Effect of Colonic Absorption on the Pharmacokinetic Properties of Delayed-Release and Extended-Release Methylphenidate: In Vivo, In Vitro, and Modeling Evaluations

Are all ADHD medications created equal? Exploring the differences that enable evening dosing

With more than 30 available stimulant medications, choosing among therapeutic options for attention-deficit/hyperactivity disorder (ADHD) has become increasingly complex and patient specific. All ADHD stimulants owe their action to variants of either amphetamine or methylphenidate, yet formulation and delivery system differences create unique pharmacokinetic and clinical profiles for each medication. A benefit of the diversity within ADHD pharmacotherapy is that it facilitates tailoring treatment to meet patient needs. Historically, there has been a constant among long-acting stimulant options, regardless of formulation, which was morning dosing. The introduction of delayed-release and extended-release methylphenidate (DR/ER-MPH) is the first long-acting stimulant that patients take in the evening, with the clinical effect delayed until awakening in the morning. This paradigm shift has generated questions among clinicians and continued interest in real-world experience and data. This review used available clinical data, real-world evidence, emerging analyses, and clinical experience to evaluate the characteristics of DR/ER-MPH and its clinical utility within the greater context of ADHD medications and to provide clinicians with practical guidance on the use of DR/ER-MPH in children, adolescents, and adults with ADHD.

Pharmacokinetics of Long-Acting Methylphenidate: Formulation Differences, Bioequivalence, Interchangeability

BACKGROUND AND OBJECTIVE: Attention deficit hyperactivity disorder is one of the most common neuropsychiatric conditions in children, and methylphenidate (MPH) is one of the first-line therapies. MPH is available in a variety of extended-release (ER) formulations worldwide, and most formulations are not considered bioequivalent due to differences in pharmacokinetics. It is hypothesized that the current bioequivalence guidelines from the different regulatory bodies may generate inconsistent findings or recommendations when assessing the bioequivalence of ER MPH formulations. This manuscript aims to conduct a comprehensive and narrative critical literature review to analyze pharmacokinetic data pertaining to ER formulations of MPH in order to assess bioequivalence, differences in regulatory guidelines, and additional pharmacokinetic-pharmacodynamic parameters that may help define interchangeability.

METHODS

A literature search was conducted in EMBASE, Medline, and Cochrane Library with no time limits. Study characteristics, non-compartmental pharmacokinetic parameters, and bioequivalence data were extracted for analysis.

RESULTS

Thirty-three studies were identified with primary pharmacokinetic data after the administration of ER MPH, of which 10 were direct comparative studies (i.e., at least 2 formulations tested within a single setting) and 23 were indirect comparisons (i.e., different experimental settings). Two formulations were consistently reported as bioequivalent across the regulatory bodies using criteria from their guidance documents, although inconsistencies have been observed. However, when additional kinetic criteria (discussed in this manuscript) were imposed, only one study met the more stringent definition of bioequivalence. Various clinical factors also had inconsistent effects on the pharmacokinetics and interchangeability of the different formulations, which were associated with a lack of standardization for assessing covariates across the regulatory agencies.

CONCLUSION

Additional pharmacokinetic parameters and consistency in guidelines across the regulatory bodies may improve bioequivalence assessments. Based on our findings, more research is also required to understand whether bioequivalence is an appropriate measure for determining MPH interchangeability. This critical review is suitable for formulation scientists, clinical pharmacologists, and clinicians.

A convolution-based in vitro-in vivo correlation model for methylphenidate hydrochloride delayed-release and extended-release capsule

Delayed-release and extended-release methylphenidate hydrochloride (JORNAY PM®) is a novel capsule formulation of methylphenidate hydrochloride, used to treat attention deficit hyperactivity disorder in patients 6 years and older. In this paper, we develop a Level A in vitro-in vivo correlation (IVIVC) model for extended-release methylphenidate hydrochloride to support post-approval manufacturing changes by evaluating a point-to-point correlation between the fraction of drug dissolved in vitro and the fraction of drug absorbed in vivo. Dissolution data from an in vitro study of three different release formulations: fast, medium, and slow, and pharmacokinetic data from two in vivo studies were used to develop an IVIVC model using a convolution-based approach. The time-course of the drug concentration resulting from an arbitrary dose was considered as a function of the in vivo drug absorption and the disposition and elimination processes defined by the unit impulse response function using the convolution integral. An IVIVC was incorporated in the model due to the temporal difference seen in the scatterplots of the estimated fraction of drug absorbed in vivo and the fraction of drug dissolved in vitro and Levy plots. Finally, the IVIVC model was subjected to evaluation of internal predictability. This IVIVC model can be used to predict in vivo profiles for different in vitro profiles of extended-release methylphenidate hydrochloride.

Adverse Events During Dosing of Delayed-release/Extended-release Methylphenidate: Learnings From the Open-label Phase of a Registration Trial and a Real-world Postmarketing Surveillance Program

PURPOSE

Delayed-release/extended-release methylphenidate (DR/ER-MPH) (formerly HLD200) is an evening-dosed agent used for the treatment of attention-deficit/hyperactivity disorder. Postmarketing surveillance data from approximately 74,000 patients exposed to DR/ER-MPH (up to June 17, 2022) were reported and compared with the open-label, treatment-optimization phase of a Phase III clinical trial to derive possible learnings on how to approach adverse events (AEs) that emerge during dose titration.

METHODS

An analysis of AEs spontaneously reported to Ironshore in postmarketing surveillance included, where available, age, dose, timing, and discontinuations. Data were summarized using descriptive statistics.

FINDINGS

A total of 395 children, adolescents, and adults reported 601 AEs in postmarketing surveillance. Five AEs were classified as serious. AEs preceded drug use discontinuation in 172 patients. Many AEs occurred early (52% were reported within 30 days) and at lower doses (54% were reported at 20 to 40 mg), similar to the trial data. Reported AEs included those similar in type but orders of magnitude lower in number than those from the clinical trial.

IMPLICATIONS

No new safety concerns were revealed in this real-world setting compared with the safety profile identified in DR/ER-MPH trial data. In real-world practices, clinicians tended to discontinue DR/ER-MPH treatment after AE onset, whereas trial investigators continued to optimize treatment and found that AEs were generally tolerable, suggesting that health care practitioners may consider developing strategies to manage tolerability issues with DR/ER-MPH treatment on AE emergence rather than immediately discontinuing use of the drug to provide optimal therapeutic benefit.

CLINICALTRIALS

gov identifier: NCT02493777.

Pediatric attention deficit hyperactivity disorder (ADHD): 2022 updates on pharmacological management

INTRODUCTION

Pediatric attention-deficit disorder (ADHD) impacts a significant percentage of the population world-wide. Pharmacologic treatments have been shown to be safe and effective for managing symptoms. Various medication formulations exist, and new medication agents are continually approved each year.

AREAS COVERED

This article offers an overview of ADHD, an overview of both stimulant and non-stimulant medication options as well as an overview of stimulant misuse. It explores the medication mechanisms of action and side effect profiles, as well as offering an in-depth summary of the novel agents recently approved and soon-to-be approved for use in youth. PubMed and Medline were utilized. Search terms included children, adolescents, ADHD, and medication. FDA package inserts were reviewed for all medications.

EXPERT OPINION

New formulations of medications include an evening administered, extended, and delayed-release form of methylphenidate (DR/ER MPH), a methylphenidate pro-drug (serdexmethylphenidate) and an amphetamine patch. The availability of a new SNRI (selective norepinephrine reuptake inhibitor), viloxazine extended-release (VER), and the pending approval of a triple reuptake inhibitor (centanafadine) provides welcome additions to the prescriber's toolbox.

Quantitative Characterization of the Smoothness of Extended-release Methylphenidate Pharmacokinetic Profiles

OBJECTIVE

Extended-release methylphenidate (ER-MPH) formulations used to treat attention deficit hyperactivity disorder (ADHD) have complex pharmacokinetic (PK) profiles, resulting from differing ratios of immediate-release and extended-release components and/or their site of absorption. This study aimed to evaluate the smoothness of PK curves of ER-MPHs.

DESIGN

The integral of the second derivative squared was evaluated for modeled PK curves, with smaller values indicating a smoother curve. The calculated smoothness of each PK curve was normalized by dividing by Cmax 2 to derive a normalized smoothness parameter appropriate across the dose range of each formulation. Calculations used modeled PK curves from 100mg delayed-release and ER-MPH (DR/ER-MPH), 54mg osmotic release oral system MPH (OROS MPH), 60mg MPH controlled-release delivery (MPH CD), 60mg ER-MPH oral suspension (MEROS), 20mg ER dexmethylphenidate (d-MPH ER), and 60mg multilayer-release MPH (MLR-MPH).

RESULTS

The Cmax2-normalized smoothness value was consistent across DR/ER-MPH doses, allowing for relevant comparisons across formulations. Normalized smoothness values differed widely; the lowest normalized smoothness was 0.05 with DR/ER-MPH and ranged up to 9.56 with d-MPH ER.

CONCLUSION

DR/ER-MPH demonstrated a smoother PK profile compared to the highest dose of other ER-MPH formulations. While the benefits of a smooth PK profile remain to be tested clinically, having fewer peaks and troughs has been hypothesized to reduce waxing and waning of therapeutic effects throughout the day, and more gradual changes in MPH plasma levels have been hypothesized to lower the risk of likeability and potentially abate afternoon symptom rebound.