Friday, January 31, 2014
VERY USEFUL INFORMATION
Anyone planning a trip to the dentist, foot doctor or anything else? Here is a list of acceptable anesthetics for sulfite sensitive people. We can only use Amide type. (I believe when I had a recent trip to the dentist they used Mepivacaine to numb me)
ALLERGIC REACTIONS TO LOCAL ANESTHETICS
Hypersensitivity reactions to local anesthetics are quite rare and generally account for less than 1% of all reported adverse drug reactions. In truth, most allergic reactions to local anesthetics are attributed to other factors such as the pharmacologic properties of anesthetics, acute toxicity, psychomotor reactions, or the presence of preservatives.
Local anesthetics are generally classified into 2 categories based upon the intermediate chain linkage component of their structure – esters or amides (Table 1).
Table 1. Classification of local anesthetics.
|Ester-type anesthetics||Amide-type anesthetics|
Ester type anesthetics are metabolized via a degradation process to a para-aminobenzoic acid (PABA) metabolite. PABA is highly antigenic and is the most likely source of allergic reactions with regards to local anesthetics. Patients with allergies to PABA may show cross-reactivity among ester and amide type anesthetics that contain methylparaben, a preservative agent found in local anesthetic solutions. Methylparaben is metabolized to PABA. Other substances contained within local anesthetic solutions such as sodium bisulfite and metabisulfite may contribute to the development of allergic reactions as well. Allergic reactions to amide-type anesthetics alone are rare.
Skin testing via patch, prick, intradermal, subcutaneous, or nasal mucosal administration of local anesthetics may aid in differentiating a true immunologic reaction from an autonomic or toxic reaction. Skin testing regimens vary as to whether they assess the development of immediate or delayed-type reactions.
Patients determined to have an immunologic reaction to ester-type anesthetics via skin testing or history should be given a preservative-free amide-type anesthetic. If a patient is allergic to an amide-type anesthetic, skin testing should be performed to determine if cross-reactivity with other amide-type anesthetics is present. If cross-reactivity exists, skin testing should be performed again to verify existence of an allergy to an ester-type anesthetic. Generally, cross-reactivity and allergic reactions between the 2 anesthetic groups are unlikely due to their differing metabolic pathways.
For the rare patient who is allergic to both ester and amide-type anesthetics, or in an emergent situation with a patient who has a questionable history of local anesthetic allergy, alternative therapies such as diphenhydramine, opioids, or general anesthetics may be used.