الفهرس 
Spot light on the pharmacology of local anestheticsOnly 14 pages are availabe for public view
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Abstract
Dermatology is a medical and surgical specialty with a distinguished history in the development and advancement of diagnostic, therapeutic, and cosmetic procedures, many of these procedures frequently involve injections or surgery, and can cause pain and discomfort.
Knowledge of local anesthesia is critically important to perform dermatologic surgery. Over the last decade several important advances in the delivery of local anesthesia have greatly facilitated the dermatologist’s ability to perform increasingly complex surgeries.
There are two groups of local anesthetics: ester group e.g. (Cocaine, Procaine) have an ester linkage and is metabolized by pseudo-cholinesterase enzyme in the plasma, whereas the amide group, e.g. (Lidocaine, Prolicaine) with an amide linkage, is metabolized in the liver. Ester group is less frequently used because of a higher incidence of allergy.
The choice of a local anesthetic at a particular concentration should be dictated by the type of procedure contemplated. For a simple procedure such as skin biopsy, the agent used should have a rapid onset of action, whereas for a more complex procedure an anesthetic with a longer duration is preferred. For most procedures categorized in dermatologic surgery, 1% lidocaine with epinephrine is as excellent choice.
Local anesthetics are extremely safe drugs if used properly without exceeding the recommended dose. Adverse effects are divided into: local reactions such as pain, ecchymosis, infection and nerve damage and systemic reactions which are divided into two groups, those that occur at low blood levels (allergic and psychogenic) and those that occur at higher blood levels (Central nervous system and cardiovascular reactions).
There are several methods of inducing local anesthesia in dermatology e.g. topical anesthesia, infiltrative anesthesia, field block, peripheral nerve block and tumescent anesthesia.
Topical anesthesia is considered one of the most recent advances for dermatologic surgery. It is now used for simple procedures such as: shave biopsies, electrocautery of epidermal growth, superficial laser surgery and to provide anesthesia for painless needle insertion.
Infiltrative anesthesia is the most commonly used method of anesthetizing the skin. The local anesthetic is placed directly at the nerve ending either intradermal or subcutaneous.
A field block represents a variant of infiltrative anesthesia in which the local anesthetic is placed around the operative site anesthetizing nerve fibers leaving from the area. The area of anesthesia should extend beyond the outer limits of the proposed surgery.
Peripheral nerve block describes the technique of local anesthetic administration that inhibits nerve conduction at the nerve trunk rather than at the nerve endings. Peripheral nerve blocks commonly used in dermatologic practice include supraorbital/supratrochlear blocks (forehead and vertex of the scalp), infraorbital blocks (ala of the nose, medial check, lower eyelids, and upper lip), mental blocks (chin, lower cheek, and lips), median, radial and ulnar blocks (hand block), digital blocks and ankle blocks.
Tumescent local anesthesia is a type of infiltrative anesthesia in which a very dilute concentration of local anesthetic solution is directly injected into the operative site. It is used successfully in liposuction, hair transplantation and dermabrasion.
Local anesthesia is an integral aspect in many dermatological procedures. Its effects provide a reversible loss of sensation in a limited area of skin, allowing dermatologists to perform diagnostic and therapeutic procedures safely, with minimal discomfort and risk to the patient.