Nitrosamines, recognized as potential carcinogens, have emerged as impurities of concern in pharmaceutical products. This study evaluates the formation risk of active pharmaceutical ingredient (API) fragment nitrosamine drug substance-related impurities (NDSRIs) derived from secondary amine related impurities that may be present in human drug products throughout their shelf life. Leveraging publicly available data from the Food and Drug Administration (FDA) Global Substance Registration System (GSRS), the carcinogenic potency categorization approach (CPCA), and available maximum daily dose (MDD) information, we identified 446 secondary amine related impurities linked to 218 individual APIs in human drug products. A simulation was conducted to assess the risk of API fragment NDSRI formation from these secondary amine related impurities, incorporating factors such as impurity levels, nitrosamine conversion ratio, MDD, and acceptable intake (AI) limits. The findings reveal that, under varying conditions of secondary amine related impurity levels and nitrosamine conversion ratios, a proportion of the API fragment NDSRI impurities may exceed recommended AI limits. Based on these simulation outcomes, we propose and discuss control strategies to mitigate nitrosamine-related risks.

Accurately determining the mutagenicity of small-molecule N-nitrosamine drug impurities and nitrosamine drug substance-related impurities (NDSRIs) is critical to identifying mutagenic and cancer hazards. In the current study we have evaluated several approaches for enhancing assay sensitivity for evaluating the mutagenicity of N-nitrosamines in the bacterial reverse mutagenicity (Ames) test. Preincubation assays were conducted using five activation conditions: no exogenous metabolic activation and metabolic activation mixes employing both 10% and 30% liver S9 from hamsters and rats pretreated with inducers of enzymatic activity. In addition, preincubations were conducted for both 60 min and 30 min. These test variables were evaluated by testing 12 small-molecule N-nitrosamines and 17 NDSRIs for mutagenicity in Salmonella typhimurium tester strains TA98, TA100, TA1535, and TA1537, and Escherichia coli strain WP2 uvrA (pKM101). Eighteen of the 29 N-nitrosamine test substances tested positive under one or more of the testing conditions and all 18 positives could be detected by using tester strains TA1535 and WP2 uvrA (pKM101), preincubations of 30 min, and S9 mixes containing 30% hamster liver S9. In general, the conditions under which NDSRIs were mutagenic were similar to those found for small-molecule N-nitrosamines.

The mitigation of nitrosamine formation in drug products has been studied and approaches such as using formulations with pH modifiers and antioxidants have been shown to decrease the formation of nitrosamines. However, more studies are needed to explore the effectivness of mitigation strategies with different drug models and formulations. The primary objective of this work was to assess the role of different antioxidants and pH modifiers in tablet formulations to mitigate the formation of NDMA, prepared in-house, using metformin hydrochloride as a model drug. A study design for manufacturing metformin hydrochloride formulations was created to evaluate potential mitigation stratigies. The formulations were prepared by wet granulation that included a sodium nitrite spike and various antioxidants such as ascorbic acid, caffeic acid and ferulic acid at various concentrations that may inhibit nitrosamine formation. The study design also included pH modifiers such as hydrochloric acid and sodium carbonate. The metformin hydrochloride formulations were placed under stability conditions that included humidity, temperature and time over a six month period. NDMA inhibition was found to be most effective in formulations with basic pH, followed by the addition of tested antioxidants with 0.1% concentrations in the formulations. All tested antioxidants showed complete mitigation in formulations with 0.5% and 1% concentrations. In summary, basic pH and the inclusion of antioxidants exhibited the potential to mitigate the formation of NDMA in metformin hydrochloride tablets.

The presence of mutagenic and carcinogenic N-nitrosamine impurities in medicinal products poses a safety risk. While incorporating antioxidants in formulations is a potential mitigation strategy, concerns arise regarding their interference with drug absorption by inhibiting intestinal drug transporters. Our study screened thirty antioxidants for inhibitory effects on key intestinal transporters—OATP2B1, P-gp, and BCRP in HEK-293 cells (OATP2B1) or membrane vesicles (P-gp, BCRP) using 3H-estrone sulfate, 3H-N-methyl quinidine, and 3H-CCK8 as substrates, respectively. The screen identified that butylated hydroxyanisole (BHA) and carnosic acid inhibited all three transporters (OATP2B1, P-gp, and BCRP), while ascorbyl palmitate (AP) inhibited OATP2B1 by more than 50%. BHA had IC50 values of 71 ± 20 µM, 206 ± 14 µM, and 182 ± 49 µM for OATP2B1, BCRP, and P-gp, respectively. AP exhibited IC50 values of 23 ± 10 µM for OATP2B1. The potency of AP and BHA was tested with valsartan, an OATP2B1 substrate, and revealed IC50 values of 26 ± 17 µM and 19 ± 11 µM, respectively, in HEK-293-OATP2B1 cells. Comparing IC50 values of AP and BHA with estimated intestinal concentrations suggests an unlikely inhibition of intestinal transporters at clinical concentrations of drugs formulated with antioxidants.

Reformulation with addition of antioxidants is one potential mitigation strategy to prevent or reduce nitrosamine drug substance-related impurities (NDSRIs) in drug products. To explore whether there could be other approaches to demonstrate bioequivalence for a reformulated oral product, which typically needs in vivo bioequivalence studies to support the changes after approval, the effects of antioxidant on the in vitro permeability of BCS III model drug substances were investigated to see whether there could be any potential impact on drug absorption. Six antioxidants were screened and four (ascorbic acid, cysteine, α-tocopherol and propyl gallate) were selected based on their nitrosamine inhibition efficiencies. The study demonstrated that these four antioxidants, at the tested amounts, did not have observable impact on the in vitro permeability of the BCS III model drug substances across Caco-2 cell monolayers in the In Vitro Dissolution Absorption System (IDAS). An in vitro permeability study could be considered as part of one potential bioequivalence bridging approach for reformulated low-risk immediate release solid oral products and oral suspension products. Other factors such as the influence of antioxidants on intestinal transporter activities should be considered where appropriate.

Nitrosamine compounds are classified as potential human carcinogens, the origin of these impurities can be broadly classified in two categories, nitrosamine impurity found in drug products that are not associated with the Active Pharmaceutical Ingredient (API), such as N-nitrosodimethylamine (NDMA) or nitrosamine impurities associated with the API, such as nitrosamine drug substance-related impurities (NDSRIs). The mechanistic pathway for the formation of these two classes of impurities can be different and the approach to mitigate the risk should be tailored to address the specific concern. In the last couple of years number of NDSRIs have been reported for different drug products. Though, not the only contributing factor for the formation of NDSIRs, it is widely accepted that the presence of residual a nitrites/nitrates in the components used in the manufacturing of the drug products can be the primary contributor to the formation of NDSRIs. Approaches to mitigate the formation of NDSRIs in drug products include the use of antioxidants or pH modifiers in the formulation. The primary objective of this work was to evaluate the role of different inhibitors (antioxidants) and pH modifiers in tablet formulations prepared in-house using bumetanide (BMT) as a model drug to mitigate the formation of N-nitrosobumetanide (NBMT). A multi-factor study design was created, and several bumetanide formulations were prepared by wet granulation with and without sodium nitrite spike (100 ppm) and different antioxidants (ascorbic acid, ferulic acid or caffeic acid) at three concentrations (0.1%, 0.5% or 1% of the total tablet weight). Formulations with acidic and basic pH were also prepared using 0.1 N hydrochloric acid and 0.1 N sodium bicarbonate, respectively. The formulations were subjected to different storage (temperature and humidity) conditions over 6 months and stability data was collected. The rank order of N-nitrosobumetanide inhibition was highest with alkaline pH formulations, followed by formulations with ascorbic acid, caffeic acid or ferulic acid present. In summary, we hypothesize that maintaining a basic pH or the addition of an antioxidant in the drug product can mitigate the conversion of nitrite to nitrosating agent and thus reduce the formation of bumetanide nitrosamines.

This paper describes a new FDA's pharmaceutical quality assessment system: Knowledge-aided Assessment & Structured Application (KASA). The KASA system is designed to: 1) capture and manage knowledge during the lifecycle of a drug product; 2) establish rules and algorithms for risk assessment, control, and communication; 3) perform computer-aided analyses of applications to compare regulatory standards and quality risks across applications and facilities; and 4) provide a structured assessment that minimizes text-based narratives and summarization of provided information. When fully developed and implemented, KASA will enrich the effectiveness, efficiency, and consistency of regulatory quality oversight through lifecycle management of products and facilities, and information sharing in a standardized and structured format. Ultimately, KASA will advance FDA's focus on pharmaceutical quality, the foundation for ensuring the safety and efficacy of drugs.

The chapter contains brief surveys of current approaches used in countries around the world in the regulation of naturally-derived complex drugs. There is a marked diversity in the scientific and regulatory approaches in different regions, depending on history, the recognition and integration of traditional medicine systems, the evolution of regulatory bodies, and government regulatory philosophies. In the USA, there is a sharp regulatory distinction between drug and non-drug entities, based primarily on whether or the intended use is for treatment, prevention, or mitigation of disease states; for example, an herbal preparation may be registered as a botanical drug conforming to drug laws and guidelines, or it may be marketed essentially in the form of a dietary supplement. However, in many countries such as Europe, there is a particular regulatory class "herbal medicinal products" with some specific regulations within the framework for medicinal products. Countries such as Australia and Canada have developed a more comprehensive and tailored approach developing regulatory frameworks working off the therapeutic good/drug model that captures most herbal and traditional medicines on the market. In Asia, the regulatory approaches provide a special framework for the traditional systems of medicine, such as Ayurveda or traditional Chinese medicine (TCM). Interestingly in India, there is the development of hybrid categories, wherein some products from traditional medicine can be modified or specially formulated and marketed. In these subchapters, the heterogeneous environments, histories, and regulatory intents are captured and reflected for the USA, Europe, Canada, Australia, China, India, and World Health Organization and National Institute for Biological Standards and Control. However, these subchapters are instructive for background and context in the book's treatment of the regulation of naturally-derived complex mixture drugs in this age of globalization.

A fundamental premise for generic approval is that the generic drug product contains the "same" active pharmaceutical ingredient as the brand name product. The vast majority of generics are traditional "small-molecule" drugs that have a simple chemical structure that is easily characterized. For those cases it is relatively straightforward to demonstrate the active ingredient is the "same" as the brand name. In complex drug substances, the active ingredient is not a traditional single-entity small molecule, but rather a distribution of molecular species. For those cases, there are scientific challenges toward demonstrating the "same" active ingredient. Over the past few years, FDA has approved generic versions of some complex active ingredients, including Lovenox (enoxaparin sodium) injection and Copaxone (glatiramer acetate) injection. Despite the fact these two active ingredients possess a significant level of molecular heterogeneity, an understanding of the origin of this heterogeneity, based upon source material and manufacturing process considerations, provides the basis for a simplified framework to demonstrate active ingredient sameness. This book chapter provides an overview of the common themes used to approve generics of these complex mixtures.

Iron carbohydrate colloid drug products are intravenously administered to patients with chronic kidney disease for the treatment of iron deficiency anemia. Physicochemical characterization of iron colloids is critical to establish pharmaceutical equivalence between an innovator iron colloid product and generic version. The purpose of this review is to summarize literature-reported techniques for physicochemical characterization of iron carbohydrate colloid drug products. The mechanisms, reported testing results, and common technical pitfalls for individual characterization test are discussed. A better understanding of the physicochemical characterization techniques will facilitate generic iron carbohydrate colloid product development, accelerate products to market, and ensure iron carbohydrate colloid product quality.

Peptides are a fast growing segment in the pharmaceutical industry. Consequently, the industry and regulatory agencies are increasing their focus on the regulatory path and quality considerations for peptide development and manufacturing. Although most peptides are synthetic, manufactured by solid phase synthesis, nevertheless they are complex molecules with challenging quality and regulatory aspects. This paper provides a structured overview of relevant quality issues for chemically synthesized peptides used as active pharmaceutical ingredients (API) in drug products. It addresses the unique characteristics of peptides pertaining to structural and physicochemical characterization, manufacturing and in process controls, impurities and aggregates arising from manufacturing and storage, along with their potential impact on safety (including immunogenicity) and efficacy of the peptide drug products.

Cold flow, the movement of adhesive beyond the edge of a transdermal drug delivery system (TDDS) or between the release liner slit, can affect the quality of the drug product and result in patient use issues such as difficulty in removal from packaging and unintentional removal of the product during wear due to increased tackiness on the edge and backing of the TDDS. In this study, different techniques for measuring cold flow of United States marketed transdermal drug delivery systems are assessed including a wiping method with various ways of calculating cold flow, a macroscopic rating method and a microscope evaluation. The amount of cold flow measured from the wiping method was dependent upon the calculation method. Assessment of cold flow may be a combination of quantitative and qualitative methods. Appearance criteria can assess potential use issues caused by cold flow if TDDS are difficult to remove from pouches and if release liners detach from the adhesive matrix during attempted removal due to cold flow adhering the backing to the pouch. A quantitative cold flow method captures the degree to which cold flow extends beyond the perimeter of the backing and through the release liner slit. The method(s) selected by a TDDS manufacturer to measure cold flow should be applicable to the individual product and scientifically justified.

On September 16 and 17, 2014, the Food and Drug Administration (FDA) and Product Quality Research Institute (PQRI) inaugurated their Conference on Evolving Product Quality. The Conference is conceived as an annual forum in which scientists from regulatory agencies, industry, and academia may exchange viewpoints and work together to advance pharmaceutical quality. This Conference Summary Report highlights key topics of this conference, including (1) risk-based approaches to pharmaceutical development, manufacturing, regulatory assessment, and post-approval changes; (2) FDA-proposed quality metrics for products, facilities, and quality management systems; (3) performance-based quality assessment and clinically relevant specifications; (4) recent developments and implementation of continuous manufacturing processes, question-based review, and European Medicines Agency (EMA)-FDA pilot for Quality-by-Design (QbD) applications; and (5) breakthrough therapies, biosimilars, and international harmonization, focusing on ICH M7 and Q3D guidelines. The second FDA/PQRI conference on advancing product quality is planned for October 5–7, 2015.

This paper summarises the proceedings of a recent workshop which brought together pharmaceutical scientists and dermatologists from academia, industry and regulatory agencies to discuss current regulatory issues and industry practices for establishing therapeutic bioequivalence (BE) of dermatologic topical products. The methods currently available for assessment of BE were reviewed as well as alternatives and the advantages and disadvantages of each method were considered. Guidance on quality and performance of topical products was reviewed and a framework to categorise existing and alternative methods for evaluation of BE was discussed. The outcome of the workshop emphasized both a need for greater attention to quality, possibly, via a Quality-By-Design (QBD) approach and a need to develop a "whole toolkit" approach towards the problem of determination of rate and extent in the assessment of topical bioavailability. The discussion on the BE and clinical equivalence of topical products revealed considerable concerns about the variability present in the current methodologies utilized by the industry and regulatory agencies. It was proposed that academicians, researchers, the pharmaceutical industry and regulators work together to evaluate and validate alternative methods that are based on both the underlying science and are adapted to the drug product itself instead of single "universal" method.

The study objective was to evaluate the thermodynamic stability of iron sucrose complexes as determined by molecular weight (m.w.) changes. The first part of the study focused on the effect of thermal stress, pH, electrolyte or excipient dilution on the stability of a colloidal iron drug product. Part two focused on the physical and chemical evaluation of the colloidal nature of iron sucrose using a series of characterization experiments: ultracentrifugation, dialysis, particle size, zeta potential, and osmotic pressure analysis. A validated Taguchi-optimized high performance gel permeation chromatography method was used for m.w. determinations. Results indicate m.w. of the iron sucrose complex remained unchanged after excipient dilution, ultracentrifugation, dialysis, and electrolyte dilution. Electrolyte dilution studies indicated the lyophilic nature of the iron sucrose colloid with a particle size of 10nm and zeta potential of 0 mV. The complex deformed at low pH and reformed back at the formulation pH. The complex is stable under mild-to-moderate temperature <50°C but aggregates following prolonged exposure to high temperatures >70°C. In conclusion, the resistance of the complex to breakdown by electrolytic conditions, excipient dilution, ultracentrifugation and the reversible complexation after alteration of formulation pH suggest iron sucrose is a lyophilic colloid in nature and lyophilic colloidals are thermodynamically stable.

The emergence of quality by design as a relatively new systematic science and risk-based approach has added a new dimension to pharmaceutical development and manufacturing. This review attempts to discuss the quality by design elements and concepts applied for topical semisolid products. Quality by design begins with defining a quality target product profile as well as critical quality attributes. Subsequently, this is followed by risk identification/risk analysis/risk evaluation to recognize critical material attributes and critical process parameters, in conjunction with design of experiments or other appropriate methods to establish control strategies for the drug product. Several design-of-experiment examples are included as practical strategies for the development and optimization of formulation and process for topical drug products.

This review presents considerations which can be employed during the development of a semi-solid topical generic product. This includes a discussion on the implementation of quality by design concepts during development to ensure the generic drug product has similar desired quality attributes to the reference-listed drug (RLD) and ensure batch to batch consistency through commercial production. This encompasses the concept of reverse-engineering to copy the RLD as a strategy during product development to ensure qualitative (Q1) and quantitative (Q2) formulation similarity, as well as similarity in formulation microstructure (Q3). The concept of utilizing in vitro skin permeation studies as a tool to justify formulation differences between the test generic product and the RLD to ensure a successful pharmacodynamic or clinical endpoint bioequivalence study is discussed. The review concludes with a discussion on drug product evaluation and quality tests as well as in vivo bioequivalence studies.

In 2010, the US Food and Drug Administration (FDA) approved a generic low-molecular-weight heparin without clinical safety or efficacy data under the Abbreviated New Drug Application (ANDA) pathway. To enable a determination of active ingredient sameness of generic and innovator enoxaparin products, the FDA developed a scientifically rigorous approach based on five criteria: first, equivalence of physicochemical properties; second, equivalence of heparin source material and mode of depolymerization; third, equivalence in disaccharide building blocks, fragment mapping and sequence of oligosaccharide species; fourth, equivalence in biological and biochemical assays; and finally, equivalence of in vivo pharmacodynamic profile. In addition to fulfillment of these criteria, FDA also used in vitro , ex vivo and model animal data to ensure there was no increased immunogenicity risk of the generic enoxaparin product relative to the brand name product. The approval of the highly complex enoxaparin product using this framework under the ANDA pathway represents a major development. It also suggests that analytical and scientific advancements may in certain cases allow the elimination of unnecessary in vivo testing in animals and humans.

The purpose of this study was to characterize and evaluate differences of protamine sulfate, a highly basic peptide drug, obtained from five different sources, using orthogonal thermal and spectroscopic analytical methods. Thermogravimetric analysis and modulated differential scanning calorimetry showed that all five protamine sulfate samples had different moisture contents and glass transition and melting temperatures when temperature was modulated from 25 to 270°C. Protamine sulfate from source III had the highest residual moisture content (4.7 ± 0.2%) at 105°C, resulting in the lowest glass transition (109.7°C) and melting (184.2°C) temperatures compared with the other four sources. By Fourier-transform infrared (FTIR) spectroscopy, the five sources of protamine sulfate had indistinguishable spectra, and the spectra were consistent with a predominantly random coil conformation in solution and a minor population in a β-sheet conformation (~12%). Circular dichroism spectropolarimetry confirmed the FTIR results with prominent minima at 206 nm observed for all five sources. Finally, proton (1H) nuclear magnetic resonance spectroscopy showed that all five protamine sulfate sources had identical spectra with backbone amide chemical shifts between 8.20 and 8.80 ppm, consistent with proteins with predominantly random coil conformation. In conclusion, thermal analyses showed differences in the thermal behavior of the five sources of protamine sulfate, while spectroscopic analyses showed the samples had a predominantly random coil conformation with a small amount of β-sheet present.

FDA’s bioequivalence recommendation for Zolpidem Tartrate Extended Release Tablets is the first to use partial AUC (pAUC) metrics for determining bioequivalence of modified-release dosage forms. Modeling and simulation studies were performed to aid in understanding the need for pAUC measures and also the proper pAUC truncation times.