LOCAL ANESTHETICS BENZOCAINE BUTAMBEN

 SYNTHESIS OF BENZOCAINE

Synthesis of benzocaine or ethyl-p-amino benzoate done by the following pathway---

Nitration of toluene gives p-nitro toluene that on oxidation give p-nitro benzoic acid, on esterification p-nitro benzoic acid transfer to ethyl p-nitro benzoate that on reduction give ethyl-p-amino benzoate or benzocaine.

The solubility of benzocaine in water is very poor therefore it is used as ointment and can be applied directly to wounds, ulcerated surfaces and mucous surfaces.Its anesthetic action usually works for the period it remains in contact with the affected areas such as skins or mucous membranes. A 1% cream or lotion available for topical application.It is used as important ingredient in various types of  powders, lotions, ointment, creams, aerosol sprays for pain reliever.

SYNTHESIS OF BUTAMBEN

Synthesis of butamben or butyl-p-amino benzoate done by the following pathway---

Nitration of toluene gives p-nitro toluene that on oxidation give p-nitro benzoic acid, on esterification with n-butanol, p-nitro benzoic acid transfer to butyl p-nitro benzoate that on reduction give butyl-p-amino benzoate or butamben.

The solubility of butamben in water is very low therefore it is used as important ingredient in various types of  powders, lotions, ointment, creams, aerosol sprays for pain reliever, and can be applied directly to wounds, ulcerated surfaces and mucous surfaces.Its anesthetic action usually works for the period it remains in contact with the affected areas such as skins or mucous membranes.

SYNTHESIS OF PROCAINE HYDROCHLORIDE

Synthesis of procaine hydrochloride done by the following pathway---

p-amino benzoic acid react with 2-hydroxy triethyl amine in presence of sulphuric acid and heat it give procaine base, which on treatment with HCl give procaine hydrochloride.

It is used for infiltrative anesthesia, nerve block, spinal anesthesia, epidural block.

SYNTHESIS OF TETRACAINE HYDROCHLORIDE

Synthesis of tetracaine hydrochloride done by the following pathway---

p-amino benzoic acid react with n-butyl bromide in presence of sodium carbonate and ethanol to produce ethyl-p-butyl amino benzoate. When ethyl-p-butyl amino benzoate react with 2-dimethyl amino ethanol in presence of NaOEt and heat tetracaine base is produced, which on treatment with HCl give tetracaine hydrochloride.

 

Tetracaine is lipid soluble due to the presence of nonpolar n-butyl group . Tetracaine has a long duration (3 hours) action and a delayed onset of action (15 minutes), it is used as a spinal anesthatic,caudal anesthatic.