VPT 311: General and Systemic Veterinary Pharmacology (2+1)

QUANTAL DOSE RESPONSE CURVE

• Quantal DR curve due to biological variation ( diff. among individuals in response to same treatment) the response to drug dose in a population occurs as a frequency distribution.
• A cumulative freq. Distribution (as % of individuals showing effect plotted against log dose ---> yields the quantal DR curve
• The dose that produces desired effect in 50% - ED₅₀
• The dose that produces death in 50% - LD₅₀
• Therapeutic index = LD₅₀ / ED₅₀