ERYTHROMYCIN

ERYTHROMYCIN

Brand Names : Erythromycin A: Abomacetin: EMU: Ery Derm: Ery-Tab; Erythrocin; Erythromast 36; Erythromid; ERYC; Erycin; Erycinum; Erymysin; Ilotycin; Reticin; Staticin; Torlamicina; EMycin; Eritromicina; Erythromycinum.

Erythromycin, a macrollide antibiotic isolated from a culture of Streptomyces erythreus by McGuire in 1952, is a mono-acidic base. On hydrolysis, it forms a basic sugar, desosamine, and a neutral sugar, cladinose. There are three erythromycins produced duringfermentation, designated as A, B, and C; A is a major and most important component.

The amino sugar attached through a glycosidic link to the number 5 carbon atom is desosamine. The tertiary amino nature of desosamine confers a basic character to erythromycin which is involved in the formation of acid salts. The other carbohydrate structure linked as a glycoside to carbon atom 3. is called cladinose. Erythromycins A and B contain the same sugar moieties, desosamine, and cladinose. They differ in position 12 of the aglycone, erythronolide, A having an hydroxyl substituent. Component C contains desosamine and the same aglycone present in A but differs by the presence of mycarose, instead of cladinose.

Erythromycin is a bitter compound, white or slightly yellow, odourless, slightly hygroscopic crystals or powder; crystallized from water; m.p. 135-140°. After melting at 135-140°, it resolidifies and melts again at 190-1939. It readily forms salts with acids. It is slightly soluble in water; less soluble at higher temperatures: soluble in alcohol, methyl alcohol, chloroform and 2 M hydrochloric acid)Saturated aqueous solutions develop an alkaline pH in the range of 8.0 to 10.5. It is extremely unstable at a pH of 4 or lower. The optimum pH for stability of erythromycin is near neutrality. It is stored in airtight containers and protected from light.

The free base erythromycin may be used in oral dosage. In order to reduce its bitter taste and to provide more acceptable pharmaceutical forms for its administration, two types of derivatives of erythromycin are prepared. One type of derivatives are salts formed by acids such as the glucoheptonate, lactobionate and stearate. The other type of derivatives are produced by esterification of the hydroxyl group of the desosamine moiety, such as the ethyl carbonate, ethyl succinate and propionate (estolate). The carbonate ester is hydrolyzed in the gastrointestinal tract to the active base before absorption. However, the ethyl succinate and propionate esters are biologically active themselves and need not be hydrolyzed to show anti-infective action. In gastrointestinal tract, these compounds may be partially hydrolyzed and on absorption provide a more rapid onset and higher and more prolonged therapeutic concentration in the blood.

The glucoheptonate (gluceptate) and lactobionate salts are water-soluble which may be administered parenterally. The stearate salt is water-insoluble and tasteless and is used in tablets and suspensions. The ethyl carbenate ester is also water-insoluble-and employed for paediatric suspension.

Uses

Erythromycin is used in the treatment of infections due to susceptible organisms. It is often used as an alternative to penicillin in infections due to gram-positive cocci. It may be some of the given as an adjunct to antitoxin in the treatment of diphtheria. agents respo A 0.5% ophthalmic ointment it is used to cure infected eyes. A psittacosis. 2% solution is applied in the treatment of acne of vulgaris. known as Erythromycin thiocyanate is used in veterinary medicine.

Adverse Effect

Gastro-intestinal disturbances are fairly common with The tet erythromycin, especially with large doses, but serious side- congeneric C effects are rare. Reversible deafness has occurred after high cyclic naph doses of erythromycin. Hepatotoxicity has been reported after Streptomyce administration of erythromycin, most commonly used as the an antibiot estolate. Irritation or sensitivity reactions may occur after the consists of topical administration of the drug.