Efficacy and safety of lisdexamfetamine dimesylate in children with attention-deficit/hyperactivity disorder and recent methylphenidate use

New Drugs to Treat ADHD: Opportunities and Challenges in Research and Development

Since the landmark MTA (Multimodal Treatment of ADHD) trial unequivocally demonstrated the efficacy of methylphenidate, catecholaminergic drugs, especially stimulants, have been the therapeutic mainstay in treatment of Attention-Deficit Hyperactivity Disorder (ADHD). We review the new drugs which have entered the ADHD formulary. The lessons learned from drug-candidates that have succeeded in clinical trials together with those that have not have also been considered. What emerges confirms and consolidates the hypothesis that clinically effective ADHD drugs indirectly or directly increase catecholaminergic neurotransmission in the prefrontal cortex (PFC). Attempts to enhance catecholaminergic signalling through modulatory neurotransmitter systems or cognitive-enhancing drugs have all failed. New drugs approved for ADHD are catecholaminergic reuptake inhibitors and releasing agents, or selective noradrenaline reuptake inhibitors. Triple reuptake inhibitors with preferential effects on dopamine have not been successful. The substantial number of failures probably accounts for a continued focus on developing novel catecholaminergic and noradrenergic drugs, and a dearth of drug-candidates with novel mechanisms entering clinical development. However, substantial improvements in ADHD pharmacotherapy have been achieved by the almost exclusive use of once-daily medications and prodrugs, e.g. lisdexamfetamine and Azstarys^®, which improve compliance, deliver greater efficacy and reduce risks for diversion and abuse.

Review of lisdexamfetamine dimesylate in children and adolescents with attention deficit/hyperactivity disorder

OBJECTIVE

Lisdexamfetamine dimesylate is a stimulant prodrug with low abuse and diversion potential that is used in treatment of attention deficit hyperactivity disorder (ADHD) in children, adolescents and adults. This current literature review article aims to examine safety and efficacy of LDX in children and adolescents for the treatment of ADHD based on currently available data.

METHODS

Relevant English language articles were identified through computerized searches of the MEDLINE database (PubMed and EMBASE) and clinical trials registry up to January 2020 using the following search terms: lisdexamfetamine dimesylate, pro-drug stimulant, attention-deficit and hyperactivity disorders, ADHD, safety, efficacy, children, adolescents, Vyvanse. Forty-two articles were reviewed, 34 of which were included into this review, selected by the limit "clinical trials". This article represents the pharmacological profile, efficacy and safety data of LDX for the treatment of ADHD in children and adolescents.

RESULTS

The collection of studies reviewed identified that LDX was both safe and efficacious in the treatment of ADHD. The most commonly exhibited side effects were appetite suppression, weight loss, headache and insomnia. In comparison to placebo, LDX significantly improved ADHD symptoms and overall quality of life in children and adolescents. In comparison to atomoxetine, LDX showed statistically significant improvements in inattention, impulsivity, and activities of daily living. In comparison to OROS-MPH and placebo, LDX and OROS-MPH showed improvements with the CGI-I score, and ADHD-RS-IV, however, LDX was superior.

CONCLUSION

Patients have seen statistically significant improvements in their ADHD symptomatology in the classroom environment, health related quality of life, and their overall behavior in comparison to placebo, atomoxetine, and OROS-MPH. However, clinical judgment should be utilized when prescribing LDX due to patient specific needs and the side effect profile.

New Formulations of Stimulants: An Update for Clinicians

In the last 15 years, there has been a marked increase in the number of available stimulant formulations with the emphasis on long-acting formulations, and the introduction of several novel delivery systems such as orally dissolving tablets, chewable tablets, extended-release liquid formulations, transdermal patches, and novel "beaded" technology. All of these formulations involve changes to the pharmaceutical delivery systems of the two existing compounds most commonly employed to treat attention-deficit/hyperactivity disorder (ADHD), amphetamine (AMP) and methylphenidate (MPH). In addition to these new formulations, our knowledge about the individual differences in response has advanced and contributes to a more nuanced approach to treatment. The clinician can now make increasingly informed choices about these formulations and more effectively individualize treatment in a way that had not been possible before. In the absence of reliable biomarkers that can predict individualized response to ADHD treatment, clinical knowledge about differences in MPH and AMP pharmacodynamics, pharmacokinetics, and metabolism can be utilized to personalize treatment and optimize response. Different properties of these new formulations (delivery modality, onset of action, duration of response, safety, and tolerability) will most likely weigh heavily into the clinician's choice of formulation. To manage the broad range of options that are now available, clinicians should familiarize themselves in each of these categories for both stimulant compounds. This review is meant to serve as an update and a guide to newer stimulant formulations and includes a brief review of ADHD and stimulant properties.

Comparative efficacy, acceptability, and tolerability of lisdexamfetamine in child and adolescent ADHD: a meta-analysis of randomized, controlled trials

Background

Several studies have shown that lisdexamfetamine (LDX) is efficacious in children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

Objectives

Aims of this study were to systematically review the efficacy, acceptability, and tolerability of LDX in child and adolescent ADHD. Any randomized controlled trials (RCTs) of LDX versus placebo carried out in children and adolescents with ADHD were included.

Data sources

The searches of the SCOPUS, MEDLINE, CINAHL and Cochrane Controlled Trials Register were performed in September 2014. Additional searches in the ClinicalTrials. gov and EU Clinical Trials Register database were conducted.

Study eligibility criteria, participants, and interventions

This review included all RCTs of LDX versus placebo which were carried out in children and adolescents up to 18 years old. Additionally, the included studies must have reported the final outcomes of: i) severity of ADHD symptoms with standardized scales, ii) rates of improvement, iii) rates of discontinuation. To be more thorough, the languages of such RCTs were not limited.

Study appraisal and synthesis methods

The abstracts from databases were inspected and the full text versions of relevant trials were examined and extracted for important outcomes. The efficacious measurements included either the pooled mean end-point or changed scores of ADHD rating scales, and the rate of improvement. Acceptability and tolerability were measured by the pooled overall discontinuation rate and the pooled discontinuation rate due to adverse events, respectively. A random effect model technique was utilized to synthesize the mean differences (either standardized mean differences or weighted mean differences) and relative risks (RRs) with 95% confidence intervals (CIs).

Results

A total of 1,016 children and adolescents with ADHD were included. The dosage of LDX was 30 to 70 mg/day. The pooled mean change scores of LDX-treated group was significantly greater than that of the placebo (weighted mean difference [95% CI] of −15.20 [−19.95, −10.46], I²=94%). The pooled improvement rate of the LDX-treated group was also significantly higher than that of the placebo (RR [95% CI] of 0.34 [0.24, 0.47], I²=80%). The pooled overall discontinuation rate between the two groups was not significantly different (RR [95% CI] of 0.78 [0.46, 1.31], I²=63%). Similarly, the pooled discontinuation rate due to adverse events between the two groups showed no significant difference (RR [95% CI] of 1.99 [0.70, 5.64], I²=0%).

Limitations

The number of included studies was limited (five RCTs).

Conclusion

According to the present review, LDX was effective and well-tolerated in the treatment of child and adolescent ADHD. Unfortunately, the acceptability of LDX was not better than the placebo. Since the number of included studies was limited, the outcome from this review should be carefully interpreted and considered as preliminary. Further studies, therefore, should be conducted to confirm these findings.

Implication of key findings

Lisdexamfetamine is an efficacious stimulant for treating child and adolescent ADHD.

Update on optimal use of lisdexamfetamine in the treatment of ADHD

Lisdexamfetamine (LDX) has been a recent addition to the treatment armamentarium for Attention Deficit Hyperactivity Disorder (ADHD). It is unique among stimulants as it is a prodrug, and has been found to be safe and well-tolerated medication in children older than 6 years, adolescents and adults. It has a smooth onset of action, exerts its action up to 13 hours and may have less rebound symptoms. LDX has proven to be effective in the treatment of ADHD in placebo controlled trials, and improved performance in simulated academic and work environments have been noticed. Both stimulant-naïve and stimulant-exposed patients with ADHD appear to benefit from LDX. It has also shown some promise in improving emotional expression and executive function of patients with ADHD. Adverse effects such as decrease in sleep, loss of appetite and others have been reported with LDX use, just as with other stimulant formulations. Since most such studies exclude subjects with preexisting cardiac morbidity, prescribing precautions should be taken with LDX in such subjects, as with any other stimulant. Study subjects on LDX have been reported to have low scores on drug likability scales, even with intravenous use; as a result, LDX may have somewhat less potential for abuse and diversion. There is a need for future studies comparing other long acting stimulants with LDX in ADHD; in fact clinical trials comparing LDX with OROS (osmotic controlled-release oral delivery system) methylphenidate are currently underway. Furthermore, the utility of this medication in other psychiatric disorders and beyond ADHD is being investigated.