Local Anesthesia
Local Anesthetic Drug Cinchocaine Base Powder CAS 85-79-
Definition
ChEBI: A monocarboxylic acid amide that is the 2-(diethylamino)ethyl amide of 2-butoxyquinoline-4-carboxylic acid. One of the most potent and toxic of the long-acting local anesthetics, its parenteral use was restricted to spinal anesthesia. It is now generally o ly used (usually as the hydrochloride) in creams and ointments and in suppositories for temporary relief of pain and itching associated with skin and anorectal conditions.
Manufacturing Process
A benzene solution of 2.2 parts of α-chloro-γ-quinoline-carboxylic acid chloride is gradually mixed, while cooling, with 2.3 parts of unsymmetrical diethylethylenediamine. When the reaction is at an end the solution is washed with water and the new base extracted by means of hydrochloric acid. The base is precipitated by means of sodium carbonate and extracted with benzene. The solvent is distilled and the base recrystallized from petroleum ether. The α-chloro-γ-quinoline-carboxylic acid diethyl-amino-ethylene amide forms colorless lamina crystals of melting point 74°C. With acids the base forms neutral salts soluble in water.
A solution of 2.5 parts of sodium in n-butylalcohol is boiled with 30 parts of α- chloro-γ-quinoline-carboxylic acid diethyl-amino-ethylene-amide in a reflux apparatus, and when the reaction is over the excess of butylalcohol is distilled. The remaining base is taken up with ether; the solution is washed with water and dried. The solvent is then distilled. The α-n-butoxy-γ-quinoline. carboxylic acid diethyl-amino-ethylene-amide forms as colorless crystals, after recrystallization from petroleum ether melting point of it 64°C.
In practice it is usually used as hydrochloride.
General Description
Articaine has a secondary nitrogen with a pKa of 7.8. It containsan aromatic thiophene ring bioisostere of the phenylring found in most other amide anesthetics. The log P of abenzene ring is 2.13 and the thiophene ring log P is 1.81,thus the thiophene ring is more hydrophilic than a phenylring. Although the thiophene ring has less lipid solubilitythan a phenyl ring, articaine is a lipid-soluble compound dueto the propylamine, the branched methyl and the substitutionson the thiophene ring. The onset of action of articaineis similar to lidocaine’s onset of action.Tips: hcl soluble in water, base insoluble in water. (Some Base dissolves in hot water!)
Clinical Use
Articaine is availablein a 4% solution with epinephrine for use in infiltrationand nerve block anesthesia.Articaine is metabolized rapidly via plasma and tissuecarboxyesterase to its primary metabolite, the inactive,water-soluble carboxylic acid. Approximately 40% to 70%of articaine administered epidurally is metabolized to thecarboxylic acid, articainic acid. Approximately 4% to 15%of the articainic acid undergoes glucuronide conjugationand only 3% of the dose is recovered unchanged in theurine. The rapid plasma metabolism and reported inactivityof the carboxylic acid metabolite make articaine a potentiallysafer anesthetic agent when multiple or large dosesare necessary.
Uses
Cinchocaine is a local anesthesic,used for Na+ channel blocker.
Local anesthesia strength: the anesthesia effect of some base is stronger than hcl)
Tetracaine>Lidocaine>Benzocaine>Procaine
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