Prolonged-release liquid type of pharmaceutical preparation comprising drug-resin complex and benzoate preservative

Claim 1

A prolonged-release liquid type of pharmaceutical preparation comprising: (a) 0.1-45.0 w/v % of diffusion barrier-coated complex particles, which are prepared by adsorbing a pharmacologically active drug onto ion exchange resin particles to form drug-resin complex particles, treating the drug-resin complex particles with an impregnating agent to form treated complex particles, and then coating the treated complex particles with ethylcellulose, wherein said ethylcellulose has an ethoxyl group content of 44.0-47.5%; (b) a preservative selected from the group consisting, (i) one of para-hydroxybenzoic acid esters, wherein if methyl para-hydroxybenzoate is chosen, the preparation contains it at a concentration of 0.05-0.75 w/v %; if ethyl para-hydroxybenzoate is chosen, the preparation contains it at a concentration of 0.05-0.075 w/v %; if propyl para-hydroxybenzoate is chosen, the preparation contains it at a concentration of 0.03-0.05 w/v %; and if butyl para-hydroxybenzoate is chosen, the preparation contains it at a concentration of 0.01-0.015 w/v %; (ii) a mixture of two or more of para-hydroxybenzoic acid esters, wherein if a mixture of methyl para-hydroxybenzoate and propyl para-hydroxybenzoate is chosen, the preparation contains the former at a concentration of 0.05-0.10 w/v % and the latter at a concentration of 0.01-0.02 w/v %, respectively; and (iii) sodium benzoate at a concentration of 0.1-0.5 w/v %; and the percent dissolution of the drug from the drug-resin complex changes minimally upon storage at 25° C. for a long period of time, (c) a solvent, wherein said preparation can be stably stored for a long time without loss of its controlled-release property.