Pharmaceutical impurities: regulatory perspective for Abbreviated New Drug Applications

Impurities in drug substances and drug products have been important regulatory issues in the Office of Generic Drugs by having significant impact on the approvability of Abbreviated New Drug Application (ANDAs). This review begins with a discussion of ANDAs and its similarity/differences with NDAs, highlighting the importance of control of pharmaceutical impurities in generic drug product development and regulatory assessment. An overview of the FDA draft guidance documents "ANDAs: Impurities in Drug Substances" and "ANDAs: Impurities in Drug Products" are provided. This introduces the identification and qualification procedures for ANDAs and approaches to the establishment of acceptance criteria for both drug substance and drug product. Case studies included in this review illustrate the proposed pathway for determination of impurities and their acceptance criteria, based upon the general principles of these guidances.     

Toxicity of excipients--a Food and Drug Administration perspective

Excipients are essential components of drug products. They are also potential toxicants. Examples of known excipient-induced toxicities include renal failure and death from diethylene glycol, osmotic diarrhea caused by ingested mannitol, hypersensitivity reactions from lanolin, and cardiotoxicity induced by propylene glycol. Proposals to test or market new drug products in the United States should adequately address the safety of the proposed exposure to the excipients in those products. The specific safety data that may be needed will vary depending upon the clinical situation, including such factors as the duration, level, and route of exposure, but may include acute, repeat-dose, reproductive, and genetic toxicity data, carcinogenicity data, and specialized toxicology information, such as sensitization or local irritation data. Many guidances exist to aid in the development of pharmaceuticals, including the International Conference on Harmonization (ICH) documents and various Food and Drug Administration/Center for Drug Evaluation and Research (FDA/CDER) pharmacology and toxicology guidances. The FDA/CDER has recently adopted a new guidance for industry, "Nonclinical Studies for Development of Pharmaceutical Excipients," which focuses on issues associated with development of safety databases that will support clinical use of excipients in drug products. The new guidance document is introduced and discussed in this article.     

Toxicological overview of impurities in pharmaceutical products

While the use of pharmaceuticals is always a balance of risks and benefits, the same is not true for impurities in pharmaceuticals; impurities convey only risk. A number of international guidelines and regional guidances instruct drug developers and regulatory agencies on how to evaluate and control impurities in drug substances and drug products. While impurities should always be reduced to the lowest levels that are reasonably practical, it is acknowledged that impurities cannot be reduced to zero and specifications for impurities need to be established. This chapter discusses practical and theoretical methods for qualification of different classes of impurities.     

药物杂质的毒理学评价要求及进展

 药物原料或制剂中的杂质可能引起临床不良反应。杂质毒理学评价是药物研究的重要内容。ICH关于药物及制剂杂质方面指导原则规定了杂质的报告、鉴定和质控限度,含量超过质控限度的杂质应进行毒理学评价。但指导原则对于研发阶段的药物杂质和遗传毒性杂质的限度未作明确要求。EMEA对于遗传毒性杂质制定了专门的指导原则,引入了毒理学担忧阈值（TTC）的概念对遗传毒性杂质限度进行控制,遗传毒性杂质每日接触量应小于1.5 μg。FDA也推荐采用TTC原则控制遗传毒性和致癌性杂质。本文结合ICH,EMEA及美国FDA等指导原则,对药物杂质毒理学评价的要求及其进展进行了综述。     

Absorption Enhancers: Applications and Advances

Absorption enhancers are functional excipients included in formulations to improve the absorption of a pharmacologically active drug. The term absorption enhancer usually refers to an agent whose function is to increase absorption by enhancing membrane permeation, rather than increasing solubility, so such agents are sometimes more specifically termed permeation enhancers. Absorption enhancers have been investigated for at least two decades, particularly in efforts to develop non-injection formulations for peptides, proteins, and other pharmacologically active compounds that have poor membrane permeability. While at least one product utilizing an absorption enhancer for transdermal use has reached the market, quite a few more appear to be at the threshold of becoming products, and these include oral and transmucosal applications. This paper will review some of the most advanced absorption enhancers currently in development and the formulation technologies employed that have led to their success. In addition, a more basic review of the barriers to absorption and the mechanisms by which those barriers can be surmounted is presented. Factors influencing the success of absorption-enhancing formulations are discussed. If ultimately successful, the products now in development should offer non-injection alternatives for several peptide or protein drugs currently only administered by injection. The introduction of new absorption enhancers as accepted pharmaceutical excipients, and the development of formulation technologies that afford the greatest benefit/risk ratio for their use, may create opportunities to apply these enabling technologies more broadly to existing drugs with non-optimal delivery properties.     

Chemistry,Manufacturing, and Controls Information in NDAs and ANDAs,Supplements, Annual Reports,and Other Regulatory Filings

Advice to the pharmaceutical industry regarding the chemistry, manufacturing, and controls and microbiology (sterility assurance) information to be included in regulatory submissions to the Center for Drug Evaluation and Research (CDER) can be found in the pertinent statutes, regulations, and guidances. The primary statute is the Federal Food, Drug and Cosmetic Act (the Act); applicable regulations appear in 21 CFR 312 and 314. Neither the Act nor the regulations provide sufficient detail on the information that should be included in these submissions. Over the past 14 years CDER has issued a series of guidelines and guidances that provide specific detail related to the recommended filing mechanisms and information that CDER expects applicants to provide. Some of these guidances are applicable to original submissions and some are applicable to post-approval changes. This article will provide an overview of The Act, the pertinent regulations, and the pre- and post-approval guidances.     

Guidelines and pharmacopoeial standards for pharmaceutical impurities: Overview and critical assessment

ICH/regional guidances and agency scrutiny provide the regulatory framework for safety assessment and control of impurities in small-molecule drug substances and drug products. We provide a critical assessment of the principal impurity guidances and, in particular, focus on deficiencies in the derivation of the threshold of toxicological concern (TTC) as applied to genotoxic impurities and the many toxicological anomalies generated by following the current guidelines on impurities. In terms of pharmacopoeial standards, we aim to highlight the fact that strictly controlling numerous impurities, especially those that are minor structural variants of the active substance, is likely to produce minimal improvements in drug safety. It is believed that, wherever possible, there is a need to simplify and rebalance the current impurity paradigm, moving away from standards derived largely from batch analytical data towards structure-based qualification thresholds and risk assessments using readily available safety data. Such changes should also lead to a minimization of in vivo testing for toxicological qualification purposes. Recent improvements in analytical techniques and performance have enabled the detection of ever smaller amounts of impurities with increased confidence. The temptation to translate this information directly to the regulatory sphere without any kind of safety evaluation should be resisted.     

共无定形给药系统研究进展

共无定形药物是将活性药物成分和其他药物或辅料等小分子固体组分混合形成的一种二元单相无定形固体分散体给药系统。作为一种新颖的药物传递系统，共无定形药物可能改善水难溶性药物的溶解度和口服生物利用度问题，为仿制药物和复方药物的开发提供了新的策略和思路。近年来，共无定形药物在学术和制药工业领域受到广泛关注。本文综述了共无定形药物的载体材料的筛选、制备方法、物理稳定机制，以及体外溶出性能和体内吸收情况，并对共无定形药物的未来发展前景进行了展望。     

Green synthesis and properties of arginine derived complexes for assorted drug delivery systems: A review

In the current scenario, green technologies in chemistry and various fields create attention to every researcher. The green synthesis provides environmentally and eco-friendly raw materials and intermediate products, making a simple process without using harmful and toxic reactants. Amino acids are one of the reactants from which the intermediates or excipients can be made using the straightforward methodology, and these are utilized in drug delivery via a different route of Administration. By employing such medication at a cellular level, we can eliminate the adverse events and toxicity of chemically synthesized excipients and achieve a better therapeutic effect. In the present paper, Arginine was reviewed as the starting material from which the greener excipients can be synthesized, and these materials were employed for drug delivery systems. However, some of the synthetic processes employed chemicals, and also usage of the synthesized green material in the formulation of different dosage forms may require proper guidelines, but still, the research is going on for the application of green excipients for therapeutic purposes. Moreover, Arginine, as such, is an amino acid. It can also be utilized in different formulations as an active ingredient, which was also emphasized in the review paper from past research and patents.This review aims to be comprehensive and have general interest for chemists as it involves the various routes by which excipients were synthesized and the study, including the properties of different excipients and their application.     

Excipient-drug interactions in parenteral formulations

Excipients are added to parenteral formulations to enhance or maintain active ingredient solubility (solubilizers) and/or stability (buffers, antioxidants, chelating agents, cryo- and lyoprotectants). Excipients also are important in parenteral formulations to assure safety (antimicrobial preservatives), minimize pain and irritation upon injection (tonicity agents), and control or prolong drug delivery (polymers). These are all examples of positive or synergistic interactions between excipients and drugs. However, excipients may also produce negative effects such as loss of drug solubility, activity, and/or stability. This review article will highlight documented interactions, both synergistic and antagonistic, between excipients and drugs in parenteral formulations. The reader will gain better understanding and appreciation of the implications of adding formulation ingredients to parenteral drug products.     

Case studies with new excipients: development, implementation and regulatory approval

The purpose of this article is to describe the process whereby new excipients become accepted and to describe three case studies to illustrate the process. New excipients are defined according to the 2005 FDA Guidance on Nonclinical Safety Evaluation of New Excipients. The requirements for safety data submission for new excipients used in different classes of products for different durations are outlined in the guidance. Currently, the development of new excipients is linked to the development and approval of new drug products that contain them. New excipients that are used in US-approved drug products become listed in the FDA Inactive Ingredients Guide (IIG) database. Thereafter, US Pharmacopeia monographs for the new excipients are proposed. New excipients are reviewed and become accepted in the same way in Europe and Japan, except that there is no equivalent IIG database. Therefore, the focus of this article will be on the FDA review process. Three case studies, polyoxyl 15 hydroxystearate, sulfobutyl ether cyclodextrin and silicified microcrystalline cellulose, are used to illustrate how new excipients are accepted and implemented.     

Pharmaceutical excipient development: the need for preclinical guidance

Pharmaceutical excipients have a vital role in drug formulations, a role that has tended to be neglected as evidenced by the lack of mechanisms to assess excipient safety outside a new drug application process. Currently, it is assumed that an excipient is "approved" when the new drug formulation, of which it is a constituent, receives regulatory acceptance. Existing regulations and guidelines indicate that new (novel) excipients should be treated as new chemical entities with full toxicological evaluation. No guidance is available for potentially useful materials (essentially new excipients) available from other industries, e.g., food additives or for established excipients with a new application, e.g., dose route change. However, despite this situation, drug companies are actively evaluating new materials or applying new uses to established excipients. Recently developed excipients (e.g., materials giving "sugar-free" status to medical preparations, the cyclodextrins, and the hydrofluoroalkane inhalation propellants) and excipients undergoing development (e.g., chitosan, various enteric coating substances, liposomes, polymers derived from glycolic and lactic acids, and vaccine adjuvants) are all discussed. In light of many other areas of drug development having recently benefited from new or updated regulatory guidance, specific guidance to assist companies in the development of their excipients is urgently needed. Also, an excipient testing strategy would be an excellent topic for inclusion for International Conference on Harmonisation (ICH) consideration. Such guidance/discussion would complement the current advances in pharmacopoeial standardization of excipient quality. As a consequence, it may be possible to have excipients reviewed by a committee of an international pharmacopoeia with the safety data assessed by elected experts and published.     

Strategies for the identification, control and determination of genotoxic impurities in drug substances: a pharmaceutical industry perspective

Regulations alarmed the control of genotoxic impurities in drug substances at lower level based on the threshold of toxicological concern and daily dose. This review explores the details of various regulations and guidances, toxicology assessment, identification of structural alerts, synthetic origins, different synthetic approaches for elimination or control, various analytical determination strategies and pharmaceutical industry concern towards genotoxic impurities.     

The Impact of N-nitrosamine Impurities on Clinical Drug Development

Over the past few years, an increasing number of commercially available drugs have been reported to contain N-nitrosamine impurities above acceptable intake limits. Consequent interruption or discontinuation of the manufacturing and distribution of several marketed drugs has culminated into shortages of marketed drugs, including the antidiabetic drug metformin and the potentially life-saving drug rifampin for the treatment of tuberculosis. Alarmingly, the clinical development of new investigational products has been complicated as well by the presence of N-nitrosamine impurities in batches of marketed drug. In particular, rifampin is a key clinical index drug employed in drug-drug interaction (DDI) studies, and as a result of nitrosamine impurities regulatory bodies no longer accept the administration of rifampin in DDI studies involving healthy subjects. Drug developers are now forced to look at alternative approaches for commonly employed perpetrators, which will be discussed in this review.     

Lipid-based formulations for oral administration of poorly water-soluble drugs

Lipid-based drug delivery systems have shown great potentials in oral delivery of poorly water-soluble drugs, primarily for lipophilic drugs, with several successfully marketed products. Pre-dissolving drugs in lipids, surfactants, or mixtures of lipids and surfactants omits the dissolving/dissolution step, which is a potential rate limiting factor for oral absorption of poorly water-soluble drugs. Lipids not only vary in structures and physiochemical properties, but also in their digestibility and absorption pathway; therefore selection of lipid excipients and dosage form has a pronounced effect on the biopharmaceutical aspects of drug absorption and distribution both in vitro and in vivo. The aim of this review is to provide an overview of the different lipid-based dosage forms from a biopharmaceutical point of view and to describe effects of lipid dosage forms and lipid excipients on drug solubility, absorption and distribution.     

N-亚硝胺类基因毒性杂质的研究进展

自“缬沙坦事件”之后，N-亚硝胺类基因毒性杂质引起了业界的广泛关注。本文概述了药物中N-亚硝胺类基因毒性杂质和相关检测方法的研究进展，以及近20年来国内外有关药物中基因毒性杂质监管指南的完善历程。N-亚硝胺类基因毒性杂质作为一类高反应活性的基因毒性杂质，主要来源于药物合成过程中发生的副反应，以及药物在储存或者运输过程中发生的氧化或还原等反应。所有的动物实验表明，N-亚硝胺类具有很强的致癌性。在理论上，所有药物都存在N-亚硝胺类杂质或被N-亚硝胺类杂质污染的风险，由于该类化合物在药物中常以痕量形式存在，在分析检测过程中药物基质干扰大，因此建立便捷、高效的分析方法是非常有必要的。     

Toxicological Implications of Nasal Formulations

Various nasal formulations have been tested for their suitability to deliver drugs through the nasal cavity. This route is especially of interest where the dose of drug is small and the drug may undergo an extensive first-pass metabolism and/or decomposition while passing through the gastrointestinal tract. Unfortunately, the nasal mucosa does not have same type of tolerability to all drugs and additives used in formulations. Some chemicals may damage the nasal epithelia or alter the mucociliary defensive mechanism of the nose. There also is a possibility that the drug can transport directly from nasal cavity to the brain via the olfactory route. Several methods have been developed to study the impact of drugs and excipients on the integrity of the nose. In some cases, the in vitro results did not correlate well with in vivo data, due to lack of reproducibility of the natural body environment, and some in vitro methods may not be sensitive enough and thus may complicate interpretation of the results. This review provides a toxicological evaluation of different drugs and additives used to optimize a nasal formulation. Certain chemicals are now routinely used as additives in nasal formulations. Although these compounds are most likely safe, if they are used over the long term, they may damage the epithelia of the nose. For multidose preparations, preservatives are often included in nasal delivery systems and may cause ciliotoxic effects. Both physicochemical parameters of drugs as well as formulation materials should be considered in evaluating the overall effect ofa drug product on the nose. Therefore, any prior knowledge of the effect of drugs and additives on the nasal epithelia ultimately will assist in the development of nasal products. Furthermore, as the sites of absorption in the nasal cavity are somewhat limited, evaluation of the long-term tolerability of a nasal formulation is of great importance.     

ICH Q3D Drug Product Elemental Risk Assessment: The Use of An Elemental Impurities Excipients Database

The purpose of this publication is to show how an elemental impurities excipient database can be used in assisting the execution of a drug product elemental impurities risk assessment as required by the ICH Q3D guidelines. As a result of this exercise, we have demonstrated that the database, used in conjugation with other sources of information, is a credible source of elemental impurity levels in excipients therefore, a valuable source of information in completion of drug product risk assessments. This useful collection of data helps to reduce the burden of analytical testing for elemental impurities in excipients.     

语音播报提醒功能对早期药物临床试验中采血时间的影响

化药注射剂中的不溶性微粒可能从原辅包材料、生产过程、储存运输,以及使用过程中引入。控制注射剂中不溶性微粒的产生是减少输液不良反应、保障用药安全的重要措施。通过参考有关注射剂中不溶性微粒的国内外药典标准、指导原则和研究文献,探讨不溶性微粒产生的主要原因,并提出有效控制策略和相关建议,以期为控制化药注射剂的质量提供相应参考。