Conclusions/limitations
- Compared to placebo, GXR monotherapy resulted in clinical improvement in ADHD symptoms, with a moderate effect size.
- The most common AEs were mild to moderate and congruent with known adverse effects of guanfacine. Sedation effects mostly transpired within the first week of medication administration and were transient.
- Limitations: The findings might not be generalizable to non-Japanese patients. The duration of the study was short. Patients with a wide range of psychiatric and medical comorbidities were excluded. Two-thirds of the participants were male, and there was a disparity in participant age in the GXR and placebo groups.
6. Reimherr FW, Gift TE, Steans TA, et al. The use of brexpiprazole combined with a stimulant in adults with treatment-resistant attention-deficit/hyperactivity disorder. J Clin Psychopharmacol. 2022;42(5):445-453. doi:10.1097/JCP.0000000000001592
While stimulants are a mainstay ADHD treatment, some patients have a partial response or do not respond to amphetamines or methylphenidate. Reimherr et el14 assessed the efficacy and safety of adding brexpiprazole (BXP) to a stimulant.
Study design
- This randomized, double-blinded, placebo-controlled trial recruited 559 stimulant-naive patients and 174 patients who had not responded to previous stimulant therapy.
- Participants were adults age 18 to 55 with a primary diagnosis of ADHD according to DSM-IV-TR criteria and the Conners Adult ADHD Diagnostic Interview. Other inclusion criteria were having a CAARS score ≥29 and a CGI-S score ≥4.
- Exclusion criteria included being at risk for suicide; having current substance abuse or positive alcohol/drug screens; a history of good response to prestudy treatment; a clinically significant medical condition; fasting blood glucose >200 mg/dL or hemoglobin A1C >7%; and hospitalization in past 12 months from a diabetic complication, uncontrolled hypertension, ischemic heart disease, or epilepsy. Further exclusion criteria included a history of psychosis, current MDD or BD, current panic disorder, uncontrolled comorbid psychiatric condition, or clinically significant personality disorder. Investigators excluded any patient with severe DSM-IV axis I or II disorders or abnormal/psychopathological behaviors.
- The trial consisted of 3 segments. Part 1 was screening. If the patient was currently receiving a stimulant but not fully responding, the medication was discontinued for at least 5 half-lives.
- Part 2 (5 weeks) involved administering a stimulant plus a single-blind placebo (597 patients completed this phase). The stimulant was chosen by the investigator, who had the option of using 1 of 2 amphetamine derivatives (mixed amphetamine salts capsules or lisdexamfetamine dimesylate capsules) or 1 of 2 methylphenidate derivatives (methylphenidate hydrochloride ER tabs or dexmethylphenidate HCl ER capsules). If a patient did not respond to a particular stimulant prior to the study, they were given a different stimulant from the list. Patients continued the same stimulant throughout the trial. Patients were monitored for a response, defined as a ≥30% decrease in CAARS score or a CAARS score <24, or a CGI-I score of 1 or 2 at Week 5. Patients who did not show this improvement were categorized as open-label nonresponders.
- Part 3 (6 weeks) involved administering a stimulant plus double-blind BXP vs placebo (stimulant-naive n = 167, stimulant nonresponders n = 68). Nonresponders continued the stimulant (at the same dose reached at the end of Part 2) and added either BXP (n = 155) or continued placebo (n = 80). Patients who responded in Part 2 were continued on the stimulant plus placebo and were not randomized. Patients were started on BXP 0.25 mg/d, and the medication could be titrated to 2 mg/d during the following 3 weeks, depending on the benefit vs AE profile. After the third week, the dose could be decreased but not increased.
- The primary outcome was a change in CAARS score. Secondary measurements included the CGI-S, Wender-Reimherr Adult Attention Deficit Disorder Scale (WRAADDS), Montgomery-Åsberg Depression Rating Scale (MADRS), and BDI.
Outcomes
- Stimulant-naive patients were equally divided among the 4 stimulant groups, and previous nonresponders who continued to not respond in Part 2 were more likely to be given methylphenidate HCl or lisdexamfetamine dimesylate.
- Patients with a history of nonresponse had less response to stimulants in Part 2 compared to stimulant-naive patients, as seen by 27% (n = 167) of stimulant-naive patients entering Part 3 compared to 39% of prior nonresponders (n = 68; P = .0249).
- ADHD improvement with BXP appeared to be greater among pretrial nonresponders.
- For stimulant nonresponders before and during the study, at the end of the double-blind endpoint (Part 3; Week 11), WRAADDS total score was significantly improved in the BXP group compared to the placebo group (P = .013; d = 0.74), with most beneficial effects seen in the hyperactivity/restlessness, emotional dysregulation factor, and impulsivity categories.
- For stimulant nonresponders before and during the study, there was no significant difference at the end of Week 11 on the CAARS (P = .64), MADRS (P = .37), or BDI (P = .73). There was a trend toward significance on the CAARS subscale for hyperactive/impulsive (P = .09).
- For prestudy stimulant-naive patients who did not respond to stimulants in Part 2 and were randomized in Part 3, there was not a significant difference between BXP and placebo at Week 11 as assessed on WRAADDS, CAARS, MADRS, or BDI.
- As assessed on WRAADDS, 50% in the BXP group had a response compared to 41% in the placebo group (Fisher exact = 0.334). Under the emotional dysregulation factor category of the WRAADDS, 64% in the BXP group had a response compared to 41% in the placebo group (Fisher exact = 0.064). The attention factor category showed a 40% improvement in the BXP group compared to 32% in the placebo group (Fisher exact = 0.344).
- There were 2 serious AEs in the BXP group (gall bladder inflammation and diarrhea) and 2 in the placebo group (pneumonia and urinary tract infection). There was no statistically significant difference between groups with regards to common AEs (ie, fatigue, heartburn/nausea/stomachache, weight loss), although there was a trend to significant for insomnia in the BXP group (P = .083).
Conclusions/limitations
- Stimulant-naive patients experienced no improvement with adjunctive BXP.
- For prior stimulant nonresponders, there was no significant difference between BXP vs placebo on the primary outcome of the CAARS score, but there was an improvement as observed by assessment with the WRAADDS.
- The largest change in the WRAADDS occurred in the emotional dysregulation factor compared to the attention factor.
- BXP appeared to be well tolerated.
- Limitations: The WRAADDS was administered without the patients’ significant other/collateral. Raters were not trained in the use of the WRAADDS. Patients with a wide range of psychiatric and medical comorbidities were excluded. Fewer patients were recruited in the prior stimulant nonresponder group.
Bottom Line
Recent randomized controlled trials suggest that methylphenidate, amphetamine extended-release, viloxazine extended-release, and guanfacine extended-release improved symptoms of adult attention-deficit/hyperactivity disorder (ADHD). There were no improvements in ADHD symptoms with adjunctive brexpiprazole.
Related Resources
- Parikh AR, Baker SA. Adult ADHD: pharmacologic treatment in the DSM-5 era. Current Psychiatry. 2016;15(10):18-25.
- Akbar HN. Why we should be scrutinizing the rising prevalence of adult ADHD. Current Psychiatry. 2022; 21(7):e1-e2. doi:10.12788/cp.0268
Drug Brand Names
Amantadine • Gocovri
Amphetamine extended-release tablet • Dyanavel XR
Atomoxetine • Strattera
Brexpiprazole • Rexulti
Bupropion • Wellbutrin
Dexmethylphenidate • Focalin
Fluoxetine • Prozac
Guanfacine extended- release • Intuniv
Lisdexamfetamine • Vyvanse
Methylphenidate • Concerta, Methylin
Theophylline • Elixophyllin
Viloxazine • Qelbree