The strongest topical anesthetic is not necessarily the one with the highest concentration of the active pharmaceuticals ingredients (API’s). The reason why this is the case is because, factually, the API’s need to penetrate the skin. Many compounded anesthetics are marketed to medical spas, dermatologists and plastic surgery centers as the strongest topical anesthetic because they are highly concentrated, such as the commonly known BLT mixtures which can be as high as 20%, 10%, 10% respectively, benzocaine, lidocaine, tetracaine. When inspecting these “strongest topical anesthetic” creams and gels, the user will typically find gritty material in the cream. The grit is insoluble API’s that are not only too large to get into the skin, but also may cause adverse events when the grit gets into the eyes for example. There was actually a serious adverse event when grit from one of these strongest topical anesthetic products entered the patients eye, under the eye shield, and caused corneal damage.
In terms of actual numbing effect, the strongest topical anesthetic will include skin penetrating agents, also known as drivers, which help the API’s enter the skin where they can perform their action. The action of the API, is naturally to block the neuronal transmissions of pain signals. The API’s in the strongest topical anesthetic creams, or any topical anesthetics for that matter, enter the high voltage sodium ion channel and block sodium from entering. Sodium is the catalyst to pain signals being transmitted due to the depolarizing effect to the nerve. The strongest topical anesthetic will have a method of delivering the API in concentration enough to emit its effect. Any additional API will not improve the effect any more than the amount necessary to exert it. In fact, any additional API may only serve to increase the risk of adverse events from cumulative absorption in the system.
Adequately concentrated topical anesthetics with appropriate drivers can serve the purpose of adequate numbing while limiting the risk of adverse events. Some of the known safe and effective drivers are:
These drivers assist in the delivery of the small molecule API’s (benzocaine, lidocaine, tetracaine and prilocaine) of even the strongest topical anesthetic into the skin.