Which of the following drugs contains an ester group?

Articaine is the correct choice because it contains an ester group in its chemical structure. Unlike other local anesthetics listed, which are amide-based, articaine has both an amide and an ester component. The presence of the ester group in articaine is significant because it influences the drug's metabolism and potential for causing allergic reactions. Esters are generally hydrolyzed by plasma cholinesterase, which leads to a shorter duration of action compared to amides that typically have a longer half-life due to hepatic metabolism.

In contrast, lidocaine, mepivacaine, and prilocaine are all classified as amides. These drugs have a similar structure characterized by an amide linkage, allowing for different pharmacokinetics and potential side effects compared to ester-based local anesthetics. Amides tend to be more stable and less likely to provoke allergic reactions than esters, which is an important consideration in clinical practice.