Neuromodulator Signaling Bidirectionally Controls Vesicle Numbers in Human Synapses.

Neuromodulators bind to pre- and postsynaptic G protein-coupled receptors (GPCRs), are able to quickly change intracellular cyclic AMP (cAMP) and Ca2+ levels, and are thought to play important roles in neuropsychiatric and neurodegenerative diseases. Here, we discovered in human neurons an unanticipated presynaptic mechanism that acutely changes synaptic ultrastructure and regulates synaptic communication. Activation of neuromodulator receptors bidirectionally controlled synaptic vesicle numbers within nerve terminals. This control correlated with changes in the levels of cAMP-dependent protein kinase A-mediated phosphorylation of synapsin-1. Using a conditional deletion approach, we reveal that the neuromodulator-induced control of synaptic vesicle numbers was largely dependent on synapsin-1. We propose a mechanism whereby non-phosphorylated synapsin-1 "latches" synaptic vesicles to presynaptic clusters at the active zone. cAMP-dependent phosphorylation of synapsin-1 then removes the vesicles. cAMP-independent dephosphorylation of synapsin-1 in turn recruits vesicles. Synapsin-1 thereby bidirectionally regulates synaptic vesicle numbers and modifies presynaptic neurotransmitter release as an effector of neuromodulator signaling in human neurons.

Attention-deficit/hyperactivity disorder in pregnancy and the postpartum period.

Attention-deficit/hyperactivity disorder is a childhood-onset neurodevelopmental disorder that frequently persists into adulthood with 3% of adult women having a diagnosis of attention-deficit/hyperactivity disorder. Many women are diagnosed and treated during their reproductive years, which leads to management implications during pregnancy and the postpartum period. We know from clinical practice that attention-deficit/hyperactivity disorder symptoms frequently become challenging to manage during the perinatal period and require additional support and attention. There is often uncertainty among healthcare providers about the management of attention-deficit/hyperactivity disorder in the perinatal period, particularly the safety of pharmacotherapy for the developing fetus. This guideline is focused on best practices in managing attention-deficit/hyperactivity disorder in the perinatal period. We recommend (1) mitigating the risks associated with attention-deficit/hyperactivity disorder that worsen during the perinatal period via individualized treatment planning; (2) providing psychoeducation, self-management strategies or coaching, and psychotherapies; and, for those with moderate or severe attention-deficit/hyperactivity disorder, (3) considering pharmacotherapy for attention-deficit/hyperactivity disorder, which largely has reassuring safety data. Specifically, providers should work collaboratively with patients and their support networks to balance the risks of perinatal attention-deficit/hyperactivity disorder medication with the risks of inadequately treated attention-deficit/hyperactivity disorder during pregnancy. The risks and impacts of attention-deficit/hyperactivity disorder in pregnancy can be successfully managed through preconception counselling and appropriate perinatal planning, management, and support.

Association between Early Guanfacine Discontinuation and Somnolence for Attention-Deficit/Hyperactivity Disorder.

Guanfacine, used as a medication for attention-deficit/hyperactivity disorder (ADHD), leads to a high incidence of somnolence, in contrast to methylphenidate, which leads to a high incidence of insomnia. The impact of somnolence on continuing guanfacine treatment is unclear. Therefore, we investigated the reasons for discontinuing guanfacine and analyzed the factors associated with discontinuation caused by somnolence. We surveyed 96 patients under guanfacine from July 2017 to December 2021 at the Saga University Hospital. Patients who discontinued guanfacine by the end date of our study were divided into a median early and late group. We compared the reasons for discontinuation in both groups. Of all patients, 47 continued and 49 discontinued guanfacine. A higher percentage of patients discontinued guanfacine caused by somnolence for ≤70 d than for >70 d of treatment (44.0 vs. 8.3%; p = 0.008). When stratified by the concomitant use of other ADHD drugs, somnolence resulted in a higher discontinuation rate for ≤70 d than for >70 d of treatment without concomitant use (55.0 vs. 7.1%; p = 0.009). Nonetheless, concomitant use resulted in no difference. In conclusion, somnolence affects the early discontinuation of guanfacine as an ADHD drug. The combination of methylphenidate or atomoxetine may decrease withdrawal caused by somnolence.

Anxiety and dysautonomia symptoms in patients with a NaV1.7 mutation and the potential benefits of low-dose short-acting guanfacine.

PURPOSE: Guanfacine is an α2A-adrenergic receptor agonist, FDA-approved to treat attention-deficit hyperactivity disorder and high blood pressure, typically as an extended-release formulation up to 7 mg/day. In our dysautonomia clinic, we observed that off-label use of short-acting guanfacine at 1 mg/day facilitated symptom relief in two families with multiple members presenting with severe generalized anxiety. We also noted anecdotal improvements in associated dysautonomia symptoms such as hyperhidrosis, cognitive impairment, and palpitations. We postulated that a genetic deficit existed in these patients that might augment guanfacine susceptibility. METHODS: We used whole-exome sequencing to identify mutations in patients with shared generalized anxiety and dysautonomia symptoms. Guanfacine-induced changes in the function of voltage-gated Na+ channels were investigated using voltage-clamp electrophysiology. RESULTS: Whole-exome sequencing uncovered the p.I739V mutation in SCN9A in the proband of two nonrelated families. Moreover, guanfacine inhibited ionic currents evoked by wild-type and mutant NaV1.7 encoded by SCN9A, as well as other NaV channel subtypes to a varying degree. CONCLUSION: Our study provides further evidence for a possible pathophysiological role of NaV1.7 in anxiety and dysautonomia. Combined with off-target effects on NaV channel function, daily administration of 1 mg short-acting guanfacine may be sufficient to normalize NaV channel mutation-induced changes in sympathetic activity, perhaps aided by partial inhibition of NaV1.7 or other channel subtypes. In a broader context, expanding genetic and functional data about ion channel aberrations may enable the prospect of stratifying patients in which mutation-induced increased sympathetic tone normalization by guanfacine can support treatment strategies for anxiety and dysautonomia symptoms.

Therapeutics for Substance-Using Women: The Need to Elucidate Sex-Specific Targets for Better-Tailored Treatments.

In the last decade, alcohol consumption in the US has risen by 84% in women compared with 35% in men. Furthermore, research has shown that sex- and gender-related differences may disadvantage women in terms of developing a range of psychological, cognitive, and medical problems considerably earlier in their drinking history than men, and despite consuming a similar quantity of substances. While this "telescoping" process has been acknowledged in the literature, a concomitant understanding of the underlying biobehavioral mechanisms, and an increase in the development of specific treatments tailored to women, has not occurred. In the current chapter we focus on understanding why the need for personalized, sex-specific medications is imperative, and highlight some of the potential sex-specific gonadal and stress-related adaptations underpinning the accelerated progress from controlled to compulsive drug and alcohol seeking in women. We additionally discuss the efficacy of these mechanisms as novel targets for medications development, using exogenous progesterone and guanfacine as examples. Finally, we assess some of the challenges faced and progress made in terms of developing innovative medications in women. We suggest that agents such as exogenous progesterone and adrenergic medications, such as guanfacine, may provide some efficacy in terms of attenuating stress-induced craving for several substances, as well as improving the ability to emotionally regulate in the face of stress, preferentially in women. However, to fully leverage the potential of these therapeutics in substance-using women, greater focus needs to the placed on reducing barriers to treatment and research by encouraging women into clinical trials.

Current and future nonstimulants in the treatment of pediatric ADHD: monoamine reuptake inhibitors, receptor modulators, and multimodal agents.

Attention-deficit/hyperactivity disorder (ADHD), the single most common neuropsychiatric disorder with cognitive and behavioral manifestations, often starts in childhood and usually persists into adolescence and adulthood. Rarely seen alone, ADHD is most commonly complicated by other neuropsychiatric disorders that must be factored into any intervention plan to optimally address ADHD symptoms. With more than 30 classical Schedule II (CII) stimulant preparations available for ADHD treatment, only three nonstimulants (atomoxetine and extended-release formulations of clonidine and guanfacine) have been approved by the United States Food and Drug Administration (FDA), all of which focus on modulating the noradrenergic system. Given the heterogeneity and complex nature of ADHD in most patients, research efforts are identifying nonstimulants which modulate pathways beyond the noradrenergic system. New ADHD medications in clinical development include monoamine reuptake inhibitors, monoamine receptor modulators, and multimodal agents that combine receptor agonist/antagonist activity (receptor modulation) and monoamine transporter inhibition. Each of these "pipeline" ADHD medications has a unique chemical structure and differs in its pharmacologic profile in terms of molecular targets and mechanisms. The clinical role for each of these agents will need to be explored with regard to their potential to address the heterogeneity of individuals struggling with ADHD and ADHD-associated comorbidities. This review profiles alternatives to Schedule II (CII) stimulants that are in clinical stages of development (Phase 2 or 3). Particular attention is given to viloxazine extended-release, which has completed Phase 3 studies in children and adolescents with ADHD.

Heteromerization between α2A adrenoceptors and different polymorphic variants of the dopamine D4 receptor determines pharmacological and functional differences. Implications for impulsive-control disorders.

Polymorphic alleles of the human dopamine D4 receptor gene (DRD4) have been consistently associated with individual differences in personality traits and neuropsychiatric disorders, particularly between the gene encoding dopamine D4.7 receptor variant and attention deficit hyperactivity disorder (ADHD). The α2A adrenoceptor gene has also been associated with ADHD. In fact, drugs targeting the α2A adrenoceptor (α2AR), such as guanfacine, are commonly used in ADHD treatment. In view of the involvement of dopamine D4 receptor (D4R) and α2AR in ADHD and impulsivity, their concurrent localization in cortical pyramidal neurons and the demonstrated ability of D4R to form functional heteromers with other G protein-coupled receptors, in this study we evaluate whether the α2AR forms functional heteromers with D4R and weather these heteromers show different properties depending on the D4R variant involved. Using cortical brain slices from hD4.7R knock-in and wild-type mice, here, we demonstrate that α2AR and D4R heteromerize and constitute a significant functional population of cortical α2AR and D4R. Moreover, in cortical slices from wild-type mice and in cells transfected with α2AR and D4.4R, we detect a negative crosstalk within the heteromer. This negative crosstalk is lost in cortex from hD4.7R knock-in mice and in cells expressing the D4.7R polymorphic variant. We also show a lack of efficacy of D4R ligands to promote G protein activation and signaling only within the α2AR-D4.7R heteromer. Taken together, our results suggest that α2AR-D4R heteromers play a pivotal role in catecholaminergic signaling in the brain cortex and are likely targets for ADHD pharmacotherapy.

Guanfacine toxic ingestion with subsequent cardiogenic pulmonary edema.

Guanfacine is a central alpha-2 agonist often prescribed for Attention-deficit hyperactive disorder as well as tic disorder, with a usual dose of 1-4 mg per day. Due to its sympatholytic mechanism of action, Guanfacine can cause autonomic instability and hypotension. It can additionally cause cardiac dysfunction to include symptomatic bradycardias and contractility suppression. The authors present a case of a 17 year-old male with an ingestion of 80 mg of extended release Guanfacine with delayed onset cardiogenic pulmonary edema requiring mechanical ventilation. Previous pediatric ingestions have generated bradycardia, hypotension, and decreased level of consciousness, responsive to intravenous fluids, vasopressors, and occasionally naloxone. However, cardiogenic pulmonary edema from reduced cardiac contractility is a novel consequence of extended release Guanfacine ingestion. With Guanfacine's extended half-life, this unique case underscores the importance of emergency providers' familiarity with this toxidrome as well the necessity for prolonged, close observation following Guanfacine ingestion.

Norepinephrine May Oppose Other Neuromodulators to Impact Alzheimer's Disease.

While much of biomedical research since the middle of the twentieth century has focused on molecular pathways inside the cell, there is increasing evidence that extracellular signaling pathways are also critically important in health and disease. The neuromodulators norepinephrine (NE), serotonin (5-hydroxytryptamine, 5HT), dopamine (DA), acetylcholine (ACH), and melatonin (MT) are extracellular signaling molecules that are distributed throughout the brain and modulate many disease processes. The effects of these five neuromodulators on Alzheimer's disease (AD) are briefly examined in this paper, and it is hypothesized that each of the five molecules has a u-shaped (or Janus-faced) dose-response curve, wherein too little or too much signaling is pathological in AD and possibly other diseases. In particular it is suggested that NE is largely functionally opposed to 5HT, ACH, MT, and possibly DA in AD. In this scenario, physiological "balance" between the noradrenergic tone and that of the other three or four modulators is most healthy. If NE is largely functionally opposed to other prominent neuromodulators in AD, this may suggest novel combinations of pharmacological agents to counteract this disease. It is also suggested that the majority of cases of AD and possibly other diseases involve an excess of noradrenergic tone and a collective deficit of the other four modulators.

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.

Safety and efficacy of guanfacine extended-release in adults with attention-deficit/hyperactivity disorder: an open-label, long-term, phase 3 extension study.

BACKGROUND: To assess the safety and efficacy of long-term administration of guanfacine extended-release (GXR) in adults with attention-deficit/hyperactivity disorder (ADHD). METHODS: In this open-label, long-term, phase 3 extension study in Japan, 150 patients transitioned from a double-blind trial, and 41 newly enrolled patients received once daily GXR (starting dose 2 mg/day, maintenance dose 4-6 mg/day) for 50 weeks. Primary outcome measures were the frequency and nature of treatment-emergent adverse events (TEAEs); secondary outcome measures included the change from week 0 in ADHD Rating Scale IV with Adult Prompts (ADHD-RS-IV; Japanese version) total and subscale scores, Conners' Adult ADHD Rating Scales (CAARS), Clinical Global Impression-Improvement (CGI-I) and Patient Global Impression-Improvement (PGI-I) scales, and quality of life (QoL) and executive functioning measures. RESULTS: Of all patients, 94.2% (180/191) reported ≥1 TEAE and 19.9% (38/191) discontinued because of a TEAE. Most TEAEs were mild to moderate in severity; there were two serious TEAEs and no deaths. Commonly reported TEAEs (≥10% of patients) were somnolence, thirst, nasopharyngitis, decreased blood pressure, postural dizziness, bradycardia, malaise, constipation, and dizziness. Mean changes from week 0 in ADHD-RS-IV total and subscale scores and CAARS subscale scores were significantly improved in former placebo or GXR patients and new patients at last observation (p < .0001), and the percentage of patients with very much or much improved CGI-I and PGI-I scores increased. CONCLUSIONS: There were no major safety concerns during long-term GXR administration in adults with ADHD. After long-term treatment, patients had significant improvements from baseline in ADHD symptoms, QoL, and executive functioning. TRIAL REGISTRATION: Japan Primary Registries Network ( https://rctportal.niph.go.jp/en/ ): JapicCTI-163232, registered 04/21/2016.

Guanfacine extended-release for cannabis use disorder: a pilot feasibility trial.

Background: Currently, there are no established pharmacotherapies for cannabis use disorders (CUDs). As a long-acting alpha-2-adrenergic receptor agonist, guanfacine extended-release (G-XR) could be useful in the treatment of CUDs by mitigating withdrawal and improving behavioral control.Objectives: To evaluate the feasibility and tolerability of G-XR as a treatment for CUDs.Methods: In an eight-week open-label outpatient pilot trial, we evaluated the safety and tolerability of G-XR in 22 cannabis dependent individuals. Using 2 different titration schedules, G-XR was gradually titrated to a dose of 4 mg or the highest dose tolerated. All participants received standard medication management.Results: Retention at week eight was 41%. Average daily amount of cannabis use (in grams: F1,86 = 8.74, p = .004; in dollars: F1,86 = 16.67, p < .0001) and cannabis using days (F1,86 = 7.67, p = .007) significantly reduced over the course of study participation. There were no significant differences between the titration schedules on emergence of side effects (Fisher exact test, p = .378) or retention (Log-Rank Test X21 = 0.021, p = .886). A total of 3 participants achieved 3 weeks or greater of total abstinence.Conclusions: G-XR is a feasible treatment for CUDs, and should be evaluated further in an efficacy trial.

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.

Identification of the Hypertension Drug Guanfacine as an Antivirulence Agent in Pseudomonas aeruginosa.

An alternative solution to the cyclical development of new antibiotics is the concept of disarming pathogens without affecting their growth, thereby eliminating the selective pressures that lead to resistant phenotypes. Here, we have employed our previously developed HiTES methodology to identify one such compound against the ESKAPE pathogen Pseudomonas aeruginosa. Rather than induce silent biosynthetic gene clusters, we used HiTES to suppress actively expressed virulence genes. By screening a library of 770 FDA-approved drugs, we identified guanfacine, a clinical hypertension drug, as an antivirulence agent in P. aeruginosa. Follow-up studies showed that guanfacine reduces biofilm formation and pyocycanin production without altering growth. Moreover, we identified a homologue of QseC, a sensor His kinase used by multiple pathogens to turn on virulence, as a target of guanfacine. Our studies suggest that guanfacine might be an attractive antivirulence lead in P. aeruginosa and provide a template for uncovering such molecules by screening for downregulators of actively expressed biosynthetic genes.

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.

Guanfacine monotherapy for ADHD/ASD comorbid with Tourette syndrome: a case report.

BACKGROUND: Patients with attention deficit/hyperactivity disorder (ADHD) often experience comorbid conditions, such as autism spectrum disorder (ASD) and Tourette syndrome (TS). Although pharmacotherapies are effective for treating ADHD, they are likely to elicit a variety of adverse effects. It is, thus, important to select an effective and well-tolerated pharmacotherapeutic treatment for patients with ADHD/ASD comorbid with TS. CASE PRESENTATION: We report the case of a 10-year-old boy with ADHD/ASD comorbid with TS who was treated with guanfacine (GUAN). He experienced several side effects of atomoxetine (ATX) and methylphenidate (MPH) before being treated with GUAN. In the presented case, symptoms of ADHD as well as tic symptoms were improved by treatment with GUAN. CONCLUSION: GUAN might be effective and well tolerated in the treatment of patients with ADHD/ASD comorbid with TS who experience side effects of ATX and MPH.

Guanfacine Attenuates Adverse Effects of Dronabinol (THC) on Working Memory in Adolescent-Onset Heavy Cannabis Users: A Pilot Study.

The cannabinoid-1 receptor (CB1R) agonist Δ9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, adversely effects working memory performance in humans. The α2A-adrenoceptor (AR) agonist guanfacine improves working memory performance in humans. The authors aimed to determine the effects of short-term (6 days) treatment with guanfacine on adverse cognitive effects produced by THC. Employing a double-blind, placebo-controlled crossover design, the cognitive, subjective, and cardiovascular effects produced by oral THC (20 mg) administration were determined twice in the same cannabis users: once after treatment with placebo and once after treatment with guanfacine (3 mg/day). Compared with performance at baseline, THC negatively affected accuracy on spatial working memory trials while participants were maintained on placebo (p=0.012) but not guanfacine (p=0.497); compared with placebo, accuracy was significantly (p=0.003, Cohen's d=-0.640) improved while individuals were treated with guanfacine. Similarly, compared with baseline, THC increased omission errors on an attentional task while participants were maintained on placebo (p=0.017) but not on guanfacine (p=0.709); compared with placebo, there were significantly (p=0.034, Cohen's d=0.838) fewer omissions while individuals were maintained on guanfacine. Although THC increased visual analog scores of subjective effects and heart rate, these increases were similar during treatment with placebo and guanfacine. THC did not significantly affect performance of a recognition memory task or blood pressure while individuals were maintained on either treatment. Although preliminary, these results suggest that guanfacine warrants further testing as a potential treatment for cannabis-induced cognitive deficits.

Long-term safety and efficacy of guanfacine extended release in children and adolescents with ADHD.

Data are reported from SPD503-318, a phase 3, open-label, safety study of guanfacine extended release (GXR) in European children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Participants received dose-optimized GXR (1-7 mg/day) for up to 2 years. Of 215 enrolled participants, 214 were included in the safety population and 133 completed the study. Participants' mean age was 11.7 years and 73.8% were male. Overall, 177 participants (82.7%) experienced a treatment-emergent adverse event (TEAE). TEAEs reported in at least 10% of participants were somnolence (36.0%), headache (28.5%), fatigue (20.1%), and nasopharyngitis (11.7%). Serious TEAEs were reported in 4.7% of participants and TEAEs leading to discontinuation were reported in 3.3% of participants. There were no deaths. Mean z-scores for BMI were stable throughout the study. The incidence of sedative TEAEs (somnolence, sedation, and hypersomnia) peaked during week 3 and decreased thereafter. Small changes from baseline to the final assessment in mean supine pulse [- 5.5 bpm (standard deviation, 12.98)] and blood pressure [systolic, 0.6 mmHg (9.32); diastolic, 0.2 mmHg (9.17)] were reported. ADHD symptoms initially decreased and remained significantly lower than baseline at study endpoint. At the final assessment, the mean change in ADHD-RS-IV total score from baseline was - 19.8 (standard error of mean, 0.84; nominal p < 0.0001). In conclusion, GXR was well tolerated and more than 60% of participants completed the 2-year study.

Autonomic instability in a dehydrated child on guanfacine: Case report and literature review.

An 8-year-old girl on guanfacine extended-release (GXR) for attention-deficit/hyperactivity disorder presented with somnolence, bradycardia and hypotension during a heat wave. No overdose was suspected. She was admitted to the intensive care unit for monitoring and ongoing fluid resuscitation for hypotension. Electrocardiogram showed intermittent atrioventricular dissociation. Upon restarting the drug post-discharge, blood pressures were normal, and follow-up electrocardiograms documented asymptomatic bradycardia but no dissociation. GXR is used as monotherapy or adjunct therapy in the treatment of inattention and hyperactivity in children. No published paediatric or adult study has documented atrioventricular dissociation, bradycardia or hypotension significant enough to warrant hospital admission. This case suggests that GXR can pose a hemodynamic risk to children in the context of elevated environmental temperatures and dehydration. Clinicians should be aware of this potential complication and should counsel patients about signs and symptoms of hypotension, bradycardia, bradypnea and somnolence.