When manufacturers develop drugs for human use, they start by testing a range of doses and schedules. In essence, they are looking to balance toxicity and efficacy. A higher dose may produce more biologic activity but at a cost of increased toxicity. A lower dose may be safer but might give up some biologic activity. If the drug is rapidly cleared, then more frequent dosing might be desirable. If the drug has a long half-life or has irreversible binding to the target, less frequent dosing may suffice.