GB761757A - Alginate pastes - Google Patents

Abstract

Readily spreadable pharmaceutical pastes and the like are prepared by dissolving a comminuted, solid, water-soluble alginate in an aqueous solution of a salt of a metal, the alginate of which is water-insoluble, in a quantity in excess of the stoichiometric equivalent of the quantity of said salt in said aqueous solution, the concentration of said salt in said aqueous solution not exceeding 2 per cent, and preferably 1 per cent, by weight and the solubility of said in water under the operating conditions being not less than 1 gram per 100 millilitres water and such that it dissolves completely in water at the concentrations used. In the case of salts more readily soluble than the alginate, both alginate and salt may be added simultaneously to the water and the mixture stirred until the reactants have dissolved. In general, the quantity of salt used should be not less than 1 per cent and not more than 50 per cent of the stoichiometric equivalent of the quantity of alginate used. Specified alginates are the alkali metal, magnesium, ammonium, amine, alkyolamine and glycol alginates. Specified coagulating salts are those of the alkaline earth metals (other than magnesium), aluminium, iron, lead, nickel and zinc; especially calcium acetate, benzoate, chloride, lactate, nitrate nitrite, propinate, salicylate and calcium salts of organic acids having dissociation constants not exceeding 1.55 X-10-4. The pastes consist essentially of water, a water-soluble alginate, a water-insoluble alginate and a water-soluble salt of the basic component of said water-soluble alginate with an acid which forms a readily water-soluble salt with the basic component of the water-insoluble alginate. Optional ingredients are oils, powders, perfumes and colouring matters. The preparations may be in the form of powders capable of forming the pastes when dispersed in water.