Should You Run a Dedicated TQT Study? Sponsor and Regulatory Considerations on Substitution Pathways to Assess QT Liability.

Cardiac safety regulatory guidance for drug development has undergone several monumental shifts over the past decade as technological advancements, analysis models and study best practices have transformed this landscape. Once, clinical proarrhythmic risk assessment of a new chemical entity (NCE) was nearly exclusively evaluated in a dedicated thorough QT (TQT) study. However, since the introduction of the International Council for Harmonisation (ICH) E14/S7B Q&A 5.1 and 6.1 TQT substitutions, drug developers are offered an alternative pathway to evaluate proarrhythmic risk during an ascending dose study in healthy volunteers or during a powered patient study, respectively. In addition, the findings as well as the manner in which nonclinical studies are conducted (i.e., utilizing best practices) can dictate the need for a positive control in the clinical study and/or affect the labeling outcome. Drug sponsors are now faced with the option of pursuing a dedicated TQT study or requesting a TQT substitution. Potential factors influencing the choice of pathway include the NCE mechanism of action, pharmacokinetic properties, and safety profile, as well as business considerations. This tutorial will highlight the regulatory framework for integrated arrhythmia risk prediction models to outline drug safety, delineate potential reasons why a TQT substitution request may be rejected and discuss when a standalone TQT is recommended.

Randomized trial of pharmacokinetic and pharmacodynamic effects of 13.2 mg intranasal epinephrine treatment in congestion.

BACKGROUND: Nasal congestion could affect the absorption of an epinephrine nasal spray (ENS). OBJECTIVE: To compare the pharmacokinetics of 13.2 mg ENS with nasal congestion vs without congestion and vs intramuscular (IM) treatments. METHODS: This phase I, open-label, 4-period randomized crossover study enrolled 51 healthy adults with seasonal allergies into cohorts that received a single dose of 13.2 mg ENS (NDS1C; Bryn Pharma, Lebanon, New Jersey) administered as 2 consecutive sprays in either opposite nostrils (cohort 1) or the same nostril (cohort 2). Both cohorts received 13.2 mg ENS with and without nasal allergen challenge (NAC), 0.3 mg IM epinephrine by autoinjector, and 0.5 mg IM epinephrine by manual syringe (MS). RESULTS: The ENS after NAC resulted in higher extent and peak exposures and more rapid time to maximum plasma concentration vs ENS without NAC and IM treatments. In cohort 1, the maximum observed baseline-adjusted epinephrine plasma concentration (pg/mL) of ENS with NAC, IM autoinjector, IM MS, or ENS without NAC was 458.0, 279.0, 364.2, and 270.1, respectively, and in cohort 2 was 436.3, 228.2, 322.3, and 250.8, respectively. The maximum observed baseline-adjusted epinephrine plasma concentration geometric mean ratio (90% CI) for ENS with NAC vs without NAC in cohort 1 was 170% (123%-234%), and in cohort 2 was 174% (115%-263%). In cohort 1, the time to maximum plasma concentration was 15, 21, 45, and 25 minutes, respectively, and in cohort 2 was 18, 20, 45, and 20 minutes, respectively (P < .01 for ENS with NAC vs IM MS). The postdose mean heart rate and blood pressure remained stable and relatively similar to predose values regardless of plasma epinephrine concentration. Mild nausea and headache were the most common adverse events with ENS. CONCLUSION: The 13.2 mg ENS with congestion exhibited enhanced absorption vs IM treatments and ENS without congestion and seemed to be well tolerated. There was no clinically impactful relationship between pharmacodynamic effects and plasma epinephrine concentration.

Clinically important interaction between tedisamil and verapamil.

Tedisamil, a class III antiarrhythmic drug, is a P-glycoprotein substrate. Tedisamil treatment may implicate coadministration with class IV antiarrhythmics such as verapamil, a P-glycoprotein inhibitor. Pharmacokinetic and pharmacodynamic interactions between tedisamil and verapamil were evaluated in a double-blind, crossover study. Twelve healthy volunteers received a 3-day treatment of tedisamil (100 mg bid), verapamil (180 mg bid), a combination of these drugs, or placebo. Blood pressure and electrocardiograms were assessed daily and cardiac output and pharmacokinetics on day 3. Combination of tedisamil and verapamil increased tedisamil plasma concentrations (AUC(0-12 h): +77%, CI(90%): +51% to +108%; C(max): +78%, CI(90%): +57% to +102%) compared to tedisamil monotreatment but decreased plasma concentrations of verapamil (AUC(0-12 h): -21%, CI(90%): -32% to -8%; C(max): -28%, CI(90%): -39% to -14%) and norverapamil (AUC(0-12 h): -17%, CI(90%): -28% to -6%; C(max): -20%, CI(90%):-29% to -10%) compared to verapamil monotreatment. Compared to placebo, verapamil and the combination treatment increased PR by 23.5 (CI(95%): 17.9 to 29.2) ms and 12.2 (5.7 to 17.0) ms, respectively. Compared to placebo, tedisamil and the combination treatment increased QTc by 27.8 (15.8 to 39.8) ms and 45.7 (33.7 to 57.7) ms, respectively. Thus, concomitant use of tedisamil with P-glycoprotein inhibitors likely results in clinically significant drug interactions.

Effects of a nonpeptide motilin receptor antagonist on proximal gastric motor function.

AIM: To assess the effects of the motilin receptor antagonist RWJ-68023 on basal and motilin-stimulated proximal gastric volume. METHODS: Eighteen healthy male volunteers received RWJ-68023 in two different doses or placebo for 135 min. After 45 min, subjects received a motilin infusion for 90 min. Proximal gastric volume was measured with a barostat at constant pressure and during isobaric distensions. Abdominal symptoms were scored using visual analogue scales. Motilin and RWJ-68023 concentrations were assessed by radioimmunoassay and liquid chromatography-mass spectrometry, respectively. RESULTS: Both dosages of RWJ-68023 were safe and well tolerated. The most common adverse events were of gastrointestinal origin. RWJ-68023 did not affect basal proximal gastric volume, but the high-dose RWJ-68023 reduced the contractile effect of motilin on the stomach. This antagonizing effect of RWJ-68023 was only significant (P = 0.014) during the distension procedure. CONCLUSIONS: The RWJ-68023 doses used in this study were selected to accomplish plasma concentrations that would block the motilin effect entirely. However, the antagonizing effect of RWJ-68023 was partial and only present when the tonic condition of the stomach was modulated by motilin.

Motilin effects on the proximal stomach in patients with functional dyspepsia and healthy volunteers.

This study investigates motilin effects on the proximal stomach in patients with functional dyspepsia (FD) and healthy volunteers. Eight healthy volunteers and 12 patients with FD were infused with synthetic motilin or placebo. Proximal gastric volume was measured with a barostat at constant pressure and during isobaric distensions. Abdominal symptoms were scored by visual analog scales. Plasma motilin concentrations were measured by radioimmunoassay. Motilin concentrations and baseline gastric volumes were similar for patients and healthy volunteers. Motilin, compared with placebo, reduced gastric volume by 112 ml [F(29,195); confidence interval (CI) 95%] in patients and by 96 ml [F(-7,200); CI 95%] in healthy volunteers. In patients, motilin decreased compliance by 76 ml/mmHg [F(9,143); CI 95%] compared with placebo, which was similar in volunteers [66 ml/mmHg; F(11,120); CI 95%]. Patients were more nauseous during motilin compared with placebo (P = 0.04), whereas healthy volunteers did not experience nausea. We conclude that in a fasted condition, FD patients have a similar proximal gastric motor response to motilin as healthy volunteers, but experience an exaggerated sensation of nausea.