Pharmacokinetic studies: Oral ketamine may seem disadvantageous because of 17% bioavailability, mainly due to first-pass drug metabolism in the liver. However, there is not a wide variability in bioavailability from patient-to-patient (mean 16.6%, SE = 2.8%) and hence a predictable oral dosing can be achieved. Although investigators have tested formulations with sublingual or buccal transmucosal administration of ketamine, in practice they fail to increase the ketamine bioavailability versus oral ketamine. Ketamine as nasal spray is problematic for acute use, since the amount of drug is difficult to control using an atomizer.