68 nlr 45 in order to determine whether the molecule being tested is safe enough to put into a living system. The second stage is that of dosage studies, designed to come up with a metric for the dose of the drug to be admin-istered. Predictably, the efFcacy of a drug increases with its dose, but so too does its toxicity; the aim is therefore to Fnd an optimum range within which efFcacy is maximized without too greatly compromising safety. If the drug is too toxic when tried on animals, the trial will not proceed any further, but if acceptable dose ranges can be determined, the third stage is a three-phase trial in humans. Phase 1 trials are conducted on a small number of healthy volunteers to test the drug’s basic safety, since drugs that seem safe in animals may still show adverse effects in humans. Phase 2, which serves as a bridge, involves larger, scaled-up efFcacy and safety trials on as many as a few hundred subjects, who may be either patients or healthy individuals. Phase 3 involves large-scale randomized trials on
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