When considering a medication, it is necessary to understand its bioavailability. Bioavailability is the amount of a substance that can enter the bloodstream and have a positive effect on the body after it has been administered through a certain method. It's a measure of how well the body can absorb and use a drug or nutrient after it has been taken in by a particular route such as swallowing a pill or getting a shot. The amount of substance that enters the bloodstream can be influenced by different factors, such as the form and amount of the substance, how it's given, and the person's own physical state.

IV Ketamine has a bioavailability of 100%, while IM ketamine has a bioavailability of 93%. Intranasal administration of ketamine, including (S)-ketamine, has a range of 35% to 50% bioavailability. In contrast, oral ketamine has a bioavailability of approximately 20%. Although there are only a few studies, subcutaneous ketamine presents an intriguing alternative.