CARBOCAINE- mepivacaine hydrochloride injection, solution
THESE SOLUTIONS ARE INTENDED FOR DENTAL USE ONLY.
CARBOCAINE (mepivacaine hydrochloride), a tertiary amine used as a local anesthetic, is 1-methyl-2′, 6′ — pipecoloxylidide monohydrochloride with the following structural formula:
|C15 H22 N2 0.HCl M.W. 282.81|
It is a white, crystalline, odorless powder soluble in water, but very resistant to both acid and alkaline hydrolysis.
NEO-COBEFRIN, a sympathomimetic amine used as a vasoconstrictor in local anesthetic solution, is (-)--(1-Aminoethyl)-3, 4-dihydroxybenzyl alcohol with the following structural formula:
|C9 H13 NO3 M.W. 183.21|
It is a white or buff-colored crystalline solid, freely soluble in aqueous solutions of mineral acids, but practically insoluble in water.
DENTAL CARTRIDGES MAY NOT BE AUTOCLAVED.
CARBOCAINE 3% (30 mg/mL) injection and CARBOCAINE 2% (20 mg/mL) with NEO-COBEFRIN 1:20,000 injection are sterile solutions for injection.
|Each mL contains:||2%||3%|
|Mepivacaine hydrochloride||20 mg||30 mg|
|Sodium chloride||4 mg||6 mg|
|Potassium metabisulfite||1.2 mg||–|
|Sodium hydroxide q.s. ad pH|
|Hydrochloric acid||0.5 mg||–|
|Water for injections qs. ad.||1 mL||1 mL|
|The pH of the 2% cartridge solution is adjusted between 3.3 and 5.5 with NaOH.|
|The pH of the 3% cartridge solution is adjusted between 4.5 and 6.8 with NaOH.|
CARBOCAINE stabilizes the neuronal membrane and prevents the initiation and transmission of nerve impulses, thereby effecting local anesthesia.
CARBOCAINE is rapidly metabolized, with only a small percentage of the anesthetic (5 to 10 percent) being excreted unchanged in the urine. CARBOCAINE because of its amide structure, is not detoxified by the circulating plasma esterases. The liver is the principal site of metabolism, with over 50 percent of the administered dose being excreted into the bile as metabolites. Most of the metabolized mepivacaine is probably resorbed in the intestine and then excreted into the urine since only a small percentage is found in the feces. The principal route of excretion is via the kidney. Most of the anesthetic and its metabolites are eliminated within 30 hours. It has been shown that hydroxylation and N-demethylation, which are detoxification reactions, play important roles in the metabolism of the anesthetic. Three metabolites of mepivacaine have been identified from adult humans: two phenols, which are excreted almost exclusively as their glucuronide conjugates, and the N-demethylated compound (2′, 6′ — pipecoloxylidide).
The onset of action is rapid (30 to 120 seconds in the upper jaw; 1 to 4 minutes in the lower jaw) and CARBOCAINE 3% (30 mg/mL) injection will ordinarily provide operating anesthesia of 20 minutes in the upper jaw and 40 minutes in the lower jaw.
CARBOCAINE 2% (20 mg/mL) with Neo-Cobefrin 1:20,000 injection provides anesthesia of longer duration for more prolonged procedures, 1 hour to 2.5 hours in the upper jaw and 2.5 hours to 5.5 hours in the lower jaw.
CARBOCAINE does not ordinarily produce irritation or tissue damage.
Neo-Cobefrin is a sympathomimetic amine used as a vasoconstrictor in local anesthetic solutions. It has pharmacologic activity similar to that of Epinephrine but it is more stable than Epinephrine. In equal concentrations, Neo-Cobefrin is less potent than Epinephrine in raising blood pressure, and as a vasoconstrictor.
Carbocaine Indications and Usage
CARBOCAINE is indicated for production of local anesthesia for dental procedures by infiltration or nerve block in adults and pediatric patients.
CARBOCAINE is contraindicated in patients with a known hypersensitivity to amide-type local anesthetics.
RESUSCITATIVE EQUIPMENT AND DRUGS SHOULD BE IMMEDIATELY AVAILABLE. (See ADVERSE REACTIONS).
Reactions resulting in fatality have occurred on rare occasions with the use of local anesthetics, even in the absence of a history of hypersensitivity.
Fatalities may occur with use of local anesthetics in the head and neck region as the result of retrograde arterial flow to vital CNS areas even when maximum recommended doses are observed. The practitioner should be alert to early evidence of alteration in sensorium or vital signs.
The solution which contains a vasoconstrictor (CARBOCAINE 2% (20 mg/mL)) should be used with extreme caution for patients whose medical history and physical evaluation suggest the existence of hypertension, arteriosclerotic heart disease, cerebral vascular insufficiency, heart block, thyrotoxicosis and diabetes, etc.
The solution which contains a vasoconstrictor (CARBOCAINE 2% (20 mg/mL)) also contains potassium bisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in non-asthmatic people. CARBOCAINE 3% (30 mg/mL) is SULFITE FREE.
CARBOCAINE, along with other local anesthetics, is capable of producing methemoglobinemia. The clinical signs of methemoglobinemia are cyanosis of the nail beds and lips, fatigue and weakness. If methemoglobinemia does not respond to administration of oxygen, administration of methylene blue intravenously 1-2 mg/kg body weight over a 5 minute period is recommended.
The American Heart Association has made the following recommendations regarding the use of local anesthetics with vasoconstrictors in patients with ischemic heart disease: “Vasoconstrictor agents should be used in local anesthesia solutions during dental practice only when it is clear that the procedure will be shortened or the analgesia rendered more profound. When a vasoconstrictor is indicated, extreme care should be taken to avoid intravascular injection. The minimum possible amount of vasoconstrictor should be used.” (Kaplan, EL. editor: Cardiovascular disease in dental practice, Dallas 1986, American Heart Association).
Methemoglobinemia: Cases of methemoglobinemia have been reported in association with local anesthetic use; CARBOCAINE, along with other local anesthetics, is capable of producing this condition. Although all patients are at risk for methemoglobinemia, patients with glucose-6-phosphate dehydrogenase deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, infants under 6 months of age, and concurrent exposure to oxidizing agents or their metabolites are more susceptible to developing clinical manifestations of the condition. If local anesthetics must be used in these patients, close monitoring for symptoms and signs of methemoglobinemia is recommended.
Signs of methemoglobinemia may occur immediately or may be delayed some hours after exposure, and are characterized by cyanosis of the skin, nail beds and lips, and/or abnormal coloration of the blood, fatigue and weakness. Methemoglobin levels may continue to rise; therefore, immediate treatment is required to avert more serious central nervous system and cardiovascular adverse effects, including seizures, coma, arrhythmias, and death. Discontinue CARBOCAINE and any other oxidizing agents. Depending on the severity of the signs and symptoms, patients may respond to supportive care, i.e., oxygen therapy, hydration. If methemoglobinemia does not respond to administration of oxygen, a more severe clinical presentation may require treatment with methylene blue exchange transfusion, or hyperbaric oxygen.
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