Managing Drug Toxicities & Drug Interactions: Clinical Pharmacology Case-based Discussion

Introduction A drug interaction occurs when one drug alters the pharmacological effect (enhanced or decreased) of another drug. In human medicine there are several resources available to screen for drug interactions, and there are specific guidelines and agencies to report suspected drug interactions to. In veterinary medicine screening, monitoring, and reporting of drug interactions are rarely performed; therefore, the incidence of drug interactions in companion animals is unknown. With the increase in number of approved veterinary drugs, continued use of human drugs, compounding, and extra label drug use, the potential for drug interactions is likely to increase. Today, multiple drugs are often prescribed to treat or control disease in companion animals, and this combination therapy can increase the potential for drug interactions. A drug interaction can occur during the preparation, administration, or dispensing process. Types of drug interactions include pharmaceutical (drug-formulation), pharmacokinetic, and pharmacodynamic. Veterinarians should be aware of the more common drug interactions and the resources available for screening to avoid such interactions.