Nov/Dec 2008
Volume 4, Issue 10

Reversal of soft-tissue local anesthesia with phentolamine mesylate in adolescents and adults

Hersh EV, Moore PA, Papas AS, et al. J Amer Dent Assoc. 2008;139(8):1080-1093

Abstract

Background. The authors conducted two multicenter, randomized, double-blinded,controlled Phase III clinical trials to study the efficacy and safety of phentolamine mesylate (PM) in shortening the duration and burden of soft-tissue anesthesia. The study involved 484 subjects who received one of four commercially available local anesthetic solutions containing vasoconstrictors for restorative or scaling procedures.

Methods. On completion of the dental procedure, subjects randomly received a PM or a sham injection (an injection in which a needle does not penetrate the soft tissue) in the same site as the local anesthetic injection in a 1:1 cartridge ratio after the procedure was completed. The investigators measured the duration of soft-tissue anesthesia by using a standardized lip- and tongue-tapping procedure every five minutes for five hours. They also evaluated functional measures and subject-perceived altered function, sensation, appearance, and safety.

Results. Median recovery times in the lower lip and tongue for subjectsin the PM group were 70 minutes and 60 minutes, respectively. Median recovery times in the lower lip and tongue for subjects in the sham group were 155 minutes and 125 minutes, respectively. Upper lip median recovery times were 50 minutes for subjects in the PM group and 133 minutes for subjects in the sham group. These differences were significant (P < .0001). Recovery from actual functional deficits and subject-perceived altered function, sensation, and appearance showed significant differences between the PM and the sham groups.

Conclusions. PM was efficacious and safe in reducing the duration of local anesthetic-induced soft tissue anesthesia and the associated functional deficits.

Clinical Implications. Clinicians can use PM to accelerate reversal of soft-tissue anesthesia and the associated functional deficits.

Commentary

What if? What if you could inject a drug to reduce recovery time to half in a site that has been anesthetized for a dental procedure that in most cases will not have postoperative discomfort when the anesthetic wears off? Would you use this drug? Ask your patients if they did not have to be numb for hours and hours, but could have less than half the time of numbness, would they accept this supplemental treatment? I did just that when I was introduced to the injectable drug phentolamine mesylate (PM) (OraVerse [Novalar Pharmaceuticals, San Diego, CA]). PM is indicated for the reversal of soft tissue anesthesia (ie, anesthesia of the lip and tongue) and the associated functional deficits resulting from an intraoral submucosal injection of a local anesthetic containing a vasoconstrictor. The proposed mechanism of action of PM is the blockage of the vasoconstriction associated with epinephrine used in dental anesthetics.1

So what do patients think? I asked patients and friends, if I could use a drug to reverse dental anesthesia sooner, even if it cost extra, they would want me to use it? The answer was an overwhelming “Yes.”

These three very well-designed and executed clinical studies investigated the use of PM in children, adolescents, and adults. For mandibular blocks, soft tissue anesthesia typically lasts 3 to 5 hours, which is longer than what is required for routine restorative and periodontal cleaning procedures. Prolonged soft tissue anesthesia for children has been shown to cause soft tissue trauma, cheek, tongue, and lip biting. In a study evaluating soft tissue trauma, it was shown that 16% of 4- to 7-year-olds and 13% of 8- to 11-year-olds had trauma.2 The clinical study with 152 children demonstrated a significant reduction in recovery time of more than half: 60 minutes with PM and 135 minutes with a sham injection. Accelerated recovery from the effects of block anesthesia using PM can reduce posttreatment lip and tongue injuries. PM is recommended for use with children over the age of 6 or weighing 33 lbs or more. The dosage recommendations are listed on the drug information sheet. For children, the benefits of PM are significant to the clinician and parent.

For the adolescent and adult patient, the reversal of soft tissue anesthesia for routine restorative and periodontal cleaning procedures is perceived by our patients as a quality-of-life issue. The side effects of local anesthesia that our patients dislike include difficulty speaking, difficulty eating and drinking, drooling, and inadvertent biting of the tongue, cheeks, and lips. Patients also have altered appearance—or the perception of altered appearance—resulting from the local anesthetic agent. PM is very effective for adolescents and adults. Again, the mean recovery time from the effects of local anesthesia for a mandibular block and for a maxillary infiltration was more than halved. The accelerated reversal of this FDA-approved drug will be welcomed by your patients. Finally there is a safe and effective local anesthetic reversal agent for improved patient management and patient satisfaction.

References

1. Moore PA, Hersh EV, Papas AS, et al. Pharmacokinetics of lidocaine with epinephrine following local anesthesia reversal with phentolamine mesylate. Anesth Prog. 2008; 55(2):40-48.

2. College C, Feigal R, Wandera A, Strange M. Bilateral versus unilateral mandibular block anesthesia in a pediatric population. PediatrDent. 2000;22(6):453-457.

About the Author

Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics, Prosthodontics and Operative Dentistry
University of Maryland Dental School
Baltimore, Maryland

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