Pharmacokinetic study of a novel oral formulation of S-adenosylmethionine (MSI-195) in healthy subjects: dose escalation, food effect and comparison to a commercial nutritional supplement product.

BACKGROUND: A novel, high bioavailability oral, enteric coated tablet formulation of S-adenosylmethionine (MSI-195) has been developed for life science application. The present research reports on a Phase 1 study to (i) determine the safety of single doses of MSI-195 (ii) to determine the dose proportionality of MSI-195 at doses of 400, 800 and 1600 mg (iii) determine the pharmacokinetics of MSI-195 compared with a commercial reference product (SAM-e Complete™) over 24 h and (iv) to determine the effect of food on the pharmacokinetic profile of MSI-195 in human subjects. METHODS: This study was a pharmacokinetic and safety evaluation of MSI-195 and a commercial comparator broken into two stages. The first stage was an exploratory single ascending dose design of MSI-195 in 8 healthy normal male volunteers. The second stage was a single dose evaluation, targeting 26 male and female volunteers at set doses of MSI-195 and commercial comparator in a cross-over design followed by a food effect study on MSI-195. Plasma samples were collected and assayed for S-adenosylmethionine using a validated HPLC method with MS/MS detection. The main absorption and disposition parameters were calculated using a non-compartmental approach with a log-linear terminal phase assumption. Statistical analysis was based on an ANOVA model or t test as appropriate. RESULTS: MSI-195 was found to be generally well tolerated with an adverse event profile similar to the SAM-e Complete™ comparator product. The relative bioavailability of MSI-195 was approximately 2.8-fold higher than SAM-e Complete based on area under the curve (AUC) ratios for the two products and the MSI-195 formulation exposure based on AUC was found to be approximately dose proportional. There was a significant food effect for MSI-195 with a delayed time to maximum absorption Tmax, going from 4.5 h under fasted conditions to 13 h under fed conditions, and area under the curve with food reduced to 55% of that seen under fasting conditions. CONCLUSIONS: The overall conclusion was that MSI-195 was well tolerated and has markedly higher bioavailability compared with both the SAM-e Complete™ commercial product tested and, on a per mg basis, products reported in other literature. TRIAL REGISTRATION: ClinicalTrials.gov, identifier NCT04623034 . Retrospectively registered Nov 9, 2020.

Early score fluctuation and placebo response in a study of major depressive disorder.

Early score fluctuation in double-blind, placebo-controlled studies may affect the reliability of the baseline measurement and adversely affect the eventual study outcome. We examined the effect of early score fluctuation during a 2-week double-blind placebo lead-in period in a phase II, double-blind, placebo-controlled trial of adjunctive s-adenosyl methionine (MSI-195) in MDD subjects who had had an inadequate response to ongoing antidepressant treatment. The overall study failed to meet its specified endpoints. We examined the score trajectories of all placebo-assigned subjects during the double-blind placebo lead-in period and subsequent 6-week treatment period. Placebo-assigned subjects with ≥20% HamD17 or MADRS score fluctuations (improvement or worsening) during the double-blind placebo lead-in period (prior to randomization) had significantly higher rates of placebo response and remission at week 8 compared to subjects with <20% response. A post-hoc analysis of evaluable subjects taken from the ITT population that excluded subjects with ≥20% early score response yielded higher effect sizes for both the HamD17 and MADRS sub-groups and statistical significance for MSI-195 over placebo in the MADRS sub-group (p = 0.012) with an effect size of 0.404. A reliable baseline measure is an asset for signal detection. These post-hoc findings suggest that study designs that anticipate and attempt to manage early response prior to randomization may yield more meaningful outcome data for trials of MDD and possibly other disorders as well.

An augmentation study of MSI-195 (S-adenosylmethionine) in Major Depressive Disorder.

We conducted a 6-week double-blind, placebo-controlled, augmentation study comparing the efficacy and safety of MSI-195 800 mg (a proprietary formulation of S-adenosylmethionine) or placebo added to ongoing antidepressant medication (ADT) in acutely depressed subjects with Major Depressive Disorder (MDD) who had experienced an inadequate response to their ongoing ADT (The Horizon Study, ClinicalTrials.gov NCT01912196). There were 234 eligible subjects randomized to either MSI-195 (n = 118) or placebo (n = 116). There were no overall statistically significant differences found between MSI-195 added to ongoing ADT compared to placebo on any of 3 depression-rating instruments (HamD17, MADRS, IDS-SR30) in the ITT set. MSI-195 was generally safe and well tolerated with predominantly mild gastrointestinal side effects. Post-hoc analyses examined factors that might have affected study outcome. The ITT set was divided into subjects enrolled during the 1st half (first nine months) and 2nd half of the study. MSI-195 added to ongoing ADT was significantly better than placebo on both the HamD17 and MADRS in the 1st half (p = 0.03 and 0.02 respectively), but not in the 2nd half of the study. Several demographic and clinical characteristics were significantly different between the two study segments including body mass index, pre-randomization symptom severity fluctuation, number of lifetime depressive episodes, and anxious depression sub-type. Thus, the characteristics of the enrolled subjects changed between the 1st and 2nd half of the study. These post-hoc findings highlight the inherent challenges encountered for subject selection in double-blind, placebo controlled trials and compel further investigation of enrollment criteria and moderating factors that affect treatment. The favorable safety profile and clinical benefit observed with MSI-195 in the 1st half of this study warrant further investigation in MDD.