Selecting an antipsychotic is dependent on the patient’s previous experience with treatment, their preferences, and their values. I must make sure that whatever I am prescribing is going to reduce symptoms, first and foremost. This involves a discussion with the patient regarding their prior experiences. In addition, there are several adverse events that can occur with any antipsychotic medicine, and they often vary individually, such that a particular side effect may be experienced by some patients but not others. 

For me, the 3 adverse events that I think about with every patient are activation or akathisia, the degree of sedation or somnolence, and changes in weight that they may have experienced with previous treatments. These adverse events are relatively common with the medications that we use today, and the patient’s history of and susceptibility to these effects influence which agents I gravitate toward and which agents I tend to avoid. To continue taking a particular medication, the patient needs to perceive that it is a reasonable choice for them.

With respect to individual agents, if we look historically at the antipsychotics that have been available over the past half century, all of them were fairly similar in their significant association with drug-induced movement disorders. The second-generation antipsychotics, consistent with their definition as atypical, are less likely to cause movement disorders; however, this side effect is not eliminated completely. Early second-generation antipsychotics can cause weight gain, some to a more significant degree than others; with continued treatment, metabolic disturbances may develop, sometimes rather quickly. 

The most recently introduced second-generation antipsychotics have a lower risk of metabolic side effects, and I welcome having these additional options. The more choices that we have that are different, the better we will be able to select the right medication for each patient. What I find particularly exciting on the horizon are the novel antipsychotics with completely different mechanisms of action. Time will tell whether these agents will be better tolerated and more efficacious than previous agents for certain patients.

As Dr Citrome suggested, when selecting an antipsychotic medication, it is very important to have a process of shared decision making with the patient to understand what their prior experience has been and what their preferences are. Many patients perceive weight gain as the most troubling side effect, but there are certainly other side effects that may be troublesome but not as widely appreciated.

First-episode patients and early phase patients who are just beginning treatment with antipsychotic drugs are in a very critical stage that can really lay the foundation for what follows. We know that since the patient is drug naive, they are probably going to have a more significant response to lower doses of an antipsychotic medication compared with a more chronic patient. At the same time, since they have never taken these medicines, they will likely also be more sensitive to some of the side effects.

Early in the course of illness, many patients do not accept the fact that they are ill, and therefore many individuals do not really want to take medication. So, if they are taking treatment and they do experience side effects, it may provide an additional reason for them to discontinue that medication. In fact, we see a lot of data illustrating how frequently first-episode or early phase patients discontinue their treatment. In a situation where we do not have any information about prior antipsychotics (eg, first-episode or early phase patients), we really want to choose an agent that is well tolerated because it is going to have a tremendous impact on whether the patient will continue to take it.

The long-term side effect that patients have been particularly concerned about with the older drugs is tardive dyskinesia, which still occurs with some of the newer agents, but the risk is lower. However, the newer agents are also being used more broadly in patients with affective disorders, so we need to be on the lookout for tardive dyskinesia in a broader patient population. At present, the 3 novel agents that carry a low risk of tardive dyskinesia are brexpiprazole, cariprazine, and lumateperone, and, among the newer agents, lumateperone has a very good adverse-effect profile and is unusually well tolerated. Other long-term side effects that we are most concerned about are the metabolic side effects, and the newer drugs also, in general, have less propensity to produce these effects. That is good news.

As my colleagues have stated, the advantages of the newer antipsychotics have been predominantly related to improvements in tolerability. The last 3 antipsychotic agents to be approved by the US Food and Drug Administration were brexpiprazole, cariprazine, and lumateperone. Brexpiprazole and cariprazine, as dopamine partial agonists, are unlikely to raise serum prolactin. Hyperprolactinemia is an issue for many patients because it can result in endocrine adverse effects. Lumateperone, a dopamine D₂ antagonist with only modest D₂ receptor occupancy, is also unlikely to cause prolactin-related adverse effects or extrapyramidal symptoms. In clinical trials, the rate of extrapyramidal symptoms, including akathisia, with lumateperone was very low. Numerically, the rate of akathisia was even lower in the lumateperone group than in the placebo group. Lumateperone also has a very high affinity for serotonin 5HT_2A receptors, and antagonism of these receptors may contribute to its antipsychotic mechanism. This affinity for 5HT_2A receptors also helps to mitigate dopamine D₂–related adverse effects. 

As Dr Citrome said, the introduction of newer agents has improved on certain aspects of tolerability that may have been problematic for earlier second-generation antipsychotics. I think that one important advantage of having these newer agents, as Dr Kane alluded to, is that many patients do not want to be on a particular medication simply due to adverse effects. If we can find a medication to which a patient responds and that they also tolerate, it is really a win for everybody.