Manufacturing Process

The N-(diethylaminoethyl)-2-methoxy-4-aminobenzamide used as the starting material may be prepared from o-toluidine. The o-toluidine is initially nitrated with nitric acid to produce 4-nitro-o-toluidine. The 4-nitro-o-toluidine is then converted to 2-hydroxy-4-nitrotoluene by heating with nitrous acid. By reacting the resulting 2-hydroxy-4-nitrotoluene with dimethyl sulfate, 2- methoxy-4-nitrotoluene is formed. The 2-methoxy-4-nitrotoluene is oxidized with potassium permanganate to produce 2-methoxy-4-nitrobenzoic acid. The latter substituted benzoic acid is treated with thionyl chloride to form 2- methoxy-4-nitrobenzoyl chloride. A methyl ethyl ketone solution of the 2- methoxy-4-nitrobenzoyl chloride is added over a period of about 1? hours to a methyl ethyl ketone solution containing an equal molecular quantity of N,Ndiethylethylene diamine while stirring and maintaining the temperature between 0°C and 5°C. The N-(diethylaminoethyl)-2-methoxy-4- nitrobenzamide hydrochloride formed precipitates. It is filtered, washed twice with methyl ethyl ketone, dissolved in alcohol, and reduced catalytically in an absolute isopropyl alcohol solution to form N-(diethylaminoethyl)-2-methoxy- 4-aminobenzamide. The base is obtained by precipitating with sodium hydroxide.80 g (0.3mol) of N-(2-diethylaminoethyl)-2-methoxy-4-aminobenzamide are dissolved in small portions in 150 cc of acetic acid. The mixture is cooled and 45 g (0.45 mol) of acetic anhydride are added, and the solution obtained is heated for two hours on a water bath. After cooling, the solution is decanted into a round-bottomed flask with a stirrer, a thermometer and a tube for introducing the chlorine. It is stirred and the current of chlorine is passed through, the temperature being maintained between 20°C and 25°C. The stirring is continued for one hour after the completion of the absorption of the chlorine.The mixture obtained is poured into 2 liters of water and the base is precipitated with 30% soda. The precipitated base is extracted with 400 cc of methylene chloride. After evaporation of the solvent, the N-(2- diethylaminoethyl)-2-methoxy-4-acetamino-5-chlorobenzamide formed crystallizes. The melting point is 86°C to 87°C and the yield is 95%.To obtain the corresponding amino derivative, 109 g of base are heated under agitation in a round-bottomed flask with 300 cc of 35-36% concentrated hydrochloric acid and 600 cc of water. It is heated on a water bath until dissolution is complete, then maintained at boiling point for 90 minutes, cooled, diluted with 1 liter of water, and neutralized with about 350 cc of 30% soda. The N-(2-diethylaminoethyl)-2-methoxy-4-amino-5-chlorobenzamide formed crystallizes, is centrifuged and washed in water. Its melting point is 122°C and the yield is 74%.To obtain the corresponding dihydrochloride, the base is dissolved in absolute alcohol (3 volumes) and to that solution is added 5 N alcoholic hydrochloric acid. The dihydrochloride precipitates, is centrifuged and washed with alcohol. It is a solid white material, having a melting point of 134°C to 135°C.

Therapeutic Function

Antiemetic

Definition

ChEBI: A member of the class of benzamides resulting from the formal condensation of 4-amino-5-chloro-2-methoxybenzoic acid with the primary amino group of N,N-diethylethane-1,2-diamine.

Brand name

Maxolon (King); Reglan (Baxter Healthcare); Reglan (Robins); Reglan (Schwarz Pharma).

General Description

Metoclopramide is typically employed as an antiemetic drug or a gastrointestinal prokinetic drug in adults and children.