An assessment of the effects of neurokinin1 receptor antagonism against nausea and vomiting: Relative efficacy, sites of action and lessons for future drug development.

A broad-spectrum anti-vomiting effect of neurokinin1 receptor antagonists (NK1 RA), shown in pre-clinical animal studies, has been supported by a more limited range of clinical studies in different indications. However, this review suggests that compared with vomiting, the self-reported sensation of nausea is less affected or possibly unaffected (depending on the stimulus) by NK1 receptor antagonism, a common finding for anti-emetics. The stimulus-independent effects of NK1 RAs against vomiting are explicable by actions within the central pattern generator (ventral brainstem) and the nucleus tractus solitarius (NTS; dorsal brainstem), with additional effects on vagal afferent activity for certain stimuli (e.g., highly emetogenic chemotherapy). The central pattern generator and NTS neurones are multifunctional so the notable lack of obvious effects of NK1 RAs on other reflexes mediated by the same neurones suggests that their anti-vomiting action is dependent on the activation state of the pathway leading to vomiting. Nausea requires activation of cerebral pathways by projection of information from the NTS. Although NK1 receptors are present in cerebral nuclei implicated in nausea, and imaging studies show very high receptor occupancy at clinically used doses, the variable or limited ability of NK1 RAs to inhibit nausea emphasizes: (i) our inadequate understanding of the mechanisms of nausea; and (ii) that classification of a drug as an anti-emetic may give a false impression of efficacy against nausea vs. vomiting. We discuss the potential mechanisms for the differential efficacy of NK1 RA and the implications for future development of drugs that can effectively treat nausea, an area of unmet clinical need.

Managed care considerations for the treatment of chronic cough.

Chronic cough (CC), defined as a daily cough lasting longer than 8 weeks in adults, is a common condition in the United States. CC is a diagnosis of exclusion associated with a substantial economic burden related to increased healthcare and medication utilization, decreased work productivity, a greater incidence of cough-related comorbidities, and reduced quality of life. CC treatment guidelines recommend stepwise treatment with specific nonpharmacologic therapies and pharmacologic agents. However, many patients may still have incomplete or no symptom relief, encounter response attenuation over time, or experience intolerable adverse effects. New targeted therapies for refractory CC are currently under development, including the purinergic 2X3 receptor antagonists gefapixant, BLU-5937, and sivopixant (S-600918) and the neurokinin-1 receptor antagonist orvepitant. These targeted agents may have improved efficacy and safety profiles, helping fill unmet treatment needs. If approved, managed care organizations must develop formulary placement and utilization management criteria based on clinical guideline recommendations, expert opinion, and cost-effectiveness analyses to support the clinically appropriate use of these targeted therapies for best patient outcomes.

Cost-minimization analysis of GSTP1c.313A>G genotyping for the prevention of cisplatin-induced nausea and vomiting: A Bayesian inference approach.

BACKGROUND: Chemotherapy-induced nausea and vomiting are concerning adverse events resulting from cancer treatment, and current guidelines recommend the use of neurokinin-1-selective antagonists, such as fosaprepitant, in highly emetogenic schemes. However, the implementation of this strategy may be limited by the cost of treatment. GSTP1 c.313A>G genotype was recently described as a predictor of vomiting related to high-dose cisplatin. We hypothesized that the inclusion of routine GSTP1 c.313A>G screening may be promising in financial terms, in contrast to the wide-spread use of fosaprepitant. METHODS: A cost-minimization analysis was planned to compare GSTP1 c.313A>G genotyping versus overall fosaprepitant implementation for patients with head and neck cancer under chemoradiation therapy with high-dose cisplatin. A decision analytic tree was designed, and conditional probabilities were calculated under Markov chain Monte Carlo simulations using the Metropolis-Hastings algorithm. The observed data included patients under treatment without fosaprepitant, while priors were derived from published studies. RESULTS: To introduce screening with real-time polymerase chain reaction, an initial investment of U$ 39,379.97 would be required, with an amortization cost of U$ 7,272.97 per year. The mean cost of standard therapy with fosaprepitant is U$ 243.24 per patient, and although the initial cost of routine genotyping is higher, there is a tendency of progressive minimization at a threshold of 155 patients (Credible interval-CI: 119 to 216), provided more than one sample is incorporated for simultaneous analysis. A resulting reduction of 35.83% (CI: 30.31 to 41.74%) in fosaprepitant expenditures is then expected with the implementation of GSTP1 c.313A>G genotyping. CONCLUSION: GSTP1 c.313A>G genotyping may reduce the use of preventive support for chemotherapy induced nausea and lower the overall cost of treatment. Despite the results of this simulation, randomized, interventional studies are required to control for known and unknown confounders as well as unexpected expenses.

Cost-utility analysis of aprepitant for patients who truly need it in Japan.

PURPOSE: Neurokinin-1 receptor antagonist (NK1RA) is recommended to prevent chemotherapy-induced nausea and vomiting (CINV) in patients who receive highly or moderately emetogenic chemotherapy (HEC or MEC, respectively). We previously reported that aprepitant, an NK1RA, was needed to control CINV in 43% and 12% of patients who received HEC and MEC, respectively (Support Care Cancer 23:905-912, 2015). To elucidate the cost-effectiveness of aprepitant in these patients, a cost-utility analysis according to the necessity of aprepitant was performed. METHODS: A decision-analytic model was developed according to the necessity of aprepitant and CINV responses in both acute and delayed phases of chemotherapy. Probabilities of health states and medical costs were derived from the results of the abovementioned trial. RESULT: In patients who received HEC and needed aprepitant, the incremental cost-effectiveness ratio (ICER) with aprepitant, relative to the regimen with no aprepitant, was 7912 US dollars (USD) per quality-adjusted life year (QALY) gained, which was far below the commonly accepted threshold of 50,000 USD/QALY. The ICER was 27,457 USD/QALY in patients who received MEC and needed aprepitant. In contrast, in patients who received HEC or MEC but did not need aprepitant, the ICER was 175,959 or 478,844 USD/QALY, respectively. CONCLUSION: Regardless of whether a patient received HEC or MEC, aprepitant use was highly cost-effective for patients who truly needed it. These results warrant further research to predict the necessity of NK1RA treatment before initiating emetogenic chemotherapies.

ItchApp©: An App-based eDiary for Assessment of Chronic Pruritus in Clinical Trials.

Performing a reliable assessment of chronic pruritus remains a challenge. Electronic diaries are often used, but many of the scales have not been validated. ItchApp© was developed for Android smartphones in order to address this lack. A total of 40 subjects with chronic pruritus completed questionnaires both on paper and with ItchApp© (verbal rating scale, numerical rating scale, dynamic pruritus score) in order to validate the software application. Strong correlations were found for test-retest reliability (intraclass correlation coefficient: 0.865-0.977) and convergent validity (Spearman's r: 0.442-0.924). A feasibility questionnaire for ItchApp© revealed a high level of user friendliness and compliance. This was confirmed in a randomized controlled trial with 68 subjects, for which the clinically important difference in the numerical rating scale values for ItchApp© was calculated (2.61 points). In summary, ItchApp© is a recently developed eDiary that can provide experts with a reliable evaluation of patients with chronic pruritus. It will be made available for future clinical trials.

Mechanical Conflict System: A Novel Operant Method for the Assessment of Nociceptive Behavior.

A new operant test for preclinical pain research, termed the Mechanical Conflict System (MCS), is presented. Rats were given a choice either to remain in a brightly lit compartment or to escape to a dark compartment by crossing an array of height-adjustable nociceptive probes. Latency to escape the light compartment was evaluated with varying probe heights (0, .5, 1, 2, 3, and 4 mm above compartment floor) in rats with neuropathic pain induced by constriction nerve injury (CCI) and in naive control rats. Escape responses in CCI rats were assessed following intraperitoneal administration of pregabalin (10 and 30 mg/kg), morphine (2.5 and 5 mg/kg), and the tachykinin NK1 receptor antagonist, RP 67580 (1 and 10 mg/kg). Results indicate that escape latency increased as a function of probe height in both naive and CCI rats. Pregabalin (10 and 30 mg/kg) and morphine (5 mg/kg), but not RP 67580, decreased latency to escape in CCI rats suggesting an antinociceptive effect. In contrast, morphine (10 mg/kg) but not pregabalin (30 mg/kg) increased escape latency in naive rats suggesting a possible anxiolytic action of morphine in response to light-induced fear. No order effects following multiple test sessions were observed. We conclude that the MCS is a valid method to assess behavioral signs of affective pain in rodents.