Setting impurity limits for endogenous substances: Recommendations for a harmonized procedure and an example using fatty acids

Endogenous substances, such as fatty, amino, and nucleic acids, are often purposefully used in parenterally pharmaceuticals, but may be present as impurities. Currently, no consensus guidance exists on setting impurity limits for these substances. Specific procedures are needed, as the amount and types of toxicity data available for endogenous substances are typically far less than those for other chemical impurities. Additionally, the parenteral route of administration of these substances is inherently non-physiological, resulting in potentially different or increased severity of toxicity. Risk Assessment Process Maps (RAPMAPs) are proposed as a model to facilitate the development of health-based exposure limits (HBELs) for endogenous substances. This yielded a framework that was applied to derive HBELs for several fatty acids commonly used in parenteral pharmaceuticals. This approach was used to derive HBELs with further vetting based on anticipated perturbations in physiological serum levels, impacts of dose-rate, and consideration of intermittent dosing. Parenteral HBELs of 100-500 mg/day were generated for several fatty acids, and a proposed class-based limit of 50 mg/day to be used in the absence of chemical-specific data. This default limit is consistent with the low toxicity of this chemical class and ICH Q3C value for Class 3 solvents.

An Evaluation of the Occupational Health Hazards of Peptide Couplers

Peptide couplers (also known as amide bond-forming reagents or coupling reagents) are broadly used in organic chemical syntheses, especially in the pharmaceutical industry. Yet, occupational health hazards associated with this chemical class are largely unexplored, which is disconcerting given the intrinsic reactivity of these compounds. Several case studies involving occupational exposures reported adverse respiratory and dermal health effects, providing initial evidence of chemical sensitization. To address the paucity of toxicological data, a pharmaceutical cross-industry task force was formed to evaluate and assess the potential of these compounds to cause eye and dermal irritation as well as corrosivity and dermal sensitization. The goal of our work was to inform health and safety professionals as well as pharmaceutical and organic chemists of the occupational health hazards associated with this chemical class. To that end, 25 of the most commonly used peptide couplers and five hydrolysis products were selected for in vivo, in vitro, and in silico testing. Our findings confirmed that dermal sensitization is a concern for this chemical class with 21/25 peptide couplers testing positive for dermal sensitization and 15 of these being strong/extreme sensitizers. We also found that dermal corrosion and irritation (8/25) as well as eye irritation (9/25) were health hazards associated with peptide couplers and their hydrolysis products (4/5 were dermal irritants or corrosive and 4/5 were eye irritants). Resulting outcomes were synthesized to inform decision making in peptide coupler selection and enable data-driven hazard communication to workers. The latter includes harmonized hazard classifications, appropriate handling recommendations, and accurate safety data sheets, which support the industrial hygiene hierarchy of control strategies and risk assessment. Our study demonstrates the merits of an integrated, in vivo -in silico analysis, applied here to the skin sensitization endpoint using the Computer-Aided Discovery and REdesign (CADRE) and Derek Nexus programs. We show that experimental data can improve predictive models by filling existing data gaps while, concurrently, providing computational insights into key initiating events and elucidating the chemical structural features contributing to adverse health effects. This interactive, interdisciplinary approach is consistent with Green Chemistry principles that seek to improve the selection and design of less hazardous reagents in industrial processes and applications.

Special endpoint and product specific considerations in pharmaceutical acceptable daily exposure derivation

Recently, a guideline has been published by the European Medicines Agency (EMA) on setting safe limits, permitted daily exposures (PDE) [also called acceptable daily exposures (ADE)], for medicines manufactured in multi-product facilities. The ADE provides a safe exposure limit for inadvertent exposure of a drug due to cross-contamination in manufacturing. The ADE determination encompasses a standard risk assessment, requiring an understanding of the toxicological and pharmacological effects, the mechanism of action, drug compound class, and the dose-response as well as the pharmacokinetic properties of the compound. While the ADE concept has broad application in pharmaceutical safety there are also nuances and specific challenges associated with some toxicological endpoints or drug product categories. In this manuscript we discuss considerations for setting ADEs when the following specific adverse health endpoints may constitute the critical effect: genotoxicity, developmental and reproductive toxicity (DART), and immune system modulation (immunostimulation or immunosuppression), and for specific drug classes, including antibody drug conjugates (ADCs), emerging medicinal therapeutic compounds, and compounds with limited datasets. These are challenging toxicological scenarios that require a careful evaluation of all of the available information in order to establish a health-based safe level.

Use of acute and chronic ecotoxicity data in environmental risk assessment of pharmaceuticals

For many older pharmaceuticals, chronic aquatic toxicity data are limited. To assess risk during development, scale-up, and manufacturing processes, acute data and physicochemical properties need to be leveraged to reduce potential long-term impacts to the environment. Aquatic toxicity data were pooled from daphnid, fish, and algae studies for 102 active pharmaceutical ingredients (APIs) to evaluate the relationship between predicted no-effect concentrations (PNECs) derived from acute and chronic tests. The relationships between acute and chronic aquatic toxicity and the n-octanol/water distribution coefficient (D(OW)) were also characterized. Statistically significant but weak correlations were observed between toxicity and log D(OW), indicating that D(OW) is not the only contributor to toxicity. Both acute and chronic PNEC values could be calculated for 60 of the 102 APIs. For most compounds, PNECs derived from acute data were lower than PNECs derived from chronic data, with the exception of steroid estrogens. Seven percent of the PNECs derived from acute data were below the European Union action limit of 0.01 μg/L and all were anti-infectives affecting algal species. Eight percent of available PNECs derived from chronic data were below the European Union action limit, and fish were the most sensitive species for all but 1 API. These analyses suggest that the use of acute data may be acceptable if chronic data are unavailable, unless specific mode of action concerns suggest otherwise.

A risk-based approach to managing active pharmaceutical ingredients in manufacturing effluent

The present study describes guidance intended to assist pharmaceutical manufacturers in assessing, mitigating, and managing the potential environmental impacts of active pharmaceutical ingredients (APIs) in wastewater from manufacturing operations, including those from external suppliers. The tools are not a substitute for compliance with local regulatory requirements but rather are intended to help manufacturers achieve the general standard of "no discharge of APIs in toxic amounts." The approaches detailed in the present study identify practices for assessing potential environmental risks from APIs in manufacturing effluent and outline measures that can be used to reduce the risk, including selective application of available treatment technologies. These measures either are commonly employed within the industry or have been implemented to a more limited extent based on local circumstances. Much of the material is based on company experience and case studies discussed at an industry workshop held on this topic.

Threshold of toxicological concern (TTC) for developmental and reproductive toxicity of anticancer compounds

Pharmaceutical companies develop specialized therapies to treat late stage cancer. In order to accelerate life-saving treatments and reduce animal testing, compounds to treat life-threatening malignancies are allowed modified requirements for preclinical toxicology testing. Limited data packages in early drug development can present product quality challenges at multi-product manufacturing facilities. The present analysis established an endpoint-specific threshold of toxicological concern (TTC) for developmental and reproductive toxicity (DART) for anticancer compounds. A comprehensive database was created consisting of over 300 no-observed adverse effect levels (NOAELs) for DART of 108 anticancer compounds. The 5th percentile NOAEL for developmental and reproductive toxicity was 0.005 mg/kg/day (300 μg/day), resulting in a human exposure threshold of 3 μg/day assuming standard uncertainty factors and a 60 kg human bodyweight. The analysis shows this threshold is protective for developmental and reproductive toxicity of highly potent groups of anticancer compounds. There were similar TTC values calculated for direct-acting and indirect-acting anticancer compounds.

Application of the threshold of toxicological concern concept to pharmaceutical manufacturing operations

A scientific rationale is provided for estimating acceptable daily intake values (ADIs) for compounds with limited or no toxicity information to support pharmaceutical manufacturing operations. These ADIs are based on application of the "thresholds of toxicological concern" (TTC) principle, in which levels of human exposure are estimated that pose no appreciable risk to human health. The same concept has been used by the US Food and Drug Administration (FDA) to establish "thresholds of regulation" for indirect food additives and adopted by the Joint FAO/WHO Expert Committee on Food Additives for flavoring substances. In practice, these values are used as a statement of safety and indicate when no actions need to be taken in a given exposure situation. Pharmaceutical manufacturing relies on ADIs for cleaning validation of process equipment and atypical extraneous matter investigations. To provide practical guidance for handling situations where relatively unstudied compounds with limited or no toxicity data are encountered, recommendations are provided on ADI values that correspond to three categories of compounds: (1) compounds that are likely to be carcinogenic, (2) compounds that are likely to be potent or highly toxic, and (3) compounds that are not likely to be potent, highly toxic or carcinogenic. Corresponding ADIs for these categories of materials are 1, 10, and 100 microg/day, respectively.

Underascertainment of deaths using social security records: a recommended solution to a little-known problem

Complete and accurate ascertainment of vital status is of great importance in cohort studies. Recently, during the vital status ascertainment phase of an ongoing occupational mortality study, the authors discovered a potentially serious problem with use of the Pension Benefit Information Company's tracing service or any tracing that relies on records from the Social Security Administration (SSA) Death Master File to identify deaths. Their investigation revealed that a number of US states restrict the information in the SSA's Death Master File that is available to researchers and the public as a source of death information. As a result of these findings, the authors recommend a revised two-stage vital status tracing protocol. For stage I, data on all subjects for whom vital status is unconfirmed should be sent to the SSA. For stage II, information on all subjects to whom SSA assigned an unknown vital status as well as all subjects whom SSA identified as known decedents should be submitted to the National Death Index. This new protocol will enable researchers to maximize vital status ascertainment while containing costs associated with death identification.

A 50-year historical cohort mortality study of workers in a pharmaceutical plant

An historical cohort study was conducted of workers at a pharmaceutical manufacturing plant. The cohort mortality experience of workers ever employed at the plant over the period from 1950 to 1999 was examined. The 1958 workers accumulated 44,294 person-years of experience at the plant, and a total of 384 deaths were identified. Our findings from external comparisons based on standardized mortality ratios (SMRs) in the cohort provide no evidence of excess mortality risk from all causes combined (SMR=0.75), all cancers combined (SMR=0.96), or from certain other individual causes of death. No patterns of excess mortality risk were apparent after stratifying on age and sex or job classification. The mortality experience of this cohort was generally more favorable than that of the general population.