Drug that causes tachycardia, mydriasis, and urinary’ retention –
**Core Concept**
The question targets the clinical effects of a specific drug class, specifically the anticholinergic properties that lead to tachycardia, mydriasis, and urinary retention. Anticholinergic drugs block the action of acetylcholine at muscarinic receptors in the central and peripheral nervous system, leading to these characteristic side effects.
**Why the Correct Answer is Right**
The correct answer is a drug that blocks muscarinic receptors, leading to tachycardia due to decreased parasympathetic tone on the heart, mydriasis due to unopposed sympathetic tone on the pupils, and urinary retention due to decreased detrusor muscle contraction. The muscarinic receptors involved in these effects are primarily M2 in the heart, M3 in the pupils, and M3 in the bladder.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question as it does not have anticholinergic properties.
**Option B:** This option does not have significant anticholinergic effects and is not associated with tachycardia, mydriasis, and urinary retention.
**Option C:** This option is incorrect as it is a cholinergic agonist, which would have opposite effects to those described in the question.
**Clinical Pearl / High-Yield Fact**
The "dead ant" mnemonic can be used to remember the anticholinergic side effects: dry (dry mouth, dry skin), red (mydriasis), hot (fever), and antsy (agitation and confusion).
**Correct Answer: B. Atropine**