New Patents on Topical Anesthetics
Antonio G. Richetta,
Anesthesia is defined as a total or partial loss of sensation and it may be general, local or topical, depending on
the method of drug administration and area of the body affected. General anesthesia is a reversible state of unconsciousness
produced by anesthetic agents, characterized by amnesia, muscle relaxation and loss of sensitivity to pain of the
whole body. General anesthetic drugs can be classified into two main groups according to their predominant molecular
pharmacological effects: volatile and intravenous agents. Local anesthesia produce a reversible loss of sensation in a portion
of the body and it reversibly block impulse conduction along nerve axons and other excitable membrane. All local
anesthetics (LA) are membrane stabilizing drugs; they reversibly decrease the rate of depolarization and repolarization of
excitable membranes. They act mainly by inhibiting sodium influx through sodium-specific ion channels in the neuronal
cell membrane, in particular the voltage-gated sodium channels. When the influx of sodium is interrupted, an action potential
cannot arise and signal conduction is inhibited. The main local anesthetic (LA) agents for skin anesthesia are benzocaine
(aminoester), prilocaine and lidocaine (aminoamides) which are commercially available as gels, ointments and
creams (benzocaine and eutectic mixture of lidocaine and prilocaine) or as a bioadhesive (lidocaine) with different compositions
(vehicles and excipients) for adults or pediatric use. Topical anesthetics decrease anxiety, pain and discomfort
during cutaneous procedures and provide effective analgesia with rapid onset, prolonged duration and minimal side effects.
This article outlines the different classes of topical anesthetics available and gives an overview of the mechanism of
action, metabolism of each different class, of the possible complications that can occur because of their use and their possible
treatment options and new patents.
Keywords: Analgesia, dermatologic procedures, muscle relaxation, new patents, pain, topical anesthetics.
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