N-1 Substituted sulphonamides

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Chapter: Medicinal Chemistry : Antibacterial Sulphonamides

i. Sulphanilamide ii. Sulphacetamide (Albucid) iii. Sulphasalazine iv. Sulphadiazine v. Sulphadimidine vi. Sulphamerazine (Solumedine) vii. Sulphadimethoxine viii. Sulpha methoxy pyridazine ix. Sulphaphenazole x. Sulpha Isoxazole (Lipo Gantrisin, Gantrisin) xi. Sulphamethoxazole (Gantanol) xii. Sulphaguanidine


Antibacterial Sulphonamides - Synthesis and Drug Profile

N-1 Substituted sulphonamides

 

i. Sulphanilamide


Synthesis

Route-I. From: Benzene


Route-II. From: Nitrobenzene


Route-III. From: Aniline


Uses: It is used in veterinary medicine as an antibacterial agent.

 

ii. Sulphacetamide (Albucid)


Synthesis


Properties and uses: It exists as white crystalline powder, bitter in taste. Used in the treatment of bacterial infections of urinary tract.

Assay: Dissolve the sample in water and hydrochloric acid. Titrate with sodium nitrite and determine the end point potentiometrically.

Dose: Dose for eyes, as drops 10%, 15%, 20%, and 30%; in ointments 2.5% and 6% of Sulphacetamide.

 

iii. Sulphasalazine


Synthesis


Metabolism: It undergoes reductive metabolism by gut bacteria, converting the drug into sulfapyridine and 5-amino salicylic acid, which are active components.


Properties and uses: Sulphasalazine is a bright yellow or brownish-yellow fine powder, very slightly soluble in alcohol, practically insoluble in methylene chloride. It dissolves in dilute solutions of alkali hydroxides. It is used in the treatment of ulcerative colitis.

Assay: Dissolve and dilute the sample in 0.1 M sodium hydroxide and add 0.1 M acetic acid and measure the absorbance at the maxima of 359 nm using ultraviolet spectrophotometer.

Dosage forms: Sulphasalazine tablets B.P.

 

iv. Sulphadiazine


Synthesis

Step-I. Preparation of formyl acetic acid


Step II. Synthesis of 2-Aminopyrimidine


Step III. Synthesis of p-acetamido benzene sulphonyl chloride (PABS)


Step IV. Condensation of p-acetamido benzene sulphonyl chloride with 2-aminopyrimidine


Properties and uses: Sulphadiazine is a white or yellowish-white or pinkish-white crystalline powder or crystals, insoluble in water, slightly soluble in acetone, very slightly soluble in alcohol, and soluble in solutions of alkali hydroxides and in dilute mineral acids. It is used in the treatment of canceroids and rheumatic fever.

Assay: Dissolve the sample in water and hydrochloric acid. Titrate the mixture with sodium nitrite and determine the end point potentiometrically.

Dose: Usual dose is 2–8 g per day

Dosage forms: Sulphadiazine tablets I.P., Sulphadiazine injection B.P.

 

v. Sulphadimidine


Synthesis


Properties and uses: It exists as white crystalline powder with a bitter taste, insoluble in water, and sparingly soluble in alcohol. It is less effective in meningeal infection because of its poor penetration into the cerebrospinal fluid.

Dose: Dose is 3 g initially and subsequent doses up to 6 g per day in divided doses.

 

vi. Sulphamerazine (Solumedine)


Synthesis

Step I. Preparation of PABS

Synthesized as mentioned under Sulphadiazine

Step II. Preparation of 2-amino-4-methyl pyrimidine


Step III. Condensation of products of Step I and II


Uses: Used as an antibacterial agent.

Dose: Dose is 4 g initially, and subsequent dose is 1 g every 6 h

 

vii. Sulphadimethoxine


Synthesis


 

viii. Sulpha methoxy pyridazine


Synthesis


 

ix. Sulphaphenazole


Synthesis


 

x. Sulpha Isoxazole (Lipo Gantrisin, Gantrisin)


Synthesis


Properties and uses: It exists as white to slightly yellowish crystalline powder and is odourless, soluble in water and in dilute hydrochloric acid. Used in the treatment of urinary tract infections.

Assay: Dissolve the sample in water and hydrochloric acid. Titrate the mixture with sodium nitrite and determine the end point potentiometrically.

Dose: Initial dose is 2–4 g orally for adults and maintenance dose is 4–8 g per day in divided doses.

 

xi. Sulphamethoxazole (Gantanol)


Synthesis


Properties and uses: Sulphamethoxazole is a white or almost white crystalline powder, practically insoluble in water, soluble in acetone, sparingly soluble in ethanol, dissolves in dilute solutions of sodium hydroxide and in dilute acids. Used in the treatment of bacterial infections.

Assay: Dissolve the sample in dilute hydrochloric acid and add potassium bromide. Cool in ice and titrate against 0.1N Sodium nitrate. Determine the end point electrometrically.

Dose: Orally 2 g followed by 1 g every 8 h.

Dosage forms: Co-trimoxazole intravenous infusion B.P., Co-trimoxazole oral suspension B.P., Paediatric co-trimoxazole oral suspension B.P., Co-trimoxazole tablets B.P., Dispersible co-trimoxazole tablets B.P., Paediatric co-trimoxazole tablets B.P.

 

xii. Sulphaguanidine


Properties and uses: Sulphaguanidine is a white, fine crystalline powder, soluble in dilute mineral acids, very slightly soluble in water and ethanol, slightly soluble in acetone, but insoluble in methylene chloride. Used in the treatment of local intestinal infections, specifically, bacillary dysentery.

Assay: Dissolve the sample in dilute hydrochloric acid and add potassium bromide. Cool in ice and titrate against 0.1N sodium nitrate. Determine the end point electrometrically.

Synthesis



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