Nifedipine loaded chitosan microspheres prepared by emulsification phase-separation.
A high yield of nifedipine-chitosan microspheres could be obtained using an emulsification phase-separation method. A high level of entrapment of nifedipine in the microspheres was achieved. The microspheres exhibited excellent swelling properties. Differential scanning calorimetry, X-ray diffractometry, and scanning electron microscopy confirmed that at 1.84% loading, nifedipine was dispersed molecularly. The microspheres exhibited faster release at low loadings compared to high loadings. Fitting the data to the coupled Fickian/case II equation, showed that at low loadings polymer relaxation coefficients (k2) were high. As the polymer content increased in the microspheres, the value of n (diffusional exponent characteristic of the release mechanism) approached one, which is indicative of zero order.
Dhawan
S
S
University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India 160014. kdd@glide.net.in
Singla
A K
AK
D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000302:isolation & purification; D048271:Chitosan; D003692:Delayed-Action Preparations / Q000737:chemistry; D004337:Drug Carriers / Q000302:isolation & purification; D016503:Drug Delivery Systems / Q000379:methods*; D006601:Hexoses / Q000494:pharmacology; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009543:Nifedipine / Q000008:administration & dosage* / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility; D013997:Time Factors
D003692:Delayed-Action Preparations; D004337:Drug Carriers; D006601:Hexoses; D002686:Chitin; D048271:Chitosan; D009543:Nifedipine; C005693:sorbitan trioleate