A hospital nurse is taking Imipramine for a phobic anxiety disorder, and her patient is being treated with chlorpromazine for a psychotic disorder. Which of the following adverse effect is likely to occur in both of them?

**Core Concept**
Imipramine, a tricyclic antidepressant (TCA), and chlorpromazine, a typical antipsychotic, both have anticholinergic properties. Their concomitant use can lead to additive anticholinergic effects.

**Why the Correct Answer is Right**
The anticholinergic effects are primarily due to the blockade of muscarinic acetylcholine receptors in the central and peripheral nervous system. This blockade can lead to dry mouth, blurred vision, urinary retention, and constipation. The combination of these medications can exacerbate these side effects, making them more pronounced.

**Why Each Wrong Option is Incorrect**

* **Option A:** Orthostatic hypotension is a common side effect of antipsychotics but is not directly related to the combination of imipramine and chlorpromazine.
* **Option B:** Weight gain is a potential side effect of both imipramine and chlorpromazine, but it is not the most likely adverse effect to occur in both patients.
* **Option C:** QT interval prolongation is a concern with the use of TCAs like imipramine, but it is not a direct result of the combination with chlorpromazine.

**Clinical Pearl / High-Yield Fact**
When combining medications with anticholinergic properties, monitor patients closely for signs of anticholinergic toxicity, such as dry mouth, blurred vision, urinary retention, and constipation.

**Correct Answer:** C.

✓ Correct Answer: C. Ohostatic hypotension