the juice was extracted from the fruits and subjected to centrifuge . in the supernatant equal amount of ethanol was added and kept it in refrigerator for 30 min , then centrifuge the mixture and dry at room temp . fine powder was collected as bio - polymer . for the granulation 1% , 3% and 5% solution of polymer was made in distilled water and appropriate amount of lactose ( 10 gm ) was added to it . then granules were subjected to resize with sieve#16 . before compression of granules , 2%talc and 2% fine powder were mixed well . for the preparation of sustained release tablets containing rifampicin same procedure was followed with 3% and 5% of polymer for preparation of sustained release tablets . additional tablets of 100 mg , 200 mg and 400 mg were prepared using 5% concentration of the polymer . the biopolymer from citrus limetta was isolated and evaluated for release retardant property in sustained release tablet . among the three formulations , fm-3 shows hardness of 5moh , friability of ( .90 ) , weight variation of ( 5.0 ) . it had t50% and t 80% of 1.34 hrs and 2.52 hrs at ph ( 1.2 ) respectively . in - vitro release study for tablets prepared by using 5% conc . of polymer graph for cumulative % drug release vs time of rifampicin at ph ( 1.2 ) observation table for release study the results indicated that the selected biopolymer had a good release retardant property thus it can be concluded that the selected biopolymer can be utilized as low cost natural biocompatible and biodegradable agent .
the advantages of biopolymers over synthetic polymers are low cost , natural origin , free from side effects , biocompatible , bio - acceptable , environmental friendly processing , local availability , better patient tolerance as well as public acceptance . 
 sustained release tablets containing rifampicin was prepared by adding 100 mg polymer and 50 mg drug and granules . 
 same procedure was followed with 3% and 5% of polymer for preparation of sustained release tablets . 
 additional tablets of 100 mg , 200 mg and 400 mg were prepared using 5% of the polymer . 
 the results indicated that the selected biopolymer had a good release retardant property thus it can be concluded that the selected biopolymer can be utilized as low cost natural biocompatible and biodegradable agent .