“The dose makes the poison” – Paracelsus (c. 1493– 1541), born Theophrastus von Hohenheim
The Threshold of Toxicological Concern (TTC) refers to levels of mutagenic impurities expected to pose a negligible carcinogenic risk.1 The US FDA, the EMA (European Medicines Agency), and the European Food Safety Authority (EFSA) all have TTC values and regulations in place for food and active pharmaceutical ingredients (APIs), along with numerous other products.2,3 Originally, these standards were applied to TTC levels from oral ingestion but have expanded to even include cosmetics and fragrances.4,5
One tool to assess risk is the use of Cramer classes for organic impurities. They range from I-III, indicating a low, medium, or high probability of toxicity.5
There are numerous tools and techniques to assess TTC, depending on the product (food, water, and other beverages, APIs, or cosmetics) and the mutagenic impurity. AMPAC Analytical can utilize TTC guidelines and risk assessments to establish method development and validation targets that ensure acceptable levels of mutagenic impurities in your API or food products. Contact us today to learn more about analytical strategies to control mutagenic impurities.
Forced Degradation is an important addendum to our previous post on Stability and Storage. Stressors are applied to new APIs and drug products to determine their degradation pathways and products under a variety of environmental conditions, including acid, base, light, heat, and oxidation. Forced degradation studies are also known as stress testing, stress studies, stress decomposition studies, and forced decomposition studies. These conditions “…are more severe than accelerated (stability) conditions and thus generate degradation products that can be studied to determine the stability of the molecule.”1
Regulatory requirements for forced degradation were enacted by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) in 1993.2 However, these guidelines “are very general in (the) conduct of forced degradation and do not provide details about the practical approach towards stress testing. Although forced degradation studies are a regulatory requirement and scientific necessity during drug development, it is not considered as a requirement for (a) formal stability program.”1 However, stability studies have become a requisite for new drug moieties. In the absence of specific guidelines, the amount of stress needs to be representational: “Overstressing a molecule can lead to degradation profiles that are not representative of real storage conditions and perhaps not relevant to method development. Therefore, stress-testing conditions should be realistic and not excessive.”3
AMPAC Analytical (AAL), an SK pharmteco company, can assist with forced degradation studies for products at all phases of development, in tandem with stability, storage, and method development, to ensure the viability of the drug products as they were designed. We introduce forced degradation studies early in method development to ensure your product quality throughout the development lifecycle. Contact AAL today to learn more.
The Background, Advantages of, and Considerations for Radiolabeled Peptides The use of radiolabeled peptides is a well-established tool in researching and treating many diseases and conditions. Selective receptor-targeting peptides are utilized as agents due to their rapid circulatory and tissue clearance and the high affinity and specificity to their targets. Peptides also have a relatively small size and low molecular weight compared to proteins and antibodies. There have been innovations and improvements in the design of peptides that incorporate chemical modifications with “impressive diagnostic accuracy and sensitivity.”1 Coupling these peptides with radiolabeling for peptide receptor radionuclide imaging (PRRI) and therapy (PRRT) has yielded remarkable results. In fact, a historical summary of radiolabeled peptides asserts, “The emergence of radiolabeled peptides for use with PET/CT such as 68Ga, 18F, and 64Cu, and the use of new receptor binding ligands…, have revolutionized PRRI and improved its diagnostic power beyond expectation.”2
“Criteria for a successful peptide tracer,” to be utilized for PRRI, “are a high target specificity, a high binding affinity, long metabolic stability, and a high target-to-background ratio.”3
Oncology and Radiolabeled Peptides Oncology has benefited from the “tumor-philic” properties of Arg-Gly-Asp (RGD) peptides “because of their high affinity and selectivity for integrin αvβ3 – one of the most extensively examined targets of angiogenesis. Since the level of integrin αvβ3 expression has been established as a surrogate marker of angiogenic activity, imaging αvβ3 expression can potentially be used as an early indicator of the effectiveness of antiangiogenic therapy at the molecular level.”4 In addition to integrin αvβ3 expression, “tumor angiogenesis…has been well recognized as an essential hallmark for tumor growth, invasion, and metastasis.”4 All this has made RGD-containing peptides “promising molecular agents for imaging angiogenesis.”5
Beyond Oncology Since integrins are “involved in adhesion between cells and the extracellular matrix” and, as such, are associated with normal and pathological states, this family of receptors is useful for targeting a range of diseases.6 Current applications include “cardiovascular imaging, atherosclerosis imaging, remodeling after myocardial infarct or stroke, imaging of myocardial ischemia, identification of abdominal aortic aneurysm, imaging of chronic inflammation, pulmonary inflammation, assistance with bone marrow evaluations, and tissue engineering.”6
A Brief History of RGD Peptides and Radiolabeling Although radiopharmaceutical therapies, which can concurrently detect and treat tumors (i.e., theranostics, a portmanteau of therapeutics and diagnostics), have been around for eighty years, it was not until the combination of these payloads was combined with peptides that the potential for better targeting became a reality. The use of the RGD peptide sequence to attach to cells was first reported by M.D. Pierschbacher and E. Ruoslahti in Nature, nearly forty years ago in 1984, as a feature of fibronectin.5,7 Next, targeting tumors with radioactive peptides began, initiated by OctreoScan’s breakthrough in the early 1990s, wherein somatostatin receptor subtype 2 (SST-2) positive tumors were identified.8,9 After that, the first monomeric integrin-specific PET tracer used in patients was F-Galacto-RGD, a glycosylated RGD-peptide.5,10 Since then, the tripeptide R-G-D sequence has generally been utilized as a tracer, carrying the isotope to integrins that are expressed on both tumor cells and activated endothelial cells of tumor neo-vasculature. In the ensuing years, advancements have continued apace, and going forward, the intersection of PRRI/PRRT from radiolabeled peptides combined with AI, precision, and personalized medicine assures transformative innovations.
Obstacles and Numerous Options for Radiolabeled Peptide Production Because of their established safety, development, and design history, and “the fact that there are many RGD-based tracers with known pharmacokinetics, it can be useful to use them in the imaging of diseases that currently have no accurate method of diagnosis available.”6 However, there are barriers to synthesizing radiolabeled peptides: itcan be a time-consuming, complex, multi-step process. It is also highly variable based on the peptide. Other drawbacks include the intricacies of radiolabeling and the lack of automation for some of these protocols.
Fortuitously, RGDs radiopeptides are not the only ones exhibiting exciting potential for diagnostic imaging and targeted radionuclide therapies.An extensive review article from Paweł Kręcis et al. that appeared in Bioconjugate Chemistry is recommended, as it presents some developments and perspectives in both aforementioned areas regarding the research on somatostatin, bombesin, vasoactive intestinal peptide, gastrin, neurotensin, and exendin peptide analogs, among others.11 It includes the application of radiolabeled peptides and antibodies and an analysis of clinical trials reported in 2008-2018.
Finally, just a few of the current companies doing interesting things in radiopharmaceuticals include Aktis Oncology, Mariana Oncology, Point Biopharma, and Rayze Bio. AMPAC Fine Chemical and AMPAC Analytical, both SK pharmteco companies, have been at the vanguard of small molecule and analytical developments utilizing innovative technologies and techniques directed by teams with decades of experience. If you have a radiolabeled peptide targeted for development, our teams can design, validate, optimize, and analyze your project, ranging from research to commercial quantities. Contact us today for more information.
The CGMP guidance for APIs from the FDA states that raw material specifications should be established and documented. The guide’s key line states, “Quality measures should include a system for testing raw materials, packaging materials, intermediates, and APIs. (19.23)”1
All raw materials used in producing APIs for clinical trials must be evaluated by testing or received from the supplier with accompanying analysis and subsequently subjected to identity testing. Raw materials and intermediates need to be designated by names and/or specific codes so that any special quality characteristics can be readily identified. Furthermore, written procedures should provide for the identification, documentation, appropriate review, and approval of any changes to raw materials. Additionally, changes to supply sources of critical raw materials should be treated according to the FDA’s established change control guidelines.
A Range of Tests for Raw Materials Are Available Some of the categories and tests that can be utilized for raw materials testing include:
Determination of Physical Properties (appearance/description, density, refractive index, pH, water content by Karl Fischer titration (coulometric and volumetric), the color and clarity of the solution, conductivity, optical rotation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), osmolality, particle counting, particle size distribution (wet and dry), total organic carbon (TOC), and various compendial tests)
Identification (appearance/description, infrared spectroscopy – ATR, salt pellets, and salt plates (for liquids), nuclear magnetic resonance (NMR), liquid chromatography – HPLC and UHPLC, gas chromatography (GC), ion chromatography (IC), mass spectrometry (MS), ultraviolet spectroscopy (UV), X-ray powder diffraction (XRPD), residue on ignition/sulfated ash, ICP-MS and ICP-OES for elemental impurities, and various compendial tests)
Assay and Impurity Testing (standard titration methods, liquid chromatography (both HPLC and UHPLC) detection systems including UV, MS, RI, and CAD (charged aerosol detection), residual solvents testing utilizing gas chromatography systems equipped with FID flame-ionization detection), ECD (electron capture detection), TCD (thermal conductivity detection) and MS, ICP-OES, ICP-MS, and a variety of pharmacopeia methods such as residue on ignition/sulfated ash, heavy metals, etc.)
Pharmacopeia Testing (the ability to qualify and implement monographs and testing chapters from the various pharmacopeias and their standards, including USP (United States Pharmacopoeia), EP (European Pharmacopoeia), BP (British Pharmacopoeia), JP (Japanese Pharmacopoeia), FCC (Food Chemical Codex), and ACS (American Chemical Society, Reagent Standards))
Trust – and Verify – Your Raw Materials Testing Solution The range of testing requirements, procedures, and record-keeping can be daunting. It is crucial to have an experienced, reputable, and thorough laboratory available to ensure that each raw material is released in accordance with regulations. It is also important that the partner you choose to perform these tasks does so in a timely manner, communicating every step of the way. AMPAC Analytical has decades of experience along with the resources to provide all the analytical solutions listed above, combined with a responsive customer service attitude, and a demonstrated history of regulatory audit compliance. We urge that you contact AMPAC Analytical today to learn more about you can trust and verify all your raw materials.
“The dose makes the poison” – Paracelsus (c. 1493– 1541), born Theophrastus von Hohenheim
Forced Degradation is an important addendum to our 
