Porosity asymmetric membrane capsules were prepared to study the relationship between the capsule formulation and drug release. Cellulose acetate (CA) and pore formers were used in the capsule shell formulation as the main semipermeable membrane material. The capsules were permeable to both water and dissolved solutes. Using sparingly soluble drug acetaminophen as a model, cumulative release was calculated. The slope of the release profile from the distilled water had good relationship with the concentration of the pore formers F68. The release of acetaminophen was independent to the pH, osmotic pressure of dissolution medium, but influenced by intensity of agitation. When the concentration of pore former was low, zero-order release behavior was observed within 24 h which was consistent with Fickian diffusion model. When the concentration of pore former was high, however, Higuchi model release was found which is caused by Fickian diffusion and osmotic pressure release. With scanning electron microscope (SEM), the surface structure and cross-section of the capsule shell were also studied before and after drug delivery. With simple preparation and broad scope of drug application, porosity asymmetric membrane capsules can give desired drug extended release and show more convenience than controlled tablets with laser drilling.

Objective: To prepare porous membrane osmotic pump capsules and investigate the factors influencing release behavior.Methods: With cellulose acetate(CA)as capsule materials,PEG-400 and PEG-2000 as plasticizer and pore former,shell of osmotic pump capsules was prepared by dip plastic method.Different pore-forming materials and osmogents influencing release behavior were investigated with paracetamol as a model drug and the factors were identified by werapamil hydrochloride and sarpogrelate hydrochloride.surface and cross-section of capsule shell were also studied under scanning electron microscope.Results: Porosity membrane osmotic pump capsules can control the release of drug during a desired time according to optimise the pore former contents and osmogents,respectively.Conclusion: Porous membrane osmotic pump capsules enjoy more advantages than ordinary osomotic tablets,which showed poten-tial to be a new controlled-release drug delivery system.

OBJECTIVE: To establish the method for the content determining of Indomethacin colon-targeting capsule in artificial colon juice. METHODS: RP-HPLC method was adopted. The determination was performed on Hypersil ODS2 C18 column with mobile phase consisted of acetonitrile-0.1 mol·L-1 glacial acetic acid(60 ∶ 40) at flow rate of 1 mL·min-1. The detection wavelength was set at 228 nm and the column temperature was 25 ℃. The injection volume was 20 μL. RESULTS:The linear range of indomethacin was 2.0～50.0 μg·mL-1(r=0.999 9). The recovery rates of it at low, medium and high concentrations were 100.37%,99.87%,100.00% with RSD of 0.29%, 0.31%, 0.74%, respectively. CONCLUTION: The method is accurate, reliable and precision for the content determination of indomethacin in artificial colon juice.

OBJECTIVE To develop a new pulsatile release capsule drug delivery system and explore the factors influening the drug pulsed release of the system at the desired time.METHODS The insoluble semipermeable capsule body was prepared by dipping-drying process and filling the body with drug powder or mixture of drug and osmotic additives.The stopper was made through compressing the pectin powder,and stuffed the body.The insoluble body was capped into a stomach-soluble capsule,followed with the enteric coating outside the capsule.Then in vitro release was investigated.RESULTS The system was not deformed in artificial gastric fluid and the drug was not released.The pulsatile release in the artificial intestinal fluid(pH 7.4) was affected by the thickness of enteric coating,pore formers content of insoluble capsule body and the ratio of osmotic additives.CONCLUSION The mechanism of this pulsatile release capsule is simple,and the components can be prepared individually.The drug release can be desired as required,and the system suit to a variety of drugs.The pulsatile release capsule is expected to be a new type of drug pulse delivery system.