Definition Bioavailability of IM, rectal, and PO routes are 87, 18, and 27%, respectively. According to Smith’s Anesthesia (Chapter 7), “times for peak serum concentrations after intramuscular, rectal, and oral administration were 15, 30, and 53 minutes, respectively, whereas the drug clearance and bioavailability via these three different routes were 10.4, 50.8, and 33.4 mL/kg […]