Evaluating Guanfacine Hydrochloride in the Treatment of Attention Deficit Hyperactivity Disorder (ADHD) in Adult Patients: Design, Development and Place in Therapy.

Attention-deficit/hyperactivity disorder (ADHD) is characterized by age-inappropriate and impairing levels of inattention, hyperactivity, or impulsivity, or a combination of these characteristics. It is estimated to affect around 4% of adults worldwide. In the past few decades, prescriptions for ADHD drugs (psychostimulants and non-psychostimulants) have increased significantly. However, the efficacy and safety of adult ADHD medications remains controversial. Guanfacine extended-release (GXR) is a non-psychostimulant ADHD drug that is a selective α2A-adrenergic receptor agonist, first approved for treatment of adult ADHD in Japan in June 2019. Our aim was to provide an overview of GXR pharmacology and review the studies on efficacy and safety that have been conducted in adults with ADHD. The beneficial actions of guanfacine are thought to be attributed to the strengthening of prefrontal cortical network connections, which regulate attention, emotion, and behavior via the activity at post-synaptic α2A receptors. Current evidence of GXR efficacy and safety suggests that GXR is an effective monotherapy treatment option for adults with ADHD.

Chronic Administrations of Guanfacine on Mesocortical Catecholaminergic and Thalamocortical Glutamatergic Transmissions.

It has been established that the selective α2A adrenoceptor agonist guanfacine reduces hyperactivity and improves cognitive impairment in patients with attention-deficit/hyperactivity disorder (ADHD). The major mechanisms of guanfacine are considered to involve the activation of the postsynaptic α2A adrenoceptor of glutamatergic pyramidal neurons in the frontal cortex, but the effects of chronic guanfacine administration on catecholaminergic and glutamatergic transmissions associated with the orbitofrontal cortex (OFC) are yet to be clarified. The actions of guanfacine on catecholaminergic transmission, the effects of acutely local and systemically chronic (for 7 days) administrations of guanfacine on catecholamine release in pathways from the locus coeruleus (LC) to OFC, the ventral tegmental area (VTA) and reticular thalamic-nucleus (RTN), from VTA to OFC, from RTN to the mediodorsal thalamic-nucleus (MDTN), and from MDTN to OFC were determined using multi-probe microdialysis with ultra-high performance liquid chromatography. Additionally, the effects of chronic guanfacine administration on the expression of the α2A adrenoceptor in the plasma membrane fraction of OFC, VTA and LC were examined using a capillary immunoblotting system. The acute local administration of therapeutically relevant concentrations of guanfacine into the LC decreased norepinephrine release in the OFC, VTA and RTN without affecting dopamine release in the OFC. Systemically, chronic administration of therapeutically relevant doses of guanfacine for 14 days increased the basal release of norepinephrine in the OFC, VTA, RTN, and dopamine release in the OFC via the downregulation of the α2A adrenoceptor in the LC, OFC and VTA. Furthermore, systemically, chronic guanfacine administration did not affect intrathalamic GABAergic transmission, but it phasically enhanced thalamocortical glutamatergic transmission. The present study demonstrated the dual actions of guanfacine on catecholaminergic transmission-acute attenuation of noradrenergic transmission and chronic enhancement of noradrenergic transmission and thalamocortical glutamatergic transmission. These dual actions of guanfacine probably contribute to the clinical effects of guanfacine against ADHD.

Pharmacotherapy of attention deficit/hyperactivity disorder in individuals with autism spectrum disorder: A systematic review of the literature.

AIM: To assess the empirical evidence for the treatment of attention deficit/hyperactivity disorder (ADHD) in populations with autism spectrum disorder (ASD). METHODS: A systemic PubMed, PsychINFO, Embase, and Medline database search of peer-reviewed literature was conducted. Included in the review were controlled trials published in English with sample sizes ⩾10 participants examining the safety and efficacy of anti-ADHD medication in ASD populations. Data was extracted on relevant variables of study design, demographics, associated psychopathology, medication dose, efficacy, and tolerability. RESULTS: Nine controlled trials met the inclusion and exclusion criteria: five with methylphenidate, three with atomoxetine, and one with guanfacine. Sample sizes ranged from 10 to 128 with 430 children participating across all the trials. In all the trials, treatment response was significantly superior to placebo. However, almost all trials assessed only hyperactivity, and most included only participants with intellectual disability with high levels of irritability. None of the trials distinguished agitation from hyperactivity. The response on hyperactivity for methylphenidate and atomoxetine was less than that observed in the neurotypical population; however, the response for guanfacine surpassed results observed in neurotypical populations. Treatment-emergent mood lability (i.e. mood dysregulation and mood-related adverse events) was frequently associated with methylphenidate and guanfacine treatments. Worse treatment outcomes were associated with individuals with lower intellectual capability compared with those with higher IQs. CONCLUSIONS: here is a scarcity of controlled trials examining ADHD treatments in ASD populations, particularly in intellectually capable individuals with ASD and in adults. Response to ADHD medications in ASD were adversely moderated by the presence of intellectual disability and mood lability.

Efficacy and safety of guanfacine extended-release in Japanese adults with attention-deficit/hyperactivity disorder: Exploratory post hoc subgroup analyses of a randomized, double-blind, placebo-controlled study.

AIM: Previously, we reported on the efficacy and safety of guanfacine extended-release (GXR) in Japanese adults with attention-deficit/hyperactivity disorder (ADHD) from a phase 3, double-blind, placebo-controlled, randomized trial. In this exploratory post hoc analysis, we assessed the efficacy and/or safety of GXR in the following subgroups: ADHD-combined (ADHD-C) and ADHD-predominantly inattentive (ADHD-I) subtypes, age (≥31, <31 years), sex (male, female), and body weight (≥50, <50 kg). METHODS: The primary efficacy endpoint was change from baseline in the Japanese version of the investigator-rated ADHD-Rating Scale-IV (ADHD-RS-IV) with adult prompts (total scores) at week 10. RESULTS: The efficacy analysis population included 200 patients (GXR, 100; placebo, 100). ADHD-RS-IV total score effect sizes (GXR vs placebo) were similar across all subgroups (total population: 0.52, ADHD-C: 0.51, ADHD-I: 0.52, ≥31 years: 0.61, <31 years: 0.47, male: 0.50, female: 0.57). There were no major differences in the incidence/types of treatment-emergent adverse events (TEAEs) across the subgroups. The incidence of significant TEAEs (34.3%, 10.6%) and TEAEs leading to discontinuation (34.3%, 12.1%) were approximately three times higher in females than males, respectively. The incidence of TEAEs in patients weighing <50 kg and ≥50 kg was 100% and 73.6% during dose optimization and 40% and 24.4% during the maintenance period, respectively. CONCLUSION: Findings from this post hoc analysis in adults with ADHD support the efficacy and safety of GXR regardless of ADHD subtype, age, or sex and suggest that careful monitoring for TEAEs and GXR dose optimization is considered for all patients, as needed.

Effects of the α-2 Adrenergic Receptor Agonists Lofexidine and Guanfacine on Food-Cocaine Choice in Socially Housed Cynomolgus Monkeys.

Although norepinephrine (NE) does not appear to play a prominent role in mediating the abuse-related effects of cocaine, studies have indicated that NE α-2 receptor agonists can attenuate reinstatement of extinguished cocaine self-administration in rats and monkeys and can decrease cocaine craving in humans. In the present studies, we examined the effects of two α-2 receptor agonists, lofexidine and guanfacine, on choice between food and cocaine (0.0-0.1 mg/kg per injection) in cynomolgus monkeys. Male and female subjects were housed in stable same-sex social groups of four; social rank did not influence the effects of lofexidine and guanfacine. When administered acutely, lofexidine (0.03-3.0 mg/kg, i.v.) significantly decreased cocaine choice in females (n = 7) but not males (n = 8). However, in males, the same lofexidine doses produced dose-dependent decreases in core body temperature (n = 7), and acute guanfacine (0.003-1.0 mg/kg, i.v.) significantly decreased cocaine choice (n = 11). When lofexidine was administered for five consecutive days to a subset of the monkeys in whom lofexidine acutely decreased cocaine choice, tolerance to this effect developed to varying degrees of completeness in three of three males and two of four females. Taken together, these data suggest that α-2 receptor agonists can produce small decreases in the reinforcing strength of cocaine relative to food and that, even when efficacy is observed after acute administration, tolerance to the decreases in cocaine choice are apparent and more likely in males compared with females. SIGNIFICANCE STATEMENT: Cocaine use disorder remains a significant public health problem with no US Food and Drug Administration-approved treatments. Although cocaine elevates dopamine, serotonin, and norepinephrine (NE), the latter target has received less research. The present study noted modest effects of NE agonists on the relative reinforcing strength of cocaine with greater efficacy in female compared with male monkeys.

Interaction between Mesocortical and Mesothalamic Catecholaminergic Transmissions Associated with NMDA Receptor in the Locus Coeruleus.

Noncompetitive N-methyl-D-aspartate/glutamate receptor (NMDAR) antagonists contribute to the pathophysiology of schizophrenia and mood disorders but improve monoaminergic antidepressant-resistant mood disorder and suicidal ideation. The mechanisms of the double-edged sword clinical action of NMDAR antagonists remained to be clarified. The present study determined the interaction between the NMDAR antagonist (MK801), α1 adrenoceptor antagonist (prazosin), and α2A adrenoceptor agonist (guanfacine) on mesocortical and mesothalamic catecholaminergic transmission, and thalamocortical glutamatergic transmission using multiprobe microdialysis. The inhibition of NMDAR in the locus coeruleus (LC) by local MK801 administration enhanced both the mesocortical noradrenergic and catecholaminergic coreleasing (norepinephrine and dopamine) transmissions. The mesothalamic noradrenergic transmission was also enhanced by local MK801 administration in the LC. These mesocortical and mesothalamic transmissions were activated by intra-LC disinhibition of transmission of γ-aminobutyric acid (GABA) via NMDAR inhibition. Contrastingly, activated mesothalamic noradrenergic transmission by MK801 enhanced intrathalamic GABAergic inhibition via the α1 adrenoceptor, resulting in the suppression of thalamocortical glutamatergic transmission. The thalamocortical glutamatergic terminal stimulated the presynaptically mesocortical catecholaminergic coreleasing terminal in the superficial cortical layers, but did not have contact with the mesocortical selective noradrenergic terminal (which projected terminals to deeper cortical layers). Furthermore, the α2A adrenoceptor suppressed the mesocortical and mesothalamic noradrenergic transmissions somatodendritically in the LC and presynaptically/somatodendritically in the reticular thalamic nucleus (RTN). These discrepancies between the noradrenergic and catecholaminergic transmissions in the mesocortical and mesothalamic pathways probably constitute the double-edged sword clinical action of noncompetitive NMDAR antagonists.

Discinesia asociada a ADCY5 en la infancia: a propósito de una familia y revisión actualizada / ADCY5-associated dyskinesia in young children: a case report of a family and an updated review

INTRODUCCIÓN: La discinesia de la mutación ADCY5 es un raro trastorno del movimiento de inicio en la infancia. Se caracteriza por movimientos coreicos aislados o asociados a mioclonías y distonías que afectan a las extremidades, el cuello y la cara. El escaso número de pacientes y familias no permite aún una adecuada relación genotipo-fenotipo. OBJETIVOS: Presentar el caso de un niño con trastornos del movimiento de inicio precoz en el seno de una familia con tres generaciones de afectados, y realizar una revisión actualizada de la casuística y el tratamiento de esta rara enfermedad. CASO CLÍNICO: Varón de 6 años, remitido por retraso del lenguaje e hiperactividad. Tras seis meses de seguimiento, comenzó a presentar movimientos coreicos de predominio facial y de la raíz de los miembros, especialmente al despertar. Al año de seguimiento, se evidenció corea generalizado en reposo con afectación orofacial y torpeza en la marcha. Como antecedentes familiares destacaban su madre, abuelo, tío y prima maternos, que fueron diagnosticados de síndrome de Meige (distonía oromandibular y músculos periorbitarios) con trastornos del movimiento de tipo coreiforme sin filiar desde la infancia. El estudio cerebral por resonancia magnética no presentó alteraciones. Se realizó un exoma clínico dirigido a trastornos del movimiento que descubrió la mutación patógena en el gen ADCY5 causante de la discinesia familiar autosómica. CONCLUSIÓN: La mutación c.1126G > A p.A376T muestra una historia natural con un fenotipo clínico no progresivo en tres generaciones de afectados, con inicio en la infancia y respuesta al tratamiento con guanfacina

INTRODUCTION. Dyskinesia of the ADCY5 mutation is a rare movement-onset disorder in childhood. It is characterized by isolated chorea movements or associated with myoclonus and dystonia affecting the limbs, neck and face. The low number of patients and families still does not allow an adequate genotype-phenotype relationship. AIMS. The case of a child with movement disorders of early onset is presented in a family with three generations of affected members. An updated review of the casuistry and management of this rare disease is made. CASE REPORT: A 6-year-old boy referred for language delay and hyperactivity. After six months of follow-up he begins to show chorea movements of predominantly facial and limb roots, especially when waking up. At one year of follow-up, generalized chorea at rest with orofacial involvement and awkward gait begins to show. His family history includes his mother, grandfather, maternal uncle and cousin, who were diagnosed with Meige's syndrome (oromandibular dystonia and periorbital muscles) with choreiform-like movement disorders without affiliation since childhood. The brain study by MRI showed no alterations. A clinical exome targeting movement disorders was performed that discovered the pathogenic mutation in the ADCY5 gene causing autosomal familial dyskinesia. CONCLUSION: The c.1126G>A p.A376T mutation shows a natural history with a non-progressive clinical phenotype in three generations of affected members, with childhood debut and response to guanfacine treatment

Efficacy and Safety of Guanfacine Extended-Release in the Treatment of Attention-Deficit/Hyperactivity Disorder in Adults: Results of a Randomized, Double-Blind, Placebo-Controlled Study.

OBJECTIVE: To assess guanfacine extended-release (GXR) efficacy and safety in adults with attention-deficit/hyperactivity disorder (ADHD). METHODS: This phase 3, double-blind, placebo-controlled study (conducted between October 2016 and July 2017) included Japanese patients aged ≥ 18 years with ADHD (DSM-5). Patients received GXR (n = 101) or placebo (n = 100) titrated from 2 mg/d to 4-6 mg/d (dose-optimization; 5 weeks), followed by 4-6 mg/d (dose-maintenance; 5 weeks), then tapered doses to 2 mg/d (2 weeks). Primary endpoint was change from baseline in total score on the Japanese version of the ADHD-Rating Scale IV with adult prompts (ADHD-RS-IV) at week 10. Other measures were ADHD-RS-IV subscales, Clinical Global Impression-Improvement scale (CGI-I) and Patient Global Impression-Improvement scale (PGI-I) (percentage of patients very much improved/much improved), treatment-emergent adverse event (TEAE) incidences, and TEAEs leading to discontinuation. RESULTS: Compared with placebo, there was statistically significantly greater improvement in ADHD-RS-IV total score reduction with GXR (least squares mean ± SE: GXR vs placebo, -11.55 ± 1.10 vs -7.27 ± 1.07; P = .0005; effect size 0.52). There were significantly greater improvements in GXR for ADHD-RS-IV inattention (-7.39 ± 0.79 vs -4.89 ± 0.76; P = .0032) and hyperactivity-impulsivity (-3.84 ± 0.54 vs -2.10 ± 0.52; P = .0021) subscale scores, CGI-I scores (48.1% vs 22.6%; P = .0007), and PGI-I scores (25.3% vs 11.8%; P = .0283). More patients in the GXR versus the placebo group reported TEAEs (81.2% vs 62.0%) and discontinued due to TEAEs (19.8% vs 3.0%). The main TEAEs in the GXR group were somnolence, thirst, blood pressure decrease, nasopharyngitis, postural dizziness, and constipation; most TEAEs were mild to moderate in severity. CONCLUSIONS: In Japanese adults with ADHD, GXR improved ADHD symptoms without any major safety concerns. Trial Registration: Japan Primary Registries Network (https://rctportal.niph.go.jp/en): JapicCTI-163231

Evaluation of the current data on guanfacine extended release for the treatment of ADHD in children and adolescents.

Introduction: Attention-deficit/hyperactivity disorder (ADHD) commonly occurs in children, adolescents, and adults. Although symptoms of ADHD often respond robustly to treatment with stimulants (amphetamine or methylphenidate), not all patients are appropriate candidates for treatment with these drugs. Guanfacine extended-release (GXR) is a non-stimulant alternative drug approved for the treatment of ADHD in the United States (U.S.), Canada, and Europe.Areas covered: The chemistry, pharmacokinetics, mechanism of action and dosage of GXR are presented. Efficacy and safety data obtained in clinical trials with subjects aged 6-17 years for both GXR monotherapy and use in combination with stimulants are described. Meta-analyses comparing GXR to other drugs are presented. MedWatch surveillance data collected for GXR since approval in the U.S. are also discussed.Expert opinion: Although GXR is effective for the treatment of ADHD and has a different side effect profile than stimulants, it is not as impressive in reducing symptoms. Despite the availability of multiple pharmacological treatments for ADHD, there remains an unmet need for formulations as potent as stimulants but with fewer adverse effects. Several pharmacological agents for ADHD treatment are in development. It is not clear that any of these compounds will replace currently available formulations as first-line alternatives.

Treatment Patterns, Health Care Resource Utilization, and Health Care Cost Associated with Atypical Antipsychotics or Guanfacine Extended Release in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder in Quebec, Canada.

Objective: To assess treatment patterns, health care resource utilization, and health care costs associated with use of atypical antipsychotics (AAPs) or the nonstimulant guanfacine extended release (GXR) after stimulant therapy for attention-deficit/hyperactivity disorder (ADHD). In Canada, GXR is approved as a monotherapy for children and adolescents with ADHD or as an adjunct to stimulants, and AAPs are commonly used off-label as an adjunct to stimulants. Methods: Health care claims data (January 1, 2007 to March 31, 2016) from Quebec's provincial health plan were assessed for individuals with ADHD, 6-17 years of age, who received ≥1 stimulant followed by a first AAP or GXR prescription (index medication), without a diagnosis for which AAPs are indicated. Results: Overall, 1327 individuals were included (AAPs, 1098; GXR, 229). Rates of discontinuation, augmentation, or switching of the index medication did not differ between AAPs and GXR during the first follow-up year. Discontinuation rates were significantly lower with GXR than with AAPs during the second year (22.0% vs. 35.9%; p = 0.03). GXR and AAPs resulted in similar increases in total health care cost. In GXR users, the increase in prescription drug cost after 6 months was higher than in AAP users, whereas the increase in overall medical cost was higher with AAPs than GXR, owing to more psychiatric department visits. Conclusions: In children and adolescents with ADHD who used AAPs or GXR after stimulants, secondary treatment changes were similar with both treatments after 1 year, but discontinuation rates were significantly lower with GXR than with AAPs in the second year. The greater increase in prescription cost with GXR was balanced by a greater increase in overall medical costs with AAPs, resulting in no overall difference in total health care cost between the two treatments.

Metabolite profiling of guanfacine in plasma and urine of healthy Japanese subjects after oral administration of guanfacine extended-release tablets.

Guanfacine is used for the treatment of attention-deficit/hyperactivity disorder (ADHD). Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), metabolite profiling of guanfacine was performed in plasma and urine collected from healthy Japanese adults following repeated oral administration of guanfacine extended-release formulation. Unchanged guanfacine was the most abundant component in both plasma and urine (from the MS signal intensity). In plasma, the M3 metabolite (a sulfate of hydroxy-guanfacine) was the prominent metabolite; the M2 metabolite (a glucuronide of a metabolite formed by monooxidation of guanfacine), 3-hydroxyguanfacine and several types of glucuronide at different positions on guanfacine were also detected. In urine, the M2 metabolite and 3-hydroxyguanfacine were the principal metabolites. From metabolite analysis, the proposed main metabolic pathway of guanfacine is monooxidation on the dichlorobenzyl moiety, followed by glucuronidation or sulfation. A minor pathway is glucuronidation at different positions on guanfacine. As the prominent metabolites in plasma were glucuronide and sulfate of hydroxyguanfacine, which have no associated toxicity concerns, further toxicity studies of the metabolites, for example in animals, were not deemed necessary.

Weight and Height in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder: A Longitudinal Database Study Assessing the Impact of Guanfacine, Stimulants, and No Pharmacotherapy.

Objectives: To assess the impact of long-term pharmacotherapy with guanfacine immediate- or extended-release (GXR), administered alone or as an adjunctive to a stimulant, on weight and height in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Methods: Data were extracted from U.S. Department of Defense medical records for patients 4-17 years of age at index date (initiation of any study medication following a year without ADHD medications, or diagnosis if unmedicated) with weight/height measurements for the analysis period (January 2009-June 2013) and the previous year (baseline). Longitudinal weight and height z-scores were analyzed using multivariable regression in three cohorts: guanfacine (initial period of guanfacine exposure), first-line stimulant monotherapy (initial period of exposure), and unmedicated. Guanfacine cohort subgroups were based on previous/concurrent stimulant exposure. Results: The weight analyses included 47,910 patients (66.8% male) and the height analyses 41,248 (67.2% male). Mean initial exposure in the weight analyses was 237 days (standard deviation [SD] = 258, median = 142) for guanfacine and 257 days (SD = 284, median = 151) for first-line stimulant monotherapy, and was similar in the height analyses. Modeling indicated that guanfacine monotherapy was not associated with clinically meaningful deviations from normal z-score trajectories for weight (first-line, n = 943; nonfirst-line, n = 796) or height (first-line, n = 741; nonfirst-line, n = 644). In patients receiving guanfacine adjunctive to a stimulant, modeled weight (n = 1657) and height (n = 1343) z-scores followed declining trajectories. In this subgroup, mean standardized weight/height had decreased during previous stimulant monotherapy. For first-line stimulant monotherapy, modeled weight (n = 32,999) and height (n = 28,470) z-scores followed declining trajectories during year 1. In the unmedicated cohort, modeled weight (n = 11,515) and height (n = 10,050) z-scores were stable. Conclusions: Guanfacine monotherapy (first-line or nonfirst-line) was not associated with marked deviations from normal growth in this modeling study of children and adolescents with ADHD. In contrast, growth trajectories followed an initially declining course with stimulants, whether given alone or with adjunctive guanfacine.

Guanfacine Extended Release for the Reduction of Aggression, Attention-Deficit/Hyperactivity Disorder Symptoms, and Self-Injurious Behavior in Prader-Willi Syndrome-A Retrospective Cohort Study.

Objective: To examine the role of Guanfacine Extended Release (GXR) in the management of behavioral disturbances in patients with Prader-Willi Syndrome (PWS). Methods: Twenty from a total of 27 individuals with genetically confirmed PWS, 6-26 years of age, with the following symptoms were identified: significant aggression/agitation, skin picking, and/or symptoms of attention-deficit/hyperactivity disorder (ADHD). Response to GXR for the above noted symptoms was categorized as improved, worsened, or unchanged, while assessing for side effects and tolerability. Results: Eleven of the 20 individuals reported skin-picking, 17 reported aggression/agitation, and 16 reported symptoms of ADHD. Nine (81.8%), 14 (82.3%), and 15 (93.7%) individuals showed an improvement in skin-picking, aggression/agitation, and ADHD, respectively, while on GXR treatment. Two patients with prior complaints of psychotic symptoms did not respond to GXR. Of note, no abnormal weight gain or significant adverse reaction was observed in this group, while on GXR. Conclusions: In this study, GXR demonstrated improvement in symptoms of skin picking, aggression/agitation, and ADHD in patients with PWS. GXR was not effective in reducing psychosis or agitation related to psychotic symptoms. Future studies are warranted to further establish the utility of GXR in PWS patients.

Effects of acute and sub-chronic administrations of guanfacine on catecholaminergic transmissions in the orbitofrontal cortex.

The selective α2A adrenoceptor agonist guanfacine reduces hyperactivity and improves cognitive impairment in patients with attention-deficit/hyperactivity disorder (ADHD). The major mechanisms of guanfacine have been considered to involve activation of postsynaptic α2A adrenoceptor in frontal pyramidal neurons. However, the effects of chronic guanfacine administration on catecholaminergic transmissions associated with the orbitofrontal cortex (OFC) remain unclear. To explore the mechanisms of action of guanfacine on catecholaminergic transmission, the effects of its acute local or sub-chronic systemic administration on catecholamine release within pathways from locus coeruleus (LC) to OFC and reticular thalamic nucleus (RTN), from RTN to mediodorsal thalamic nucleus (MDTN), and from MDTN to OFC were determined using multi-probe microdialysis with ultra-high performance liquid chromatography. Acute OFC local administration of guanfacine did not affect catecholamine release in OFC. Acute LC local and sub-chronic systemic administrations of guanfacine reduced norepinephrine release in LC, OFC and RTN, and also reduced GABA release in MDTN, whereas AMPA-induced (perfusion with AMPA into NDTN) releases of l-glutamate, norepinephrine and dopamine in OFC were enhanced by sub-chronic systemic guanfacine administration. This study identified that catecholaminergic transmission is composed of three pathways: direct noradrenergic and co-releasing catecholaminergic LC-OFC pathways and intermediate LC-OFC (LC-RTN-MDTN-OFC) pathway. We demonstrated the dual actions of guanfacine on catecholaminergic transmission: attenuation of direct noradrenergic LC-OFC transmission at the resting stage and enhancement of direct co-releasing catecholaminergic LC-OFC transmission via GABAergic disinhibition in the intermediate LC-OFC pathway. These dual actions of guanfacine probably contribute to clinical actions of guanfacine against ADHD and its comorbid symptoms. This article is part of the Special Issue entitled 'Current status of the neurobiology of aggression and impulsivity'.

Pharmacokinetics and Pharmacodynamics of Immediate-Release Versus Extended-Release Guanfacine in Adult Daily Smokers.

BACKGROUND: Guanfacine is Food and Drug Administration approved for hypertension and attention-deficit hyperactivity disorder and has been used off-label for migraine prophylaxis, heroin withdrawal, and more recently smoking cessation. Previous studies have shown positive effects of 3 mg/d of immediate-release (IR) guanfacine on smoking outcomes, but the dose equivalency of the IR and extended-release (ER) formulations is unknown. PROCEDURES: A within-subject design was used to compare the pharmacokinetics and pharmacodynamics of 3 mg/d of IR, 4 mg/d of ER, and 6 mg/d of ER guanfacine in adult daily smokers (n = 5). Plasma medication levels, vital signs, cigarettes per day, tobacco craving, and adverse events were assessed. Medication was titrated to stable dosing after each laboratory day (3 mg/d IR, then 4 mg/d ER, then 6 mg/d ER). RESULTS: Plasma medication levels did not differ between the 3 mg/d of IR and 4 mg/d of ER doses after 24 hours from last dose and were highest at the 6 mg/d of ER dose (3 mg/d IR: M = 3.40 ng/mL, SE = 0.34 vs 4 mg/d ER: M = 3.46 ng/mL, SE = 0.67 vs 6 mg/d ER: M = 5.92 ng/mL, SE = 1.02). All doses of guanfacine decreased heart rate and blood pressure from baseline. Absolute values of cigarettes per day (6 mg/d ER) and tobacco craving (4 and 6 mg/d ER) were lowest with the ER formulations. Treatment-emergent adverse events were subject rated as minimal to mild, except dry mouth. CONCLUSIONS: We demonstrated similar pharmacokinetic profiles between 3 mg/d of IR guanfacine and 4 mg/d of ER guanfacine, as hypothesized. All doses of guanfacine were well tolerated.

Dorsal BNST α2A-Adrenergic Receptors Produce HCN-Dependent Excitatory Actions That Initiate Anxiogenic Behaviors.

Stress is a precipitating agent in neuropsychiatric disease and initiates relapse to drug-seeking behavior in addicted patients. Targeting the stress system in protracted abstinence from drugs of abuse with anxiolytics may be an effective treatment modality for substance use disorders. α2A-adrenergic receptors (α2A-ARs) in extended amygdala structures play key roles in dampening stress responses. Contrary to early thinking, α2A-ARs are expressed at non-noradrenergic sites in the brain. These non-noradrenergic α2A-ARs play important roles in stress responses, but their cellular mechanisms of action are unclear. In humans, the α2A-AR agonist guanfacine reduces overall craving and uncouples craving from stress, yet minimally affects relapse, potentially due to competing actions in the brain. Here, we show that heteroceptor α2A-ARs postsynaptically enhance dorsal bed nucleus of the stria terminalis (dBNST) neuronal activity in mice of both sexes. This effect is mediated by hyperpolarization-activated cyclic nucleotide-gated cation channels because inhibition of these channels is necessary and sufficient for excitatory actions. Finally, this excitatory action is mimicked by clozapine-N-oxide activation of the Gi-coupled DREADD hM4Di in dBNST neurons and its activation elicits anxiety-like behavior in the elevated plus maze. Together, these data provide a framework for elucidating cell-specific actions of GPCR signaling and provide a potential mechanism whereby competing anxiogenic and anxiolytic actions of guanfacine may affect its clinical utility in the treatment of addiction.SIGNIFICANCE STATEMENT Stress affects the development of neuropsychiatric disorders including anxiety and addiction. Guanfacine is an α2A-adrenergic receptor (α2A-AR) agonist with actions in the bed nucleus of the stria terminalis (BNST) that produces antidepressant actions and uncouples stress from reward-related behaviors. Here, we show that guanfacine increases dorsal BNST neuronal activity through actions at postsynaptic α2A-ARs via a mechanism that involves hyperpolarization-activated cyclic nucleotide gated cation channels. This action is mimicked by activation of the designer receptor hM4Di expressed in the BNST, which also induces anxiety-like behaviors. Together, these data suggest that postsynaptic α2A-ARs in BNST have excitatory actions on BNST neurons and that these actions can be phenocopied by the so-called "inhibitory" DREADDs, suggesting that care must be taken regarding interpretation of data obtained with these tools.

Enteral Guanfacine to Treat Severe Anxiety and Agitation Complicating Critical Care After Cardiac Surgery.

This article is the first reported case describing the off-label use of enteral immediate-release guanfacine, a long-acting α-2 adrenergic agonist most commonly used in the treatment of attention-deficit hyperactivity disorder, for sedation in a patient with severe anxiety and agitation limiting mechanical ventilation weaning several days after cardiac surgery. In this case, after several days of unsuccessful attempts to control his agitation and anxiety with conventional therapies, guanfacine therapy was initiated, and the patient was rapidly weaned from all other sedatives and mechanical ventilation shortly thereafter. The patient was weaned from guanfacine therapy without evidence of bradycardia, hypotension, or rebound syndrome. Enteral guanfacine therapy should be further studied as a potentially useful and cost-effective sedative therapy for patients with severe anxiety and/or agitation in the intensive care unit following cardiac and thoracic surgical procedures.

A randomized, placebo-controlled trial of extended-release guanfacine in children with autism spectrum disorder and ADHD symptoms: an analysis of secondary outcome measures.

In a prior report, we showed that extended-release guanfacine (GEXR) is safe and effective for children with autism spectrum disorder (ASD) accompanied by ADHD symptoms. Here, we examine the impact of GEXR on oppositional behavior, anxiety, repetitive behavior, and sleep disturbance. Sixty-two subjects with ASD (53 boys, 9 girls; ages 5-14 years) were randomly assigned to GEXR (n = 30) or placebo (n = 32) for 8 weeks. Outcomes include the Home Situation Questionnaire-Modified for ASD (HSQ-ASD), Anxiety scale of the Child and Adolescent Symptom Inventory (CASI), Children's Yale-Brown Obsessive-Compulsive Scale-Modified for ASD (CYBOCS-ASD), and Children's Sleep Habits Questionnaire (CSHQ). A repeated measures linear mixed model was used to determine the effects of treatment group and time on HSQ scores. For other measures, change from baseline was evaluated with Analysis of Covariance (ANCOVA).After 8 weeks of treatment, parent ratings of oppositional behavior on the HSQ declined by 44% (per item mean from 3.4 to 1.9) in the GEXR group compared to 12% (from 3.3 to 2.9) for placebo (p = 0.004). Repetitive behavior on the CYBOCS-ASD showed a significantly greater decline in GEXR-treated participants compared to placebo (24% vs. <1%, p = 0.01). No group differences were observed on CASI Anxiety or CSHQ (p = 0.64 and 0.75, respectively). GEXR was effective in reducing oppositional behavior and, more modestly, repetitive behavior. GEXR was not superior to placebo for anxiety, though baseline anxiety ratings were low. GEXR did not significantly improve sleep habits. Future studies could focus on repetitive behavior or anxiety, symptoms with limited treatment options.

Healthcare utilization and costs of children with attention deficit/hyperactivity disorder initiating atomoxetine versus extended-release guanfacine.

OBJECTIVES: To compare 1-year direct healthcare costs and utilization among children and adolescents initiating non-stimulant medications atomoxetine (ATX) or extended-release guanfacine (GXR). METHODS: In this retrospective, observational cohort study, children and adolescents aged 6-17 years with attention deficit/hyperactivity disorder (ADHD) who had ≥1 prescription claim for ATX or GXR between December 31, 2009 and January 1, 2011 were identified in the MarketScan Commercial or Multi-State Medicaid claims databases. The first claim was set as the index. Patients with no claims for other ADHD medications that overlapped with the days' supply for the index therapy during the post-period were classified as initiating monotherapy. All-cause and ADHD-related utilization and costs (2011 US$) and treatment patterns (adherence and persistence) were evaluated during the 12 months following index. Propensity score adjustment accounted for differences in patient characteristics, and bootstrapping was used for comparisons. RESULTS: A total of 13,239 children and adolescents with ADHD met the study criteria (4,411 ATX initiators and 8,828 GXR initiators). There were 2,699 ATX monotherapy patients. In propensity-score-adjusted analyses, mean all-cause total costs were significantly less for monotherapy ATX initiators than for GXR initiators ($7,553 vs $10,639; difference = -$3,086, p < .0001), as were mean ADHD-related total costs ($3,213 vs $4,544; difference = -$1,330, p < .0001). Monotherapy ATX initiators had significantly fewer all-cause and ADHD-related total medical visits and ∼22 days shorter persistence to index therapy (p < .0001). Results were similar for secondary analyses comparing all ATX with all GXR initiators, regardless of monotherapy or combination regimen, and comparing only monotherapy initiators. CONCLUSIONS: Children and adolescents with ADHD who initiated ATX monotherapy incurred lower all-cause and ADHD-related total healthcare costs than patients who initiated GXR. This was due in part to less healthcare resource utilization and slightly shorter persistence for ATX patients. These findings may aid decision-making and inform future studies, but must be tempered due to inherent observational research limitations.