Each class of product may undergo different types of preclinical research.  For instance, drugs may undergo pharmacodynamics (what the drug does to the body) (PD), pharmacokinetics (what the body does to the drug) (PK), ADME, and toxicology testing.  This data allows researchers to allometrically estimate a safe starting dose of the drug for clinical trials in humans.  Medical devices that do not have drug attached will not undergo these additional tests and may go directly to good laboratory practices (GLP) testing for safety of the device and its components. Some medical devices will also undergo biocompatibility testing which helps to show whether a component of the device or all components are sustainable in a living model. Most preclinical studies must adhere to GLPs in ICH Guidelines to be acceptable for submission to regulatory agencies such as the Food & Drug Administration in the United States.
Typically, both in vitro and in vivo tests will be performed.  Studies of drug toxicity include which organs are targeted by that drug, as well as if there are any long-term carcinogenic effects or toxic effects causing illness.