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Title Benzyl Alcohol more Effective Alternative Anesthetic Compared with Diphenhydramine Hydrochloride
Clinical Question Does the use of Diphenhydramine Hydrochloride (Benadryl) in a patient allergic to Amide anesthetics display clinically superior efficiency when compared to Benzyl Alcohol during a dental procedure?
Clinical Bottom Line Although the efficacy of Benzyl Alcohol as an anesthetic compared to Diphenhydramine is not significantly different, the pain produced by infiltration of Diphenhydramine is a major factor that renders it less desirable than Benzyl Alcohol as a substitute anesthetic in a dental procedure. (See Comments on the CAT below)
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 9832659Bartfield/1998 30 Adult PatientsRandomized Controlled Clinical Trial
Key resultsThirty subjects were enrolled. The median pain score upon infiltration of diphenhydramine was 55 mm, compared with 12.5 mm for lidocaine and 5 mm for benzyl alcohol (P =.001). Pairwise comparisons showed that all possible combinations were statistically significant. The 3 anesthetics were different with respect to duration of anesthesia (P <.001). Pairwise comparisons revealed a longer duration of anesthesia for lidocaine than for diphenhydramine or benzyl alcohol, but no significant difference was found between diphenhydramine and benzyl alcohol. Pain sensation returned within the 45-minute study period in only 3 of 30 lidocaine injections, compared with 11 of 30 benzyl alcohol injections and 19 of 30 diphenhydramine injections (P =.001). CONCLUSION: Benzyl alcohol is a better alternative than diphenhydramine as a local anesthetic for lidocaine-allergic patients.
#2) 11728763Bartfield/2001 52 subjects with simple lacerations. Randomized Controlled Clinical Trial
Key resultsThe median infiltration pain score for Benzyl Alcohol, 7.5 mm, was less than for lidocaine, 19.5 mm (p = 0.049). Although more patients receiving Benzyl Alcohol required additional anesthesia as compared to lidocaine (8/26 versus 2/26), this difference did not reach statistical significance. Benzyl Alcohol is a reasonable alternative local anesthetic to lidocaine for patients who are allergic to lidocaine.
#3) 10216324Wilson/1999 30 healthy adultsRandomized Controlled Trial
Key resultsBenzyl alcohol was 48% less painful on injection into skin than placebo (P <.008) and 42% less painful on injection than lidocaine with epinephrine (P <.05). Lidocaine with epinephrine and placebo were equally painful on injection. After the 5-minute measurement, benzyl alcohol provided significantly better anesthesia than placebo during the remaining observation period (VAS score 48%, 49%, and 51% decreased from baseline at 15, 30, and 45 minutes, respectively, all P <.02 versus placebo). However, benzyl alcohol provided less effective anesthesia than lidocaine with epinephrine (VAS score 72%, 76%, 84%, and 88% decreased from baseline at 5, 15, 30, and 45 minutes, respectively, all P <.001 versus placebo) throughout most of the observation period. CONCLUSION: Benzyl alcohol with epinephrine provides prolonged cutaneous anesthesia, although it is not as effective as lidocaine with epinephrine. However, benzyl alcohol is significantly less painful on injection than lidocaine with epinephrine, and it may offer an alternative for local anesthesia.
#4) 8198309Ernst/1994 Ninety-eight adults with linear skin lacerations without end-organ involvement were included; 48 received lidocaine and 50 received diphenhydramine.Randomized Controlled Clinical Trial
Key resultsPatient and physician ratings were ranked without regard to treatment group, and rank sum scores were calculated for each group. General linear models and multivariate analysis of variance were used to analyze the ranked sum scores. The power of the study to detect a ranked sum difference of 15 was 0.8 with P < .05 considered statistically significant. Lidocaine was found to be significantly more effective as a local anesthetic for facial lacerations according to both patients (P < .002) and physicians (P < .004). There was no statistically significant difference between 1% lidocaine and 0.5% diphenhydramine for pain of injection or suturing for all other locations according to both patients and physicians. Overall mean and median scores for injection and suturing with diphenhydramine corresponded to the mild pain category according to patients. CONCLUSION: Although not a replacement for lidocaine, diphenhydramine is a viable alternative for anesthesia in the repair of minor lacerations.
#5) 8363115Dire/1993 Ten healthy male volunteers, aged 26 to 38 years old.Randomized Controlled Trial
Key resultsNo 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. CONCLUSION: 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.
Evidence Search "Lidocaine"[Mesh] AND ("Benzyl Alcohol"[Mesh] OR "Diphenhydramine"[Mesh]) ...view in PubMed
Comments on
The Evidence
The studies done are ideal for the comparison in question, the next step in research would be to further the studies of each of the anesthetics to one another by doing more direct trials.
Applicability The evidence for comparisons of Benzyl Alcohol and Diphenhydramine to lidocane is well documented, however, evidence of these two being compared is limited. Yet, the gathered information leads to the conclusion that is needed for this clinical scenario. In a scenario where the dental patient is allergic to Amide anesthetics (e.g., lidocaine) the clinician has to approach the treatment in the most efficient/patient friendly manner. Benzyl Alcohol is the ideal substitute because it will render less infiltration discomfort to the patient and provide the anesthesia necessary for the procedure. The only factor to consider is that Benzyl Alcohol will be needed in greater quantities than the average anesthetic dose since its potency is not as strong; yet this characteristic is also shared by the other less desirable substitute Diphenhydramine.
Specialty/Discipline (Endodontics) (General Dentistry) (Oral Surgery) (Pediatric Dentistry) (Periodontics) (Prosthodontics) (Restorative Dentistry)
ID# 600
Date of submission: 05/03/2010spacer Revised: 04/16/2012
E-mail orjuela@livemail.uthscsa.edu
Author Wilmer Paul Orjuela
Co-author(s) e-mail
Faculty mentor/Co-author Gregory Spackman, DDS, MBA
Faculty mentor/Co-author e-mail SPACKMAN@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
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Comments on the CAT
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by Phillip Garrett, Ryan Angwin, Ashley Hutto (San Antonio, TX) on 01/07/2013
A PubMed search in January 2013 found similar evidence, however no new relevant research was found. As stated in the CAT, no further studies comparing specific anesthetics to each other have been published.

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