Adult ADHD: 6 studies of pharmacologic interventions

Conclusions/limitations

• AMPH ER TAB reduced symptoms in adults with ADHD as assessed by improvement in PERMP-T scores.
• The safety and tolerability profile of AMPH ER TAB were comparable to other stimulants, with expected rises in blood pressure and heart rate.
• Limitations: Patients were required to be titrated to 20 mg/d of AMPH ER TAB, instead of following a flexible titration based on an individual’s response. Some participants may have had greater improvement at a higher or lower dose. This study did not compare AMPH ER TAB to other stimulants. The 5-week duration of this study limited the ability to evaluate long-term efficacy and tolerability. Patients with a wide range of psychiatric or medical comorbidities were excluded.

5. Iwanami A, Saito K, Fujiwara M, et al. 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. J Clin Psychiatry. 2020;81(3):19m12979. doi:10.4088/JCP.19m12979

Guanfacine extended-release (GXR) is a selective alpha 2A-adrenergic receptor agonist approved for treating ADHD in children and adolescents.¹⁷ Iwanami et al¹³ evaluated the efficacy and safety of GXR for adults.

Study design

• This randomized, double-blinded, placebo-controlled trial enrolled Japanese adults age ≥18 who were diagnosed with ADHD according to DSM-5 criteria and scored ≥24 on the ADHD-Rating Scale IV (ADHD-RS-IV) and ≥4 on CGI- I.
• Exclusion criteria included having anxiety, depression, substance use disorder, tic disorder, BD, personality disorder, schizophrenia, or intellectual disability; a moderate or severe psychiatric disorder requiring treatment other than counseling; seizures; increased risk for suicide; a history of cardio­vascular disease, including prolonged QTc/abnormal ECG/abnormal labs, orthostatic hypotension, or continuous bradycardia; or taking medications that affect blood pressure or heart rate.
• Overall, 101 participants were randomized to the GXR group and 100 to the placebo group. Approximately two-thirds of the study population was male. Patients received GXR or placebo once daily at approximately the same time.
• There were 5 phases to the trial. The screening period occurred over 1 to 4 weeks. Part 1 of the treatment period consisted of 5 weeks of medication optimization. Participants were started on GXR 2 mg/d and were required to be receiving a minimum dose of 4 mg/d starting at Week 3. Clinicians were allowed to increase the dose 1 mg/d per week starting at Week 4 based on clinical response to a maximum dosage of 6 mg/d. Part 2 of the treatment period consisted of 5 weeks of maintenance at 4 to 6 mg/d. The tapering period to 2 mg/d occurred over 2 weeks. The follow-up period lasted 1 week.
• Efficacy measurements included the Japanese version of the ADHD-RS-IV and translations of the English-language CAARS, CGI-I, and CGI-S. Participant-reported measures included the Patient Global Impression-Improvement scale (PGI-I), Adult ADHD Quality of Life Questionnaire (AAQoL), and BRIEF-A.
• The primary outcome was the difference in ADHD-RS-IV total score from baseline to the end of the maintenance period (Week 10).
• Safety assessments were completed at Week 5 (end of dose optimization period), Week 10 (end of dose maintenance period), and Week 12 (tapering period).

Outcomes

• The average GXR dose during the maintenance period was 5.07 mg/d.
• Compared to the placebo group, the GXR group had more patients age <30 (47% vs 39%) and fewer patients age ≥40 (17% vs 27%). Baseline ADHD-RS-IV scores in both groups were comparable. At baseline, 51% in the GXR group had a combined inattentive/hyperactive-impulsive presentation and 47% had a predominately inattention presentation, with similar characteristics in the placebo group (49% combined, 49% inattention).
• At Week 10, the least squares mean change from baseline on the ADHD-RS-IV total score was significantly greater in the GXR group than in the placebo group (-11.55 ± 1.10 vs -7.27 ± 1.07; P = .0005), with an effect size of 0.52. There was a greater decrease in the ADHD-RS-IV scores starting at Week 4 and continuing to Week 10 (P < .005).
• There were also significant differences favoring GXR on the ADHD-RS-IV hyperactivity-impulsivity subscale score (P = .0021) and ADHD-RS-IV inattention subscale score (P = .0032).
• There were significant differences in the CAARS total ADHD score (P = .0029) and BRIEF-A scores on the inhibit (P = .0173), initiate (P = .0406), plan/organize (P = .174), and global executive composite index (P = .0404) scales. There was no significant difference in the total AAQoL score (P = .0691), but there was a significant improvement in the AAQoL life productivity subscore (P = .0072).
• At Week 10, there were also significant improvements in the CGI-I scores (P = .0007) and PGI-I scores (P = .0283). The CGI-S scores were similar at all time points.
• Overall, 81.2% of GXR patients reported AEs compared to 62% in the placebo group. There was 1 serious treatment-emergent AE (a suicide attempt) that the authors concluded was unrelated to the study drug. No deaths occurred. The most common AEs (incidence ≥10% in either group) included somnolence, thirst, nasopharyngitis (occurring more in the placebo group), blood pressure decrease, postural dizziness, and constipation. The main AEs leading to discontinuation were somnolence and blood pressure decrease. Overall, 19.8% of patients receiving GXR discontinued treatment due to AEs, compared to 3% in the placebo group.
• Heart rate, blood pressure, and QTc (corrected by the Bazett formula) were decreased in the GXR group at Week 10 while QT and RR intervals increased, and most returned to normal by Week 12.

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