Regulatory respiratory data refinement with reduced animal usage.

Area of Science:

• Preclinical drug safety assessment
• Respiratory pharmacology
• In vivo animal models

Background:

• Regulatory preclinical safety assessment requires evaluating drug effects on the respiratory system before human trials.
• Current methods like head-out plethysmography (HOP) and whole body plethysmography (WBP) primarily measure ventilatory parameters.
• Direct measurement of airway mechanics is crucial for inhaled drug safety testing.

Purpose of the Study:

• To enhance respiratory safety testing strategies for drug candidates.
• To evaluate a telemetered pleural pressure - head-out plethysmography (PP-HOP) model for direct airway mechanics measurement.
• To assess a crossover study design in WBP to reduce animal usage and variability.

Main Methods:

• Rats were surgically implanted with telemetry devices for pleural pressure measurement in the PP-HOP model.
• Respiratory function was assessed using HOP with methacholine challenge.
• WBP assessments were conducted in rats using a crossover design with theophylline administration.

Main Results:

• The PP-HOP model successfully detected expected changes in ventilatory parameters and airway mechanics (e.g., increased pulmonary resistance).
• The WBP crossover study showed comparable sensitivity and statistical power to parallel group designs for detecting respiratory changes.
• The crossover design in WBP demonstrated reduced variability and animal usage.

Conclusions:

• Telemetered pleural pressure measurement combined with HOP offers an improved respiratory testing strategy for inhaled drugs.
• For non-inhaled drugs, WBP with a crossover design is an effective alternative to parallel groups, reducing animal numbers without losing statistical power.
• These refined methods contribute to more efficient and ethical preclinical respiratory safety assessments.