Abstract: The present invention relates to a new compound of 2-amino-9-(2-substituted ethyl)purine and an effective method for preparing 9-[4-acetoxy-3-(acetoxymethyl)but-1-yl]-2-aminopurin (famciclovir) using the same. The 2-amino-9-(2-substituted ethyl)purine according to the invention is represented by the following formula (II?): (Formula II?) wherein R is a hydroxy, halogen, mesyloxy or tosyloxy group. The inventive method for the preparation of famciclovir comprises the steps of halogenating 2-amino-9-(2-substituted ethyl)purine to give 2-amino-9-(2-halogenoethyl)purine, and reacting the halogenated compound with diethylmalonate. The inventive preparation method allows famciclovir, a purine derivative drug with effective antiviral activity, to be prepared in a high selectivity of 100% in a pure form by using the inventive new compound of 2-amino-9-(2-substituted ethyl)purine.

Abstract: The present invention relates to a simple and effective method for preparing a tamsulosin HCl sustained-release tablet and a tamsulosin HCl sustained-release tablet produced thereby. The method comprises the steps of: dissolving tamsulosin HCl as an active ingredient in an organic solvent; dissolving the tamsulosin HCl solution in hydroxypropylmethylcellulose phthalate to prepare a binder solution; and kneading the binder solution with a hydroxypropylmethylcellulose phthalate/glyceryl dibehenate mixture as an excipient and allows tamsulosin HCl to be released at uniformly controlled amounts in a subtained-release manner in vivo by controlling drug release rate according to different pH environments in vivo, so that it shows improved bioavailability and minimized side effects.

Abstract: Disclosed is a process for preparing 9-[4-acetoxy-3-(acetoxymethyl)but-1-yl]-2-aminopurine (called Famciclovir), a drug of purine derivatives having antiviral activity. This process comprises reacting 2-aminopurine with 2-acetoxymethyl-4-bromobut-1-yl-acetate in the presence of thallium (I) ethoxide to give the desired compound. According to this process, the desired compound can be prepared in very high selectivity and purity under mild reaction conditions.