The major advantage of amide local anesthetics over esters is lack of allergenicity. There is controversy about whether allergic reactions to amides exist. Esters have a much greater allergic potential than amides.
Lack of allergenicity
Ease of delivery
The total dosage administered of lidocaine local anesthetic is 72 mg, and the total dosage administered of epinephrine would be 0.036 mg. Each cartridge contains 1.8 ml of local anesthetic solution, with a total of 36 mg in a 2% solution. The patient received two cartridges, making the total dosage 72 mg. Each cartridge containing a 1:100,000 concentration of epinephrine has a total of 0.018 mg/cartridge, which is multiplied times the number of cartridges for a total epinephrine dosage of 0.036 mg.
48 mg lidocaine, 0.036 mg of epinephrine
60 mg lidocaine, 0.048 mg of epinephrine
36 mg lidocaine, 0.036 mg of epinephrine
72 mg lidocaine, 0.036 mg of epinephrine
18 mg lidocaine, 0.018 mg of epinephrine
Procaine is a PABA ester that is used as an antiarrhythmic agent and combined with penicillin to form procaine penicillin G. It is not used as a local anesthetic in dentistry today because of a high incidence of allergic reactions. Mepivicaine, bupivacaine, prilocaine, and lidocaine are all amide local anesthetics.
Amides are primarily metabolized in the liver, and esters are hydrolyzed to PABA by blood plasma pseudocholinesterase and liver esterases. Patients with an atypical form of pseudocholinesterase may develop a systemic toxicity, not an allergic reaction, although esters have much high incidence of allergenicity.
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Antihistamines are not a component of local anesthetics, although some antihistamines have a weak local anesthetic action. All of the other components may be added to increase the effectiveness of the local anesthetic. Vasoconstrictors may be added to decrease systemic toxicity and prolong the anesthetic action. If a vasoconstrictor is added, an antioxidant will be required prevent its breakdown. Sodium chloride is added to make the solution compatible with body fluids, or isotonic. Sodium hydroxide is added to adjust the pH of the solution to between 6 and 7.
Patients with cardiovascular disease who are able to have elective dental treatment should receive epinephrine-containing local anesthetic in the lowest possible dose of vasopressor with use of the aspiration and very slow injection technique to achieve profound, long-lasting anesthesia. Administration of no more than 0.04 mg of epinephrine (the cardiac dose) in lidocaine 2% with 1:100,000 epinephrine would be the safest choice. In the past, many practitioners were concerned that use of a local anesthetic with a vasoconstrictor could exacerbate existing cardiovascular disease; however, current research indicates that effective local anesthesia prevents production of uncontrolled endogenous epinephrine in dangerous levels.
Lidocaine 2% with 1:100,000 epinephrine
Mepivicaine 2% with 1:20,000 levonordefrin (Neo-Cobefrin)
Mepivicaine 3%, plain
Lidocaine 2% with 1:50,000 epinephrine
Mepivicaine is an amide local anesthetic, whereas procaine, propoxycaine, and tetracaine are ester local anesthetic agents.
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