amide amylocaine articaine benzocaine benzoic acid bupivacaine butacaine cas registry number carticaine chemical formula chemistry chloroprocaine cinchocaine cocaine dimethocaine ester etidocaine hexylcaine iontocaine levobupivacaine lidocaine local anesthetic mepivacaine meprylcaine molar mass orthocaine piperocaine prilocaine procaine propoxycaine proxymetacaine pubchem risocaine ropivacaine simplified molecular input line entry specification sodium channel blocker tetracaine trimecaine