A randomized, multicenter trial assessing the effects of rapastinel compared to ketamine, alprazolam, and placebo on simulated driving performance

N-methyl-D-aspartate ionotropic glutamatergic receptor (NMDAR) modulators, including rapastinel and ketamine, elicit rapid and sustained antidepressant responses in patients with treatment-resistant major depressive disorder. This phase I, randomized, multicenter, placebo-controlled, five-period, crossover, single-dose study evaluated simulated driving performance of healthy participants (N = 107) after single doses of rapastinel slow intravenous (i.v.) bolus 900 and 1800 mg, alprazolam oral 0.75 mg (positive control), ketamine i.v. infusion 0.5 mg/kg (clinical comparator), and placebo ~ 45 min before driving. The primary end point was SD of lateral position (SDLP) during the 60-min 100-km simulated driving scenario. Additional measures of driving performance, sleepiness, and cognition were also evaluated. To assess effects over time, mean SDLP was calculated for each 10-min interval of driving. Sensitivity of the assays was confirmed with alprazolam (all placebo comparisons p < 0.02). Rapastinel 900 and 1800 mg did not significantly affect simulated driving performance compared to placebo (both p > 0.5). Both rapastinel doses resulted in significantly less impaired driving compared to alprazolam or ketamine (all p < 0.002); ketamine significantly impaired driving compared to placebo (p = 0.0001). Results for the additional measures were similar to the primary end point. No new safety signals were observed for any study interventions. This first study of rapastinel effects on simulated driving found that rapastinel 900 and 1800 mg did not impair driving performance, but ketamine 0.5 mg/kg resulted in significantly impaired driving performance. Ketamine's effects on driving were maintained for at least 105 min, indicating that clinicians should be vigilant to prevent or postpone driving in patients after ketamine treatment.

Atogepant and sumatriptan: no clinically relevant drug-drug interactions in a randomized, open-label, crossover trial

Aim: To evaluate pharmacokinetic interactions of atogepant with sumatriptan, an open-label, randomized, crossover study was conducted. Patients & methods: Thirty healthy adults received atogepant 60 mg, sumatriptan 100 mg, or coadministered drugs. Primary end point was geometric mean ratios (GMRs) and 90% CIs of interventions for area under the plasma concentration-time curve from time 0 to t (AUC_0-t) or infinity (AUC_0-∞) and peak plasma concentration (C_max). Results: Atogepant GMRs for AUC_0-t and AUC_0-∞ versus with sumatriptan were within 90% CI 0.80-1.25, indicating no interaction; atogepant C_max was reduced by 22% (GMR: 0.78; 90% CI: 0.69-0.89) with sumatriptan. Sumatriptan GMRs for AUC_0-t, AUC_0-∞ and C_max versus with atogepant were within 90% CI 0.80-1.25. Conclusion: Atogepant with sumatriptan had no clinically relevant pharmacokinetic interactions.

Effects of CYP3A4 and P-glycoprotein inhibition or induction on the pharmacokinetics of ubrogepant in healthy adults: Two phase 1, open-label, fixed-sequence, single-center, crossover trials

Background:

Ubrogepant is metabolized by cytochrome P450 3A4 (CYP3A4) and is a P-glycoprotein (P-gp) substrate.

Objective:

To assess effects of multiple-dose moderate-strong CYP3A4 and strong P-gp inhibitors and inducers on ubrogepant pharmacokinetic (PK) parameters.

Methods:

Two phase 1, open-label, fixed-sequence, single-center, crossover trials enrolled healthy adults to receive ubrogepant 20 mg with/without verapamil 240 mg (a moderate CYP3A4 inhibitor) or ketoconazole 400 mg (a strong CYP3A4 and P-gp transporter inhibitor) (Study A), or ubrogepant 100 mg with/without rifampin 600 mg (a strong CYP3A4 inducer and P-gp inducer) (Study B). Outcomes included ubrogepant PK parameters (area under plasma concentration-time curve, time 0 through infinity [AUC0-∞], peak plasma concentration [Cmax]), and safety (treatment-emergent adverse events [TEAEs]). PK parameters were compared between ubrogepant with/without coadministered medications using linear mixed-effects models. Cmax and AUC0-∞ least-squares geometric mean ratios (GMR) of ubrogepant with/without coadministration were constructed.

Results:

Twelve participants enrolled in Study A and 30 in Study B. AUC0-∞ and Cmax GMR (90% CI) were 3.53 (3.32–3.75) and 2.80 (2.48–3.15), respectively, for ubrogepant with verapamil; 9.65 (7.27–12.81) and 5.32 (4.19–6.76) with ketoconazole; and 0.22 (0.20–0.24) and 0.31 (0.27–0.36) with rifampin. TEAEs were predominantly mild; no treatment-related serious TEAEs or TEAE-related discontinuations occurred.

Conclusion:

The PK of ubrogepant were significantly affected by the concomitant use of CYP3A4 moderate-strong inhibitors and strong inducers.

A Single Supratherapeutic Dose of Atogepant Does Not Affect Cardiac Repolarization in Healthy Adults: Results From a Randomized, Single-Dose, Phase 1 Crossover Trial

Atogepant is a selective, oral calcitonin gene–related peptide receptor antagonist in development for preventive treatment of migraine. This randomized, double‐blind, phase 1 crossover study evaluated the cardiac repolarization effect of a single supratherapeutic (300 mg) atogepant dose vs placebo in healthy adults. Moxifloxacin 400 mg was the open‐label active control. The primary end point was a change from baseline in Fridericia‐corrected QT intervals (ΔQTcF). Sixty participants were randomized to atogepant 300 mg, placebo, and moxifloxacin; 59 (98.3%) completed all interventions. Assay sensitivity was confirmed: lower 90% confidence interval limit for QTcF interval change from baseline (ΔΔQTcF) for moxifloxacin was >5 millisecond vs placebo at prespecified 2‐, 3‐, and 4‐hour time points. Following single‐dose atogepant 300 mg, mean atogepant ΔΔQTcF and upper 90% confidence interval limits were lower than the 10‐millisecond threshold at all time points. Atogepant mean peak plasma concentration was 3197 ng/mL, area under the concentration‐time curve from time 0 to time t was 16 640 ng • h/mL, area under the concentration‐time curve from time 0 to 24 hours was 16 607 ng • h/mL, and median time to peak plasma concentration was 2.1 hours. The incidence of adverse events was low; no serious adverse events or elevations of liver enzymes were reported. Overall, a single supratherapeutic dose of atogepant was safe and did not impact cardiac repolarization in healthy participants.

Pharmacokinetics and safety of ubrogepant when coadministered with calcitonin gene-related peptide-targeted monoclonal antibody migraine preventives in participants with migraine: A randomized phase 1b drug-drug interaction study

Objective

To evaluate the impact of two calcitonin gene–related peptide (CGRP)‐targeted monoclonal antibodies (mAbs), erenumab and galcanezumab, on the pharmacokinetic (PK) profile, safety, and tolerability of ubrogepant.

Background

People taking CGRP‐targeted mAbs for migraine prevention sometimes take ubrogepant, an oral small‐molecule CGRP receptor antagonist, for acute treatment of breakthrough migraine attacks.

Design

In this two‐arm, multicenter, open‐label, phase 1b trial, adults with migraine were randomized to arm 1 (ubrogepant ± erenumab) or arm 2 (ubrogepant ± galcanezumab). The PK profile of ubrogepant was characterized for administration before and 4 days after CGRP‐targeted mAb injection. Participants received single‐dose ubrogepant 100 mg on day 1, subcutaneous erenumab 140 mg (arm 1) or galcanezumab 240 mg (arm 2) on day 8, and ubrogepant 100 mg once daily on days 12–15. In each study arm, serial blood samples were drawn on days 1 and 12 for measurement of plasma ubrogepant concentrations. The primary outcomes were area under the plasma ubrogepant concentration–time curve (AUC) from time 0 to t post‐dose (AUC_0–t) and from time 0 to infinity (AUC_0–inf), and maximum plasma concentration (C_max) of ubrogepant when ubrogepant was administered before or after a single dose of erenumab or galcanezumab. Vital signs and laboratory parameters were monitored.

Results

Forty participants enrolled (20 per arm; mean [standard deviation] ages, 32.2 [8.9] and 38.4 [8.8] years; 50% [10/20] and 60% [12/20] female in arms 1 and 2, respectively). There were no significant differences in ubrogepant C_max after versus before erenumab administration (geometric least‐squares mean [LSM] ratio, 1.04 [90% CI, 0.93–1.16]), and no significant differences in AUC_0–t (1.06 [0.96–1.16]) or AUC_0–inf (1.05 [0.96–1.15]). Similarly, ubrogepant C_max (1.00 [90% CI, 0.82–1.20]), AUC_0–t (1.05 [0.90–1.23]), and AUC_0–inf (1.05 [0.90–1.22]) geometric LSM ratios were statistically equivalent after galcanezumab versus ubrogepant alone. Treatment‐emergent adverse events (TEAEs) were similar to those reported with each treatment alone. No serious TEAEs, TEAEs leading to discontinuation, or clinically relevant changes in laboratory parameters or vital signs were reported.

Conclusions

The PK profile of ubrogepant was not significantly changed and no safety concerns were identified when ubrogepant was coadministered with erenumab or galcanezumab.

Single-Dose Pharmacokinetics and Safety of Atogepant in Adults With Hepatic Impairment: Results From an Open-Label, Phase 1 Trial

Atogepant is a selective oral calcitonin gene‐related peptide receptor antagonist in development for migraine prevention. Here, we report the pharmacokinetics (PK) and safety of single‐dose 60 mg atogepant in participants with severe, moderate, or mild hepatic impairment and matched participants with normal hepatic function from an open‐label, parallel‐group, single‐dose phase 1 trial. Thirty‐two participants aged 45 to 72 years were enrolled, which included 8 each with severe, moderate, mild, or no hepatic impairment. All participants completed the study. Atogepant was rapidly absorbed (median time to maximum plasma concentration, ∼2 hours) with an apparent terminal elimination half‐life of ∼11 hours. Compared with participants with normal hepatic function, the change in maximum plasma concentrations of atogepant were –4%, –12%, and +9% in participants with severe, moderate, or mild hepatic impairment, respectively. Overall systemic exposures to atogepant were 15% to 38% higher in participants with hepatic impairment compared with those with normal hepatic function, but these differences are not expected to be clinically relevant given the established safety profile of atogepant. Only 1 adverse event was reported: mild rhinorrhea in a participant with moderate hepatic impairment. Overall, atogepant was safe and not associated with any clinically relevant change in PK in participants with severe, moderate, or mild hepatic impairment.

Population Pharmacokinetics of Cariprazine and its Major Metabolites

BACKGROUND AND OBJECTIVES

Cariprazine, a dopamine D₃-preferring D₃/D₂ receptor partial agonist, is approved for the treatment of adults with schizophrenia (1.5-6 mg/day) and manic/mixed (3-6 mg/day) episodes associated with bipolar I disorder. This population pharmacokinetic analysis describes the concentration-time profiles of cariprazine and its two major active metabolites, desmethyl-cariprazine (DCAR) and didesmethyl-cariprazine (DDCAR). Additionally, the potential impact of patient characteristics, creatinine clearance, and cytochrome P450 2D6 (CYP2D6) metabolizer status on the pharmacokinetics of cariprazine and its metabolites was evaluated.

METHODS

Data from three phase 1 and ten phase 2/3 studies in adult patients with schizophrenia or bipolar mania were included. Nonlinear mixed-effects pharmacokinetic modeling was performed using the NONMEM software package. Compartmental modeling was performed sequentially with the cariprazine elimination rate used as the DCAR formation rate and likewise the elimination rate of DCAR used with a delay as the DDCAR formation rate.

RESULTS

Cariprazine pharmacokinetics were described by a three-compartment model with zero-order input of the dose to a depot compartment followed by first-order absorption and first-order elimination. DCAR and DDCAR pharmacokinetics were described by two-compartment models with linear elimination. Statistically significant predictors of pharmacokinetic parameters included weight, sex, and race, though differences in exposures were not large enough to require an adjustment in dose. Creatinine clearance was not a statistically significant predictor of drug clearance, and a post hoc analysis found that CYP2D6 metabolizer status was not associated with changes in exposure levels for cariprazine, DCAR, or DDCAR. The median time to 90% of steady state was approximately 1 week for cariprazine and DCAR and 3 weeks for DDCAR.

CONCLUSIONS

Population pharmacokinetic modeling provided a quantitative description of the concentration-time profile of cariprazine and its metabolites.

Evaluation of the Pharmacokinetic Interaction of Ubrogepant Coadministered With Sumatriptan and of the Safety of Ubrogepant With Triptans

Objective

To evaluate the potential for pharmacokinetic interaction and the safety and tolerability when ubrogepant and sumatriptan are coadministered in a Phase 1 study in healthy participants, and to inform the safety and tolerability of ubrogepant alone and in combination with triptans in Phase 3 trials in participants with migraine.

Background

Calcitonin gene–related peptide is a potent vasodilatory neurotransmitter believed to play a key role in the pathophysiology of migraine. Ubrogepant (UBRELVY™) is a potent and selective antagonist of the human calcitonin gene–related peptide receptor approved for the acute treatment of migraine. Sumatriptan is a serotonin receptor agonist and the most commonly used triptan for the acute treatment of migraine. Ubrogepant could be prescribed with triptans.

Design

The Phase 1 study was a single‐center, open‐label, randomized, 3‐way crossover, single‐dose, pharmacokinetic interaction study, where participants received each of 3 oral treatments with a 7‐day washout period between treatments: single dose of ubrogepant 100 mg, single dose of sumatriptan 100 mg, and ubrogepant 100 mg plus sumatriptan 100 mg. Pharmacokinetic parameters were calculated using a model‐independent approach. The ACHIEVE I and II trials were 2 multicenter, single‐attack, randomized, Phase 3 trials in adults with a history of migraine with or without aura. Participants had the option to take a second dose of study medication or rescue medication to treat a nonresponding migraine or a migraine recurrence from 2 to 48 hours after the initial dose of study medication. Rescue medication options included acetaminophen, nonsteroidal anti‐inflammatory drugs, opioids, anti‐emetics, or triptans. Treatment‐emergent adverse events were evaluated up to 30 days after the last dose in the Phase 1 and Phase 3 studies.

Results

Ubrogepant median time to maximum plasma concentration was delayed (3 hours [range: 1‐5 hours] vs 1.5 hours [range: 1‐4 hours]), mean maximum plasma concentration was reduced by 24% (coefficient of variation: 37.4%) when ubrogepant was coadministered with sumatriptan (n = 29) compared with ubrogepant administered alone (N = 30). No significant effect was observed on the area under the plasma concentration‐time curve of ubrogepant. Sumatriptan area under the curve and maximum plasma concentration showed no significant change when sumatriptan was coadministered with ubrogepant (n = 29), but the sumatriptan time to maximum plasma concentration was delayed (1 hour [range: 0.5‐5 hours] vs 3 hours [range: 0.5‐6 hours]. No treatment‐emergent adverse events were reported with the coadministration of ubrogepant 100 mg and sumatriptan 100 mg in the Phase 1 study. The pooled safety data from ACHIEVE trials (N = 1938) showed similar rates of treatment‐related treatment‐emergent adverse events between participants who took ubrogepant alone and participants who took ubrogepant and a triptan as a rescue medication (14.9% [53/355] vs 12.8% [5/39] in the ubrogepant 100 mg treatment group, respectively).

Conclusions

Although there were slight alterations in ubrogepant pharmacokinetic parameters when coadministered with sumatriptan, such changes are expected to have minimal clinical relevance, especially because no changes were seen in sumatriptan area under the curve and maximum plasma concentration when coadministered with ubrogepant. Coadministration of ubrogepant with sumatriptan was well tolerated in healthy participants in the Phase 1 study, and coadministration of ubrogepant with triptans was well tolerated in participants with migraine in the Phase 3 trials. No new safety concerns for ubrogepant were identified across all trials.

Evaluation of the pharmacokinetic interaction and safety of ubrogepant coadministered with acetaminophen or nonsteroidal anti-inflammatory drugs: A randomized trial

Background:

Ubrogepant is a novel, oral calcitonin gene–related peptide receptor antagonist approved by the US Food and Drug Administration for acute treatment of migraine with or without aura in adults.

Objectives:

To assess potential pharmacokinetic (PK) drug–drug interactions in healthy participants and inform the safety and tolerability of ubrogepant alone and in combination with acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) in healthy participants and participants with migraine.

Methods:

Two phase 1, three-way crossover studies randomized healthy adults to 100 mg ubrogepant alone, 1000 mg acetaminophen or 500 mg naproxen alone, and 100 mg ubrogepant plus 1000 mg acetaminophen or 500 mg naproxen. Geometric mean ratios (GMRs) and 90% confidence intervals were calculated based on statistical comparison of maximum plasma drug concentration ( C max) and area under the plasma drug concentration–time curve (AUC) for treatment in combination versus alone. Two phase 3 randomized trials included adults with migraine. Treatment-emergent adverse events (TEAEs) were evaluated.

Results:

Time to C max and terminal elimination half-life for all treatments were unchanged when coadministered. Ubrogepant C max and AUC increased by approximately 40% when coadministered with acetaminophen. Acetaminophen C max decreased by 24% (GMR = 0.76) when coadministered with ubrogepant. There were no significant PK interactions between ubrogepant and naproxen. TEAE rates in the acetaminophen and NSAID rescue medication groups were similar to ubrogepant alone.

Conclusions:

Coadministration of ubrogepant and acetaminophen resulted in a statistically significant increase in ubrogepant exposure and a decrease in acetaminophen C max; however, these changes were not clinically relevant. No statistically or clinically relevant changes in PK were associated with ubrogepant and naproxen coadministration. No safety concerns were identified for ubrogepant alone or in combination with acetaminophen or NSAIDs.

Relationship Between Plasma Concentrations and Clinical Effects of Cariprazine in Patients With Schizophrenia or Bipolar Mania

Population pharmacokinetic/pharmacodynamic modeling (via NONMEM) was used to describe longitudinal exposure‐response relationships for total cariprazine (sum of cariprazine and its major active metabolites) in 2,558 patients with schizophrenia or bipolar mania. Drug exposure metrics were explored for potential relationships with efficacy and safety end points. Total cariprazine exposures were significantly related to reductions in Positive and Negative Syndrome Scale (PANSS) or Young Mania Rating Scale (YMRS) total scores in schizophrenia or bipolar mania, respectively, via a maximum effect (E_max)‐type relationship. Typical steady‐state plasma concentrations after 3 and 4.5 mg/day were associated with 50% of maximum typical reductions in PANSS and YMRS total scores, respectively. Time‐weighted cariprazine exposures had significant relationships with the probability of common adverse events (AEs). Dose increase was associated with increased efficacy but was also associated with an increase in AEs. Results of these pharmacokinetic/pharmacodynamic analyses support that the recommended dose range (1.5–6 mg/day for schizophrenia and 3–6 mg/day for bipolar mania) provides an appropriate benefit‐risk balance between cariprazine efficacy and safety.

Single Therapeutic and Supratherapeutic Doses of Ubrogepant Do Not Affect Cardiac Repolarization in Healthy Adults: Results From a Randomized Trial

Ubrogepant is a novel, oral calcitonin gene-related peptide receptor antagonist currently under US Food and Drug Administration (FDA) review for the acute treatment of migraine attacks. This double-blind, four-period crossover study compared the cardiac repolarization effect of therapeutic (100 mg) and supratherapeutic (400 mg) ubrogepant doses vs. placebo in healthy adults. Moxifloxacin 400 mg was used as an open-label active control, and the primary end point was change from baseline in Fridericia-corrected QT intervals (ΔQTcF). Assay sensitivity was demonstrated via statistically significant QTcF prolongation with moxifloxacin vs. placebo. After single oral doses of ubrogepant, the least squares mean placebo-corrected ΔQTcF (ΔΔQTcF) and 90% confidence intervals (CIs) did not exceed the 10-millisecond regulatory threshold at any timepoint. The 90% CI upper bounds were 2.46 milliseconds and 2.69 milliseconds for ubrogepant 100 and 400 mg, respectively. Categorical and concentration-based analyses were consistent with the primary result, showing no significant impact of ubrogepant on cardiac repolarization.

Relationship between the timing of relapse and plasma drug levels following discontinuation of cariprazine treatment in patients with schizophrenia: indirect comparison with other second-generation antipsychotics after treatment discontinuation

OBJECTIVE

To explore the timing of relapse following drug discontinuation and its relationship to estimated plasma levels and elimination half-life by comparing data from a randomized, placebo-controlled discontinuation study of cariprazine with those from similarly designed and conducted randomized control trials of other oral atypical antipsychotics (AAPs).

METHODS

Data from a long-term, randomized, double-blind, placebo-controlled relapse prevention study in participants with schizophrenia (NCT01412060) were analyzed. Similarly designed, published studies of other AAPs were used for comparison. Time to drug-placebo relapse separation and relapse rates were estimated from Kaplan-Meier curves and evaluated descriptively. Separation was defined as a sustained difference of ≥5% incidence of relapse between the AAP and placebo curves.

RESULTS

The Kaplan-Meier curve for cariprazine showed a time to drug-placebo relapse separation at 6-7 weeks after randomization, compared to the Kaplan-Meier curves for the other AAPs, which showed earlier separation at 1-4 weeks. The placebo relapse rates at 4 weeks after randomization were 5% for cariprazine and 8-34% for other AAPs. Geometric mean values of model-predicted plasma concentrations for total active cariprazine moieties (sum of cariprazine, desmethyl-cariprazine, and didesmethyl-cariprazine) were 20.0 and 6.1 nM at 2 and 4 weeks after discontinuation, respectively. Elimination half-lives of other AAPs and their active metabolites (<4 days) suggest that plasma concentrations would be low or negligible at 2-4 weeks after last dose.

CONCLUSION

Discontinuation of cariprazine treatment appeared to be associated with a delayed incidence of relapse compared with other AAPs, which may be due to the longer half-life of cariprazine and its active metabolites.

Preferential binding to dopamine D3 over D2 receptors by cariprazine in patients with schizophrenia using PET with the D3/D2 receptor ligand [(11)C]-(+)-PHNO

RATIONALE

Second-generation antipsychotics occupy dopamine D2 receptors and act as antagonists or partial agonists at these receptors. While these drugs alleviate positive symptoms in patients with schizophrenia, they are less effective for treating cognitive deficits and negative symptoms. Dopamine D3 receptors are highly expressed in areas of the brain thought to play a role in the regulation of motivation and reward-related behavior. Consequently, the dopamine D3 receptor has become a target for treating negative symptoms in combination with D2 antagonism to treat positive symptoms in patients with schizophrenia.

OBJECTIVE

The purpose of this study was to determine the cariprazine receptor occupancies in brain for D2 and D3 receptors in patients with schizophrenia.

METHODS

Using [(11)C]-(+)-PHNO as a radioligand, positron emission tomography (PET) scans were performed in eight patients at baseline and postdose on days 1, 4, and 15. Plasma and cerebrospinal fluid (CSF) samples were analyzed for cariprazine concentrations.

RESULTS

A monotonic dose-occupancy relationship was observed for both receptor types. After 2 weeks of treatment, near complete (∼100 %) occupancies were observed for both receptors at a dose of 12 mg/day. At the lowest cariprazine dose (1 mg/day), mean D3 and D2 receptor occupancies were 76 and 45 %, respectively, suggesting selectivity for D3 over D2 receptors at low doses. An exposure-response analysis found a ∼3-fold difference in EC50 (D3 = 3.84 nM and D2 = 13.03 nM) in plasma after 2 weeks of dosing.

CONCLUSION

This PET imaging study in patients with schizophrenia demonstrated that cariprazine is a D3-preferring dual D3/D2 receptor partial agonist.

A novel once-daily fixed-dose combination of memantine extended release and donepezil for the treatment of moderate to severe Alzheimer's disease: two phase I studies in healthy volunteers

BACKGROUND

Combining two standard-of-care medications for Alzheimer's disease (AD) into a single once-daily dosage unit may improve treatment adherence, facilitate drug administration, and reduce caregiver burden. A new fixed-dose combination (FDC) capsule containing 28 mg memantine extended release (ER) and 10 mg donepezil was evaluated for bioequivalence with co-administered commercially available memantine ER and donepezil, and for bioavailability with regard to food intake.

METHODS

Two phase I, single-dose, randomized, open-label, crossover studies were conducted in 18- to 45-year-old healthy individuals. In MDX-PK-104 study, fasting participants (N = 38) received co-administered memantine ER and donepezil or the FDC. In MDX-PK-105 study, participants (N = 36) received three treatments: intact FDC taken while fasting or after a high-fat meal, or FDC contents sprinkled on applesauce while fasting. Standard pharmacokinetic parameters for memantine and donepezil were calculated from the plasma concentration time-curve using non-compartmental analyses. Linear mixed-effects models were used to compare: (a) FDC versus co-administered individual drugs; (b) FDC fasted versus with food; and (c) FDC sprinkled on applesauce versus FDC intact, both fasted. Safety parameters were also evaluated.

RESULTS

The FDC capsule was bioequivalent to co-administered memantine ER and donepezil. There was no significant food effect on the bioavailability of the FDC components. There were no clinically relevant differences in time to maximum plasma concentration or safety profiles across treatments.

CONCLUSIONS

An FDC capsule containing 28 mg memantine ER and 10 mg donepezil is bioequivalent to commercially available memantine ER and donepezil, and bioavailability is not affected by food intake or sprinkling of capsule contents on applesauce.

Effect of renal impairment on the pharmacokinetics of levomilnacipran following a single oral dose of levomilnacipran extended-release capsule in humans

Purpose

Levomilnacipran extended-release (ER) is indicated for treatment of major depressive disorder in adults. We evaluated the pharmacokinetic and safety profile of levomilnacipran ER in individuals with impaired renal function.

Methods

A total of 32 individuals participated in four groups (eight in each group) with normal, mild, moderately, or severely impaired renal function. Each participant received one dose of levomilnacipran ER 40 mg. Blood and urine were assayed using liquid chromatography/tandem mass spectrometry. Results between normal and renally impaired groups were compared using analysis of variance. Safety measures included adverse events, laboratory evaluations, vital signs, suicidality, and electrocardiograms.

Results

Following administration of levomilnacipran, mean (standard deviation) maximum plasma concentration in participants with normal renal function, and mild, moderate, or severe renal impairment was 83.9 (21.0), 81.8 (23.4), 98.7 (18.1), and 122.1 (35.1) (ng/mL), respectively; area under the curve from time zero to infinity was 2,101.0 (516.9), 2,587.8 (649.9), 4,016.4 (995.4), and 5,900.8 (1,799.3) (h·ng/mL), respectively; terminal elimination half-life was 13.5 (2.8), 17.3 (3.5), 19.1 (4.6), and 27.7 (7.4) (hours), respectively; and renal clearance was 175.9 mL/min, 114.7 mL/min, 69.9 mL/min, and 28.6 mL/min, respectively. Levomilnacipran ER was generally well tolerated with no safety issues of concern identified.

Conclusion

Renal impairment was associated with increased plasma levels of levomilnacipran and prolonged half-life. No dose adjustment is required for individuals with mild renal impairment; the recommended maximum daily maintenance dose of levomilnacipran ER should not exceed 80 mg for individuals with moderate renal impairment and 40 mg for individuals with severe renal impairment.

Milnacipran: a selective serotonin and norepinephrine dual reuptake inhibitor for the management of fibromyalgia

Milnacipran, a serotonin and norepinephrfrine reuptake inhibitor with preferential inhibition of norepinephrine reuptake over serotonin, is approved in the United States for the management of fibromyalgia. Owing to its effects on norepinephrine and serotonin, as well as its lack of activity at other receptor systems, it was hypothesized that milnacipran would provide improvements in pain and other fibromyalgia symptoms without some of the unpleasant side effects associated with other medications historically used for treating fibromyalgia. The clinical safety and efficacy of milnacipran 100 and 200 mg/day in individuals with fibromyalgia has been investigated in four large, randomized, double-blind, placebo-controlled studies and three long-term extension studies. The clinical studies used composite responder analyses to identify the proportion of individual patients reporting simultaneous and clinically significant improvements in pain, global status, and physical function, in addition to assessing improvement in various symptom domains such as fatigue and dyscognition. In the clinical studies, patients receiving milnacipran reported significant improvements in pain and other symptoms for up to 15 months of treatment. Most adverse events were mild to moderate in severity and were related to the intrinsic pharmacologic properties of the drug. Long-term exposure to milnacipran did not result in any new safety concerns. As with other serotonin and norepinephrine reuptake inhibitors, increases in heart rate and blood pressure have been observed in some patients with milnacipran treatment.

Effects of milnacipran on cardiac repolarization in healthy participants

Milnacipran is approved for management of fibromyalgia in the United States. In this double-blind, placebo- and active drug-controlled study (N = 100), effects of supratherapeutic doses of milnacipran on cardiac repolarization were evaluated in healthy volunteers. The primary outcome was the largest mean difference between milnacipran and placebo in time-matched baseline-adjusted QT interval corrected for heart rate using an individual correction formula (QTcNi). In addition, data were analyzed using the Fridericia formula (QTcF) and a post hoc piecewise QTcNi analysis based on a dichotomous cut of RR interval data at 800 ms. Moxifloxacin (400 mg single dose) was used to establish assay sensitivity. Using the QTcNi method, the largest difference in baseline-adjusted QTcNi between milnacipran 300 mg bid and placebo was -4.7 ms (90% confidence interval [CI]: -9.4 to -0.1), indicating no QT prolongation. Analysis using the Fridericia formula (QTcF) showed a maximum adjusted mean change of +7.7 ms, but QTcF versus RR interval plots indicated overcorrection with this method. The piecewise QTcNi correction method demonstrated a more accurate correction for drug-induced heart rate increase; mean baseline-adjusted between-group difference was +0.9 ms (90% CI: -6.6 to 8.3). The results suggest that milnacipran would not significantly affect cardiac repolarization at clinically relevant therapeutic and supratherapeutic concentrations.

A pilot evaluation of the safety, tolerability, pharmacokinetics, and effectiveness of memantine in pediatric patients with attention-deficit/hyperactivity disorder combined type

BACKGROUND

Disturbances in N-methyl-D-aspartate (NMDA) receptor activity may play a role in attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

This study is a preliminary evaluation of the safety, pharmacokinetics, and effectiveness of the NMDA receptor antagonist memantine in pediatric ADHD.

METHODS

An open-label, dose-finding, 8-week, trial in outpatients 6-12 years old with ADHD combined type. Memantine oral solution (2 mg/mL) was titrated to 10 mg/day (n = 8) or 20 mg/day (n = 8). Safety data and blood samples for pharmacokinetic analyses were collected. The ADHD Rating Scale-IV (ADHD-IV) and Clinical Global Impression of Severity (CGI-S) scale measured the effectiveness of memantine.

RESULTS

There were no discontinuations due to adverse events (AEs), serious AEs, deaths, or suicides. Most AEs were mild and occurred during the first week of treatment. The 20 mg/day memantine dose was associated with a higher rate of completion and larger mean improvement on the ADHD-IV and CGI-S than 10 mg/day memantine. Pharmacokinetic analyses suggest response to memantine may be dose-dependent beyond an initial threshold concentration.

CONCLUSIONS

This pilot study suggests that a memantine dose of 20 mg/day may be a safe and possibly effective treatment for pediatric ADHD. Further investigations of memantine in ADHD appear to be warranted.

Pharmacokinetic study of memantine in healthy and renally impaired subjects

OBJECTIVE

Our objective was to evaluate the pharmacokinetics of the Alzheimer's disease treatment memantine in subjects with normal and impaired renal function.

METHODS

This was a single-center, single-dose, open-label study. Thirty-two subjects aged 18 to 80 years were assigned to 1 of 4 groups (8 subjects each) based on baseline creatinine clearance: normal renal function (>80 mL/min), mild renal impairment (50-80 mL/min), moderate renal impairment (30-49 mL/min), and severe renal impairment (5-29 mL/min). A single 20-mg memantine dose was administered under fasting conditions. Assessments included pharmacokinetic and safety measures.

RESULTS

Thirty-one subjects completed the study. There were no relevant differences in maximum memantine plasma concentration between subjects with normal and impaired renal function of any severity. The mean area under the plasma concentration versus time curve extrapolated to infinity was similar between subjects with normal and mildly impaired renal function but increased by 60% (95% confidence interval [CI], 24%-97%) and 115% (95% CI, 77%-152%) in subjects with moderate and severe renal impairment, respectively. Simulations predicted steady-state maximum concentration values of 82 ng/mL (95% CI, 70-95 ng/mL), 85 ng/mL (95% CI, 70-101 ng/mL), and 128 ng/mL (95% CI, 109-147 ng/mL) in healthy subjects, those with mild renal impairment, and those with moderate renal impairment, respectively, for the recommended dosing regimen of 10 mg twice daily; for subjects with severe renal impairment, a steady-state maximum concentration value of 84 ng/mL (95% CI, 68-101 ng/mL) was predicted for a dosing regimen of 5 mg twice daily.

CONCLUSION

On the basis of the predicted steady-state plasma concentrations with the use of the current dosing regimen of 10 mg twice daily, no dosage adjustments are needed for patients with mild or moderate renal impairment. A target dose of 5 mg twice daily is recommended in patients with severe renal impairment.

Kinetics of human erythrocyte glucose-6-phosphate dehydrogenase dimers

The steady-state kinetics of human erythrocyte glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) dimers were studied by initial rate measurement. These experiments gave intersecting double-reciprocal plots suggesting a ternary complex mechanism with a Km for NADP and glucose 6-phosphate of 11 microM and 43 microM, respectively. These studies were combined with rate measurements in the presence of one product (NADPH), dead-end inhibitors, as well as alternative substrates. The inhibition by NADPH was found to be competitive with respect to both substrates. Alternate substrates experiments gave linear double-reciprocal plots over a wide range of substrate concentrations. The results suggest that the dimeric enzyme follows either a random or a Theorell-Chance mechanism.