Effect of Sublingual Dexmedetomidine vs Placebo on Acute Agitation Associated With Bipolar Disorder: A Randomized Clinical Trial.

Importance: Acute agitation is common in patients with bipolar disorder and requires urgent management to relieve distress and to prevent escalation to aggressive behavior. Objective: To evaluate the effect of orally absorbed, sublingual dexmedetomidine, a selective α2A-adrenergic receptor agonist on symptoms of acute agitation in patients with bipolar disorder. Design, Setting, and Participants: Phase 3, randomized, double-blind, placebo-controlled trial conducted in 15 sites in the US with enrollment between February 24, 2020, and April 27, 2020, and final follow-up on May 21, 2020. A total of 380 adults with bipolar I or II disorder were randomized and 362 completed the study. Interventions: Participants were randomized to 3 groups: sublingual dexmedetomidine 180 µg (n = 127), sublingual dexmedetomidine 120 µg (n = 127), or placebo (n = 126). Main Outcomes and Measures: The primary efficacy end point was the mean change from baseline at 2 hours for the Positive and Negative Syndrome Scale-Excited Component (PEC) total score. The range of possible total scores is 5 (absence of agitation) to 35 (extremely severe). The secondary end point was the earliest time of a statistically significant change in PEC total score from baseline for the drug vs placebo. On the primary efficacy end point, to account for multiplicity associated with comparing 2 sublingual dexmedetomidine doses with placebo, the 2-sided significance level for each dose vs placebo was set at .025. Results: Of 380 patients randomized (mean age, 45.6 years; 54.8% women; and 56.1% Black individuals), 378 (99.5%) self-administered the study medication and completed the study. Baseline agitation was mild to moderate, with an overall mean PEC total score of 18.0. Two hours after taking the medication, the mean changes from baseline in PEC total score were -10.4 for sublingual dexmedetomidine 180 µg, -9.0 for sublingual dexmedetomidine 120 µg, and -4.9 for placebo. Least-square mean differences from placebo in the sublingual dexmedetomidine groups at 2 hours were -5.4 (97.5% CI, -6.6 to -4.2) for 180 µg and -4.1 (97.5% CI, -5.3 to -2.9) for 120 µg (both doses P < .001 vs placebo). Treatment effects began 20 minutes after taking the medication among patients in the sublingual dexmedetomidine groups (least-square mean difference for 180 µg, -1.1 [97.5% CI, -2.0 to -0.2]; P = .007; for 120 µg, -1.0 [97.5% CI, -1.9 to -0.1]; P = .009). Adverse events occurred in 35.7% of patients taking 180 µg of dexmedetomidine, 34.9% taking 120 µg, and 17.5% taking placebo. The most common adverse events (≥5%) in the respective 180 µg, 120 µg, and placebo groups were somnolence (21.4% and 20.6% vs 4.8%); dry mouth (4.8% and 7.1% vs 0.8%); hypotension (6.3% and 4.8% vs 0%); and dizziness (5.6% and 5.6% vs 0.8%). Conclusions and Relevance: Among patients with mild to moderate agitation associated with bipolar disorder, treatment with a sublingual film formulation of dexmedetomidine 120 µg or 180 µg, compared with placebo, resulted in significantly greater reduction in the agitation score at 2 hours. Further research is needed to understand the spectrum of patients for whom this treatment would be effective and feasible and to better understand the clinical importance of the observed effect size. Trial Registration: ClinicalTrials.gov Identifier: NCT04276883.

Efficacy and Safety of Fixed-Dose Esketamine Nasal Spray Combined With a New Oral Antidepressant in Treatment-Resistant Depression: Results of a Randomized, Double-Blind, Active-Controlled Study (TRANSFORM-1).

BACKGROUND: About one-third of patients with depression fail to achieve remission despite treatment with multiple antidepressants and are considered to have treatment-resistant depression. METHODS: This Phase 3, double-blind, multicenter study enrolled adults with moderate-to-severe depression and nonresponse to ≥2 antidepressants in the current depression episode. Eligible patients (N = 346) were randomized (1:1:1) to twice-weekly nasal spray treatment (esketamine [56 or 84 mg] or placebo) plus a newly initiated, open-label, oral antidepressant taken daily for 4 weeks. The primary efficacy endpoint was change from baseline to day 28 in the Montgomery-Asberg Depression Rating Scale total score, performed by blinded, remote raters. Based on the predefined statistical testing sequence, esketamine 84 mg/antidepressant had to be significant for esketamine 56 mg/antidepressant to be formally tested. RESULTS: Statistical significance was not achieved with esketamine 84 mg/antidepressant compared with antidepressant/placebo (least squares [LS] means difference [95% CI]: -3.2 [-6.88, 0.45]; 2-sided P value = .088). Although esketamine 56 mg/antidepressant could not be formally tested, the LS means difference was -4.1 [-7.67, -0.49] (nominal 2-sided P value = .027). The most common (>20%) adverse events reported for esketamine/antidepressant were nausea, dissociation, dizziness, vertigo, and headache. CONCLUSIONS: Statistical significance was not achieved for the primary endpoint; nevertheless, the treatment effect (Montgomery-Asberg Depression Rating Scale) for both esketamine/antidepressant groups exceeded what has been considered clinically meaningful for approved antidepressants vs placebo. Safety was similar between esketamine/antidepressant groups and no new dose-related safety concerns were identified. This study provides supportive evidence for the safety and efficacy of esketamine nasal spray as a new, rapid-acting antidepressant for patients with treatment-resistant depression. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02417064.

Drug Development in Psychiatry: The Long and Winding Road from Chance Discovery to Rational Development.

Based extensively on tables and figures, this chapter reviews drug development in psychiatry with an emphasis on antidepressants from 1950s to the present and then looks forward to the future. It begins with the chance discovery drugs and then moves to through their rational refinement using structure activity relationships to narrow the pharmacological actions of the drugs to those mediating their antidepressant effects and eliminating the effects on targets that mediate adverse effects. This approach yielded newer antidepressants which compared to older antidepressants are safer and better tolerated but nevertheless do still not treat the approximately 40% of patients with major depression (MD) which is unresponsive to biogenic amine mechanisms of action. This form of MD is commonly referred to as treatment resistant depression. Esketamine is an investigational antidepressant which has a novel mechanism of action: blockade of the glutamate NMDA receptor. Positive trials reported this year for esketamine make it likely this drug will be approved next year in the USA. These studies coupled with earlier studies with other NMDA drugs suggest approximately 60% of patient with TRD are rapidly and robustly responsive to this mechanism of action. Thus, there appears to be three forms of MD based on pharmacological responsiveness: (a) 60% responsive to biogenic amine mechanisms of action, (b) 24% (i.e., 40 × 60%) responsive to NMDA but not to biogenic amine mechanisms of action, and (c) 16% (i.e., 40 - 24%) not responsive to either of these mechanisms of action. Scientific investigation of these three groups may yield important information about the pathophysiology and/or pathoetiology of these different forms of MD. This information coupled with studies into the neurobiology (e.g., imaging studies, connectomes to name a few approaches being used) and genetics of MD should provide the fundamental knowledge which will permit a rational search for and discovery of newer antidepressant drugs and other somatic and psychotherapeutic approaches to the treatment of patients with different forms of MD based on pathophysiology and pathoetiology. Examples are given of how such discovery and development has occurred in other areas of medicine and even in central nervous system (CNS) space including six novel mechanisms of action CNS drugs which have been successfully developed and marketed over the last 25 years.

The Effect of Mineralocorticoid and Glucocorticoid Receptor Antagonism on Autobiographical Memory Recall and Amygdala Response to Implicit Emotional Stimuli.

BACKGROUND: Acutely elevated cortisol levels in healthy humans impair autobiographical memory recall and alter hemodynamic responses of the amygdala to emotionally valenced stimuli. It is hypothesized that the effects of the cortisol on cognition are influenced by the ratio of mineralocorticoid receptor to glucocorticoid receptor occupation. The current study examined the effects of acutely blocking mineralocorticoid receptors and glucocorticoid receptors separately on 2 processes known to be affected by altering levels of cortisol: the specificity of autobiographical memory recall, and the amygdala hemodynamic response to sad and happy faces. METHODS: We employed a within-subjects design in which 10 healthy male participants received placebo, the mineralocorticoid receptor antagonist spironolactone (600mg) alone, and the glucocorticoid receptor antagonist mifepristone (600mg) alone in a randomized, counter-balanced order separated by 1-week drug-free periods. RESULTS: On autobiographical memory testing, mineralocorticoid receptor antagonism impaired, while glucocorticoid receptor antagonism improved, recall relative to placebo, as evinced by changes in the percent of specific memories recalled. During fMRI, the amygdala hemodynamic response to masked sad faces was greater under both mineralocorticoid receptor and glucocorticoid receptor antagonism relative to placebo, while the response to masked happy faces was attenuated only during mineralocorticoid receptor antagonism relative to placebo. CONCLUSIONS: These data suggest both mineralocorticoid receptor and glucocorticoid receptor antagonism (and potentially any deviation from the normal physiological mineralocorticoid receptor/glucocorticoid receptor ratio achieved under the circadian pattern) enhances amygdala-based processing of sad stimuli and may shift the emotional processing bias away from the normative processing bias and towards the negative valence. In contrast, autobiographical memory was enhanced by conditions of reduced glucocorticoid receptor occupancy.

The Essential Parallels Between Clinical Practice and the Scientific Method.

This column presents a way of conceptualizing the clinical practice of medicine including psychiatry within the framework of the scientific method. The goal is to aid practicing clinicians as well as trainees. This conceptual framework will improve the care of patients as it applies a discipline relative to giving time-limited trials of the various treatments available and then an assessment of whether the treatment worked adequately or not and what to do in the latter case. In this way, this approach should decrease the risk of excessive multiple medication use to treat a specific patient. Incorporating this conceptual framework early in the training of mental health care prescribers would be desirable.

How the Food and Drug Administration Drug Approval Process Relates to the Potential Approval of Intravenous Racemic Ketamine for Treatment-resistant Major Depression.

This column focuses on the status of intravenous racemic ketamine for the treatment of patients suffering from a form of major depressive disorder that does not respond to trials of currently available biogenic amine antidepressants. To provide context, the column reviews the 3 pivotal elements of the usual Food and Drug Administration (FDA) drug approval process: (1) the unmet medical need (ie, the indication) for which the drug is being developed, (2) the efficacy of the drug for that condition, and (3) the safety/tolerability of the drug. This column is based on the author's 45-year history of drug development work and is not a statement of the FDA. There are typically 3 phases in the drug development process: (1) studies done in normal volunteers, (2) typically small-scale proof of concept studies, and (3) large-scale registration trials. This third phase is critical in determining the efficacy, safety, and tolerability of the drug in a manner that most closely follows the clinical use of the drug. This column focuses specifically on whether generally small-scale studies done in academic centers are sufficient for drug approval, and it briefly reviews lithium and clozapine as examples of psychiatric medications that had such academic research in the literature, as well as clinical use in other countries. Those data supported the unique value of these medications in patients with bipolar disorder and treatment-resistant schizophrenia (ie, the unmet medical need), respectively, and the findings led American psychiatrists to advocate for FDA approval of these medications. Their efforts led to the needed registration trials for FDA approval of these medications. This column reviews the key features of registration trials and the reason that they are critical for FDA approval, and it discusses 2 special considerations related to the intravenous administration of racemic ketamine. First, racemic ketamine is not esketamine but, instead, it contains R-ketamine in addition to S-ketamine (ie, esketamine). The second consideration is that differences between intravenous and intranasal administration may affect the safety of the drug. While safety concerns were specifically addressed in the registration trials for esketamine, comparable research remains to be done for intravenous racemic ketamine. Understanding how the FDA's drug approval process works is important for prescribers, their patients, and the public.

Cerebral Anoxia in an 18-year-old Patient Being Treated for Major Depressive Disorder: How Forensic Detective Work Uses Medical Knowledge Including Clinical Pharmacology to Solve Cases.

This column is the first of a 3-part series illustrating the importance of medical knowledge, including clinical pharmacology, in a forensic context. This first case involved an 18-year-old high school student who suffered an anoxic brain injury and remained in a state of permanent decorticate posture, unresponsive except for grunts and primitive movements until he died several years later. Our investigation began by ruling out plausible causes that were suggested by the defense in the malpractice suit. Once those possibilities were eliminated, the focus was on what accounted for the damage to the patient using general medical knowledge and clinical pharmacology. The 4 Ds of forensic psychiatry (duty, damages, dereliction, and direct cause) are the 4 elements that the plaintiff is required to prove in civil court to prevail in a malpractice suit and are applied to this case with a special focus on dereliction and direct cause. This catastrophic outcome was due to 3 factors. First, the patient had physiologically significant dehydration to the point that he had developed a reflex tachycardia to maintain his blood pressure. Second, the patient had been switched from extended to immediate-release quetiapine, resulting in a doubling of the peak concentration of the drug, which produced higher occupancy of alpha-1 adrenergic, histamine-1, and dopamine-2 receptors, causing a further drop in his blood pressure as well as increased sedation and impairment of his gag reflex. These effects occurred quickly because of the faster absorption of the IR formulation of the drug. Third, the patient had gone to sleep in a reclining chair so that his brain was above his heart and his lower extremities were below his heart, resulting in an increased "steal" of cardiac output going to his brain. These 3 factors together led the patient to aspirate and suffer a hypoxic brain injury after an episode of vomitus. This column explains the process by which the cause of this sad outcome was determined, how it was related to a dereliction of duty to the patient, and how other proposed causes were ruled out.

Life-threatening Rash Due to Lamotrigine and a Failure to Understand Its Pharmacology: How Forensic Detective Work Uses Medical Knowledge and Clinical Pharmacology to Solve Cases.

This column is the second of a 3-part series describing cases where general medical knowledge, including psychiatric and clinical pharmacology, were instrumental in determining dereliction and direct cause in a malpractice suit. This case summarizes how lamotrigine can cause dangerous consequences if its pharmacology is not properly understood. The case also illustrates how the 4 Ds of a forensic malpractice suit were met in this case. First, there was duty on the part of the prescriber which, if followed, would have prevented or minimized the damages experienced by the patient. Dereliction in the performance of a patient-physician treatment contract was a direct cause of the development of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) in this patient. An immune-mediated reaction to lamotrigine or one of its metabolites has been extensively reported in the literature, with the risk of this reaction increasing at higher doses and with more rapid titration, fulfilling the elements of direct cause. Dereliction implies a deviation from the standard of care. On the basis of the clinical information from the package insert, more likely than not a deviation from the standard of care occurred in this case when lamotrigine was titrated faster than recommended by the package insert.

A thorough QTc study of 3 doses of iloperidone including metabolic inhibition via CYP2D6 and/or CYP3A4 and a comparison to quetiapine and ziprasidone.

The potential for iloperidone, a D2/5-HT2A antipsychotic, to affect the heart rate-corrected QT interval (QTc) was assessed in the absence and presence of metabolic inhibitors in a randomized, open-label, multicenter study. QT interval prolongation by medications, including both conventional and atypical antipsychotic drugs, can predispose patients to cardiac arrhythmias and result in sudden death. Adults with schizophrenia or schizoaffective disorder and normal electrocardiograms at baseline (N = 188) were randomized 1:1:1:1:1 to iloperidone, 8 mg twice daily (BID), 12 mg BID, 24 mg once daily (QD); quetiapine, 375 mg BID; or ziprasidone, 80 mg BID during period 1 (no metabolic inhibitors present). Iloperidone BID produced mean changes in QTc Fridericia correction (QTcF) interval (8.5-9.0 milliseconds [ms]) similar to those produced by ziprasidone (9.6 ms) and higher than those produced by quetiapine (1.3 ms). Iloperidone, 24 mg QD, produced a mean QTcF change of 15.4 ms. Coadministration of metabolic inhibitors with iloperidone during periods 2 (paroxetine) and 3 (paroxetine and ketoconazole) resulted in greater increases in the QTc interval. Increased QTc was observed in individuals with specific cytochrome P450 2D6 polymorphisms. Up to 10% of patients on iloperidone experienced QTc intervals of 60 ms or longer in the presence of metabolic inhibition and QD dosing. However, no patients experienced QTc changes of clinical concern (QTc ≥ 500 ms). The most common adverse events with iloperidone were headache, anxiety, and dyspepsia. The only cardiovascular adverse events with iloperidone were non-concentration-dependent tachycardia that was mild in most patients and did not lead to further sequelae. Pharmacogenetics and recommendations are discussed.

Effect of food on the pharmacokinetics of lurasidone: results of two randomized, open-label, crossover studies.

OBJECTIVE: This study aimed to investigate the effect of prandial status and caloric and fat composition of meals on the pharmacokinetics of lurasidone. METHODS: Two randomized, open-label, crossover studies were conducted in clinically stable adults with schizophrenia or schizoaffective disorder. Study 1 (n = 16) evaluated the effect of fasting and three meal types (100 kcal/medium fat, 200 kcal/medium fat, and 800-1000 kcal/high fat), and Study 2 (n = 26) evaluated the effect of fasting and five meal types (350 kcal/high fat, 500 kcal/low fat, 500 kcal/high fat, 800-1000 kcal/low fat, and 800-1000 kcal/high fat) on the bioavailability of lurasidone. Subjects received lurasidone 120 mg once daily. Maximum serum concentration (Cmax ) and area under the serum concentration-time curve over the dosing interval (AUC0-tau ) were determined on Day 5 for each meal type. RESULTS: In Study 1, the geometric mean Cmax in the fasted state was 56.7 ng/mL compared with 123.0 ng/mL for the 800- to 1000-kcal meal; mean AUC0-tau was 360.0 versus 752.4 ng·h/mL (both p < 0.001). Lurasidone exposure following meals containing 100 and 200 kcal was substantially lower than with meals containing 800-1000 kcal. In Study 2, the geometric mean Cmax was 52.9 ng/mL in the fasted state, 161 ng/mL for the 350-kcal/high-fat meal, 135 ng/mL for the 500-kcal/high-fat meal, and 131 ng/mL for the 800- to 1000-kcal/high-fat meal; mean AUC0-tau was 390, 743, 727, and 769 ng·h/mL, respectively. For all comparisons, the 90% confidence interval of the fed to fasted ratios indicated nonequivalence. Lurasidone exposure was similar following meals containing 350-1000 kcal and was independent of fat content. CONCLUSION: Lurasidone should be administered with food-at least 350 kcal-to ensure maximum exposure.

Eight Clinical Cases and the Lessons They Taught.

Eight different cases are presented in this column, along with the lessons and principles that can be learned from each. The lessons and principles are general in nature and hence they are applicable to patients that readers will likely encounter.

Comparative Pharmacology of the 3 Marketed Dual Orexin Antagonists-Daridorexant, Lemborexant, and Suvorexant-Part 2. Principal Drug Metabolizing Enzyme, Drug-Drug Interactions, and Effects of Liver and Renal Impairment on Metabolism.

This column is the second in a 2-part series presenting the comparative pharmacology of the 3 Food and Drug Administration-approved dual orexin receptor antagonists, daridorexant, lemborexant, and suvorexant. Both of the columns in this series emphasize the pharmacokinetics of these drugs as they are relevant to their use as sleep medications. Although other classes of sleep medications are not discussed, the same pharmacokinetic principles also apply to them in terms of endeavoring to match the pharmacokinetics of an agent to the individual's usual sleep cycle. This second column in the series focuses on the metabolism of each of the 3 drugs by the cytochrome P450 enzyme CYP3A, guidance for using these agents in combination with drugs that are CYP3A inhibitors or inducers, and how to adjust dosing in patients with comorbid conditions such as hepatic or renal impairment.

Seven Mechanistically Different Classes of Medications Can Be Used to Treat Insomnia and Related Sleep Disorders.

This column reviews the neurobiology of the sleep-wake cycle as it is currently known, the 7 classes of currently available sleep-enhancing medications, and how their mechanisms of action relate to the neurobiology of sleep. Clinicians can use this information to select medications for their patients, which is particularly important because some patients respond to some of these medications but not others, or tolerate some but not others. This knowledge can also help the clinician switch among classes when a medication that was initially efficacious begins to fail a patient. It can also prevent the clinician from cycling through all of the members of a single medication class. Such a strategy is unlikely to be helpful for a patient except in the situation in which pharmacokinetic differences among members of the medication class result in some agents in that class being helpful for a patient who has either a delayed onset of action or undesirable carry-over effects with other agents in that class. An understanding of the classes of sleep-enhancing medications highlights the importance of knowing the neurobiology that underlies a psychiatric illness. The activity of a number of neurobiological circuits, such as the one reviewed in this column, has now been well established, while work to understand others is still at a much earlier stage. Psychiatrists who gain an understanding of such circuits will be better able to provide effective care for their patients.

Drug Development in Psychiatry: The Long and Winding Road from Chance Discovery to Rational Development.

Based extensively on tables and figures, this chapter reviews drug development in psychiatry with an emphasis on antidepressants from the 1950s to the present and then looks forward to the future. It begins with the chance discovery drugs and then moves to through their rational refinement using structure activity relationships to narrow the pharmacological actions of the drugs to those mediating their antidepressant effects and eliminating the effects on targets that mediate adverse effects. This approach yielded newer antidepressants which compared to older antidepressants are safer and better tolerated but nevertheless do still not treat the approximately 40% of patients with major depression (MD) which is unresponsive to biogenic amine mechanisms of action. This form of MD is commonly referred to as treatment resistant depression. Esketamine is an antidepressant which has a novel mechanism of action: blockade of the glutamate NMDA receptor. These studies coupled with earlier studies with other NMDA drugs suggest approximately 60% of patient with TRD are rapidly and robustly responsive to this mechanism of action. Thus, there appears to be three forms of MD based on pharmacological responsiveness: (a) 60% responsive to biogenic amine mechanisms of action, (b) 24% (i.e., 40 × 60%) responsive to NMDA but not to biogenic amine mechanisms of action, and (c) 16% (i.e., 40-24%) not responsive to either of these mechanisms of action. Scientific investigation of these three groups may yield important information about the pathophysiology and/or pathoetiology of these different forms of MD. This information coupled with studies into the neurobiology (e.g., imaging studies, connectomes to name a few approaches being used) and genetics of MD should provide the fundamental knowledge which will permit a rational search for and discovery of newer antidepressant drugs and other somatic and psychotherapeutic approaches to the treatment of patients with different forms of MD based on pathophysiology and pathoetiology. Examples are given of how such discovery and development have occurred in other areas of medicine and even in central nervous system (CNS) space including six novel mechanisms of action CNS drugs which have been successfully developed and marketed over the last 25 years.

Personalized Medicine in the Treatment of a Patient With Obsessive-Compulsive Disorder With Clomipramine.

Clomipramine (CIMI) is an effective treatment for obsessive-compulsive disorder in patients who have failed to respond to trials of selective serotonin transport inhibitors (eg, sertraline). The case presented here illustrates how knowledge of the pharmacodynamics and pharmacokinetics of CIMI in a specific patient can be used to personalize treatment to optimize the likelihood of efficacy (ie, maximum benefit to risk ratio). The approach described in this column considered: (1) the patient's diminished ability to clear CIMI and its major metabolite, desmethlyclomipramine due to a genetic deficiency in cytochrome P450 2D6 enzyme activity, and (2) the patient's ability to extensively convert CIMI to desmethlyclomipramine. That conversion impairs the ability to inhibit the serotonin transporter, the mechanism that is most likely responsible for the efficacy of CIMI in obsessive-compulsive disorder.

Can the Publication of Case Series or Case Reports Lead to a Change in Clinical Practice?

This column provides some criteria for evaluating whether a case series or case report may warrant publication. It will emphasize the value of having biomarker data in addition to clinical data to enhance the potential validation of the report and provide ways to test the findings in randomized, controlled clinical trials (RCTs). The potential validity of the case series or report is also high if the outcome is something that would not normally be expected such as, by way of example but not limited to, sudden death or malignant hypertension in someone who had always been normotensive. Examples illustrating how case series/case reports have changed the course of clinical practice or regulatory rules governing drug approval by the US Food and Drug Administration are presented, as well as examples of how those reports have been validated by more rigorous studies including RCTs. The column also includes a discussion of situations in which case series/case reports might have an endpoint (eg, sudden death) that would not be ethical to investigate in an RCT, as well as how biomarkers have been used in such instances to avoid serious untoward outcomes for a participant while still testing the hypothesis.

Discovery of New Transmitter Systems and Hence New Drug Targets.

The development of medications used to treat psychiatric conditions has largely proceeded through serendipity, where a potential drug to treat mental illness is identified by chance. This approach is based on a limited understanding of the underlying pathophysiology of mental illness and brain disorders. Identification of novel neurotransmitter systems has allowed for new molecular-based approaches for drug development that identify specific receptor targets to treat a specific symptom. An example of this approach includes the development of suvorexant, which is a dual orexin receptor antagonist FDA approved in 2014 for the treatment of insomnia. This chapter will discuss challenges in psychiatric drug development; the importance of identifying discrete neurotransmitter systems that target a specific symptom, not a syndrome; the orexin pathway and targets within this pathway that can be used to modulate sleep; and a high-throughput approach to streamlining drug development.

Reverse Engineering Drugs: Lorcaserin as an Example.

Novel central nervous system (CNS)-based therapies have been difficult to produce due to the complexity of the brain, limited knowledge of CNS-based disease development and associated pathways, difficulty in penetrating the blood brain barrier, and a lack of reliable biomarkers of disease. Reverse engineering in drug development allows the utilization of new knowledge of disease pathways and the use of innovative technology to develop medications with enhanced efficacy and reduced toxicities. Lorcaserin was developed as a specific 5HT2C serotonin receptor agonist for the treatment of obesity with limited off-target effects at the 5HT2A and 5HT2B receptors. This receptor specificity limited the hallucinogenic and cardiovascular side effects noted with other serotonin receptor agonists. Reverse engineering approaches to drug development reduce the cost of producing new medications, identify specific populations of patients that will derive the most benefit from therapy, and produce novel therapies with greater efficacy and limited toxicity.