The Role of Alpha-2 Agonists for Attention Deficit Hyperactivity Disorder in Children: A Review

INTRODUCTION

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders, characterized by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which is marked by symptoms such as inappropriate levels of inattention, hyperactivity, and impulsivity that can affect academic, social, and personal functioning in children and adolescents. This review summarizes clinical trials demonstrating the effectiveness of Alpha-2 agonists in reducing symptoms of inattention, hyperactivity, and impulsivity in children with ADHD. Studies were identified through a systematic search of PubMed and Cochrane databases. However, these medications' long-term safety and efficacy remain uncertain, with a lack of data on their effects on growth, cardiovascular function, and other adverse events. Further studies are required to determine these medications' optimal dose and treatment duration.

METHODS

Medications that target the noradrenergic system, such as Alpha-2 agonists, have been increasingly used as a treatment option for ADHD, with guanfacine and clonidine being two of the most commonly used medications. They function by selectively targeting Alpha-2 adrenergic receptors in the brain leading to improved attention and reduced hyperactivity and impulsivity symptoms in children with ADHD.

RESULTS

Clinical trials have demonstrated the effectiveness of Alpha-2 agonists in treating ADHD in children by reducing symptoms of inattention, hyperactivity, and impulsivity. However, these medications' long-term safety and efficacy still need to be completely understood. Due to a lack of information on the effects of Alpha-2 agonists on growth, cardiovascular function, and other long-term adverse events, more studies must investigate the optimal dose and treatment duration for these medications.

CONCLUSIONS

Despite these concerns, Alpha-2 agonists remain a valuable treatment option for ADHD in children, especially those unable to tolerate stimulant medications or who have coexisting conditions such as tic disorders. Future research should continue to explore the safety and efficacy of Alpha-2 agonists in the long term. In conclusion, Alpha-2 agonists show promise as a treatment for ADHD in children; however, the safety and efficacy of these drugs in the long term are not yet completely understood. Additional studies are required to investigate the optimal dose and treatment duration for these medications in their use as a treatment for this debilitating disease.

A Comparative Study of Intrathecal Hyperbaric Bupivacaine 0.5% with Morphine and Dexmedetomidine in Lower Limb Orthopedic Surgeries: A Double-Blind Randomized Clinical Trial

Background

Pain and its alleviation have been a challenge for humans for centuries. Sub arachnoid block is most commonly practiced method for anaesthesia for lower limb surgeries. Adjuvants like opioids and alpha 2 agonists have proven benefits in augmentation of effects of local anaesthetics for spinal anesthesia. The aim of this study was to compare the effects of morphine and dexmedetomidine for sub arachnoid block in lower limb orthopaedic surgeries.

Material and Methods

This is a prospective randomised controlled trial done in 120 patients who were posted for lower limb orthopaedic surgery. Along with bupivacaine, Group A received intrathecal dexmedetomidine while group B received intrathecal morphine.

Results

the demographic profile was comparable in both the groups. The mean duration of motor block in Group A was 359.33 ± 34.4 and in Group B was 265.71 ± 28.47. The duration of rescue analgesia was almost double in Group A as compared to Group B with P < 0.0001 (CL 95%).

Conclusion

Intrathecal dexmedetomidine and morphine both provided good postoperative analgesia. Dexmedetomidine provided a longer duration of analgesia than morphine, thereby increasing the time for first rescue analgesia, but at the cost of greater side effects.

Intranasal dexmedetomidine for adrenergic crisis in familial dysautonomia

PURPOSE

To report the use of intranasal dexmedetomidine, an α₂-adrenergic agonist for the acute treatment of refractory adrenergic crisis in patients with familial dysautonomia.

METHODS

Case series.

RESULTS

Three patients with genetically confirmed familial dysautonomia (case 1: 20-year-old male; case 2: 43-year-old male; case 3: 26-year-old female) received intranasal dexmedetomidine 2 mcg/kg, half of the dose in each nostril, for the acute treatment of adrenergic crisis. Within 8-17 min of administering the intranasal dose, the adrenergic crisis symptoms abated, and blood pressure and heart rate returned to pre-crises values. Adrenergic crises eventually resumed, and all three patients required hospitalization for investigation of the cause of the crises.

CONCLUSIONS

Intranasal dexmedetomidine is a feasible and safe acute treatment for adrenergic crisis in patients with familial dysautonomia. Further controlled studies are required to confirm the safety and efficacy in this population.

Immobilization of Asiatic Black Bears ( Ursus thibetanus ) with Medetomidine-Zolazepam-Tiletamine in South Korea

The Asiatic black bear ( Ursus thibetanus ; ABB) is a globally endangered species for which a restoration program has been ongoing in South Korea since 2001. However, there is little information on immobilization protocols for ABBs. We evaluated the use of medetomidine-zolazepam-tiletamine for their immobilization. During 2005-13, we anesthetized 60 ABBs (32 males, 28 females; 7 mo to 12 yr old) with medetomidine 0.03-0.045 mg/kg and zolazepam-tiletamine 1.54-2.3 mg/kg; reversal of anesthesia was done with atipamezole 0.15-0.225 mg/kg administered intravenously alone or intravenously and intramuscularly (50:50). Mean (and SD) for physiologic collected for 373 immobilizations of at least 60 min were: time to sedation, 7.8 (5.4) min; anesthesia induction time, 13.7 (8.1) min; complete recovery time, 14.8 (12.4) min; respiratory rate, 14 (7) breaths/min; heart rate, 51 (16) beats/min; rectal temperature, 37.3 (1.3) C; and hemoglobin oxygen saturation, 88% (6%). Few cardiopulmonary side effects occurred during immobilization and adequate depth of anesthesia was maintained for >60 min without need for supplementation. The dosage and drug combination used was effective for immobilization of ABBs with minimal adverse effects on vital signs and can be recommended in most clinical applications.

Dexmedetomidine for refractory adrenergic crisis in familial dysautonomia

OBJECTIVE

Adrenergic crises are a cardinal feature of familial dysautonomia (FD). Traditionally, adrenergic crises have been treated with the sympatholytic agent clonidine or with benzodiazepines, which can cause excessive sedation and respiratory depression. Dexmedetomidine is a centrally-acting α ₂-adrenergic agonist with greater selectivity and shorter half-life than clonidine. We evaluated the preliminary effectiveness and safety of intravenous dexmedetomidine in the treatment of refractory adrenergic crisis in patients with FD.

METHODS

Retrospective chart review of patients with genetically confirmed FD who received intravenous dexmedetomidine for refractory adrenergic crises. The primary outcome was preliminary effectiveness of dexmedetomidine defined as change in blood pressure (BP) and heart rate (HR) 1 h after the initiation of dexmedetomidine. Secondary outcomes included incidence of adverse events related to dexmedetomidine, hospital and intensive care unit (ICU) length of stay, and hemodynamic parameters 12 h after dexmedetomidine cessation.

RESULTS

Nine patients over 14 admissions were included in the final analysis. At 1 h after the initiation of dexmedetomidine, systolic BP decreased from 160 ± 7 to 122 ± 7 mmHg (p = 0.0005), diastolic BP decreased from 103 ± 6 to 65 ± 8 (p = 0.0003), and HR decreased from 112 ± 4 to 100 ± 5 bpm (p = 0.0047). The median total adverse events during dexmedetomidine infusion was 1 per admission. Median hospital length of stay was 9 days [interquartile range (IQR) 3-11 days] and median ICU length of stay was 7 days (IQR 3-11 days).

CONCLUSIONS

Intravenous dexmedetomidine is safe in patients with FD and appears to be effective to treat refractory adrenergic crisis. Dexmedetomidine may be considered in FD patients who do not respond to conventional clonidine and benzodiazepine pharmacotherapy.

Haemodynamic interactions of medetomidine and the peripheral alpha-2 antagonist MK-467 during step infusions in isoflurane-anaesthetised dogs

The haemodynamic interactions of a step infusion with medetomidine (MED) and the peripherally acting alpha-2 antagonist MK-467 (MK) were compared with MED infused alone in isoflurane-anaesthetised dogs. Eight purposely-bred Beagles were used in a randomised crossover study. Anaesthesia was induced with propofol intravenously (IV) and maintained with isoflurane in oxygen. Dogs received 1.25 µg/kg MED as a 1 min loading dose IV, along with a step-down MED infusion at rates of 8.0 µg/kg/h (step 1: 0-20 min), 5.5 µg/kg/h (step 2: 20-40 min) and 4.0 µg/kg/h (step 3: 40-95 min). Five minutes after starting the MED infusion, the dogs received MK-467 in a step-up infusion at rates of 100 µg/kg/h (step 1: 5-35 min), 200 µg/kg/h (step 2: 35-65 min) and 500 µg/kg/h (step 3: 65-95 min). Heart rate (HR), systolic (SAP) and mean arterial (MAP) blood pressures and arteriovenous oxygen content differences (a-vO2 diff) were calculated. Plasma drug concentrations were analysed. Repeated-measures general linear mixed models with Bonferroni correction were used for statistical analyses. MED infusion alone increased SAP maximally by 24.9%, MAP by 34.7% and a-vO2 diff by 222.5%, and reduced HR by 32.3%, but these changes were significantly attenuated by MK-467. Most MED effects returned to baseline during step 2 of MK-467 infusion and step 3 of MED infusion (MED/MK-467 ratio 1:18 to 1:50). Plasma concentrations of MED tended to be lower with the addition of MK-467. The use of step infusions helped to narrow down the therapeutic range for the MED/MK-467 infusion dose ratio during isoflurane anaesthesia in dogs.

Use of α(2)-Agonists in Neuroanesthesia: An Overview

α(2)-Agonists are a novel class of drugs with mechanisms of action that differ from other commonly used anesthetic drugs. They have neuroprotective, cardioprotective, and sedative effects. These unique characteristics make them potentially useful during neuroanesthesia and intensive care. We review the effects of dexmedetomidine on cerebral blood flow and cerebral metabolism, along with recent advances in using α(2)-agonists in neuroanesthesia and neurointensive care.