Polocaine (Mepivacaine Infiltration) - Description and Clinical Pharmacology

THESE SOLUTIONS ARE INTENDED FOR DENTAL USE ONLY.

DESCRIPTION

Polocaine Dental (mepivacaine hydrochloride), a tertiary amine used as a local anesthetic is 1-methyl,-2',6'-pipecoloxylidide monohydrochloride with the following structural formula:

It is a white, crystalline, odorless powder soluble in water, but very resistant to both acid and alkaline hydrolysis.

Levonordefrin, a sympathomimetic amine used as a vasoconstrictor in local anesthetic solutions, is (-)- (1-Aminoethyl)-3,4-dihydroxybenzyl alcohol with the following structural formula:

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.

3% Polocaine Dental (mepivacaine hydrochloride) Injection and 2% Polocaine Dental (mepivacaine hydrochloride) with Levonordefrin 1:20,000 Injection are sterile solutions for injection.

COMPOSITION	CARTRIDGE
Each mL contains:	2%	3%
mepivacaine hydrochloride	20 mg	30 mg
levonordefrin	0.05 mg	—
sodium chloride	4 mg	3 mg
sodium metabisulfite	0.5 mg	—
Water for Injection, qs ad	1 mL	1 mL

The pH of the 2% cartridge solution is adjusted between 3.3 and 5.5 with NaOH and/or HCl.

The pH of the 3% cartridge solution is adjusted between 4.5 and 6.8 with NaOH and/or HCl.

CLINICAL PHARMACOLOGY

Polocaine Dental stabilizes the neuronal membrane and prevents the initiation and transmission of nerve impulses, thereby effecting local anesthesia. Polocaine Dental is rapidly metabolized, with only a small percentage of the anesthetic (5 to 10 percent) being excreted unchanged in the urine. Polocaine Dental, 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 3% Polocaine Dental without vasoconstrictor will ordinarily provide operating anesthesia of 20 minutes in the upper jaw and 40 minutes in the lower jaw.

2% Polocaine Dental with Levonordefrin 1:20,000 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.

Polocaine Dental does not ordinarily produce irritation or tissue damage. Levonordefrin 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, levonordefrin is less potent than epinephrine in raising blood pressure, and as a vasoconstrictor.