Nasal Spray Shows Promise for Dental Anesthesia

Laird Harrison

June 24, 2013

An experimental nasal spray can provide maxillary dental anesthesia equivalent to a lidocaine injection, new studies show.

The phase 2 trial of the spray in 45 adults was published online May 20 and in a July clinical supplement to the Journal of Dental Research.

While that study was awaiting publication, investigators also completed equally successful phase 3 trials, and the drug is likely to receive US Food and Drug Administration approval and be released next year, said first author Sebastian Ciancio, DDS, chair of periodontics and endodontics at the University at Buffalo in New York.

"It could change the whole way people get their dental work done," Dr. Ciancio told Medscape Medical News.

The drug is being developed by St. Renatus of Fort Collins Colorado, which calls it Kovacaine Mist.

This approach to anesthesia could appeal to people who avoid dental treatments because they fear needles, he said.

The spray is based on formulas used by otolaryngologists. It combines tetracaine with oxymetazoline hydrochloride, a decongestant with astringent properties to reduce nasal swelling and lower the risk for bleeding.

For the phase 2 trial, Dr. Ciancio and colleagues recruited 45 healthy adults who needed restoration of 1 maxillary tooth. They randomly assigned 30 of these patients to receive both the nasal spray anesthetic and a sham injection. The other 15 received a placebo nasal spray of buffered saline solution and a lidocaine injection.

The nasal anesthetic consisted of 3 doses of 3% tetracaine and 0.05% oxymetazoline hydrochloride, 4 minutes apart, in both nostrils.

The injection consisted of an infiltration of 2% lidocaine hydrochloride and 1:100,000 epinephrine in a 1.8-mL cartridge given submucosally over the course of 60 seconds approximately at the apex of the tooth to be treated. The sham injection consisted of a dental syringe and a lidocaine cartridge with the cap left on the needle tip.

Investigators assessed anesthesia by applying pressure up to 20 g/cm2 with a probe in 4 sites:

  • distal to the apex of the tooth in the position of the maxillary first premolar at the deepest point in the buccal vestibule,

  • apical to the maxillary lateral incisor at the deepest point in the labial vestibule,

  • incisive papilla of the hard palate, and

  • at the junction of the alveolar process and hard palate medial to the maxillary second premolar.

For each site, the investigators asked the patients whether they felt any pain. They continued testing each site until the patient reported pain at that site when probed.

They used the Heft-Parker visual analog scale to assess pain immediately before and at 15, 20, and 60 minutes after the initial treatments, as well as at the end of the procedure. On this scale, 0 was no pain, 170 mm was maximum pain, and 85 mm was moderate pain.

Of the 30 patients in the tetracaine group, 5 (16.7%) required rescue anesthesia compared with 1 of the 15 patients receiving lidocaine (6.7%).

Rescue anesthesia consisted of 4% articaine hydrochloride with 1:100,000 epinephrine. It failed in 1 of the 5 patients.

All the remaining patients in both groups reported less-than-moderate pain.

Anesthesia lasted longer with lidocaine at sites 1 and 2, and longer with nasal spray at sites 3 and 4, with the difference in duration for site 2 being statistically significant (P = .030).

The investigators did not find a significant maximum change from baseline in heart rate, pulse oximetry, and systolic blood pressure between the 2 treatments, but they noted that the maximum mean diastolic blood pressure change from baseline was 3.43 mm Hg in the nasal spray group vs −5.07 mm Hg in the lidocaine group (P = .010).

One patient in the nasal spray group, later diagnosed with Hashimoto's disease, had moder¬ate eye tearing and moderate headache, which the investigators considered to be probably related to the nasal drug.

That patient also had moderate hypertension that was considered definitely related to the study drug. She recovered from all of these events.

In the nasal spray group, 6 had nasal stuffiness, 4 had runny noses, and 1 had sneezing and numbness on the roof of the mouth. All recovered without treat¬ment.

None of the patients had severe adverse events or discontinued the study because of an adverse event, and none complained of an altered sense of smell.

The drug is not indicated for second and third molars, said Dr. Ciancio. He declined to comment on plans for researching these indications.

So far, he does not see any disadvantages to the nasal anesthetic when compared with an infiltration, he said. "Even if it bothers you to have something sprayed in your nose, I think it would bother you less than having an injection."

However, Alfred Reader, DDS, professor and program director of endodontics, Ohio State University, Columbus, told Medscape Medical News that "a lot of work needs to be done" before the drug is released on the market.

For example, he would like to see published trials with larger groups of patients and the anesthetic properties of the drug subjected to an electric pulp test.

Dr. Reader, who was not involved in this study, pointed out that nasal drug only works for maxillary procedures, which might reduce its usefulness in attracting new patients. He also wondered whether dentists will be receptive to a new way of administering anesthetic. So far, the CompuDent system (Milestone), marketed since 1997 as providing painless injections, has not gained widespread use, he said.

Dr. Ciancio and Dr. Reader have disclosed no relevant financial relationships.

J Dent Res. 2013;92:S43-S48. Abstract

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