**Core Concept**
Nizatidine is a second-generation histamine H2 receptor antagonist (H2 blocker) used in the treatment of peptic ulcer disease, gastroesophageal reflux disease (GERD), and Zollinger-Ellison syndrome. It works by competitively inhibiting histamine at the H2 receptors in the parietal cells of the stomach, thereby reducing gastric acid secretion.

**Why the Correct Answer is Right**
The correct answer, **D. It can also lead to tachycardia**, is incorrect because Nizatidine is not commonly associated with tachycardia as a side effect. Tachycardia is more commonly associated with anticholinergic medications, such as antihistamines, antipsychotics, and some antidepressants. Nizatidine, on the other hand, is primarily associated with side effects such as drowsiness, dizziness, and dry mouth.

**Why Each Wrong Option is Incorrect**
**Option A:** H2 blockers like Nizatidine are indeed used in the treatment of peptic ulcer disease, making this statement true.
**Option B:** Nizatidine has a bioavailability of approximately 65-70%, not 100%, making this statement incorrect.
**Option C:** Nizatidine is known to enhance gastric emptying, making this statement true.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that H2 blockers like Nizatidine can cause dry mouth (xerostomia) due to their anticholinergic properties. This can be a significant side effect, especially in elderly patients or those with pre-existing dry mouth conditions.

**✓ Correct Answer: D. It can also lead to tachycardia**