Therapeutic Index (Veterinary Pharmacology)

Category: science

The ratio comparing the blood concentration at which a drug becomes toxic to the concentration at which it is clinically effective.

A narrow therapeutic index (seen in drugs like digoxin or phenobarbital) leaves a razor-thin margin for error. Small dosage miscalculations can cause severe toxicity or drug failure, requiring veterinarians to mandate regular therapeutic drug monitoring (TDM) blood draws to track levels.

Common Examples

• Because the anticonvulsant medication has a narrow therapeutic index, we scheduled a six-month blood draw to monitor serum concentrations.
• Tracking blood chemistry parameters helps veterinarians safely titrate medications with narrow therapeutic index margins over time.