Benzamycin® Pak contains erythromycin [(3R*, 4S*, 5S*, 6R*, 7R*, 9R*, 11R*, 12R*, 13S*, 14R*)-4-[(2,6- dideoxy-3-C-methyl-3-O-methyl-a- L-ribo-hexopyranosyl)-oxy]-14- ethyl-7,12,13-trihydroxy- 3,5,7,9,11,13-hexa-methyl-6-[ [3,4,6-trideoxy-3-(dimethylamino)-b-D- xylo-hexopyranosyl] oxy]oxacyclotetradecane-2,10- dione]. Erythromycin is a macrolide antibiotic produced from a strain of Saccharopolyspora erythraea (formerly Streptomyces erythreus). It is a base and readily forms salts with acids. Chemically, erythromycin is (C37H67NO13). It has the following structural formula:
Erythromycin has the molecular weight of 733.94. It is a white crystalline powder and has a solubility of approximately 1 mg/mL in water and is soluble in alcohol at 25°C. Benzamycin (erythromycin) ® Pak also contains benzoyl peroxide for topical use. Benzoyl peroxide is an oxidizing agent demonstrating antibacterial activity. Chemically, benzoyl peroxide is (C14H10O4). It has the following structural formula:
Benzoyl peroxide has the molecular weight of 242.23. It is a white granular powder and is sparingly soluble in water and alcohol and soluble in acetone, chloroform and ether. Each gram of product, as dispensed, contains 30 mg of erythromycin and 50 mg of benzoyl peroxide in a base of SD Alcohol 40B, purified water, hydroxypropyl cellulose, carbomer 934, sodium hydroxide, dioctyl sodium sulfosuccinate 75%. Each Benzamycin (erythromycin) ® Pak contains 0.8 grams of product.