Lidocaine and Prilocaine

Dosage form: cream
Drug class:Topical anesthetics

Medically reviewed by Drugs.com. Last updated on Apr 1, 2022.

Lidocaine and Prilocaine Description

Lidocaine and Prilocaine cream, USP 2.5%/2.5% is an emulsion in which the oil phase is a eutectic mixture of Lidocaine and Prilocaine in a ratio of 1:1 by weight. This eutectic mixture has a melting point below room temperature and therefore both local anesthetics exist as a liquid oil rather than as crystals. It is packaged in 30 gram tube.

Lidocaine is chemically designated as acetamide, 2-(diethylamino)-N-(2,6-dimethylphenyl), has an octanol: water partition ratio of 43 at pH 7.4, and has the following structure:

Prilocaine is chemically designated as propanamide, N-(2-methylphenyl)-2-(propylamino), has an octanol: water partition ratio of 25 at pH 7.4, and has the following structure:

Each gram of Lidocaine and Prilocaine cream contains lidocaine 25 mg, prilocaine 25 mg, polyoxyethylene fatty acid esters (as emulsifiers), carbomer homopolymer type B (as a thickening agent), sodium hydroxide to adjust to a pH approximating 9, and purified water to 1 gram. Lidocaine and Prilocaine cream contains no preservative, however it passes the USP antimicrobial effectiveness test due to the pH. The specific gravity of Lidocaine and Prilocaine cream is 1.00.

Lidocaine and Prilocaine - Clinical Pharmacology

Mechanism of Action: Lidocaine and Prilocaine cream, 2.5%/2.5%, applied to intact skin under occlusive dressing, provides dermal analgesia by the release of Lidocaine and Prilocaine from the cream into the epidermal and dermal layers of the skin and by the accumulation of Lidocaine and Prilocaine in the vicinity of dermal pain receptors and nerve endings. Lidocaine and Prilocaine are amide-type local anesthetic agents. Both Lidocaine and Prilocaine stabilize neuronal membranes by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action.

The onset, depth and duration of dermal analgesia on intact skin provided by Lidocaine and Prilocaine cream depend pr...