FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam

What is the primary outcome of tachyphylaxis?

1. Increased drug efficacy

2. Enhanced receptor sensitivity

3. Reduction in drug responsiveness

4. Extended duration of action

The correct answer is: Reduction in drug responsiveness

Tachyphylaxis refers to a rapid decrease in the response to a drug after its administration, resulting in a reduction in drug responsiveness over time. This phenomenon can occur with various medications, particularly with continuous or repeated exposure. The key feature of tachyphylaxis is that the initial drug effect diminishes quickly, meaning that higher doses of the drug may be required to achieve the same effect that was initially produced. In the context of pharmacology, tachyphylaxis can occur due to several mechanisms, including receptor desensitization, depletion of neurotransmitters, or changes in pharmacokinetics. Importantly, as the body becomes less responsive to the drug, the effectiveness of the treatment can be compromised. The other options may seem relevant but do not reflect the nature of tachyphylaxis accurately. Increased drug efficacy, enhanced receptor sensitivity, and extended duration of action do not align with the primary effect of tachyphylaxis, which is fundamentally about diminishing responsiveness rather than enhancement.