**Core Concept**
Imipramine, a tricyclic antidepressant (TCA), is primarily used to treat major depressive disorder. However, it has the potential to induce a manic or hypomanic episode in some patients, especially those with a history of bipolar disorder or a family history of mood disorders.

**Why the Correct Answer is Right**
This phenomenon is known as "switching" or "induction" of mania. It is thought to occur due to the blockade of serotonin and norepinephrine reuptake, which can lead to an increase in these neurotransmitters and subsequently cause a manic episode. The patient's symptoms of increased excitement, colourful clothes, and increased talking are indicative of a manic episode. The next step in management would be to switch to a different medication that is less likely to induce mania, such as a selective serotonin reuptake inhibitor (SSRI) or a mood stabilizer.

**Why Each Wrong Option is Incorrect**
**Option A:** Continuing Imipramine would be inappropriate as it may worsen the manic symptoms.
**Option B:** Increasing the dose of Imipramine is not recommended as it may lead to toxicity and further exacerbate the manic episode.
**Option C:** Adding a benzodiazepine may provide temporary relief but does not address the underlying issue of the manic episode.

**Clinical Pearl / High-Yield Fact**
Be aware of the potential for TCAs to induce mania, especially in patients with a history of bipolar disorder. This is a classic exam trick, and students should remember that switching to a different medication is often the best course of action in such cases.

**Correct Answer:** D.