No Effect of Plazomicin on the Pharmacokinetics of Metformin in Healthy Subjects

Plazomicin is an aminoglycoside that was engineered to overcome aminoglycoside-modifying enzymes, which are the most common aminoglycoside resistance mechanism in Enterobacteriaceae. Because plazomicin is predominantly eliminated via renal pathways, an in vitro study was conducted to determine whether plazomicin inhibits the organic cation transporter 2 (OCT2) and the multidrug and toxin extrusion (MATE1 and MATE2-K) transporters, using metformin as a probe substrate. Plazomicin inhibited OCT2, MATE1, and MATE2-K transporters with half-maximal inhibition of the transporter values of 5120, 1300, and 338 µg/mL, respectively. To determine whether this in vitro inhibition translates in vivo, an open-label, randomized, 2-period, 2-treatment crossover study (NCT03270553) was carried out in healthy subjects (N = 16), who received a single oral dose of metformin 850 mg alone and in combination with a single intravenous infusion of plazomicin 15 mg/kg. Geometric least-squares mean ratios of the test treatment (combination) vs the reference treatment (metformin alone) and 90% confidence intervals were within the equivalence interval of 80% to 125% (peak plasma concentration, 104.5 [95.1-114.9]; area under the plasma concentration-time curve from time zero to time of last quantifiable concentration, 103.7 [93.5-115.0]; area under the plasma concentration-time curve from time zero to infinity, 104.0 [94.2-114.8]). The results demonstrate that there is no clinically significant drug-drug interaction resulting from coadministration of single doses of intravenous plazomicin 15 mg/kg and oral metformin 850 mg in healthy subjects. Coadministration of plazomicin and metformin was well tolerated in healthy subjects.

1400. Mass Balance, Metabolism, and Excretion of [14C]-Plazomicin in Healthy Human Subjects

Background

Plazomicin is a next-generation aminoglycoside (AG) with a structure that protects it from common AG resistance mechanisms in Enterobacteriaceae, and with in vitro activity against extended spectrum β-lactamase-producing and carbapenem-resistant Enterobacteriaceae. The purpose of this study was to evaluate the metabolism and excretion of plazomicin in healthy human subjects.

Methods

Six healthy male subjects were administered a single 30-minute intravenous infusion of 15 mg/kg [¹⁴C]-plazomicin (~100 µCi/dose). Following administration, blood (and plasma), urine, and feces were collected for 7 days. Total radioactivity was analyzed by liquid scintillation counting; plazomicin concentration was analyzed by a validated liquid chromatography–tandem mass spectrometry method; and metabolite profiling was conducted by accelerator mass spectrometry (AMS).

Results

The majority of the total administered radioactivity was recovered in urine (89.1%), with negligible amounts (<0.2%) excreted in feces. Radioactivity was rapidly eliminated, with ~56% of the total radioactivity recovered in urine within the first 4 hours postdose and >85% recovered in urine by 48 hours postdose. Analysis of nonradiolabeled plazomicin demonstrated that 97.5% of the dose was recovered as unchanged parent drug in urine by the end of the last sampling interval. Metabolite profiling of plasma and urine using AMS showed that [¹⁴C]-plazomicin was the only definable peak present, accounting for 94.3% and 93.6%, respectively, of the total carbon content.

Conclusion

Mass balance was achieved for ¹⁴C-labeled and for nonradiolabeled plazomicin as the majority of the administered dose was recovered in urine, with negligible amounts in the feces. Plazomicin was eliminated as unchanged drug by the kidneys and thus did not appear to be metabolized to any appreciable extent. No metabolites were detected by AMS and plazomicin was the only definable peak present in plasma and urine.

Disclosures

T. Choi, Achaogen, Inc.: Employee, Salary. J. D. Seroogy, Achaogen, Inc.: Employee and Shareholder, Salary. M. Sanghvi, Xceleron: Employee, Salary. S. V. Dhuria, Achaogen, Inc.: Employee, Salary.

Use of a secure mobile application to inform clinicians on adverse event management and drug-drug interactions for ribociclib: Experiences with CT scholar in ribociclib clinical trials

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Background: Understanding and gaining familiarity with the adverse event (AE) and drug-drug interaction (DDI) potential of novel agents can be challenging, cumbersome, and time consuming for clinicians. A comprehensive and secure AE management/DDI mobile application (CT Scholar [Novartis Pharmaceuticals Corp]) was developed to ease the management of clinical trial participants with hormone receptor–positive, human epidermal growth factor receptor 2–negative advanced breast cancer receiving ribociclib. Methods: CT Scholar was designed specifically for the ribociclib clinical program to provide easy access to information on AE and DDI management. The AE management module characterizes and quickly informs drug-specific AE management based on protocol guidelines and supportive care guidance. The DDI module includes a database of > 100 drugs searchable by both trade and generic name. Number of application visits, unique users, and screen views were monitored from Jan to Sept 2016. Results: There were 1055 visits to CT Scholar (117/month) by 145 unique users (28/month), with 5764 screen views (640/month) and 5.5 screens viewed/visit. Among the most-viewed modules were hematologic AE management (1132 views), gastrointestinal AE management (771), and DDI (734). Diarrhea, neutropenia, and nausea were the most viewed submodules (308, 230, and 205 views, respectively). The information on CT Scholar was consistently shown to be accessed more quickly than information obtained from printed clinical protocols. No patients discontinued from the ribociclib studies due to AEs following the introduction of CT Scholar. Conclusions: CT Scholar was widely used by clinicians, and it responded to their needs by providing essential information, especially on prevalent AEs, which could be easily updated and rapidly accessed. Additionally, CT Scholar provides a platform showing how technology can assist clinicians and patients in managing care during a trial, which can inform the development of future supportive materials.

Phase I dose-escalation study of LCL161, an oral inhibitor of apoptosis proteins inhibitor, in patients with advanced solid tumors

PURPOSE

LCL161 antagonizes the function of inhibitor of apoptosis proteins (IAPs), thereby promoting cancer cell death. This first-in-human dose-escalation study assessed the maximum-tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of LCL161 in patients with advanced solid tumors. A second part of the study assessed the relative bioavailability of a tablet versus solution formulation.

PATIENTS AND METHODS

LCL161 was administered orally, once weekly, on a 21-day cycle to adult patients with advanced solid tumors by using an adaptive Bayesian logistic regression model with overdose control-guided dose escalation.

RESULTS

Fifty-three patients received at least one dose of LCL161 (dose range, 10 to 3,000 mg). LCL161 was well tolerated at doses up to 1,800 mg. Cytokine release syndrome (CRS) was the only dose-limiting toxicity (in three [6%] of 53 patients) and was the most common grades 3 to 4 event (in five [9%] of 53 patients). Vomiting, nausea, asthenia/fatigue, and anorexia were common but not severe. Although the MTD was not formally determined, an 1,800-mg dose was selected in compliance with the protocol for additional study, given the dose-limiting CRS at higher doses and pharmacodynamic activity at lower doses. LCL161 was rapidly absorbed, and exposure was generally increased with dose. The tablet formulation of LCL161 was better tolerated than the solution; tablet and solution formulations had similar exposures, and the solution was discontinued. No patient had an objective response. LCL161 induced degradation of cellular IAP1 protein in the blood, skin, and tumor and increased circulating cytokine levels.

CONCLUSION

The 1,800-mg dose of LCL161, administered as a single agent once weekly, in tablet formulation is the recommended dose for additional study. This combined dose and formulation was well tolerated and had significant pharmacodynamic activity, which warrants additional investigation.

Intranasal delivery to the central nervous system: mechanisms and experimental considerations

The blood-brain barrier (BBB) limits the distribution of systemically administered therapeutics to the central nervous system (CNS), posing a significant challenge to drug development efforts to treat neurological and psychiatric diseases and disorders. Intranasal delivery is a noninvasive and convenient method that rapidly targets therapeutics to the CNS, bypassing the BBB and minimizing systemic exposure. This review focuses on the current understanding of the mechanisms underlying intranasal delivery to the CNS, with a discussion of pathways from the nasal cavity to the CNS involving the olfactory and trigeminal nerves, the vasculature, the cerebrospinal fluid, and the lymphatic system. In addition to the properties of the therapeutic, deposition of the drug formulation within the nasal passages and composition of the formulation can influence the pathway a therapeutic follows into the CNS after intranasal administration. Experimental factors, such as head position, volume, and method of administration, and formulation parameters, such as pH, osmolarity, or inclusion of permeation enhancers or mucoadhesives, can influence formulation deposition within the nasal passages and pathways followed into the CNS. Significant research will be required to develop and improve current intranasal treatments and careful consideration should be given to the factors discussed in this review.

Intranasal drug targeting of hypocretin-1 (orexin-A) to the central nervous system

The blood-brain barrier (BBB) limits the distribution of systemically administered therapeutics to the central nervous system (CNS). Intranasal delivery is a noninvasive method that targets drugs to the brain and spinal cord along olfactory and trigeminal neural pathways, bypassing the BBB and minimizing systemic exposure and side effects. To assess intranasal drug targeting of a neuropeptide (hypocretin-1, HC) to the CNS, pharmacokinetics in blood, CNS tissues, and peripheral tissues were compared after intranasal and intravenous infusion to anesthetized rats. Despite a 10-fold lower blood concentration of HC with intranasal administration, both routes resulted in similar brain concentrations. Tissue-to-blood concentration ratios after intranasal administration were significantly greater in all brain regions over 2 h compared to intravenous administration, with the highest ratios in the trigeminal nerve (14-fold) and olfactory bulbs (9-fold). Intranasal delivery increased drug targeting to the brain and spinal cord 5- to 8-fold. Approximately 80% of the area under the brain concentration-time curve following intranasal administration was due to direct transport from the nasal passages. Intranasal delivery rapidly targets HC to the CNS with minimal systemic exposure, most of which reaches the brain intact by mechanisms not involving distribution from the blood and/or cerebrospinal fluid.