GB773486A - A calcium complex of tetracycline - Google Patents

Abstract

A tetracycline calcium chloride complex is prepared by reacting tetracycline in solution below pH 2.5 with calcium chloride to form a solution which is then adjusted to pH 3.0 to 6.0, and preferably 3.0 to 4.0, by means of a base such as ammonium hydroxide or sodium hydroxide, and collecting the precipitated complex. The tetracycline may be in the form of the anhydrous or crystalline base or an acid addition salt, e.g. the hydrochloride or sulphate, and is adjusted to the desired pH by means of a strong mineral acid such as hydrochloric or sulphuric acid. The reaction solvent is preferably water but may be a water miscible alcohol or ketone or an aqueous solution thereof. The preferred complex contains 4 molecules of tetracycline to 1 mol. calcium chloride. The complex is stable in aqueous suspension and is used medicinally (see Group VI). Reference has been directed by the Comptroller to Specification 747,779.ALSO:A tetracycline calcium chloride complex (see Group IV(b)) is employed in therapeutic preparations alone or in combination with other therapeutically active substances. Such preparations may be aqueous or oily suspensions, powders, tablets, troches, lozenges or capsules. Optional additions are buffers e.g. sodium citrate, preservatives e.g. phenol, suspending and dispersing agents e.g. methyl cellulose, binders such as gum tragacanth, diluents, lubricants, masticatory substances and stabilizing agents. The tetracycline calcium chloride may be coated with one or more suspending agents such as lecithin. The complex may be comminuted to any desired particle size. Specified therapeutically active substances are (a) antihistamines (b) sulpha drugs e.g. sulphadiazine (c) vitamins e.g. vitamin A (d) lipstropic agents (e) stimulants e.g. caffine (f) analgesics e.g. asprin (g) laxatives e.g. phenol phthalein (h) sedatives e.g. barbiturates (i) other antibiotics e.g. penicillin, streptomycin, dihydrostreptomycin, neomycin, bacitracin, polymixin, tyrothricin, erythromycin, aureomycin, oxytetracycline, chloramphenicol and magramycin (j) spreading agents e.g. hyaluronidase and (k) hormones e.g. cortisone. Multiple combinations of the above active materials may be used e.g. sulphadiazine and sulphamerazine. Injections of the complex in peanut oil may be gelled with aluminium monostearate. Reference has been directed by the Comptroller to Specification 747,779.