What phase in drug development determines the appropriate dose with regard to safety and toxicity?

Phase I determines the appropriate dose with regard to safety and toxicity. Phase II is performed in 100 to 300 patients who have the disease or condition to be treated. Phase III conducted in larger (several hundred to several thousand) patients in groups that the medication is ultimately intended. A comparison is between new treatment and the standard therapy or placebo. The medication is used in the manner in which it will be used after approval.