**Core Concept**
Therapeutic drug monitoring (TDM) of antihypertensive drugs involves measuring and adjusting the plasma concentrations of these medications to achieve optimal blood pressure control while minimizing adverse effects. This concept is particularly relevant for drugs with narrow therapeutic indices, where small changes in plasma concentration can significantly impact efficacy or toxicity.

**Why the Correct Answer is Right**
The primary reason TDM of antihypertensive drugs is not widely practiced is that most antihypertensive medications have a relatively wide therapeutic index, meaning that a wide range of plasma concentrations is effective in controlling blood pressure without significantly increasing the risk of adverse effects. Additionally, many antihypertensive drugs have a long half-life, allowing for once-daily dosing and reducing the need for frequent plasma concentration monitoring.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because, while it is true that some antihypertensive medications have a narrow therapeutic index, this is not the primary reason TDM is not practiced. Other factors, such as the availability of simpler and more effective dosing regimens, contribute to the lack of TDM.

**Option B:** This option is incorrect because TDM is not typically necessary for antihypertensive medications with a short half-life. In fact, these medications may require more frequent dosing, making TDM more relevant.

**Option C:** This option is incorrect because TDM can be useful for monitoring the effectiveness of antihypertensive therapy and adjusting medication regimens as needed. However, it is not a primary consideration for most antihypertensive medications.

**Option D:** This option is incorrect because, while some antihypertensive medications may have a high risk of adverse effects, this is not the primary reason TDM is not practiced. Other factors, such as the availability of simpler and more effective dosing regimens, contribute to the lack of TDM.

**Clinical Pearl / High-Yield Fact**
A key consideration when selecting antihypertensive medications is the presence of a narrow therapeutic index, which may necessitate TDM to avoid adverse effects. However, most antihypertensive medications have a wide therapeutic index, making TDM less relevant.

**Correct Answer: C.**