Bupivacaine impurity D is a local anaesthetic drug that is used in medical and dental treatments. It refers to a particular impurity that can be discovered in bupivacaine. Small amounts of chemicals that are not the intended active component but are nonetheless present in a drug product are known as impurities. It is a local anaesthetic that is used in medical and dentistry treatments to numb a particular body part. Bupivacaine impurity D functions by obstructing nerve signals in the targeted location and is a member of the amide class of local anaesthetics. Unwanted compounds that could be present in a drug product are referred to as impurities when used in the context of pharmaceuticals.