Approved treatments for bipolar disorder include “mood stabilizers” and “antipsychotics,” outdated names that do not accurately reflect the spectrum of their clinical use and mechanisms of action, which can lead to confusion, stigma, non-prescription and non-adherence. The consequences of current “antipsychotic” nomenclature and how the field of psychiatry is evolving to address the issue of psychopharmacologic classification was the focus of a plenary session delivered by Dr. Manpreet Singh, a Professor in the Department of Psychiatry and Behavioral Sciences at the University of California Davis School of Medicine, during a virtual educational webinar called “Improving the Lives of Patients with Bipolar Disorder” offered by the Neuroscience Education Institute (NEI) on March 16, 2024.
Nomenclature in psychiatry and other fields of medicine
In most therapeutic areas, drug names are based on their principal mechanism of action (MOA) or pharmacological features.1 For example, in hypertension, some of the common drug classes are beta-blockers, calcium channel blockers, and diuretics. This nomenclature allows clinicians to combine drugs using rational polypharmacy and can help educate patients about the underlying biology of their disease. Moreover, MOA-based nomenclature is consistent and accurate irrespective of the condition being treated and it is less prone to stigma because it is not explicitly tied to a disease. Yet current nomenclature in psychopharmacology tend to be based on the initial or principal drug indication (e.g., antipsychotic for psychosis, antidepressant for depression), and often makes obscure comparisons (e.g., typical/atypical).2
Indication-based nomenclature is seldom used in other fields of medicine
That being said, a challenge with applying MOA-based nomenclature to psychotropics, including antipsychotics, is that they have pleiotropic receptor actions depending on the specific molecule, and they also target a broad range of symptoms that can be common to multiple indications (e.g., depressed mood is a core symptom of unipolar and bipolar depression, and it is common in many psychotic disorders).
Consequences of inaccurate or confusing terminology
One of the key issues with the current nomenclature for antipsychotics is that it has a profound impact on how care is delivered and thus on patient outcomes. Dr. Singh cited a recent survey of 200 healthcare providers (HCPs) and 200 patients with bipolar disorder that uncovered myriad negative consequences of the term “antipsychotics” for the management of non-psychotic disorders.3 Notably, HCPs were reluctant to discuss this type of medication with their patients with bipolar disorder and felt more comfortable prescribing antidepressants, resulting in the prescription of suboptimal therapy. Patients who were offered antipsychotics reported negative feelings about the medication because of the stigma associated with psychotic disorders and they were less likely to adhere to the prescribed treatment compared to mood stabilizers.
Inaccurate terminology can be confusing, lead to non-prescription by HCPs and non-acceptance by patients
Proposed classification and nomenclature for antipsychotics
Given the recognized problems with the current terminology, work is underway to develop a new nomenclature that is based on pharmacology and neuroscience, that is simple enough to be clinically useful but still reflects the nuances and complexities of the field, that informs clinical decisions, supports patient acceptance, and can adapt to accommodate new treatments. Several different nomenclature systems have been proposed, including psychopharmacodynamic-based, mechanistic-based, multi-axial, and even data-driven ‘fingerprint’ classification systems.1,2,4 However, no clear naming protocol has been found to be ideal, and many have been too complex. The leading contender to date is the neuroscience-based nomenclature (NbN) which combines elements of both pharmacology and MOA.5 In the NbN classification, medications are classified into 11 different pharmacological domains (e.g., dopamine, glutamate, norepinephrine, etc) and 10 MOAs (e.g., enzyme inhibitor, ion channel blocker, receptor antagonist, etc). Although this classification system is the most widely recognized and accepted of the classification proposals thus far, its uptake by clinicians, patients and society has lagged.
The neuroscience-based nomenclature is the most widely recognized and accepted classification system for psychotropic medications
The long and the short of adherence in bipolar disorder
Dr. Singh concluded her presentation by addressing how the nomenclature of antipsychotics in bipolar disorder could be undermining the use of a very useful treatment strategy: long-acting injectable (LAI) antipsychotics. Adherence to oral antipsychotics has been estimated to be as low as 30–60% in bipolar patients, and this in turn increases the risk of relapse, hospitalization, and suicide.6 Although LAI antipsychotics are associated with higher rates of adherence and have demonstrated efficacy and safety in the acute and maintenance treatment of bipolar disorder, evidence suggests that they are under-utilized,7 often due to HCP expectations that patients would refuse LAI antipsychotics or presenting them as an option would have a negative impact on the therapeutic alliance.8 Dr. Singh reiterated the importance of terminology and the very real negative impacts of the current “antipsychotic” nomenclature, notably lack of use of this valuable class of medications in patients with bipolar disorder.
“Antipsychotic” nomenclature may contribute to under-utilization of LAI antipsychotics in bipolar disorder
Our correspondent’s highlights from the symposium are meant as a fair representation of the scientific content presented. The views and opinions expressed on this page do not necessarily reflect those of Lundbeck.
