A preclinical contract research organization (CRO) runs the laboratory and animal studies a drug candidate needs before it can be given to people. Biotech and pharmaceutical sponsors use preclinical CROs to test whether a candidate works, how the body handles it, and whether it is safe enough to enter clinical trials, without building that capacity themselves.
Preclinical vs. Clinical CROs
The term "contract research organization" covers two quite different businesses. Clinical CROs manage human trials: site selection, patient recruitment, monitoring, data management and biostatistics, under Good Clinical Practice. Preclinical CROs work earlier, in the lab and the vivarium, and the studies they run are what make a first-in-human trial possible.
Preclinical work is governed by different rules. Pivotal safety studies are run under Good Laboratory Practice (21 CFR Part 58 in the US and the OECD GLP principles elsewhere), and animal work is overseen by an Institutional Animal Care and Use Committee or the national equivalent. Some large organizations offer both preclinical and clinical services, but sponsors usually evaluate the two separately because the facilities, teams and expertise involved have little overlap.
What Preclinical CROs Do
A complete preclinical program moves from discovery biology to an IND or CTA safety package. The main service areas are:
- In vivo pharmacology and efficacy Testing whether a candidate engages its target and changes a disease-relevant endpoint in an animal model, from oncology xenografts to neurodegeneration and pain models. In vivo pharmacology CROs
- DMPK and ADME In vitro ADME screening and in vivo pharmacokinetics show how a drug is absorbed, distributed, metabolized and eliminated, and guide dose selection. DMPK and ADME CROs
- Toxicology Dose-range finding, then GLP repeat-dose, genetic, reproductive and immunotoxicology studies that define a safe starting dose for humans. Toxicology CROs
- Safety pharmacology The ICH S7A core battery of cardiovascular, respiratory and CNS assessments, plus ICH S7B cardiac studies. Safety pharmacology CROs
- Bioanalysis and biomarkers Validated LC-MS/MS and ligand binding assays that measure drug levels, anti-drug antibodies and biomarkers in study samples. Bioanalytical CROs
- Specialized models and surgery CNS delivery by intrathecal, ICV and intra-cisterna magna routes, medical device implantation, and other surgical models where technique drives the result. CNS and neuroscience CROs
Types of Preclinical CROs
Preclinical CROs range from a few global safety assessment organizations with sites on several continents to hundreds of specialist labs. Full-service providers can run an entire IND-enabling package under one roof, which simplifies scheduling and reporting. Specialist labs focus on a species, disease area, modality or technique, such as nonhuman primate surgery, gene therapy biodistribution or CNS electrophysiology, and often bring deeper hands-on experience in that niche.
Many sponsors use both: a lead lab for pivotal GLP studies and specialists for discovery pharmacology or difficult in-life work. Academic core facilities and contract vivarium providers fill further gaps. Contract vivarium space suits teams that want to run studies themselves.
How to Choose a Preclinical CRO
Start from the study, not the vendor. Define the species, route of administration, endpoints, GLP status and timeline, then shortlist labs with documented experience of that combination. From there, compare:
- Relevant experience How many studies like yours the lab has run in the last few years, and whether the study director you will work with ran them.
- Regulatory standing GLP compliance status and recent inspection history for regulated work, and AAALAC accreditation for the animal program.
- Capacity and timeline Whether animals, rooms and staff are available when you need them, which is often the deciding factor for nonhuman primate studies.
- In-house support Bioanalysis, clinical pathology and histopathology under the same roof shorten timelines and simplify data transfer.
- Communication How often you will hear from the study team in-life, and how quickly unexpected findings are reported.
Our CRO selection guide covers this process in detail, and the species selection guide helps with the model choice that comes before it. Emerging and virtual biotechs may also find our preclinical outsourcing guide useful.
Finding Preclinical CROs Worldwide
Preclinical capacity is spread across North America, Europe and Asia-Pacific, with dense clusters in places such as Boston and Massachusetts, the Maryland BioHealth Capital Region, North Carolina, the United Kingdom and Western Europe, and China. Because OECD Mutual Acceptance of Data allows GLP studies from member countries to support filings elsewhere, many sponsors search internationally. You can browse CROs by location, or use the A–Z directory to see every listed lab.
Frequently Asked Questions
What is the difference between a preclinical CRO and a clinical CRO?
A preclinical CRO runs laboratory and animal studies before a drug is first given to people: pharmacology, pharmacokinetics, toxicology and safety pharmacology. A clinical CRO manages human trials, including site selection, patient recruitment, monitoring and data management. Some large organizations do both, but the work, facilities and regulations are different, so sponsors usually evaluate them separately.
What services do preclinical CROs offer?
Typical services include in vitro pharmacology and ADME, in vivo efficacy in disease models, pharmacokinetics and toxicokinetics, GLP and non-GLP toxicology, safety pharmacology, genetic toxicology, bioanalysis, pathology, and specialized surgical models such as intrathecal or intracerebroventricular delivery.
How many preclinical CROs are there?
There are several hundred preclinical CROs worldwide, from a handful of large safety assessment organizations to many specialist labs focused on a single species, disease area or technique. The InVivoLabs directory lists preclinical CROs across North America, Europe and Asia-Pacific, searchable by service, species and location.
How do I choose a preclinical CRO?
Start with the study type, species and route, then shortlist labs with documented experience in that combination. Check GLP status if the study will support a regulatory filing, AAALAC accreditation, capacity on your timeline, in-house bioanalysis and pathology, and how the lab communicates during the study. A short scientific call with the study director usually tells you more than a proposal.