Double-blinded comparison of diphenhydramine versus lidocaine as a local anesthetic.
OBJECTIVE
To evaluate the efficacy, onset of action, duration of action, and side effects of 1% diphenhydramine compared with 1% lidocaine when used as a local anesthetic agent.


METHODS
Prospective, double-blinded, cross-over study.


METHODS
Emergency medicine residency program, research section.


METHODS
Ten healthy male volunteers, aged 26 to 38 years old.


METHODS
Baseline levels of sensation to pinprick (18-gauge needle) within a 2.4-cm-diameter midvolar forearm area and levels of sedation were recorded on 10.2-cm visual analog scales. Subjects then underwent subcutaneous infiltration of 20 mg (2 mL) of the study agent using a 27-gauge needle. Visual analog scale sensation and sedation scores were recorded at five, ten, and 15 minutes and then every 15 minutes until return to baseline. Subjects were studied one week later with the alternate agent. Nonparametric data were analyzed using the Mann-Whitney U test with significance at P < .05.


RESULTS
No significant differences in mean pinprick sensation were seen from baseline to 30 minutes. Significant differences were seen at 45 (P = .036) and 60 minutes (P = .036). The mean duration of effective anesthesia was significantly longer for lidocaine than diphenhydramine (81 versus 42 minutes, P = .028). No significant differences were seen in the sedation scores or in the frequencies of local reactions. One subject developed skin necrosis at the injection site with diphenhydramine.


CONCLUSIONS
The duration of local anesthesia for 1% lidocaine was significantly longer and the depth of anesthesia after 30 minutes was significantly higher than that of 1% diphenhydramine. Diphenhydramine resulted in skin necrosis in one test subject.
Dire
D J
DJ
Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City.
Hogan
D E
DE
D000328:Adult; D000779:Anesthetics, Local; D004155:Diphenhydramine; D004311:Double-Blind Method; D004342:Drug Hypersensitivity / Q000209:etiology; D006801:Humans; D007279:Injections, Subcutaneous; D008012:Lidocaine; D008297:Male; D009336:Necrosis; D010146:Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000517:prevention & control; D010147:Pain Measurement; D011446:Prospective Studies; D012871:Skin Diseases / Q000139:chemically induced; D013997:Time Factors
D000779:Anesthetics, Local; D004155:Diphenhydramine; D008012:Lidocaine