Comparison of Permitted Daily Exposure (PDE) Values for Active Pharmaceutical Ingredients (APIs) - Evidence of Robust Approach.

Permitted Daily Exposure Limits (PDEs) are set for Active Pharmaceutical Ingredients (APIs) to control cross-contamination when manufacturing medicinal products in shared facilities. With the lack of official PDE lists for pharmaceuticals, PDEs have to be set by each company separately. Although general rules and guidelines for the setting of PDEs exist, inter-company variations in the setting of PDE occur and are considered acceptable within a certain range. To evaluate the robustness of the PDE approach between different pharmaceutical companies, data on PDE setting of five marketed APIs (amlodipine, hydrochlorothiazide, metformin, morphine, and omeprazole) were collected and compared. Findings show that the variability between PDE values is within acceptable ranges (below 10-fold) for all compounds, with the highest difference for morphine due to different Point of Departures (PODs) and Adjustment Factors (AFs). Factors of PDE variability identified and further discussed are: (1) availability of data, (2) selection of POD, (3) assignment of AFs, (4) route-to-route extrapolation, and (5) expert judgement and differences in company policies. We conclude that the investigated PDE methods and calculations are robust and scientifically defensible. Additionally, we provide further recommendations to harmonise PDE calculation approaches across the pharmaceutical industry.

Identifying nonhazardous substances in pharmaceutical manufacturing and setting default health-based exposure limits (HBELs).

Contract Development and Manufacturing Organizations (CDMOs) that manufacture large, diverse portfolio of chemical and pharmaceutical substances require pragmatic risk-based decisions with respect to the safe carry-over between different chemical entities, as well as for worker protection. Additionally, CDMOs may not have access to primary study data, or data are generally lacking for a specific substance. While pharmaceuticals require the establishment of health-based exposure limits (HBELs) (e.g., occupational exposure limits [OELs] and permitted daily exposure [PDE] limits), the limits for nonhazardous substances could be set in a protective and pragmatic way by using default values, when internally required. Because there is no aligned definition provided by authorities, nor agreed default values for nonhazardous substances, we provide a decision tree in order to help qualified experts (such as qualified toxicologists) to identify the group of nonhazardous substances and to assign default HBEL values for specific routes of exposure. The nonhazardous substances discussed within this publication are part of the following subgroups: (I) inactive pharmaceutical ingredients, (II) pharmaceutical excipients or cosmetic ingredients, (III) substances Generally Recognized as Safe (GRAS), and (IV) food ingredients, additives, and contact materials. The proposed default limit values are 1 mg/m3 for the OEL and 50 mg/day for the PDE oral and intravenous (IV) route.

Disease area and mode of action as criteria to assign a default occupational exposure limit.

In the early stages of drug research and development, there are only a few or no toxicological data available for newly synthesized small molecule drug candidates (DC). Calculation of the DC's occupational exposure limit (OEL) without toxicological data is not possible. Nevertheless, an OEL is needed to indicate the level of protection required to minimize risks for laboratory researchers and technicians. For this reason, simplified guidance is required to predict possible health hazards of DCs and their corresponding safe inhalation exposure levels. Here, we evaluated 860 drug substances (DS) with OELs calculated by Novartis and grouped the DSs by disease area (DA) and then their mode of action (MoA). 28% of the evaluated DSs (n = 242) had an OEL <10 µg/m3 and 72% (n = 618) had an OEL ≥10 µg/m3. Our evaluation confirms that in the absence of any compound-specific data, the default OEL of 10 µg/m3 is a reasonably safe exposure limit for small molecule DCs. Furthermore, our analysis suggests certain DAs and MoAs as valid criteria that may be integrated into a company's specific strategy for the assessment of data-poor compounds in order to identify DCs in an early stage of their development which require a default OEL <10 µg/m3.

Deriving harmonised permitted daily exposures (PDEs) for paracetamol (acetaminophen) CAS #: 103-90-2.

In the pharmaceutical industry, cleaning criteria are required for multipurpose manufacturing facilities. These Health Based Exposure Limits (HBELs), also called permitted daily exposures (PDEs) values, are derived from toxicological and pharmacological evaluation of the active pharmaceutical ingredients (APIs). The purpose of this publication is to show an example of how authors from different companies evaluate a generic drug, paracetamol, and discuss different approaches and relevance of the nonclinical studies for deriving PDEs. PDE limits of 25 mg/day for the oral route, and 20 mg/day for the intravenous (i.v.) and inhalation (inhal.) routes, respectively, were established herein. However, it has been already recognised that there are acceptable differences in the PDE calculations, which may be based on data accessibility, company-specific science-policy decisions or expert judgments. These differences can cause up to a 3-fold lower or higher values. If unnecessarily high factors are applied, this would result in a very conservative PDE value and unneeded additional cleaning and higher manufacturing costs. The PDE values presented are considered to be protective against adverse and pharmacological effects observed in clinical trials and in this case, a very long postmarketing period of paracetamol.

What to consider for a good quality PDE document?

For the handling of active pharmaceutical ingredients (APIs) and production of medicinal products in shared facilities, the European Medicines Agency (EMA) has introduced the determination of permitted daily exposure (PDE) values to provide limits for cross-contamination. APIs have a desired pharmacological effect in the patient who intendedly uses a certain medicinal product. However, this effect is undesired in a patient that receives this API unintendedly as a cross-contamination of another medicinal product. In particular, for approved APIs for human use, a multitude of data is available on the pharmacological activity as well as adverse effects, which have to be taken into account in PDE setting. Thus, the setting of PDEs for APIs needs a structured scientific evaluation of all properties and identification of the most critical effect, which is the basis for PDE calculation. In this publication, we provide guidance on points for consideration when setting PDEs for APIs, or when evaluating the quality of documents describing the derivation of PDEs received, e.g. by third parties.

Use of the permitted daily exposure (PDE) concept for contaminants of intravitreal (IVT) drugs in multipurpose manufacturing facilities.

A toxicological evaluation to determine the product specific permitted daily exposure (PDE) value is an accepted method to determine a safe limit for the carry-over of product residues in multipurpose manufacturing facilities. The PDE calculation for intravitreal (IVT) injection of small and large molecular weight (MW) drugs follows the guiding principles set for systemic administration. However, there are specific differences with respect to the volume administered with IVT administration, pharmacokinetic and pharmacodynamics (PK-PD) parameters and potential for toxicity. In this publication, we have proposed a method to derive PDEIVT in the presence of IVT dose. In the absence of an IVT dose we have a proposed default extrapolationof the systemic PDE for intravenous (IV) administration to the PDEIVT dose by applying a factor of 500 based on comparison of the volume of vitreous humour with the plasma volume, as well as provided examples for PK-PD and toxicity considerations.

Topical otic drugs in a multi-purpose manufacturing facility: a guide on determination and application of permitted daily exposure (PDE).

Due to newly introduced EU GMP (Good Manufacturing Practice) guideline for Medicinal Products for Human and Veterinary use, product specific permitted daily exposure (PDE) for toxicological evaluation in multi-purpose facilities are required within a documented process for risk assessment. European Medicines Agency (EMA) guidance on setting PDE limits so far focused on systemic administration routes such as intravenous (IV), oral or inhalation. This article provides guidance on setting PDE values for risk management purposes in multi-purpose facilities for active pharmaceutical ingredients (APIs) applied as topical otic drugs to the outer ear canal. The therewith determined PDE otic, is used for the calculation of maximum safe carry-over (MSC) in manufacturing scenarios where a topical otic product is manufactured followed by another topical otic product.

Determination and application of the permitted daily exposure (PDE) for topical ocular drugs in multipurpose manufacturing facilities.

Limits for the carry-over of product residues should be based on toxicological evaluation such as described in the "Guideline on setting health based exposure limits for use in risk identification in the manufacture of different medicinal products in shared facilities". The toxicological evaluation should be performed also for locally administered drugs to ensure patient safety. Currently, there is no guidance on setting PDE for ocular drug substances in particular. The purpose of this investigation was to identify and describe a method for calculating a PDE value for topical ocular drugs (PDEocular). As an alternative method, extrapolation of a PDE for systemically administered drugs to a PDEocular is presented. These methods may be applied in cross-contamination risk assessments for manufacturing of topical ocular drugs. Similarly, the methods apply to systemically administered drugs, if their production precedes manufacturing of a topical ocular drug. We have examined pharmacokinetic (PK) properties of topical ocular drugs and compared them to the PK parameters of systemically administered drugs. Furthermore, we examined possible adverse effects of the carry-over in topical ocular drugs at therapeutic doses.

Applicability of surface sampling and calculation of surface limits for pharmaceutical drug substances for occupational health purposes.

Within the context of Occupational Hygiene (OH), surface sampling has been employed as a method to assess surface levels of Active Pharmaceutical Ingredients (APIs). There are potentially a number of reasons surface samples are collected including assessing potential health risks, housekeeping and cleaning effectiveness. There are no internationally accepted standards relating to collecting or interpreting surface samples for OH purposes. In the past, surface sampling results have been applied not only for estimating risks due to dermal contact, but also for other routes of exposure (e.g. inhalation, ingestion, etc). In this publication, we provide a decision tree to support the decision and value of performing surface sampling. For scenarios without conceivable skin exposure due to applied risk mitigation measures or for substances that do not penetrate the skin, surface sampling may not be needed. If the workers' health is determined to be at risk for systemic effects via skin, we propose to use the skin Permitted Daily Exposure (PDEskin), a safe skin dose independent of the exposure scenario that takes into consideration skin absorption properties of substances. For the purpose of OH monitoring, the likelihood of dermal exposure has to be understood before taking any samples, using both the PDEskin to calculate the surface limit and appropriate validated monitoring method for the surface.

Setting Occupational Exposure Limits for Genotoxic Substances in the Pharmaceutical Industry.

In the pharmaceutical industry, genotoxic drug substances are developed for life-threatening indications such as cancer. Healthy employees handle these substances during research, development, and manufacturing; therefore, safe handling of genotoxic substances is essential. When an adequate preclinical dataset is available, a risk-based decision related to exposure controls for manufacturing is made following a determination of safe health-based limits, such as an occupational exposure limit (OEL). OELs are calculated for substances based on a threshold dose-response once a threshold is identified. In this review, we present examples of genotoxic mechanisms where thresholds can be demonstrated and OELs can be calculated, including a holistic toxicity assessment. We also propose a novel approach for inhalation Threshold of Toxicological Concern (TTC) limit for genotoxic substances in cases where the database is not adequate to determine a threshold.

Mutagenicity assessment strategy for pharmaceutical intermediates to aid limit setting for occupational exposure.

Pharmaceutical intermediates (IM) are used in the synthesis of active pharmaceutical ingredients. They are not intended for human administration, yet employees may be exposed to IM during the manufacturing process. In the context of occupational health, hazard assessment of IM is needed to identify potential intrinsic hazards which could cause unwanted adverse effects. In particular, a carcinogenic potential influences the protection strategy in the workplace. DNA reactive substances may, even if present at very low levels, lead to mutations and therefore, potentially cause cancer. The use of in silico methods to predict mutagenicity is increasingly acknowledged and implemented in the recently released ICH M7 guideline for the limitation of DNA reactive impurities. In this study we investigate the possibility to apply (quantitative) structure-activity-relationships ((Q)SARs) during hazard identification to reduce the number of Ames tests needed for a hazard assessment of IM while maintaining high standards of protection of employees. Ames test outcomes for 188 substances used in the pharmaceutical production were compared with their in silico predictions using two different (Q)SAR methodologies (knowledge based and statistical) complemented by expert knowledge. The results of the analysis showed that a negative prediction for mutagenicity provides a high confidence that the IM is not mutagenic in the Ames test with the negative predictive value of 97%. On the other hand the positive predictive value was only 57% and therefore considered too low to reliably consider positive predicted IM to be mutagenic. In order to avoid any unnecessary burden for occupational health purposes caused by falsely positive predicted IM, all positive predicted IM and those with insufficient coverage by the in silico systems are submitted to an Ames test to verify or reject the prediction. It is shown that the described in silico prediction approach ensures appropriate protection strategy of the employees. Resources for performing Ames tests which do not add additional or new information for the purpose of hazard assessment could be reduced.

Classification of dermal sensitizers in pharmaceutical manufacturing.

Workers in development and manufacturing of pharmaceuticals are at risk for occupational contact dermatitis (OCD) of irritative (ICD) or allergic (ACD) origin, due to contacts with reactive intermediates (IM) and drug substances (DS). We examined, if alternative methods could replace presently used animal tests for identification of ACD in pharmaceutical development and manufacturing, without apparent loss of worker health, in line with regulations. The status of alternative methods for regulatory toxicology for consumer products has recently been reviewed by the Organisation for Economic Co-operation and Development (OECD) and the European Commission's Joint Research Center (JRC) for the European Chemicals Agency (ECHA). They concluded that prediction of skin sensitization potential, extent and quality by in vitro methods, for regulatory assessments, will depend on the regulatory purpose and level of confidence required. Some alternative methods are currently in validation. Current Globally Harmonized System (GHS) regulations on classification, labeling and packaging of substances and mixtures depend on human and animal data, whereas alternative methods may provide supportive evidence. Since the levels of workplace skin exposure to DS and IM in manufacturing of pharmaceuticals are usually not known, it is not possible to conduct quantitative risk assessments based on threshold calculations for contact sensitizers.