Evaluation of Cytochrome P450 (CYP) 3A4-Based Interactions of Levomilnacipran with Ketoconazole, Carbamazepine or Alprazolam in Healthy Subjects.

BACKGROUND AND OBJECTIVES: Levomilnacipran is a serotonin and norepinephrine reuptake inhibitor with balanced potency for the reuptake inhibition of norepinephrine and serotonin, approved in the USA for the treatment of major depressive disorder (MDD) in adults. We conducted studies in healthy human subjects to investigate pharmacokinetic interactions when levomilnacipran extended-release (ER) is administered in combination with an inhibitor (ketoconazole), an inducer (carbamazepine), or a substrate (alprazolam) of cytochrome P450 (CYP) 3A4. METHODS: Randomised, open-label studies were conducted in healthy volunteers (n = 34 ketoconazole, n = 34 carbamazepine, n = 30 alprazolam) and pharmacokinetic parameters were determined when levomilnacipran was administered alone or together with the relevant study drug. RESULTS: Co-administration of ketoconazole with levomilnacipran ER increased levomilnacipran maximum concentration (C max) by 39% [90% confidence interval (CI) 31-47%] and area under the concentration-time curve (AUC) by 57% (90% CI 47-67%), whereas carbamazepine reduced the C max and AUC of levomilnacipran by 26% (90% CI 22-30%) and 29% (90% CI 26-32%), respectively. Levomilnacipran at steady state had no significant effect on the pharmacokinetics of a single 1 mg dose of alprazolam extended release (XR); neither did single-dose alprazolam XR affect the steady-state pharmacokinetics of levomilnacipran. No new safety concerns were noted in these studies. CONCLUSIONS: Based on these results, the levomilnacipran ER dose should not exceed 80 mg once daily when used with ketoconazole, compared to 120 mg once daily in the absence of ketoconazole. No dose adjustment for levomilnacipran is suggested when levomilnacipran ER is co-administered with carbamazepine or other CYP3A4 inducers. Co-administration with levomilnacipran of drugs metabolised by CYP3A4, such as alprazolam, requires no dose adjustment due to pharmacokinetic considerations.

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.

Effect of hepatic impairment on the pharmacokinetics of levomilnacipran following a single oral dose of a levomilnacipran extended-release capsule in human participants.

BACKGROUND AND OBJECTIVES: Levomilnacipran is a serotonin and norepinephrine reuptake inhibitor with greater potency for the reuptake inhibition of norepinephrine than of serotonin, approved in the USA for the treatment of major depressive disorder (MDD) in adults. METHODS: A single-dose, open-label, parallel-group study was conducted to evaluate the effects of hepatic impairment on the pharmacokinetics of levomilnacipran in adults with mild, moderate, or severe hepatic impairment and normal controls receiving a 40 mg levomilnacipran extended-release (ER) capsule. The concentrations of levomilnacipran and its inactive metabolite, N-desethyl levomilnacipran, in plasma and urine were measured using liquid chromatography-tandem mass spectrometry methods. Pharmacokinetic parameters of levomilnacipran and N-desethyl levomilnacipran were derived and assessed. Safety parameters were assessed throughout the trial. RESULTS: No deaths, serious adverse events, or discontinuations due to adverse events occurred. The maximum plasma drug concentration (C(max)) and area under the plasma concentration-time curve from time zero to infinity (AUC(∞)) of levomilnacipran were 28 and 32 % higher, respectively, in participants with severe hepatic impairment than in healthy participants without a notable change in the terminal elimination half-life, whereas the C(max) and AUC(∞) of N-desethyl levomilnacipran were 66 and 85 % lower, respectively, suggesting liver function has minimal impact on the overall exposure of levomilnacipran but plays a significant role in the formation of the metabolite. CONCLUSIONS: A single dose of levomilnacipran ER 40 mg was generally well-tolerated in participants with varying degrees of hepatic impairment and healthy controls. Therefore, dose adjustment for levomilnacipran is not necessary in adult MDD patients with impaired liver function.

Investigation of nebivolol as a novel therapeutic agent for the treatment of Alzheimer's disease.

Nebivolol is a selective ß1 adrenergic receptor antagonist with nitric oxide-mediated vasodilatory properties utilized in the treatment of hypertension. Previously, nebivolol was shown to modulate amyloid-ß protein precursor processing in vitro. In this study, we investigated the in vivo effects of nebivolol on the modulation of amyloid neuropathology in the Tg2576 mouse model of Alzheimer's disease (AD). We found that nebivolol is brain bioavailable and can be readily detected in the brain following three weeks of treatment at a dose of 1 mg/kg/day. Moreover, this treatment regime resulted in a significant reduction of amyloid-ß neuropathology in the brain, and this reduction was inversely correlated with plasma levels of amyloid-ß. Chronic nebivolol treatment of Tg2576 mice with established amyloid neuropathology and cognitive impairments significantly reduced brain amyloid content but failed to improve cognitive function. Our study demonstrates that nebivolol is highly tolerable and safe and can significantly reduce amyloid neuropathology in the brain, which could be one of the most important parameters for primary prevention of AD. Our studies support the continued investigation of nebivolol for the treatment of AD at very early stages of the disease.

Excretion and metabolism of milnacipran in humans after oral administration of milnacipran hydrochloride.

The pharmacokinetics, excretion, and metabolism of milnacipran were evaluated after oral administration of a 100-mg dose of [¹4C]milnacipran hydrochloride to healthy male subjects. The peak plasma concentration of unchanged milnacipran (∼240 ng/ml) was attained at 3.5 h and was lower than the peak plasma concentration of radioactivity (∼679 ng Eq of milnacipran/ml) observed at 4.3 h, indicating substantial metabolism of milnacipran upon oral administration. Milnacipran has two chiral centers and is a racemic mixture of cis isomers: d-milnacipran (1S, 2R) and l-milnacipran (1R, 2S). After oral administration, the radioactivity of almost the entire dose was excreted rapidly in urine (approximately 93% of the dose). Approximately 55% of the dose was excreted in urine as unchanged milnacipran, which contained a slightly higher proportion of d-milnacipran (∼31% of the dose). In addition to the excretion of milnacipran carbamoyl O-glucuronide metabolite in urine (∼19% of the dose), predominantly as the l-milnacipran carbamoyl O-glucuronide metabolite (∼17% of the dose), approximately 8% of the dose was excreted in urine as the N-desethyl milnacipran metabolite. No additional metabolites of significant quantity were excreted in urine. Similar plasma concentrations of milnacipran and the l-milnacipran carbamoyl O-glucuronide metabolite were observed after dosing, and the maximum plasma concentration of l-milnacipran carbamoyl O-glucuronide metabolite at 4 h after dosing was 234 ng Eq of milnacipran/ml. Lower plasma concentrations (<25 ng Eq of milnacipran/ml) of N-desethyl milnacipran and d-milnacipran carbamoyl O-glucuronide metabolites were observed.

Pharmacokinetic profile of dexloxiglumide.

Dexloxiglumide is a potent and selective cholecystokinin type 1 (CCK1) receptor antagonist currently under development in a variety of diseases affecting the gastrointestinal tract such as gastro-oesophageal reflux disease, irritable bowel syndrome (IBS), functional dyspepsia, constipation and gastric emptying disorders. In female patients with constipation-predominant IBS, clinical efficacy has been demonstrated following administration of dexloxiglumide 200 mg three times daily. Dexloxiglumide is rapidly and extensively absorbed after single oral administration in humans with an absolute bioavailability of 48%. The incomplete bioavailability is due to both incomplete absorption and hepatic first-pass effect. Following multiple-dose administration of 200 mg three times daily, the accumulation is predictable, indicating time-independent pharmacokinetics. In addition, dexloxiglumide pharmacokinetics are dose-independent after both single and repeated oral three-times-daily doses in the dose range 100-400 mg. Dexloxiglumide absorption window extends from the jejunum to the colon and the drug is a substrate and a weak inhibitor of P-glycoprotein and multidrug resistance protein 1. Plasma protein binding of dexloxiglumide is 94-98% and the drug has a moderate to low volume of distribution in humans. Systemic clearance of dexloxiglumide is moderate and cytochrome P450 (CYP) 3A4/5 and CYP2C9 have been implicated in the metabolism of dexloxiglumide to produce O-demethyl dexloxi-glumide. This metabolite is further oxidised to dexloxiglumide carboxylic acid. These two major metabolites (accounting for up to 50% of dexloxiglumide elimination) have been identified. However, in human plasma the unchanged drug represents the major (up to 91%) component of the metabolic profile. The parent drug is believed to be the major contributor to the efficacy of the compound, since its major metabolites are pharmacologically inactive. In addition, the drug is a single isomer chiral drug (eutomer) that does not undergo chiral inversion into its pharmacologically inactive enantiomer (distomer). After oral administration of (14)C-dexloxiglumide, radioactivity is mainly excreted in bile and in faeces (74% of dose) with much lower excretion in urine (20% of dose). Renal excretion of unchanged dexloxiglumide is low (7% of dose in urine and faeces, 1% of dose in urine) and is dose-independent in the dose range 100-400 mg. As the kidney is a minor contributor to the elimination of dexloxiglumide and/or its metabolites in humans, the pharmacokinetics of the drug should not be affected in patients with renal insufficiency. The pharmacokinetics of dexloxiglumide are also not affected by age, sex and administration with a high-fat breakfast. Mild and moderate liver impairment do not affect the pharmacokinetics of dexloxiglumide but severe liver impairment causes increases in systemic exposure to dexloxiglumide and O-demethyl dexloxiglumide. Thus, the drug should be prescribed with caution in patients with severe hepatic impairment even though no dose adjustment is warranted. The results of different drug interaction studies have indicated that no clinically relevant metabolic and concomitant drug-drug interactions are expected during the clinical use of dexloxiglumide.

Effect of azole antifungals ketoconazole and fluconazole on the pharmacokinetics of dexloxiglumide.

AIMS: Dexloxiglumide is a new CCK(1) receptor antagonist under investigation for treatment of functional gastrointestinal disorders and is metabolized by CYP3A4 and CYP2C9. The objectives of these two separate randomized, two-period, two-treatment crossover studies were to investigate the effects of steady-state ketoconazole, a model CYP3A4 inhibitor (Study 1), and steady-state fluconazole, a model CYP2C9 inhibitor (Study 2), on the pharmacokinetics of dexloxiglumide in healthy subjects. METHODS: Plasma samples were analysed for dexloxiglumide and its primary metabolites: O-demethyl dexloxiglumide (ODM; Study 1 and 2) and dexloxiglumide carboxylic acid (DCA; Study 2). RESULTS: Following ketoconazole coadministration, dexloxiglumide C(max) increased by 32% (90% confidence intervals (CI) 112-154), with unchanged ODM C(max); AUC of dexloxiglumide and ODM increased by 36% (90% CI 124-140 and 128-142, respectively). No changes were observed in dexloxiglumide or ODM t((1/2)). Fluconazole coadministration caused a 77% increase (90% CI 154-204) in dexloxiglumide C(max), no change in ODM C(max) and a 32% decrease (90% CI 62-75) in DCA C(max). Fluconazole coadministration resulted in a 2.5-fold increase (90% CI 235-267) in dexloxiglumide AUC, 40% increase (90% CI 136-156) in ODM AUC and an 18% decrease (90% CI 82-94) in DCA AUC. The t((1/2)) of all three analytes increased by approximately 2-fold with fluconazole coadministration (P-value < 0.05). CONCLUSIONS: Ketoconazole caused a minimal increase while fluconazole caused a moderate increase in dexloxiglumide systemic exposure with no change in the adverse event profile of dexloxiglumide.

Effect of multiple-dose dexloxiglumide on the pharmacokinetics of oral contraceptives in healthy women.

This study was undertaken to evaluate the effect of dexloxiglumide, a selective cholecystokinin receptor antagonist, on the pharmacokinetics of a combination oral contraceptive (OC). A single-blind, placebo-controlled, 2-period crossover study was conducted in 24 healthy young female subjects who received Ortho Tri-Cyclen containing ethinyl estradiol (EE, 0.035 mg) and norgestimate (NE, 0.180 mg/0.215 mg/0.250 mg per 7-day phase, respectively) for 5 days (days 17-21) concurrently with either 200 mg dexloxiglumide (3 times a day on days 17-20, followed by a single dose on day 21) or matching placebo during 2 consecutive 28-day OC dosing cycles. Plasma was sampled up to 24 hours for the determination of EE, NE, and 17-deactyl norgestimate (17-DNE, a rapidly formed pharmacologically active metabolite of NE). The geometric mean ratios (GMRs, dexloxiglumide/placebo) of the plasma concentration-time curve over 24 hours with corresponding 90% confidence intervals (CIs) for EE and 17-DNE were 1.21 (1.17-1.26) and 0.92 (0.89-0.95), respectively. The GMRs (90% CI) of C(max) for EE and 17-DNE were 1.15 (1.09-1.20) and 0.93 (0.90-0.96), respectively. Coadministration of OC and dexloxiglumide was well tolerated and safe. Comparable systemic exposure of EE and 17-DNE in the presence and absence of dexloxiglumide suggests that dexloxiglumide treatment is unlikely to interfere with the safety and efficacy of oral contraceptives based on the analysis of the resulting pharmacokinetic profile.