What's new with phentolamine mesylate: a reversal agent for local anaesthesia?

Phentolamine mesylate (OraVerse), a nonselective a-adrenergic blocking drug, is the first therapeutic agent marketed for the reversal of soft-tissue anaesthesia and the associated functional deficits resulting from an intraoral submucosal injection of a local anaesthetic containing a vasoconstrictor. In clinical trials, phentolamine injected in doses of 0.2 to 0.8 mg (0.5 to 2 cartridges), as determined by patient age and volume of local anaesthetic administered, significantly hastened the return of normal soft-tissue sensation in adults and children 6 years of age and older. Median lip recovery times were reduced by 75 to 85 minutes. Functional deficits, such as drooling and difficulty in drinking, smiling, or talking--and subjects' perception of altered function or appearance--were consistently resolved by the time sensation to touch had returned to normal. Adverse effects of phentolamine injected in approved doses for reversal of local anaesthesia in patients ranging in age from 4 to 92 years were similar in incidence to those of sham injections, and no serious adverse events caused by such use were reported. The clinical use of phentolamine is viewed favorably by dentists who have administered the drug and by patients who have received it. Optimal use may require some modifications of the technique described in the package insert; cost of the agent may be influencing its widespread adoption into clinical practice. Phentolamine mesylate, in the form of OraVerse (Novalar Pharmaceuticals, San Diego, USA) represents a new therapeutic class of drugs in dentistry intended to reverse soft-tissue anaesthesia after nonsurgical dental procedures (e.g., restorative or deep scaling/root planing procedures). As shown in Figure 1, OraVerse is manufactured in 1.7 mL dental cartridges, each of which contains 0.4 mg active drug. This review describes the development of phentolamine as a dental drug, its pharmacologic characteristics, and how it may be used in clinical practice to improve patient care.