Absorption, metabolism, and excretion of the antiemetic rolapitant, a selective neurokinin-1 receptor antagonist, in healthy male subjects

Is there enough evidence to classify cycloalkyl amine substituents as structural alerts?

Basic amine substituents provide several pharmacokinetic benefits relative to acidic and neutral functional groups, and have been extensively utilized as substituents of choice in drug design. On occasions, basic amines have been associated with off-target pharmacology via interactions with aminergic G-protein coupled receptors, ion-channels, kinases, etc. Structural features associated with the promiscuous nature of basic amines have been well-studied, and can be mitigated in a preclinical drug discovery environment. In addition to the undesirable secondary pharmacology, α-carbon oxidation of certain secondary or tertiary cycloalkyl amines can generate electrophilic iminium and aldehyde metabolites, potentially capable of covalent adduction to proteins or DNA. Consequently, cycloalkyl amines have been viewed as structural alerts (SAs), analogous to functional groups such as anilines, furans, thiophenes, etc., which are oxidized to reactive metabolites that generate immunogenic haptens by covalently binding to host proteins. Detailed survey of the literature, however, suggests that cases where preclinical or clinical toxicity has been explicitly linked to the metabolic activation of a cycloalkyl amine group are extremely rare. Moreover, there is a distinct possibility for the formation of electrophilic iminium/amino-aldehyde metabolites with numerous cycloalkyl amine-containing marketed drugs, since stable ring cleavage products have been characterized as metabolites in human mass balance studies. In the present work, a critical analysis of the evidence for and against the role of iminium ions/aldehydes as mediators of toxicity is discussed with a special emphasis on often time overlooked detoxication pathways of these reactive species to innocuous metabolites.

Gingerol inhibits cisplatin-induced acute and delayed emesis in rats and minks by regulating the central and peripheral 5-HT, SP, and DA systems

Abstract

Gingerol, a biologically active component in ginger, has shown antiemetic properties. Our study aimed to explore the underlying mechanisms of gingerol on protecting rats and minks from chemotherapy-induced nausea and vomiting. The preventive impact of gingerol was evaluated in the pica model of rats and the vomiting model of minks induced by cisplatin at every 6 h continuously for a duration of 72 h. Animals were arbitrarily separated into blank control group, simple gingerol control group, cisplatin control group, cisplatin + metoclopramide group, cisplatin + three different doses gingerol group (low-dose; middle-dose; high-dose). The area postrema as well as ileum damage were assessed using H&E stain. The levels of 5-TH, 5-HT₃ receptor, TPH, SERT, SP, NK₁ receptor, PPT, NEP, DA, D2R, TH, and DAT were determined using immunohistochemistry or qRT-PCR in rats and minks. All indicators were measured in the area postrema along with ileum. The kaolin intake by rats and the incidence of CINV of minks were significantly decreased after pretreatment with gingerol in a dosage-dependent way for the duration of 0–24-h and 24–72-h. Gingerol markedly decreased the levels of 5-TH, 5-HT₃ receptor, TPH, SP, NK₁ receptor, PPT, DA, D2R, TH, alleviated area postrema as well as ileum damage, and increased the accumulation of SERT, NEP, DAT in the area postrema along with ileum of rats and minks. Gingerol alleviates cisplatin-induced kaolin intake of rats and emesis of minks possibly by regulating central and peripheral 5-HT system, SP system and DA system.

Graphic abstract

Population Pharmacokinetics of Rolapitant in Patients With Chemotherapy-Induced Nausea and Vomiting

Population pharmacokinetics of rolapitant and its active metabolite M19 were studied in 482 patients receiving this neurokinin-1 receptor antagonist in combination with a 5-hydroxytryptamine-3 receptor antagonist and dexamethasone for prevention of chemotherapy-induced nausea and vomiting (CINV). Patients received a single dose of rolapitant (range, 9-180 mg) before administration of moderately or highly emetogenic chemotherapy. Population pharmacokinetic analysis was performed via nonlinear mixed-effects modeling. Rolapitant pharmacokinetics was best characterized by a 2-compartment model. Population typical values were estimated to be 0.962 L/h for apparent oral clearance and 214 L for central compartment volume of distribution. The intercompartment clearance and peripheral compartment volume of distribution was estimated to be 2.79 L/h and 164 L, respectively. Metabolite M19 pharmacokinetics was described by a 1-compartment model with an apparent metabolite clearance of 1.83 L/h. Intersubject variability was moderate for pharmacokinetics parameters. Weight positively correlated with central compartment volume of distribution and peripheral compartment volume of distribution but not with apparent oral clearance. No other demographic, clinical, or pathophysiologic covariates, including liver and renal function, influenced rolapitant pharmacokinetics. A slight positive trend was observed between rolapitant exposure and efficacy (ie, complete response defined as no emesis and no use of rescue medication) in the delayed phase of CINV (>24-120 hours after chemotherapy). This further supports the 180-mg dose of rolapitant in CINV patients. In summary, this validated population pharmacokinetic model satisfactorily describes pharmacokinetics of rolapitant and M19 in patients with CINV. These results support the recommendation that no dose adjustment for patient variables investigated is necessary.