Plasma-concentration-time curves of fospropofol and propofol after intravenous, oral and intraduodenal administration of fospropofol to rats. Intravenous administration of fospropofol (5 mg/kg) resulted in the expected immediate high concentrations of both fospropofol (a) and propofol (b). Oral administration of higher doses of fospropofol (20 or 100 mg/kg) resulted in lower peak fospropofol plasma exposure (c) but significant and prolonged propofol exposure (d). Intraduodenal administration of high doses (30 or 100 mg/kg) resulted in similar fospropofol levels in the plasma (e) but relatively higher peak propofol exposure (f). Data shown as mean ± SEM.