Journal of Controlled Release, 5 (1987) 63-68 Elsevier Science Publishers B.V.. Amsterdam - Printed in The Netherlands 63 STUDY OF ROSIN AND ROSIN DERIVATIVES AS COATING MATERIALS FOR CONTROLLED RELEASE OF DRUG Y.V. Pathak” College of Pharmacy, Manipa1576 1 19 (India) and A. K. Dorle Department of Pharmaceutical Sciences, Nagpur University, Nagpur 440 0 10 (India) (Received May 9, 1986; accepted in revised form December 15, 1986) Rosin and rosin derivatives are widely used as film-forming agents inpaints and varnishes. Their use as coating materials has been reported. This paper describes the evaluation of rosin deriva- tives such as rosin pentaerythritol ester, rosin maleic acid adduct esterified with glycerol and pentaerythritol, and abietic acid as coating materials. Salicylic acid granules were coated and evaluated for moisture absorption, flow characteristics and in vitro dissolution studies. It is observed that rosin and pentaerythritol ester impart excellent moisture protection and these can be used for enteric coating and controlled release of drug. INTRODUCTION Rosin and rosin derivatives are widely used in paints, varnishes, printing inks, wood pol- ishes and paper products because of their film- forming properties. These are used to impart moisture protection and acid resistance to sur- faces in surface coatings. Rosin esters with glycerol, sorbitol and mannitol are found to be effective film-forming agents imparting mois- ture protection properties. These can be used for the delayed release of drug [ 11. Rosin gly- erol ester intermediates with different acid val- ues are found to be useful coating materials for delayed release of drug [ 21. A quantitative cor- relation was found between physico-chemical properties of rosin glycerol ester intermediates and their release characteristics [ 31. Rosin gly- co1 esters are also found to be useful coating materials [ 41. The product obtained by heating ‘To whom correspondence should be addressed. rosin and glycerol was used as an anhydrous binding agent in tablet formulation [ 51. A for- mula has been patented for repeat-action bead- lets using rosin and zein [ 61. We have reported the application of rosin and rosin derivatives as anhydrous binding agents in tablet formula- tions [ 7-91. Rosin pentaerythritol ester is widely used in paints, varnishes and for coating of food prod- ucts. It has better resistance to alkali and mois- ture than rosin glycerol ester [lo]. A water- repellent composition has been patented for textiles using pentaerythritol rosin ester [ 111. Rosin forms addition products with maleic acid, fumaric acid and their anhydrides. The esteri- fied products of rosin adducts are widely used as film-forming agents [ 121. Deshpande and Peter have reported the use of maleoabietic acid adduct as an enteric film-coating agent [ 131. Pentaerythritol ester of maleic-acid-modified rosin is used as a food additive [ 141. Modified 0168-3659/87/$03.50 0 1987 Elsevier Science Publishers B.V.