Benadryl as Local anesthesia agent...Interesting

Diphenhydramine as an Alternative Local Anesthetic Agent

 Peter G. Pavlidakey, MD, Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio; Erin E. Brodell, University of Richmond; Associate Professor of Internal Medicine, Northeastern Ohio Universities School of Medicine, Rootstown, Ohio; Stephen E. Helms, MD, Assistant Professor of Dermatology, Case Western Reserve University School of Medicine, Cleveland, Ohio

(J Clin Aesthetic Dermatol. 2009;2(10):37–40.)

Abstract
Patients who present with a history of “allergy” to local anesthetics are common in clinical practice. Injectable 1% diphenhydramine is a safe, inexpensive, and effective local anesthetic for simple dermatological procedures in patients who report “caine” allergies. Utilizing this agent permits the dermatologist to operate at the time of the initial visit and schedule a referral to the allergist for definitive sensitivity testing at the patient’s convenience.

Diphenhydramine hydrochloride (DPH) has numerous pharmacological uses in medicine. It is a first-generation, sedating, oral antihistamine. When topically applied, DPH has excellent anesthetic and antipruritic effects. DPH has also been shown to be an effective injectable drug for local anesthesia. This may be due to its three-dimensional structure, which is similar to other anesthetic drugs. The authors present a patient whose history of a severe “allergic” reaction to a “caine” local anesthetic prompted the use of 1% DPH to allow same-day surgery and avoid any possibility of a potentially life-threatening reaction.

DPH 1% solution  has been utilized since 1939 in the realm of dental anesthesia, surgery, and in the emergency room in patients who are allergic to local anesthetics. DPH is an ideal choice since it provides adequate anesthesia and has no allergic cross reactivity to “caine” anesthetics. A local injection of 1% DPH provides adequate anesthesia for 80 percent of people within five minutes. The duration of anesthesia is between 15 minutes and three hours, which is adequate for most common dermatological procedures.DPH is also inexpensive. The average wholesale cost (AWP) of 5% DPH is about 24 cents/cc. By comparison, injectable lidocaine costs 15 cents/cc. To prepare a 1% solution of DPH (10mg/cc), 10cc of normal saline is removed from a 50cc vial and discarded. Ten cc’s of 5% DPH are then injected into the remaining saline.