Suppose you have binding of a certain Kd. If you wanted to change the molecule so it bound more tightly you might have an effect either on the "on rate constant " or the "off rate constant" or both. To increase affinity how these rate constants need to change? Drugs normally act by binding to some receptor or enzyme. Suppose a drug is given so that its concentration in cells is around the Kd for the ligand that it binds to. How much more effect could you expect if you gave 10X as much drug. What else might you expect to happen