage confirmation, titration and qNMR are excellent techniques. 

 Concurrent with identity and quantitative testing, storage conditions and stability should be established.  This includes storage (container/closure), expiration dating, re-testing procedures, and usage and tracking.  

We Can Assist with your Reference Standard Qualifications Needs  

SK pharmteco has years of experience and numerous experts in Reference Standard Qualifications. Compendia methods (USP/EP/BP/JP) are utilized in tandem with analytical method development, validation, and transfer to ensure optimal success with your drug substances and drug products. Please contact us with any specific questions or to receive a quote for your RSQ needs.   

References  

  1. https://www.ema.europa.eu/en/documents/scientific-guideline/ich-q-6-test-procedures-acceptance-criteria-new-drug-substances-new-drug-products-chemical_en.pdf 

Shedding Light on Photo-Stability Forced Degradation

Triple Quad HPLC

blank pharmaceutical and drug packaging

Forced Degradation is the testing of a drug product or drug substance using situations more taxing than those if conditions were simply accelerated. This type of stability testing is designed to demonstrate various degradation pathways within the product or substance and assists with the development of the product itself, along with its packaging. Within forced degradation testing, there is a subset of studies known as photo-stability.  The guidelines are outlined by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) and the FDA. As the ICH Topic Q1B document states, “The intrinsic photostability characteristics of new drug substances and products should be evaluated to demonstrate that, as appropriate, light exposure does not result in unacceptable change.”1  

They recommend a range of different studies that address potential areas of concern: 

A systematic approach to photostability testing is recommended covering, as appropriate, studies such as:  

(i) Tests on the drug substance;
(ii) Tests on the exposed drug product outside of the immediate pack; and, if necessary,  

(iii) Tests on the drug product in the immediate pack; and, if necessary,  

(iv) Tests on the drug product in the marketing pack.1 

The type of lights used in photo-stability are also described.  They offer options, including:   

    • …any light source that is designed to produce an output similar to the D65/ID65 emission standard…  
    • A cool white fluorescent lamp designed to produce an output similar to that specified in ISO 10977 (1993) … 
    • A near UV fluorescent lamp having a spectral distribution from 320 nm to 400 nm with a maximum energy emission between 350 nm and 370 nm…1    

Additionally, temperature control should be maintained to minimize changes and variations.  

Triple Quad HPLC

Finally, these guidelines also provide and elucidate the differences between procedures for drug products and drug substances. It is a crucial reference for administering or simply learning more about photo-stability forced degradation testing. 

AMPAC Analytical has the equipment and expertise to provide comprehensive photo-stability studies for your products. Additionally, we have high-resolution and triple-quadrupole mass spectrometers to aid in the identification of potential degradants. Contact us today to learn how AMPAC Analytical can support your photo-stability needs.

References  

  1. https://www.fda.gov/media/71713/download (PDF) 

Resources 

Dissolution Testing and Development

An Introduction to Dissolution Testing and Development

Dissolution testing is the monitoring of drug substances in a controlled environment from a solid dosage form (i.e., capsules, tablets) to a solution state. These “tests to characterize the dissolution behavior of the dosage form, …also take disintegration characteristics into consideration, are usually conducted using methods and apparatus that have been standardized virtually worldwide over the past decade or so, as part of the ongoing effort to harmonize pharmaceutical manufacturing and quality control on a global basis.”1  

Devising a Strategy
When devising a dissolution testing strategy, “a simple but broadly applicable analytical method is always desired.”2 Dissolution analysis is generally performed via UHPLC for faster sample analysis due to the number of samples required. Creating an analytical method should incorporate guidelines from The European Medicines Agency’s (EMA) International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH), which are also interchangeable with the FDA. These are designed to “avoid redundant testing by (the) industry.”3  

It’s the Media… 
Dissolution testing is designed to mimic conditions found in the human stomach.  As these conditions vary widely from patient to patient, so too should the testing environment. The ranges for the media should allow for various pH levels. These sets should be notated and designed to simulate FaSSGF (fasted state simulated gastric fluid), FeSSIF (fed state simulated intestinal fluid), and FaSSIF (fasted state simulated intestinal fluid). Compendial media is generally HCl or sometimes acetate or phosphate pharmacopeial buffers. As mentioned, with this many simulated environments, along with multiple time sets/points, there will be many samples necessary, and analysis by UHPLC is optimal for timely turnarounds.  

We Can Assist with your Dissolution Testing and Development Needs 

AMPAC Analytical has years of experience and numerous experts in dissolution testing. We can support release testing, stability, method development, and assist with formulation development through dissolution analysis. We utilize paddle and basket apparatuses in the dissolution phase of testing. Additionally, our equipment offerings include Agilent Infinity II and Thermo Fisher Vanquish Horizon UHPLCs.  Please contact us with any specific questions or to receive a quote for your drug product dissolution testing and development needs.    

References  

  1. https://www.academia.edu/download/33056117/Pharmaceutical_Dissolution_Testing.pdf#page=15 
  2. Development and Validation of an HPLC Method for Dissolution and Stability Assay of Liquid-Filled Cyclosporine Capsule Drug Products – PMC (nih.gov) 
  3. Q4B Annex 7 (R2): Dissolution Test General Chapter | FDA 

Resources  

Some Background and Concerns About PFAS

PFAS

The Background and Concerns of PFAS

PFSA structure(Per- and) PolyFluoroAlkyl Substances (PFAS) are a class of ubiquitous chemicals that have been found in water, air, fish, and soil across the nation and worldwide. Known as “Forever Chemicals,” there are thousands of different PFAS, and they are present in consumer, commercial, and industrial products.1 Having one of the strongest bonds in organic chemistry, their structures proved to be resistant to heat, water, oil, and degradation.2 They are found in “food packaging and non-stick cookware, cosmetics, waterproof and stain-proof textiles and carpet, aqueous film forming foam (AFFF) to fight Class B fires, and as part of metal plating processes.”3 Teflon and Scotchgard were two of the pioneering products to utilize these fluoropolymers. The two most common PFAS are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

Health Concerns of PFAS

Some of the most frequently cited health concerns associated with PFAS include adverse cardiovascular, immunity, developmental, and hepatic effects.3,4The most commonly heard refrain to minimize these concerns is that if they are so prevalent, why are there
not more health issues associated with them? In fact, “The Lancet Commission on Pollution and Health reported that pollution was responsible for 9 million premature deaths in 2015, making it the world’s largest environmental risk factor for disease and
premature death.” This was updated in 2019, and those numbers held steady, accounting for one in six deaths worldwide.5/i> While this number includes all types of pollution, the impacts are clear.

The Exposure Concerns of PFAS Are Regulatory and Legal

Due to their combination of persistence, pervasiveness, mobility, and the ability of some to bioaccumulate (or build up in animals and humans), they have been in the news recently too.6 Predictably, they are also now moving through the courts.7-9 Some of the most common areas of litigation are directed at PFAS found in drinking water and firefighting foam. The regulatory initiatives are also increasing. These address a range from water and soil to numerous manmade products including food packaging.10,11 The European Chemicals Agency (ECHA) and the NIH have a wealth of guidance and regulations that apply to PFAS.12,13

PFAS Detection

The EPA has useful direction for analytical methods development and sampling research that outlines the “laboratory validation process following a particular rulemaking or guidance effort and are available to support regulatory or guidance activities.”14 For
technique and equipment, PFAS are typically analyzed by mass spectrometry, coupled with gas chromatography or liquid chromatography (GCMS and LCMS), which enables detection in the low parts per billion.

AMPAC Analytical has years of experience and numerous experts in trace analysis by mass spectrometry who can assist with method development for high-volume analyses for both common and atypical sample matrices that will allow you to stay ahead of evolving regulatory concerns. Please contact us with specific questions or to receive a quote for PFAS quantitation.

References

  1. PFAS Explained | US EPA
  2. Understanding Organofluorine Chemistry. An Introduction to the C–F bond – Chemical Society Reviews (RSC Publishing)
  3. PFAS Health Effects Database: Protocol for a Systematic Evidence Map – ScienceDirect
  4. Toxicological Profile for Perfluoroalkyls (cdc.gov)
  5. Pollution and Health: a Progress Update – The Lancet Planetary Health
  6. ‘Forever Chemicals’ Are Everywhere. What Are They Doing to Us? – The New York Times (nytimes.com)
  7. PFAS Settlements: Future of PFAS Litigation Landscape to be Determined by Upcoming Decision | Reuters
  8. PFAS: The New Frontier of Product Liability – ProQuest
  9. DuPont, Corteva, and Chemours Announce Resolution of Legacy PFAS Claims | DuPont
  10. Trends in the Regulation of Per- and Polyfluoroalkyl Substances (PFAS): A Scoping Review
  11. PFAS in Food Packaging: State-by-State Regulations – September 2023 | Bryan Cave Leighton Paisner – JDSupra
  12. Per- and Polyfluoroalkyl Substances (PFAS) – ECHA (europa.eu)
  13. Guidance on PFAS Exposure, Testing, and Clinical Follow-Up – NCBI Bookshelf (nih.gov)
  14. PFAS Analytical Methods Development and Sampling Research | US EPA

Resources

Gas Chromatography – An Introduction

A Brief History of Gas Chromatography
Gas chromatography (GC) is one of the most important and prevalent analytical tools available to chemists. It was invented in 1952 by A.T. James and A.J.P. Martin as an outgrowth of research dating back to the previous decade.1-6 Their early techniques on adsorption and partition enabled some of the later developments that A.J.P. Martin spoke about at the 1957 Lansing Symposium, entitled, “Past, Present and Future of Gas Chromatography.” He concluded his address with the following prediction: “If we tie the gas chromatograph to other pieces of laboratory equipment, we have the possibility of almost the automatic chemist…”2 While the idea of an “automatic chemist” hasn’t quite come to fruition, Martin’s belief “that the uniting instrument of the gas chromatograph in the center” of his lab of the future certainly has.2 With the meteoric rise of GC7, its adoption and adaptation continued unabated in the ensuing decades. Then, “The introduction of robust, efficient, and reproducible fused-silica capillary columns and the provision of relatively inexpensive but reliable equipment for GC-MS provided a crucial new impetus in the 1980s.”1 Interestingly, the GC column saw some major advancements within just a few miles of AMPAC Analytical Laboratories. At that location, Walter Jennings and the company he co-founded, J&W Scientific, were instrumental in the development and manufacturing of capillary GC columns. The company was eventually purchased by Agilent in 2001.8,9 

GC Capabilities
Some of the analyses that GC can do include the separation of compounds in mixtures based on the polarity of the compounds, testing for purity – or for impurities, e.g., and detection of residual solvents. Conversely, with a technique known as preparative chromatography, GC can be used to prepare pure compounds from a mixture.  In pharmaceutical analysis, there are additional applications: 

  • Analysis of various functional groups. 
  • Determining purity of pharmaceutical compounds. 
  • Analysis of drugs that are commonly abused. 
  • Determination in pharmaceutical R & D the identity of natural products that contain  complex mixtures of similar compounds. 
  • Use in metabolomics studies.10 

GC for Testing Residual Solvents
The testing of residual solvents is necessary to ensure potency and, with some solvents, to determine their potential negative effects. GC is an excellent choice to do this. Residual solvents are separated into three classifications by the ICH (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use): 

Class 1 solvents: Solvents to be avoided – Known human carcinogens, strongly suspected human carcinogens and environmental hazards. The Permissible Daily Exposure (PDE) of these solvents used in pharmaceutical products can range from 2 to 1500 parts per million (PPM).  

Class 2 solvents: Solvents to be limited – Non-genotoxic animal carcinogens or possible causative agents of other irreversible toxicity such as neurotoxicity or teratogenicity and solvents suspected of other significant but reversible toxicities. The PDE for these solvents ranges from 50 to 3880 ppm. 

Class 3 solvents: Solvents with low toxic potential – low toxic potential to man requiring no health-based exposure limit. Class 3 solvents have PDEs of 50 mg or more per day.11 

Within these three classifications, some of the most commonly used solvents are listed: 

  • Benzene (class 1)  
  • Acetonitrile, Cyclohexane, Hexane, and Methanol (class 2) 
  • Acetic Acid, Acetone, and Heptane (class 3).11,12 

Headspace GC (HSGC) and Direct Injection GC
In addition to the numerous GC developments such as column type, phase and coating techniques, and multidimensional GC, two types of sampling methods arose: direct injection (“DI”) and headspace (“HSGC”).  In the former, the sample is injected “directly” into a typical sample injector of the GC column. In HSGC, when heated, “the more volatile compounds will tend to move into the gas phase (or headspace) sample. The more volatile the compound, the more concentrated it will be in the headspace. Conversely, the less volatile (and more GC-unfriendly) components that represent the bulk of the sample will tend to remain in the liquid phase.“13 

Therefore, by extracting the “headspace vapor and injecting it into a gas chromatograph, there will be far less of the less-volatile material entering the GC column, making the chromatography much cleaner, easier, and faster.”13 Generally, HSGS is much cleaner and results in less wear on the column. For more on comparative techniques with DI and HSGC, please see the first entry in the “Resources” section below. 

We Can Assist with your GC Needs  

AMPAC Analytical has years of experience and numerous experts in Gas Chromatography who can assist with method development for analyses for both common and atypical sample matrices that will allow you to stay ahead of evolving regulatory concerns. Please contact us with any specific questions or to receive a quote for your GC needs.   

References  

  1. History of Gas Chromatography – ScienceDirect 
  2. The Development of Gas Chromatography – ScienceDirect 
  3. Gas-Liquid Chromatography: the Separation and Identification of the Methyl Esters of Saturated and Unsaturated Acids from Formic Acid to n-Octadecanoic Acid (PDF) 
  4. James A T & Martin A J P. Gas-liquid partition chromatography: the separation and microestimation of volatile fatty acids from formic acid to dodecanoic acid. Biochem. J. 50:679-90, 1952. (upenn.edu) 
  5. A New Form of Chromatogram Employing Two Liquid Phases – PMC (nih.gov) 
  6. Gas Chromatography | SpringerLink 
  7. Three Early Symposia Showing the Direction for the  Evolution of Gas Chromatography.pdf   
  8. Co-Founder of J&W Scientific, Gas Chromatography Pioneer Walter Jennings Dies | Agilent 
  9. Professor Walter Goodrich Jennings: A Remembrance (chromatographyonline.com) 
  10. Pharmaceutical Applications of Gas Chromatography 
  11. https://database.ich.org/sites/default/files/ICH_Q3C-R8_Guideline_Step4_2021_0422_1.pdf 
  12. ICH_Q3C-R8_Guideline_Step4_2021_0422_1.pdf 
  13. An Introduction to Headspace Sampling in Gas Chromatography Fundamentals and Theory (perkinelmer.com)  

Resources  

 

 

Chiral Purity Analysis – The Need to Know What Both Hands Are Doing

image illustrating chirality in chemistry

image illustrating chirality in chemistryBackground on Chiral Purity
Chirality refers to the phenomenon that occurs when a mirror image cannot be superimposed.   It is sometimes called “optical rotation”. 

The origin is from the late 19th-century Greek word kheir (‘hand’) and is one of the easiest demonstrations of the concept. Although a person’s hands may appear virtually identical, if they were switched, the outcome would be very different. Amino acids and sugars are the chiral building blocks of larger molecules such as peptides, proteins, and nucleic acids. Therefore, those polymers, in turn, are chiral as well.1 Molecules with chiral centers may have a different therapeutic impact, and this guides the need to test and control chiral purity. The effects of chiral impurities can result in horrific outcomes, as evidenced by the infamous birth defects associated with Thalidomide2 or as benign as Aspartame and sugars (the D/L sugars) that, when superimposed, can create different taste sensations (sweet versus sour, etc.) or metabolic activity. Each chiral center can generate two enantiomers. “Enantiomers or optical isomers are chiral molecules which are non-superimposable mirror images of each other,”3 and multiple chiral centers can generate diastereomers (non-mirror image isomers).   

Determining Purity
HPLC has been the primary technique for determining chiral purity, with gas chromatography used occasionally. Measurement of optical rotation is a legacy technique that is fast but not as accurate. Historically, HPLC methods used under normal phase conditions could limit the type of molecules that could be analyzed. However, now modern chiral columns are compatible with reverse phase conditions.  

Simulated Moving Bed (SMB) Chromatography as an Option for Chiral Purity Analysis
Do you have a partner for chiral separations? AMPAC Analytical has the expertise in performing chiral purity testing, along with the equipment and techniques. Additionally, our parent company, AMPAC Fine Chemicals, has decades of experience conducting chromatographic separations at a commercial scale in a highly regulated environment. Our services include SMB screening, method development, proof-of-concept demonstration, and production. We operate the largest CGMP Simulated Moving Bed (SMB) chromatography unit in the United States. These technologies and expertise are part of a one-stop shop (from 10-millimeter columns up to 1000mm). Our SMB processes can be developed in a few weeks and are easily scalable. In many cases, scale-up from gram to multi-ton quantities can be achieved in fewer than six months. Our facilities include kilo-scale and pilot-scale units to support smaller quantities, also under CGMP conditions. The SMB facilities have been inspected and approved by the FDA for the manufacturing of APIs. AFC has registered four products with regulatory authorities (FDA/EMA) using SMB technology. Along with chiral separations, we can also perform the separation of diastereomers & regioisomers. 

Contact us today for information on how we can assist with your raw material, amino acid, drug product, and API chiral purity testing or to learn more about our SMB processes.  

References  

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5104503 
  2. https://medlineplus.gov/druginfo/meds/a699032.html 
  3. https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/enantiomer 

Nitrosamines – An Update

NDMA

The linkage between nitrosamines and cancer was first postulated by William Lijinsky in 1970. Then, in 2018, N-nitroso-dimethylamine (NDMA)) was detected in an active pharmaceutical ingredient, Valsartan (an Angiotensin-II-receptor antagonist).  Finally, the FDA issued a guidance for the industry, “Control of Nitrosamine Impurities in Human Drugs”, in the fall of 2020. However, the guidelines continue to evolve. There has been an update in March of 2021, with ongoing risk assessments.  Other regulatory agencies have instituted their own, along with updates. For example, since our blog series on nitrosamines, there have been some regulatory updates from the European Medicines Agency (EMA). Their new guidelines are outlined in a document entitled, “Questions and Answers for Marketing Authorization Holders/Applicants on the CHMP Opinion for the Article 5(3) of Regulation (EC) No 726/2004 Referral on Nitrosamine Impurities in Human Medicinal Products.”1 The updated section answers the crucial question, “Which limits apply for nitrosamines in medicinal products?” 

 The answers are provided with a definition of nitrosamines and acceptable exposures: 

 “The ICH M7(R1) guideline defines N-nitrosamines as substances of the “cohort of concern” for which limits in medicinal products refer to the so-called substance-specific acceptable intake (AI) (the Threshold of Toxicological Concern, TTC, value of 1.5 ug/day cannot be routinely applied) which is associated with a negligible risk (theoretical excess cancer risk of <1 in 100,000 over a lifetime of exposure). The calculation of AI assumes a lifelong daily administration of the maximum daily dose of the medicinal product and is based on the approach outlined in the ICH M7(R1) guideline as well as the principles described in relation to the toxicological evaluation in the assessment report of the CHMP’s Article 5(3) opinion on nitrosamine impurities in human medicinal products.”1,2 (A previous blog examined TTC, here.)  

A Useful List of Nitrosamine Limits  

In Appendix 1 found on the EMA site, there is a list of more than eighty nitrosamines listed, along with CAS numbers, known medicinal sources, CPCA (Carcinogenic Potency Categorization Approach) categories, and their guidance publication dates.3,4  

Some Caveats 

There are some exceptions that should be considered. For example, the EMA states, “The ‘less than lifetime’ (LTL) approach should not be applied in calculating the limits as described above but can only be considered after consultation with competent authorities as a temporary measure until further measures can be implemented to reduce the contaminant at or below the limits defined above.”1  

Additionally, those medications intended for advanced cancers also have some exceptions. For example, “If the active substance itself is mutagenic or clastogenic at therapeutic concentrations, N-nitrosamine impurities should be controlled at limits for non-mutagenic impurities according to ICH M7(R1).”  

There is also guidance when one or more than one nitrosamines may be present. For the latter, the guidance advises one of two approaches: 

  1. The total daily intake of all identified N-nitrosamines is not to exceed the AI of the most potent N-nitrosamine identified. 
  1. The total risk level calculated for all identified N-nitrosamines is not to exceed 1 in 100,000. The approach chosen needs to be duly justified by the MAH (Marketing Authorization Holder)/Applicant.1 

Final Thoughts on Nitrosamines 

Nitrosamine guidance worldwide is ever-evolving, yet the impetus to quantify and regulate them is clear. There will doubtlessly be further updates to regulations. AMPAC Analytical Laboratories – an SK pharmteco company (AAL) is an industry leader in the detection of nitrosamines and other genotoxic impurities (GTI), We have the specialized expertise, equipment, and methodologies to detect these impurities by gas chromatography or high-performance liquid chromatography coupled with mass spectrometry to support your API project.  Also, importantly, AAL can assist in navigating those projects within today’s regulatory landscape. Please contact us with any specific questions or to receive a quote for nitrosamines or other GTIs.  

References  

  1. https://www.ema.europa.eu/en/documents/referral/nitrosamines-emea-h-a53-1490-questions-answers-marketing-authorisation-holders/applicants-chmp-opinion-article-53-regulation-ec-no-726/2004-referral-nitrosamine-impurities-human-medicinal-products_en.pdf 
  2. ICH M7 Principles – Impurity Identification and Control (europa.eu) 
  3. https://www.ema.europa.eu/en/human-regulatory/post-authorisation/referral-procedures/nitrosamine-impurities 
  4. Appendix 1 Nitrosamine AIs (europa.eu) 

Resources 

AMPAC  Analytical

General Information on Nitrosamines 

Nitrosamine and Pharmaceuticals 

Regulatory Experiences with Root Causes and Risk Factors for Nitrosamine Impurities in Pharmaceuticals
https://doi.org/10.1016/j.xphs.2022.12.022 

Dynamic Vapor Sorption

Dynamic Vapor Sorption (DVS) is a gravimetric technique used to measure the change in mass of a material in response to changes to surrounding conditions such as temperature or humidity. DVS is primarily used with water vapor but can be applied to other organic solvents as well for the physicochemical characterization of solids. 

DVS was developed by Daryl Williams, the founder of Surface Measurement Systems Ltd., in 1991. The company then delivered the first working DVS instrument to Pfizer in 1992.1 Since then, many other equipment manufacturers have entered the field. 

Figure 1: A DVS isotherm plot indicating sorption and desorption rates and hysteresis. The isotherm shows a typical hysteresis curve where the adsorption phase is almost identical to the desorption phase (i.e. reversible). Note that at 80 %RH, there is net sorption of 0.9% between adsorption and desorption traces. The material appears to be slightly hygroscopic according to the definition in Ph. Eur.2 

Sorption, Desorption, Absorption, and Adsorption
There are five main physical processes that occur during the DVS experiment. The first, sorption, is when a material takes on moisture due to increased humidity. Conversely, desorption is the process that occurs when the material loses moisture due to decreasing humidity. Sorption can be classified as one of two types. Adsorption is moisture that is observed on a surface of a material, while absorption is moisture that has penetrated the surface of a material. The fifth term and the term that relates sorption and desorption is called hysteresis. The overall chart that includes and tracks the sorption and desorption rates and hysteresis is called the isotherm. These curves are crucial for understanding the physicochemical characteristics of a solid, such as porosity, polymorphic change, or liquefying of a sample.2 

Applications 

There are numerous reasons to utilize DVS, and some of the most common within the active pharmaceutical ingredient (API) industry are: 

  • To determine the sorption isotherm;  
  • To evaluate the hygroscopicity of an API powder;  
  • To compare the hygroscopicity of different solid-state forms: solvates, polymorphs, salts, amorphicity, and cocrystals; 
  • To determine the deliquescence point of a material
  • To quantify and qualify the amorphous content in drug substance or excipient,3 and 
  • To evaluate packaging materials. 

Of course, there are a variety of other applications in other industries, including for building materials, food science, cosmetics, coatings, and sealants. 

DVS Analysis of APIs
For pharmaceutical development, DVS is used for a variety of applications, including screening early drug and excipient candidates, establishing processing parameters, and identifying packaging and storage requirements (Figure 2).4,5  

 

Figure 2: A DVS isotherm of an API showing that the material started to gain significant mass after exposure to relative humidity values of more than 60 %RH. The change here was irreversible, as demonstrated by the desorption curve. DVS could be a useful tool to suggest storage conditions in terms of humidity contents in the surrounding environment. 

However, due “to the typically slow establishment of an equilibrium, DVS experiments are rather time-consuming.”4 Nevertheless, “water content of solid active pharmaceutical ingredients and excipients, individually and when formulated in pharmaceutical dosage forms, is a parameter that should be monitored throughout the drug lifecycle.”5  

As an analytical technique for APIs, DVS has become a necessary step within drug development and production, reducing issues that can arise during manufacturing, packaging, transportation, solubility, dissolution rate, stability, or storage. AMPAC Analytical’s sister company, SK biotek Ireland Analytical Services, has the experience, technology (including a Surface Measurement System’s DVS Resolution Dual Vapor Gravimetric Sorption Analyser), and support, to assist with this vital testing. Both companies are part of SK pharmteco and can easily transfer your project from either business unit to ensure the most optimal solution and logistical support are provided to meet your product timeline. We invite you to contact our team members and discuss how we can assist with your sorption testing requirements.  

Figure 3: A SMS DVS instrument like the one located at SK biotek Ireland. 

References  

  1. https://surfacemeasurementsystems.com/our-story/ 
  1. Ph. Eur., 2023, 11.2 Edition, Chapter 2.9.39  
  1. https://www.sciencedirect.com/science/article/abs/pii/S0022354915303348 
  1. https://www.sciencedirect.com/science/article/abs/pii/S0022354918302193 
  1. https://www.sciencedirect.com/science/article/abs/pii/S0022354916325230 
  •  

Keys To Effective Method Development

Effective method development is crucial for the quality control of Active Pharmaceutical Ingredients (API) and Drug Products (DP). Thorough method development enables successful downstream method validation. 

The regulatory guidance  specifies that: 

  • Method development and validation vary by application (quantitative, qualitative, etc.). 
  • It is phase appropriate. 
  • The client may provide additional guidance/validation criteria. 
  • The validation guidance directs how AMD (analytical method development) is conducted. 

Early Adoption of Forced Degradation Analysis
It is recommended that forced degradation be performed early in the method development lifecycle and that method parameters are suitable for mass spectrometry. This will prevent many issues that could occur in later stages and ensures the primary purity method is stability-indicating (specificity). When performing forced degradation, these considerations should be weighed: 

  • Always utilize a control sample without exposure to stressors.  
  • The stressors generally consist of acid, base, peroxide, heat, and photolytic conditions. Other stressors may be used based on known material incompatibility 
  • After exposing the compound to these stressors, target 5-20% degradation of the main peak.  
  • If degradation is not observed under reasonable conditions, then the material can be considered stable under those conditions. 

Impurity Genesis and Identification Assessment
Acceptance criteria should be scaled to impurity levels. How can the method unequivocally assess the analyte of interest in the presence of likely impurities, degradants, and the sample matrix? Additional considerations include: 

  • Is the method capable of identifying and/or quantifying a specific compound? 
  • Are there solvents present that can interfere with potential impurities? 
  • Known impurities? Are the known impurities stable under the method conditions? 
  • Is the method specific for degradation byproducts for stability-indicating methods? 

Cross-Platform Method Robustness
Robustness refers to a method’s ability to meet its analytical requirements (system suitability requirements) despite small variations of the method’s parameters, such as discrete changes to a column or sample tray temperature, percent organic modifier, flow rate, and detector wavelength. This capability is typically built into the method during method development.  

Precision or Accuracy – You Need Both in Strong AMD
AMPAC Analytical development strategy involves the early adoption of forced degradation studies with the goal of every primary purity method being stability-indicating (specificity) and mass spectrometry compatible. The validation strategy is phase-appropriate and application-specific and guides the development strategy. The validation acceptance criteria guidelines are specific to the test methodology, intended use, and level. Finally, method lifecycle performance is assessed, and reevaluation or revalidation can occur.  

 

 

 

 

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