Cyclosporine is known to inhibit cytochrome P450 isoenzyme 3A4. Which of the following medications could have elevated serum concentrations due to inhibition of metabolism by concurrent cyclosporine?

Atorvastatin is the correct answer because its metabolism is primarily mediated by CYP3A4. This means that concurrent administration of cyclosporine, which inhibits CYP3A4, can lead to increased serum concentrations of atorvastatin. The other options listed (amoxicillin, metoprolol, and levothyroxine) are not primarily metabolized by CYP3A4, so their serum concentrations should not be significantly affected by concurrent cyclosporine administration.