Maximum Tolerated Dose (MTD)
MTD is a toxicological measurement of the highest daily dose of a chemical that does not cause overt toxicity a few days to two weeks after a single dose in laboratory rodents. Mice or rats will be treated with various doses of agent via ip, iv or po to determine this dose range.  Mortality, weight change, signs of toxicity, clinical chemistry and hematology measurements will be performed on rodents along with gross pathology examination and sampling of tissues for histopathology analysis.

Acute Toxicity Testing
Acute toxicity testing in rodents is important in choosing the doses for repeated-dose studies later on and proving that toxicity occurs in the organs of interest.  The agent  may be administered ip, iv, or po over duration of a few days to two weeks after a single dose in mice or rats.  Parameters evaluated are mortality, clinical pathology of tissue, gross necropsy, weight change, and signs of toxicity.

Subacute/Subchronic Toxicity Testing (Repeated Dose)
Subacute and Subchronic Toxicity determines the systemic effect of repeated doses of an agent for duration of two weeks to no greater than 10% of the total life span of the mouse or rat. The test agent is administered to the rodent via iv, ip, or po and is observed each day for signs of toxicity: weight change, mortality, etc.  The effects of treatment are evaluated via gross necropsy and clinical pathology,  and a histopathology is conducted on all animals.