A dose by any other name: neuroscience-based drug classification gains ground

The many leading journals who have already adopted Neuroscience-based Nomenclature (NbN) have now been joined by the Journal of Psychopharmacology.¹ This is an appropriate development since an editorial in this journal provided much of the initial impetus towards revising the way we describe the drugs used in psychiatry.²

Classifying agents according to our knowledge about their neurobiological effects, and not by indication, has for several years been the aim of expert groups that include the American, European and Asian Colleges of Neuropsychopharmacology. It is now becoming a reality. The new system is designed to be informative, precise and able to accommodate agents as yet undiscovered, which will have different targets. It also aims to help the prescriber decide which is the rational step to take next.

New terms for old

Broad acceptance of NbN means that we will not be using terms such as “anxiolytic” or “antipsychotic”, which group together agents that target different receptors and vary in mode of action. So patients with mental health problems should no longer be confused, and perhaps discouraged from taking drugs, by finding that an agent labeled an “antipsychotic” is being used, for example, to treat their depression; or that they have been given an “antidepressant” for their neuropathic pain.

The old nomenclature was confused and confusing

The building blocks of the new system are pharmacological domains based on the neurotransmitter, molecule or system being modified (norepinephrine, serotonin, dopamine, GABA, glutamate….) and ten modes of action. The latter are based on aspects of receptor, ion channel, uptake or enzyme activity.

App available to aid “translation”

The old class of “tricyclic antidepressants” was based on indication and chemical structure, but was not helpful with regard to mode of action. Imipramine, for example, would now be classified as a serotonin and norepinephrine reuptake inhibitor.

We used to have the indication-based class of antipsychotics, which were also known as neuroleptics or major tranquillizers, and subdivided into typical (or first generation) or atypical (second generation) subclasses. We now have agents classified, for example, as a dopamine and serotonin receptor partial agonist (D2, 5-HT1A).

An approved app available at http://nbnomenclature.org/ has been designed to aid “translation”.

The new system is designed to be precise and will accommodate agents as yet undiscovered

Along with the revised nomenclature, the new system provides for each agent a list of approved indications and information selected by the NbN Task Force on efficacy and major side effects, derived either from randomized controlled trials or widespread clinical experience.

Feedback invited

There are now more than a hundred different drugs used in psychiatry, and often the same type of drug is used for several different purposes. The old system of naming them has long been outgrown by our expanding knowledge and broader patterns of use. The ultimate aim is that the new system – based solidly on psychopharmacology – will better reveal gaps in current treatments, aid translational neuroscience, and so encourage the development of new agents effective in treating disorders of the brain.

A dose by any other name would treat as sweet

Commercial companies take great efforts with their brand names.³ It is good that psychopharmacologists too are taking nomenclature seriously: it took at least four years to produce the NbN. The Task Force that has devised the new system emphasizes that it represents only the current state of knowledge – not absolute truth – and will be continually updated in the light of new research findings.⁴ In this collaborative and open spirit, feedback and suggestions about the new system are encouraged. But what we already have represents a solid start.