New local anesthetics Anesthesiology Clinics of North America Moeen Panni, MD, PhD, Scott Segal, MD  Anesthesiology Clinics of North America  Volume 21, Issue 1, Pages 19-38 (March 2003) DOI: 10.1016/S0889-8537(02)00032-9

Fig. 1 Chemical structures of ropivacaine and the two isomers of bupivacaine. Anesthesiology Clinics of North America 2003 21, 19-38DOI: (10.1016/S0889-8537(02)00032-9)

Fig. 2 Hypothetical concentration-response curves for bupivacaine and ropivacaine. (A) Parallel concentration-response curves. The difference in MLAC (EC50) is reflected throughout the concentration range, and ropivacaine is less potent. Administration of concentrations significantly higher than the MLAC, however, will produce indistinguishable results because both drugs will be being administered near the top of their respective concentration-response curves. (B) Concentration-response curves with different slopes. The difference in MLAC would not necessarily reflect a true difference in potency between the drugs. Anesthesiology Clinics of North America 2003 21, 19-38DOI: (10.1016/S0889-8537(02)00032-9)