HYDROPHILIC MATRIX TABLETS AS ORAL CONTROLLED DRUG DELIVERY SYSTEMS IN 20TH CENTURY: A REVIEW

Matrix systems are easy to formulate compared to other controlled release dosage forms. The manufacture of matrix tablets involves the direct compression of blend of drug, retardant material and additives to form a tablet in which drug is embedded in a matrix core of the retardant. Alternatively, retardant-drug blends may be granulated prior to compression. Of the three classes of retardant material used to formulate matrix tablets, polymers that form hydrophilic matrices are attracting the attention of pharmaceutical technologists. These polymers include Methyl cellulose (MC), Hydroxy ethyl cellulose (HEC), Hydroxy popyl methyl cellulose (HPMC), Sodium carboxy methyl cellulose (NaCMC), carbomers, chitosan, plant gums etc. The hydrophilic matrix-formers alone or in combination with other excipients form gels in situ on coming in contact with biological fluids which control the drug release. The present review gives a detailed account on the factors to be considered in the design of hydrophilic matrix systems, formulation of hydrophilic matrix tablets, in vitro and in vivo evaluation methods and advances in the design of hydrophilic matrix tablets. This review further focuses on the development of oral controlled drug delivery systems using hydrophilic matrix carriers in 20^th century.