Final answer:
Cimetidine is the H2-receptor antagonist that should be avoided due to its potential to cause significant drug-drug interactions and side effects, which might include inhibiting liver enzymes and causing adverse effects like gynecomastia and impotence.
Step-by-step explanation:
Of the Hâ‚‚-receptor antagonists (H2RAs) listed, cimetidine should be avoided due to drug-drug interactions (DDIs) and side effects (SEs). Cimetidine has the potential for the most significant interactions because it can inhibit the activity of liver enzymes that metabolize many other medications, leading to increased levels of these drugs in the body and the potential for toxicity.
Compared to other H2RAs like ranitidine, famotidine, and nizatidine, cimetidine has a higher likelihood of causing side effects such as gynecomastia and impotence. H2RAs like ranitidine, famotidine, and nizatidine work by decreasing the amount of acid made in the stomach and are used to treat conditions such as ulcers; gastroesophageal reflux disease (GERD); and conditions where the stomach produces too much acid, like Zollinger-Ellison syndrome. However, for minimizing DDIs and SEs, famotidine or nizatidine may be preferred.