Experimental Pathology Laboratories, Inc., which uses the trademark EPL, is a toxicologic pathology specialist in Sterling, Virginia. The company states that it was "founded in 1971" and is "a private, employee-owned U.S. company,"[S1] and describes its services as toxicologic pathology evaluation and consultation.[S1] No in-life study service was found on the pages reviewed; that is an absence in those pages, not a finding that EPL does not house or dose animals. The reviewed pages describe evaluation of tissue from studies conducted elsewhere. This profile summarizes the services, stated compliance information, and company facts most relevant to US sponsors.
Services relevant to US drug developers
Pathology and peer review
Pathology is the core line, covering histopathology evaluation, pathology peer review, Pathology Working Groups, carcinogenicity and chronic study pathology, transmission electron microscopy and research animal model support.[S3] The company states that its "board-certified pathologists bring deep expertise across all organ systems and most animal species commonly used in discovery, investigative, and preclinical safety assessment studies,"[S3] naming fourteen organ and therapeutic systems including cardiovascular, dermal, developmental immunotoxicology, hepatobiliary, lymphoid, male and female reproductive, nervous system, ocular, renal, respiratory and skeletomuscular pathology.[S3] For carcinogenicity work it names "traditional rodent bioassays and the rasH2 transgenic mouse model."[S3] Peer review and Pathology Working Groups matter to sponsors because sponsors commissioning peer review or a Pathology Working Group should define reviewer independence, scope, reconciliation and reporting in the protocol; those terms are easier to agree before the study than after a finding is disputed from the one that ran the study.
Histology, imaging, toxicology support, and data services
The company states that "EPL's histology labs provide everything from routine tissue processing and staining to advanced dissection and multiplex immunolabeling,"[S4] covering routine haematoxylin and eosin staining, immunohistochemistry and immunofluorescence, specialty histochemical stains, aquatic animal and avian histology, and necropsy.[S4] Imaging services cover whole slide scanning, image analysis and stereology.[S7] Transmission electron microscopy is performed at a named partner facility, the Bioscience Electron Microscopy Laboratory at the University of Connecticut, using "a JEOL 1400 transmission electron microscope, equipped with an AMT Nanosprint 43M Mark II CMOS camera."[S3] Toxicology support is offered jointly with a named partner: the company states that "EPL and Aclairo's board-certified experts bring deep expertise in toxicology, with several team members dual-certified in both pathology and toxicology."[S5] The nature of the relationship between the two organizations is not described on the site. Data services cover SEND dataset generation, offered since 2017,[S6] with the company stating that "from SEND dataset generation to custom formatting for unique sponsor needs, we ensure your data is accurate, validated, and tailored for its intended use."[S6]
Regulatory ecotoxicology assays
EPL offers histopathology for regulatory endocrine disruption assays. The company states that it "played a key role in the design and validation of original EPA and OECD Tier 1 and Tier 2 assays for endocrine disruption,"[S4] and names the Fish Short-Term Reproduction Assay, the Amphibian Metamorphosis Assay, the Medaka Extended One Generation Reproduction Test, the Larval Amphibian Growth and Development Assay and an avian two-generation toxicity test in Japanese quail.[S4] This is ecotoxicology rather than pharmaceutical safety work, and is relevant to agrochemical and chemical sponsors more than to drug developers.
Quality and compliance (as stated by the company)
GLP. The company states that it "ensures your studies align with Good Laboratory Practice (GLP) guidelines as defined by the US FDA, US EPA, OECD, and other international regulatory authorities,"[S3] and describes its research animal model pathology support and its electron microscopy work as GLP-compliant.[S3] The company names US FDA, US EPA, OECD in its GLP statement.[S3] GLP compliance is determined study by study under the applicable regulation, so sponsors should confirm in the protocol which regulation their study will follow and that the final report will carry the study director's compliance statement and the quality assurance unit's statement.[R2] No GCLP or CLIA statement was found, and no AAALAC accreditation, USDA registration, OLAW Animal Welfare Assurance or IACUC statement appears on the pages reviewed. That absence is consistent with a laboratory that receives tissue rather than housing animals; it is not a gap in the same sense it would be for an in-life CRO. AAALAC International accreditation is a voluntary evaluation of an institution's animal care and use program, re-evaluated every three years,[R3] and USDA registration and an OLAW Animal Welfare Assurance relate to the Animal Welfare Act and the PHS Policy respectively;[R4][R5] none of these establishes GLP compliance, which applies to individual studies.[R2] FDA does not approve or certify laboratories; registration with FDA does not denote approval.[R6]
Company facts
Legal name
Experimental Pathology Laboratories, Inc. (EPL)[S1]
Headquarters
45600 Terminal Drive, Sterling, VA 20166, United States[S1]
Sterling, VA (headquarters) and an EPL-Boston, Massachusetts operation; no street address is published for the Boston site[S1][S8]
Employees
Not published
Service scope
Pathology, peer review and Pathology Working Groups, histology, imaging, toxicology support with a partner, data services. No in-life study, safety pharmacology, DMPK or bioanalysis service statement was found on the pages reviewed; this is not a finding that EPL cannot provide or arrange those services[S3][S4][S5][S7]
Carcinogenicity pathology
Traditional rodent bioassays and the rasH2 transgenic mouse model[S3]
Electron microscopy
Performed at the Bioscience Electron Microscopy Laboratory, University of Connecticut, on a JEOL 1400 instrument[S3]
Toxicology partner
Delivered jointly with Aclairo; the relationship is not described on the site[S5]
FDA ? "Is It Really FDA Approved?" (FDA does not approve health care providers, including laboratories; registration does not denote approval); FDA Compliance Program 7348.808 (GLP inspections of nonclinical laboratories). https://www.fda.gov/consumers/consumer-updates/it-really-fda-approved (accessed 2026-09-03)
3 Recommended Contract Research Organizations
for Non-Clinical Studies
— by Target goal and Expertise
In non-clinical development, the choice of contract research organization shapes the quality of the data and the time it takes to reach the next decision. Below, three CROs are introduced by the type of study they support: pharmacology (efficacy) studies, safety studies, and pharmacokinetic (PK/PD) studies. Each summary describes the services the company offers so that you can match a provider to your target and development objective.
Pharmacology (Efficacy) StudiesDisease-Relevant Models for Translational Drug Evaluation
Reference: SMC Laboratories, Inc. official website (https://www.smccro-lab.com/)
SMC Laboratories, Inc.
SMC Laboratories is a specialized non-clinical CRO focused on in vivo pharmacology and efficacy studies using disease-relevant animal models, particularly in fibrosis, inflammation, metabolic diseases, and oncology.
Areas of Expertise
Disease-Relevant Model Portfolio
SMC Laboratories offers models covering the liver, lung, kidney, intestine, and oncology. Its portfolio includes the proprietary STAM™ model for MASH, fibrosis, and hepatocellular carcinoma.
Study Design Based on Target Biology
Study plans are developed around the target biology, mechanism of action, disease stage, and development objective. Pharmacological endpoints can be combined with histopathology, biomarkers, and disease-specific readouts.
Support from Target Validation to Proof of Concept
With experience from more than 1,000 studies for clients in 30 countries, SMC Laboratories supports programs from target validation and candidate selection through in vivo proof-of-concept studies.
Safety StudiesComprehensive Safety Assessment for Preclinical Development
Reference: Charles River Laboratories official website (https://www.criver.com/)
Charles River Laboratories
Charles River provides non-clinical toxicology and safety assessment services for programs ranging from exploratory safety studies to IND-enabling development.
Areas of Expertise
General Toxicology Across Study Designs
Services include single- and repeat-dose toxicology, dose-range finding, and general toxicology studies across multiple species and administration routes.
Non-GLP and GLP Study Support
Charles River supports both non-GLP and GLP studies, allowing sponsors to progress from early safety characterization to studies intended for regulatory submissions.
Integrated IND-Enabling Safety Assessment
Toxicology studies can be integrated with toxicokinetics, clinical pathology, histopathology, and safety pharmacology to support interpretation and IND-enabling safety packages.
Pharmacokinetic (PK/PD) StudiesConnecting Drug Exposure with Pharmacological Response
Reference: Inotiv official website (https://www.inotiv.com/)
Inotiv
Inotiv provides integrated PK/PD, DMPK, and bioanalytical services to characterize drug exposure and its relationship with pharmacological response.
Areas of Expertise
Pharmacokinetic Characterization
PK studies characterize exposure, half-life, clearance, and other pharmacokinetic parameters needed to understand how a candidate behaves in the selected model.
Exposure–Response Evaluation
Pharmacokinetic data can be combined with pharmacodynamic endpoints and bioanalysis to evaluate the relationship between drug exposure and pharmacological response.
Integrated DMPK and Development Support
Integrated DMPK, pharmacology, and safety information supports candidate comparison, dose selection, dosing-frequency optimization, and decisions about subsequent preclinical development.
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