Topical anesthetics remain sore spot

October 19, 2008

Las Vegas - Although topical anesthetics have long been a mainstay for dermatologists, physicians have relatively little clinical data with which to evaluate them, an expert says.

Las Vegas

- Although topical anesthetics have long been a mainstay for dermatologists, physicians have relatively little clinical data with which to evaluate them, an expert says.

Meanwhile, an occlusive mask-forming product recently removed from the market will return, he says.

Except for mucous membrane areas, topical anesthetic remains an area of opportunity in the eyes of therapeutic and cosmetic dermatologists, and those who practice both disciplines, says W. Phillip Werschler, M.D., assistant clinical professor of medicine/dermatology, University of Washington.

In discussing topical anesthetics with patients, he says, "We’ll describe them as not really being enough for anything beyond injections or minor surgical procedures. So, we’re always on the lookout for something better."

Furthermore, he says patients’ pain perception can vary substantially based on everything from time of day to psychological factors such as the perceived benefit of a treatment.

"We’ve all had the experience where someone grins and bears it for a cosmetic procedure, but is extremely sensitive for a procedure to remove a skin cancer," Dr. Werschler tells Dermatology Times.

Although patients’ pain tolerance varies widely, he says, individual patients are generally consistent in how they rate pain when using tools such as visual analogue scales.

Characteristics of the ideal topical anesthetic include safety, effectiveness, quick action, easy application and sufficient duration for the procedure at hand and postoperative pain, he says.

Key classes of topical anesthetics include esters, such as tetracaine, and amides, such as lidocaine. "We have a much better understanding of the toxicity, bioavailability and metabolism of amides than we do of esters," Dr. Werschler says.

Pliaglis (tetracaine, lidocaine; maker) represents the newest topical anesthetic. Because it's a eutectic cream, he says, "The vehicle melts at a lower temperature than the components individually. The advantage is that when one puts on the skin, there's rapid diffusion and better absorption of the product."

However, Dr. Werschler says initial enthusiasm for this product faded when dermatologists found its pasty consistency difficult to work with. Anecdotally, some physicians have added a cleanser to thin out the product.

"Pliaglis has temporarily been withdrawn from the market not because of safety reasons, but because of difficulties in manufacturing the polymer base.

"I understand from Galderma that once these difficulties are resolved, the product will return to the marketplace," he says. DT

Disclosure: Dr. Werschler has a financial relationship with Galderma