Ketamine: 50 Years of Modulating the Mind – PMC – PubMed Central (PMC)

Other routes of administration are less commonly used but exist as feasible options nonetheless. Intraosseous ketamine, for instance, has slightly slower anesthetic onset compared to IV administration (71.3 s and 56.3 s, respectively; Aliman et al., 2011) but may be used in emergency settings.Ketamine can also be administered intranasally, though it has a lower bioavailability of approximately …

https://pmc.ncbi.nlm.nih.gov/articles/PMC5126726/