Ketamine was approved by the FDA in 1970 and was originally used for the induction of anesthesia. It has been shown to relieve depression and is also widely used to treat pain. For depression, it is approved by the FDA in a nasal spray form. For severe pain, it is often given intravenously. Oral ketamine is probably the least effective.
In a recent study, Australian researchers compared the pain-relieving effect of oral and sublingual ketamine in 16 patients. The study was double-blind. Sublingual administration of ketamine resulted in a faster onset of pain relief – 7 minutes with sublingual and 13 with oral. Side effects were also more common with the sublingual route. In all other measures, sublingual and oral administration produced similar pain-relieving effects.
Oral and sublingual ketamine are not available at regular pharmacies. It is, however, easily made up by compounding pharmacies. The sublingual ketamine is available as a lozenge which is also called troche. I usually prescribe ketamine infusions or troches only after a wide variety of other treatments do not provide relief.
Ketamine is a controlled drug with a potential for misuse. It can also cause psychiatric side effects such as hallucinations, disinhibition, delusional thinking, and depression.
