Pharmacy Technician Certification Board Practice Exam

What is the primary risk associated with medications that have a narrow therapeutic index?

1. Low efficacy

2. High potential for adverse reactions

3. Excessive cost

4. Limited availability

The correct answer is: High potential for adverse reactions

Medications with a narrow therapeutic index have a small margin between their effective dose and the dose that can cause toxicity. This means that even slight variations in dosage, absorption, metabolism, or elimination can lead to significant differences in drug efficacy and safety. The primary risk associated with such medications is the high potential for adverse reactions due to this tight margin. Patients taking these medications require careful monitoring and precise dosing to avoid reaching toxic levels or failing to achieve therapeutic effects. In practical terms, this translates into a need for healthcare providers to closely track blood levels of these drugs, adjust dosages based on individual patient responses, and be vigilant for any signs of toxicity or inadequate response. This monitoring is particularly crucial for agents used in conditions like epilepsy, cardiac disorders, or certain infections, where the balance between efficacy and toxicity is delicate. Other potential issues, such as high costs or limited availability, do not specifically address the inherent risks related to the therapeutic index of drugs, while low efficacy is more related to the drug's effectiveness rather than its safety profile. Thus, the high potential for adverse reactions due to the narrow therapeutic index is a critical concern that underscores the importance of proper management and oversight for these medications.