A tunable coating formulation is described for a drug delivery balloon comprising a therapeutic agent, an excipient and a plasticizer. The tunable coating includes a first therapeutic agent and a first excipient, and can have a second therapeutic agent and a second excipient. The first and second therapeutic agents have different dissolution rates during balloon inflation and therefore provide a coating that is tunable. The plasticizer in the formulation has a weigh ratio of excipient to plasticizer below 1:0.1.