Preparation And Properties Of Agar/Maltodextrin Capsules

Sustained release capsule is a kind of sustained-release material used to delay the release,absorption and metabolism of drugs in the body,which can improve the effect of drugs.In this paper,agar,maltodextrin and their mixtures were used as research objects to prepare agar/maltodextrin composite film and capsule in different ratios.The rheological and film-forming properties of agar/maltodextrin glue were studied,and on this basis,the composite film and sustained-release capsules were prepared with agar and maltodextrin as wall materials.In addition,by adding beeswax,agar/maltodextrin capsules were prepared.Adding beeswax extended the release degree of capsules to a large extent,which provided a certain theoretical basis for industrial production of plant sustained-release capsules.This paper mainly includes the following contents:（1）Rheological properties and gel strength of different ratios of agar and maltodextrin.The results of static rheological experiments showed that,with the increase of maltodextrin ratio in agar/maltodextrin glue solution,when the agar content was more than 70%,the system presents an obvious shear thinning characteristic,and the flow curve of the blend system had a good correlation with the Power Law model.The flow coefficient n of the system increased,the degree of pseudoplasticity and viscosity of the gel solution decreased,and the fluidity increased,which were beneficial to the preparation of the capsule.The addition of maltodextrin significantly reduced the viscosity and thixotropy of the agar/maltodextrin mixture.The results of dynamic rheology showed that addition of maltodextrin decreased the melting temperature and gel temperature of agar/maltodextrin glue.（2）The effects of the ratio of agar to maltodextrin on the properties of the composite film were studied.Adding maltodextrin could improve the brittleness of the composite membrane and increase the elongation at break of（EAB）the composite membrane.Compared with pure agar membrane,the ratio of agar/maltodextrin was 40:60,and the composite membrane increased by 120%.The prepared film has smooth appearance,higher light transmittance and lower swelling degree（SD）.The SD of the composite film with 40:60 ratio of agar/maltodextrin decreased by 189%.The composite film had good comprehensive properties.By adjusting the amount of maltodextrin,the solubility of composite film could be controlled,which was expected to be the material for preparing sustained-release capsules.（3）The effects of different ratios of agar/maltodextrin on capsules were investigated.The results of scanning electron microscopy showed that the agar had good compatibility with maltodextrin.The appearance of the capsule prepared was clean,without deformation,bonding or cracking,and had no odor.The adhesive temperature was determined by the wall thickness,shape and molding time of the capsule.The drying time of the capsule was determined by the rate of capsule formation and water content.The drying weight loss rate of the sustained-release capsule was less than 8.53%.The burning residue rate was less than1.15%.The crushing fragility was 0 and the tightness was 0.And the encapsulation performance was good.The above results met the requirements of the national pharmacopoeia.Using amoxicillin as model drug,the release characteristics of agar/maltodextrin capsules were analyzed through in vitro digestion simulation,and the sustained release effect of agar/maltodextrin capsules was evaluated.The results of in vitro digestion experiments showed that agar/maltodextrin capsule had good sustained-release performance and could effectively prolong the release of amoxicillin.Different ratios of agar/maltodextrin had different sustained-release time.With the increased of maltodextrin content,the sustained release time became shorter,and the ratio could be adjusted according to the demand of drugs.（4）The effects of the amount of beeswax on agar/maltodextrin composite film and capsule were investigated.In the presence of beeswax,the tensile strength（TS）,elongation at break and Young’s modulus（YM）of the film increase simultaneously.The TS,EAB and YM of the agar/maltodextrin composite membrane with 20%beeswax were 60%,40%and 95%higher than those without beeswax,respectively.The hydrophobicity of agar/maltodextrin composite film prepared by adding beeswax increased,and the contact Angle of 20%beeswax was 87.69°.Adding 15%beeswax agar/maltodextrin composite membrane has the lowest Vapor permeability coefficient（WVP）of 1.78×10^-13gm^-1s^-1pa^-1,increases the water resistance,decreases the composite membrane SD,and increases the color brightness.The prepared capsule had smooth appearance,no bonding,deformation or rupture,and no peculiar smell.The tightness,cauterization residue and fragility of the hard capsule met the national standard.The results of in vitro digestion experiments showed that addition of beeswax could prolong the release of amoxicillin of agar/maltodextrin capsules,which had good sustained-release performance.With the increased of beeswax,the sustained release time of the capsule was prolonged,which was up to 24 h.