ABSTRACT
The present study was conducted to examine the physicochemical changes during passage of drug through polymeric membranes and observe the surface morphology features of the coated pellets using scanning electron microscopy (SEM). Drug solution was first sprayed around inert pellets to form drug-layered pellets that were coated with two commercial aqueous dispersions namely, Eudragit NE30 and Kollicoat SR30 using bottom-spray fluidized bed technique. Differential scanning calorimetry (DSC) confirmed that no interactions existed between drug and polymers. Small peak of drug was observed in the DSC thermograms of Eudragit NE30 coated pellets indicating that small amount of drug was still present in the polymeric membrane after dissolution. Views of SEM revealed as the coating levels of two types of aqueous dispersions were increased the surface of the pellets become more uniform and compact. Therefore, the diffusion length for dissolution medium to enter the drug layer and dissolved drug to diffuse out would be increased at higher coating levels. The polymer surface of coated pellets after 12 hours dissolution testing seemed to be shrunk and size of the pellets were also reduced indicating the depletion of reservoir layer.
Subject(s)
Calorimetry, Differential Scanning/methods , Delayed-Action Preparations/chemistry , Chemistry, Pharmaceutical/methods , Delayed-Action Preparations/pharmacokinetics , Diffusion , Diltiazem/chemistry , Diltiazem/pharmacokinetics , Drug Carriers/chemistry , Drug Carriers/pharmacokinetics , Drug Compounding/methods , Drug Delivery Systems , Excipients/chemistry , Methacrylates/chemistry , Methacrylates/pharmacokinetics , Microscopy, Electron, Scanning , Particle Size , Polymers/chemistry , Polymers/pharmacokinetics , Polymethacrylic Acids/chemistry , Polymethacrylic Acids/pharmacokinetics , Polyvinyls/chemistry , Polyvinyls/pharmacokinetics , Solubility , Time Factors , Transition Temperature , Water/chemistryABSTRACT
The test formulation of controlled release diltiazem pellets was evaluated in vivo, in comparison with Herbesser SR. Six healthy volunteers participated in the study, conducted according to a randomized, two-way crossover study design. The preparations were compared using the pharmacokinetic parameters plasma concentration-time curve (AUC(0- infinity)), peak plasma concentration (Cmax) and time to reach maximum plasma concentration (Tmax) were estimated from the plasma concentration-time profiles for each volunteer. The test formulation was found to be comparable with the Herbesser SR in the extent of bioavailability but differ in the rate of absorption, the test formulation being less sustained. No lag time was observed in any of the volunteers indicating that both formulations started to release their drug content immediately upon rupture of the capsule but in sustained manner. Moreover, the values of pharmacokinetic parameters obtained were comparable to those reported in the literature.
