Hi Frank, it is likely that when esketamine comes to the UK it will mirror the prescribing category for which it was initially intended in the US. This often saves the pharmaceutical firm time and money. The official prescribing category comes from the granted application of the drug from the FDA which states “for the treatment of treatment-resistant depression (TRD) in adults.“. However, this potential catergorisation does not mean it cannot be prescribed for bipolar disorder, it could be prescribed “off label“. Off label is when the prescriber has sufficient information as to the efficacy of a medicine outside of its common use. You might want to search scientific databases for papers which contain the keywords “bipolar” and “esketamine” for more information on this.