Which of the following drug is associated with tachyphylaxis ?
**Core Concept**
Tachyphylaxis is a pharmacological phenomenon where the effectiveness of a drug decreases rapidly with repeated administration. This is often due to receptor desensitization, where the receptor becomes less responsive to the drug, or downregulation, where the number of receptors decreases.
**Why the Correct Answer is Right**
Tachyphylaxis is commonly seen with drugs that cause vasoconstriction, such as ergotamines and certain vasopressors. Ergotamine, a medication used to treat migraines, induces vasoconstriction by binding to serotonin receptors on blood vessels. However, with repeated administration, the serotonin receptors become desensitized, leading to a decrease in the drug's effectiveness and the onset of tachyphylaxis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not describe a drug associated with tachyphylaxis.
**Option B:** This option is incorrect because it is not a medication known to cause tachyphylaxis.
**Option C:** This option is incorrect because it is not a drug commonly associated with tachyphylaxis.
**Clinical Pearl / High-Yield Fact**
When administering medications that can cause tachyphylaxis, it's essential to consider the risk of rapid loss of efficacy and adjust dosing schedules accordingly. This is particularly important for medications used to treat acute conditions, such as migraines or hypertension.
**Correct Answer: C. Ergotamine**