Ratio of the systemic exposure from extravascular (ev) exposure to that following intravenous (iv) exposure as described by the equation: \[F=\frac{A_{\text{ev}}\ D_{\text{iv}}}{B_{\text{iv}}\ D_{\text{ev}}}\] where F is the bioavailabilty, A and B are areas under the (plasma) concentration-time curve following extravascular and intravenous administration, respectively, and Dev and Div are the administered extravascular and intravenous doses.