Assessment of Ropivacaine as a Local Anesthetic for Skin Infiltration in Skin Surgery

BACKGROUND: There has been limited examination of the use of ropivacaine, a relatively new amide local anesthetic, for skin surgery following local infiltration. Initial studies of ropivacaine show it to have a rapid onset and long duration of action. OBJECTIVE: To establish the injection characteristics of different concentrations of ropivacaine and to compare the pain of infiltration of ropivacaine with lidocaine 2% + epinephrine 1:80,000. METHOD: A double-blind placebo-controlled study was carried out on 18 healthy volunteers. Four concentrations of ropivacaine (1, 2, 5, and 7.5 mg/ml) were injected intradermally. Normal saline was used as the control. Sensation for pinprick was used to assess the onset and duration of anaesthesia. Pain of infiltration of ropivacaine and saline was additionally compared with lidocaine 2% + epinephrine 1:80,000. RESULTS: Pain of ropivacaine infiltation increased with increasing strength, but only 5 mg/ml was significantly more painful than the control P =.002). Lidocaine and epinephrine infiltration was significantly more painful than the control P =.0002) and 7.5 mg/ml ropivacaine (P =.0005). Mean times to reach full anesthesia were 74 seconds for 5 mg/ml and 51 seconds for 7.5 mg/ml. Mean times to regain full sensation were estimated as 692 minutes for 5 mg/ml and 773 minutes for 7.5 mg/ml. A vasoconstrictor effect was noted in the ropivacaine sites. CONCLUSION: Ropivacaine has a rapid onset and long duration of action. Ropivacaine produces vasoconstriction which may be clinically relevant. Even at maximum strength ropivacaine is less painful to inject than lidocaine with epinephrine.