The nurse is explaining the differences between uncontrolled and controlled substances.
Which of the following medications is a controlled substance?

Choice A rationale

Azithromycin can prolong the QT interval, leading to potential cardiac arrhythmias. Patients with a history of prolonged QT interval or other heart conditions should be monitored closely.

Choice B rationale

Constipation is not commonly associated with azithromycin use. Gastrointestinal side effects may include diarrhea or nausea but not constipation.

Choice C rationale

While tachycardia can be a side effect of some medications, azithromycin is more commonly associated with QT prolongation rather than causing increased heart rate directly.

Choice D rationale

Hyperkalemia is not typically a concern with azithromycin. Electrolyte imbalances are not a common side effect of this antibiotic.

Choice A rationale

Metastasis is when cancerous cells spread into or invade nearby tissues and can travel to distant places in the body to form new tumors. This process involves the detachment of cancer cells from the primary tumor, their movement through the bloodstream or lymphatic system, and the establishment of new tumors in other parts of the body.

Choice B rationale

Metastasis specifically involves cancerous cells, not normal cells. Normal cells do not spread and invade other tissues in a way that causes new tumor formation.

Choice C rationale

Metastasis refers to the spread of cancerous cells, not normal cells. Normal cells do not exhibit the same invasive and migratory behaviors as cancerous cells.

Choice D rationale

Metastasis involves the spread of cancerous cells, which can lead to the formation of malignant tumors in distant parts of the body. It does not treat tumors but rather contributes to the progression of cancer.