Regulatory considerations of pharmaceutical solid polymorphism in Abbreviated New Drug Applications (ANDAs)

A sponsor of an Abbreviated New Drug Application (ANDA) must have information to show that the proposed generic product and the innovator product are both pharmaceutically equivalent and bioequivalent, and therefore, therapeutically equivalent. Many pharmaceutical solids exist in several crystalline forms and thus exhibit polymorphism. Polymorphism may result in differences in the physico-chemical properties of the active ingredient and variations in these properties may render a generic drug product to be bioinequivalent to the innovator brand. For this reason, in ANDAs, careful attention is paid to the effect of polymorphism in the context of generic drug product equivalency. This review discusses the impact of polymorphism on drug product manufacturability, quality, and performance. Conclusions from this analysis demonstrate that pharmaceutical solid polymorphism has no relevance to the determination of drug substance "sameness" in ANDAs. Three decision trees for solid oral dosage forms or liquid suspensions are provided for evaluating when and how polymorphs of drug substances should be monitored and controlled in ANDA submissions. Case studies from ANDAs are provided which demonstrate the irrelevance of polymorphism to the determination of drug substance "sameness". These case studies also illustrate the conceptual framework from these decision trees and illustrate how their general principles are sufficient to assure both the quality and the therapeutic equivalence of marketed generic drug products.     

Applications of In Vitro–In Vivo Correlations in Generic Drug Development: Case Studies

In vitro–in vivo correlation (IVIVC) is a predictive mathematical model describing the relationship between an in vitro property and a relevant in vivo response. The main objective of an IVIVC is to serve as a surrogate for human bioequivalence (BE) studies, which may reduce the number of BE studies performed during the initial approval process as well as with certain scale-up and postapproval changes. The US Food and Drug Administration (FDA) published a regulatory guidance related to development, evaluation, and applications of IVIVC for extended-release (ER) oral dosage forms in September 1997. Despite the publication of this guidance, the deficiencies related to IVIVC are still identified by the Division of Bioequivalence in the process of Abbreviated New Drug Application (ANDA) review. Thus, the main objective of this article is to present the most commonly occurring deficiencies associated with IVIVCs via selected case studies from the ANDAs for oral ER drug products only. We searched internal FDA databases from January 1996 to December 2014 to identify the ANDAs for proposed generic oral ER drug products containing IVIVC. Only 14 ANDA submissions had IVIVC data, and most were not acceptable. Only one ANDA submission included adequate information related to IVIVC data enabling the completion of BE review within first review cycle. It is hoped that awareness of the deficiencies presented in our article would help the generic drug applicants to submit complete and appropriate information related to IVIVC data, ultimately, resulting in a more timely approval of ANDAs.KEY WORDS: bioequivalence, extended-release drug products, generics, IVIVC, SUPAC     

Identification of Pharmaceutical Impurities in Formulated Dosage Forms

Structure elucidation of pharmaceutical impurities is an important part of the drug product development process. Impurities can have unwanted pharmacological or toxicological effects that seriously impact product quality and patient safety. This review focuses on current analytical strategies for chemical and structural identification of pharmaceutical impurities. Potential sources and mechanisms of impurity formation are discussed for both drug substance and drug product applications. The utility of liquid chromatography–mass spectrometry (LC/MS) for providing structure-rich information is highlighted throughout this review. Other hyphenated analytical techniques including LC/nuclear magnetic resonance, gas chromatography/MS, and size-exclusion chromatography/chemiluminescent nitrogen detectors are also discussed, as LC/MS alone sometimes cannot reveal or confirm the final structures as required during dosage form development.     

Statistical Considerations in Setting Product Specifications

According to ICH Q6A (1999), a specification is defined as a list of tests, references to analytical procedures, and appropriate acceptance criteria, which are numerical limits, ranges, or other criteria for the tests described. For drug products, specifications usually consist of test methods and acceptance criteria for assay, impurities, pH, dissolution, moisture, and microbial limits, depending on the dosage forms. They are usually proposed by the manufacturers and subject to the regulatory approval for use. When the acceptance criteria in product specifications cannot be pre-defined based on prior knowledge, the conventional approach is to use data from a limited number of clinical batches during the clinical development phases. Often in time, such acceptance criterion is set as an interval bounded by the sample mean plus and minus two to four standard deviations. This interval may be revised with the accumulated data collected from released batches after drug approval. In this article, we describe and discuss the statistical issues of commonly used approaches in setting or revising specifications (usually tighten the limits), including reference interval, (Min, Max) method, tolerance interval, and confidence limit of percentiles. We also compare their performance in terms of the interval width and the intended coverage. Based on our study results and review experiences, we make some recommendations on how to select the appropriate statistical methods in setting product specifications to better ensure the product quality.     

The use of biopharmaceutic classification of drugs in drug discovery and development: current status and future extension

Bioavailability (BA) and bioequivalence (BE) play a central role in pharmaceutical product development and BE studies are presently being conducted for New Drug Applications (NDAs) of new compounds, in supplementary NDAs for new medical indications and product line extensions, in Abbreviated New Drug Applications (ANDAs) of generic products and in applications for scale-up and post-approval changes. The Biopharmaceutics Classification System (BCS) has been developed to provide a scientific approach for classifying drug compounds based on solubility as related to dose and intestinal permeability in combination with the dissolution properties of the oral immediaterelease (IR) dosage form. The aim of the BCS is to provide a regulatory tool for replacing certain BE studies by accurate in-vitro dissolution tests. The aim of this review is to present the status of the BCS and discuss its future application in pharmaceutical product development. The future application of the BCS is most likely increasingly important when the present framework gains increased recognition, which will probably be the case if the BCS borders for certain class II and III drugs are extended. The future revision of the BCS guidelines by the regulatory agencies in communication with academic and industrial scientists is exciting and will hopefully result in an increased applicability in drug development. Finally, we emphasize the great use of the BCS as a simple tool in early drug development to determine the rate-limiting step in the oral absorption process, which has facilitated the information between different experts involved in the overall drug development process. This increased awareness of a proper biopharmaceutical characterization of new drugs may in the future result in drug molecules with a sufficiently high permeability, solubility and dissolution rate, and that will automatically increase the importance of the BCS as a regulatory tool over time.     

基因毒性杂质的毒理学评估策略

基因毒性杂质的限度确定是药物安全研究的重要内容.有潜在基因毒性的杂质根据其结构特征和毒理学数据可分为5类:已知有致突变性及致癌性的杂质、有致突变性但致癌性未知的杂质、含有与药物活性成分结构无关的警示结构但无致突变性数据的杂质、含与药物活性成分相关警示结构的杂质以及致癌风险高的特殊杂质.本文以毒理学评价的方法,分类对基因...     

Common Deficiencies of <Emphasis Type="Italic">in vitro</Emphasis> Binding Bioequivalence (BE) Studies Submitted in Abbreviated New Drug Applications (ANDAs)

There are several drug products that bind phosphate or bile acid in the gastrointestinal (GI) tract to exert their therapeutic efficacy. In vitro binding studies are used to assess bioequivalence (BE) of these products. The objective of this study is to identify the common deficiencies in Abbreviated New Drug Applications (ANDAs) for these products. Deficiencies were compiled from ANDAs containing in vitro binding BE studies. The deficiencies were classified into eight categories: Pre-Study Method Validation, During-Study Sample Analysis, Study Design, Study Procedure, Dissolution/Disintegration, Analytical Site Inspection, Data Submission, and Formulations. Within each category, additional subcategories were defined to characterize the deficiencies. A total of 712 deficiencies from 95 ANDAs for 11 drug products were identified and included in the analysis. The four categories with the most deficiencies were During-Study Sample Analysis (27.8%), Pre-Study Method Validation (17.3%), Data Submission (16.7%), and Study Design (15.7%). For the During-Study Sample Analysis category, failure to submit complete raw data or analytical runs ranked as the top deficiency (32.8%). For the Study Design category, using an unacceptable alternate study design (26.8%) was the most common deficiency. Within this category, other commonly occurring deficiencies included incorrect/insufficient number of absorbent concentrations, failure to pre-treat drug product with acid, insufficient number of replicates in study, incorrect calculation of k1 and k2 values, incorrect dosage form or pooled samples used in the study, and incorrect pH of study medium. The review and approval of these products may be accelerated if these common deficiencies are addressed in the original ANDA submissions.     

Points to Consider when Establishing Drug Product Specifications for Parenteral Microspheres

Drug product specifications are a critical element of a good control strategy. Parenteral microsphere products are complex dosage forms, requiring careful development of test methods and acceptance criteria for the specifications. In particular, the in vitro release test method and acceptance criteria require rigorous scientific consideration and should be developed with an eye toward understanding the mechanisms of drug release. The final specifications need to ensure the safety, identity, strength, performance, and quality of the drug product at release and during storage through the end of its shelf-life. The specification limits are typically established based upon regulatory guidance, available data from the manufacturing process (process capability), from non-clinical, clinical, and stability studies.     

FDA“简化新药申请的透皮和局部给药系统黏附性评估的供企业用指导原则草案”介绍

美国食品药品管理局（FDA）于2023年4月发布了“简化新药申请的透皮和局部给药系统（TDS）黏附性评估的供企业用指导原则草案”,修订了2018年公布的同名指导原则草案。该修订的指导原则草案包括前言、背景、黏附性的评价、黏附性和生物等效性的综合评价以及数据提交格式5部分。重点讨论了仿制TDS黏附性的临床评价,包括其研究设计和实施以及统计分析。中国目前还没有类似的指导原则,详细介绍FDA的该指导原则草案,期望对我国仿制的TDS的黏附性评估的临床研究和药品监管部门的审评有帮助。     

Evaluation of blend uniformity and content uniformity based on 2003 stratified sampling guidance and 1999 blend uniformity analysis guidance: product A

In August 1999 the FDA issued a Draft Abbreviated New Drug Application (ANDA) Guidance for Industry titled "ANDA's: Blend Uniformity Analysis" that detailed blend uniformity sampling and acceptance criteria for the determination of final blend uniformity for generic drug products. Although this guidance was written specifically to address ANDA's, the guidance was also adopted as standard practice in the development of NDA's (New Drug Applications). The proposed release criteria established for blend uniformity were to be used in addition to, and independent from, the USP finished product uniformity release requirements. Based on the Blend Uniformity Guidance, batches that failed to meet the blend uniformity acceptance criteria should be rejected regardless of the products ability to demonstrate final product uniformity. In March 2002, the Product Quality Research Institute (PQRI) issued a proposal to the FDA with respect to both ANDA's and NDA's recommending the use of stratified sampling for final blend and in-process dosage units. The proposal recommended the use of final blend uniformity and dosage unit uniformity to demonstrate overall batch uniformity, with the possibility of using dosage unit uniformity in lieu of blend uniformity during routine commercial production. Consequently, in October 2003, the FDA issued a Draft Guidance for Industry titled "Powder Blends and Finished Dosage Units-Stratified In-Process Dosage Unit Sampling Assessment" that detailed the criteria for the use of stratified sampling and acceptance criteria to demonstrate batch uniformity. In response to the PQRI proposal, Endo Pharmaceuticals conducted an impact evaluation of the proposed PQRI sampling procedures and acceptance criteria on a product-by-product basis as compared to the 1999 Draft Guidance and current USP requirements. The evaluation of Product A demonstrates the benefit of implementing the 2003 Guidance for products that demonstrate questionable blend uniformity but acceptable finished product uniformity.     

Product selection, bioequivalence, and therapeutic equivalence: the generic drug market

Pharmacists are continually faced with drug product selection decisions. When is a generic drug product equivalent to the innovator product and, thus, a suitable candidate for generic substitution? The FDA policy has been that only drug products that are therapeutic equivalents are candidates for product selection decisions. This paper outlines the regulatory and scientific framework for the FDA's policies and requirements for generic drug products. The history and current status of the Drug Efficacy Study Implementation (DESI) project is described. Originally begun in 1966 as a review of about 3,400 drug products, the review in mid-1983 is more than 90% complete, but its impact has already affected more than 7,000 marketed drug products. The therapeutic equivalence policy and the manner in which decisions on therapeutic equivalence are communicated are reviewed. Regulatory policies for the approval of generic drug products are reviewed and specific litigation challenging the rights of generic drug manufacturers to produce generic "look-alikes" and challenging the FDA's policy that a generic drug product is a new drug requiring an approved New Drug Application for marketing is discussed. The conclusion reached is that the evaluation of regulatory requirements and science is leading to a point where all generic drug products will be known to be safe, effective and therapeutically equivalent, and pharmacists can be optimistic about the quality of products in the generic drug market.     

Progress in QSAR toxicity screening of pharmaceutical impurities and other FDA regulated products

Active ingredients in pharmaceutical products undergo extensive testing to ensure their safety before being made available to the American public. A consideration during the regulatory review process is the safety of pharmaceutical contaminants and degradents which may be present in the drug product at low levels. Several published guidances are available that outline the criteria for further testing of these impurities to assess their toxic potential, where further testing is in the form of a battery of toxicology assays and the identification of known structural alerts. However, recent advances in the development of computational methods have made available additional resources for safety assessment such as structure similarity searching and quantitative structure-activity relationship (QSAR) models. These methods offer a rapid and cost-effective first-pass screening capability to assess toxicity when conventional toxicology data are limited or lacking, with the potential to identify compounds that would be appropriate for further testing. This article discusses some of the considerations when using computational toxicology methods for regulatory decision support and gives examples of how the technology is currently being applied at the US Food and Drug Administration.     

Liposomal Drug Product Development and Quality: Current US Experience and Perspective

Research in the area of liposomes has grown substantially in the past few decades. Liposomes are lipid bilayer structures that can incorporate drug substances to modify the drug’s pharmacokinetic profile thereby improving drug delivery. The agency has received over 400 liposomal drug product submissions (excluding combination therapies), and there are currently eight approved liposomal drug products on the US market. In order to identify the pain points in development and manufacturing of liposomal drug products, a retrospective analysis was performed from a quality perspective on submissions for new and generic liposomal drug products. General analysis on liposomal drug product submissions was also performed. Results indicated that 96% of the submissions were Investigational New Drug (IND) applications, 3% were New Drug Applications (NDAs), and the remaining 1% was Abbreviated New Drug Applications (ANDAs). Doxorubicin hydrochloride was the most commonly used drug substance incorporated into the liposomes (31%). The majority of the liposomal products were administered via intravenous route (84%) with cancer (various types) being the most common indication (63%). From a quality perspective, major challenges during the development of liposomal drug products included identification and (appropriate) characterization of critical quality attributes of liposomal drug products and suitable control strategies during product development. By focusing on these areas, a faster and more efficient development of liposomal drug products may be achieved. Additionally, in this way, the drug review process for such products can be streamlined.     

How Has CDER Prepared for the Nano Revolution? A Review of Risk Assessment,Regulatory Research,and Guidance Activities

The Nanotechnology Risk Assessment Working Group in the Center for Drug Evaluation and Research (CDER) within the United States Food and Drug Administration (FDA) was established to assess the potential impact of nanotechnology on drug products. One of the working group’s major initiatives has been to conduct a comprehensive risk management exercise regarding the potential impact of nanomaterial pharmaceutical ingredients and excipients on drug product quality, safety, and efficacy. This exercise concluded that current review practices and regulatory guidance are capable of detecting and managing the potential risks to quality, safety, and efficacy when a drug product incorporates a nanomaterial. However, three risk management areas were identified for continued focus during the review of drug products containing nanomaterials: (1) the understanding of how to perform the characterization of nanomaterial properties and the analytical methods used for this characterization, (2) the adequacy of in vitro tests to evaluate drug product performance for drug products containing nanomaterials, and (3) the understanding of properties arising from nanomaterials that may result in different toxicity and biodistribution profiles for drug products containing nanomaterials. CDER continues to actively track the incorporation of nanomaterials in drug products and the methodologies used to characterize them, in order to continuously improve the readiness of our science- and risk-based review approaches. In parallel to the risk management exercise, CDER has also been supporting regulatory research in the area of nanotechnology, specifically focused on characterization, safety, and equivalence (between reference and new product) considerations. This article provides a comprehensive summary of regulatory and research efforts supported by CDER in the area of drug products containing nanomaterials and other activities supporting the development of this emerging technology.     

The use of stratefied sampling of blend and dosage units to demonstrate adequacy of mix for powder blends

In response to concerns expressed by applicants regarding inconsistent policies in establishing blend uniformity acceptance criteria to demonstrate adequacy of mix, the FDA Office of Generic Drugs (OGD) issued the draft document Guidance for Industry, ANDAs: Blend Uniformity Analysis (August 1999). Both generic and innovator pharmaceutical companies raised a number of concerns following the publication of this document. As a result, the Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) was established in February 2000. One of the primary goals of this group was to draft a scientifically based alternative to the OGD document. The resulting recommendation addresses both FDA and industry concerns by substantially enhancing product quality assurance without increasing regulatory burden. The PQRI BUWG recommends that these blend and dosage unit uniformity requirements be administered uniformly throughout the industry. PQRI submitted the following recommendation to the FDA on December 31, 2002, providing the Agency with an alternative strategy to consider when drafting future regulatory policy to assess blend and dosage unit uniformity.     

Common Deficiencies with Bioequivalence Submissions in Abbreviated New Drug Applications Assessed by FDA

Purpose

A generic product must meet the standards established by the Food and Drug Administration (FDA) to be approved for marketing in the USA. FDA approves a generic product for marketing if it is proved to be therapeutically equivalent to the reference product. Bioequivalence (BE) between a proposed generic product and its corresponding reference product is one of the major components of therapeutic equivalence. These approvals may be delayed if the BE portion of the submission is determined to be deficient. Many of these BE deficiencies recur commonly and can be avoided.

Method

We conducted a survey of the BE submissions to abbreviated new drug applications (ANDAs) over years 2001 to 2008 to identify the most commonly occurring BE deficiencies.

Results

Recurring deficiencies are found in a majority of the ANDAs reviewed by FDA’s Division of Bioequivalence. The most common deficiencies were the two deficiencies related to dissolution (method and specifications) found in 23.3% of the applications and analytical method validation and/or report found in 16.5% of the applications. The approval of generic drugs would be greatly accelerated if these deficiencies could be avoided.KEY WORDS: ANDA, bioequivalence, common deficiency, FDA     

Drug interactions evaluation: An integrated part of risk assessment of therapeutics

Pharmacokinetic drug interactions can lead to serious adverse events or decreased drug efficacy. The evaluation of a new molecular entity's (NME's) drug-drug interaction potential is an integral part of risk assessment during drug development and regulatory review. Alteration of activities of enzymes or transporters involved in the absorption, distribution, metabolism, or excretion of a new molecular entity by concomitant drugs may alter drug exposure, which can impact response (safety or efficacy). The recent Food and Drug Administration (FDA) draft drug interaction guidance (http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ucm072101.pdf) highlights the methodologies and criteria that may be used to guide drug interaction evaluation by industry and regulatory agencies and to construct informative labeling for health practitioner and patients. In addition, the Food and Drug Administration established a “Drug Development and Drug Interactions” website to provide up-to-date information regarding evaluation of drug interactions (http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm080499.htm). This review summarizes key elements in the FDA drug interaction guidance and new scientific developments that can guide the evaluation of drug-drug interactions during the drug development process.     

Application of emerging technologies in toxicology and safety assessment: regulatory perspectives

Emerging technologies applied in the regulatory field encompass a group of technologies that are used in addition to or in replacement of the standard toxicology studies conducted to support an Investigational New Drug Application (IND) or New Drug Application (NDA). The standard package includes general toxicology studies of various duration, safety pharmacology studies, genetic toxicology studies, and reproductive toxicology studies. New and emerging technologies applied to the regulation of new drugs include the use of novel biomarkers, transfected cells and transgenic animals, and the "omics" technologies (toxicogenomics, proteomics, and metabonomics). These technologies are at various stages of regulatory development and acceptance. For example, the use of transgenic animals have gained acceptance by regulatory authorities to replace a 2-year carcinogenicity assay. Alternatively, the "omics" technologies are not sufficiently advanced to achieve regulatory acceptance as replacements, although these assays have a role early in drug development and they may prove useful as supplements to standard studies. Data from these assays have been used to address specific mechanistic questions in combination with standard toxicology assays.     

Scientific Considerations of Pharmaceutical Solid Polymorphism in Abbreviated New Drug Applications

Purpose. This commentary is intended to provide a scientific perspective on pharmaceutical solid polymorphism in Abbreviated New Drug Applications (ANDAs). Methods. This report proposes recommendations for monitoring and controlling drug substance polymorphs and describes scientific considerations of pharmaceutical solid polymorphism in the determination of drug substance sameness. Results. It presents three decision trees for solid oral dosage forms or liquids containing undissolved drug substances to provide a process for evaluating when and how polymorphs of drug substances are monitored and controlled in ANDA submissions. Conclusions. It is scientifically concluded that differences in polymorphic composition of drug substances in generic drug products and reference-listed drugs are not directly relevant in the determination of drug substance sameness in ANDAs.