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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 10 (1993), S. 525-534 
    ISSN: 1573-904X
    Keywords: factorial experimental design ; response surface methodology (RSM) ; ethylcellulose ; Surelease ; ibuprofen ; fluid-bed coating ; latex film ; microindentation hardness ; zero-order drug release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Formulation and process variables play an important role in the film-forming properties of coating polymers. Three selected independent coating process variables, namely, percent solids content in the coating polymeric dispersion, inlet-air temperature, and spray rate of the polymeric dispersion, were investigated in this study to determine their effect on the performance characteristics of tablets coated with a plasticized aqueous ethylcellulose dispersion (Surelease) in a fluid-bed equipment. Response surface methodology (RSM) was utilized to study the complex relationship between these process variables and selected response variables. Three response variables were considered, namely, rate of drug release from the “untreated” coated tablets and the “thermal-treated” coated tablets and microindentation hardness of the untreated coated tablets. A 12-point factorial experimental design was utilized, and three-dimensional (3-D) response surface plots were generated using a second-order polynomial model. The model provided information needed to predict optimal process conditions. Drug release from the coated tablets followed zero-order kinetics. Inlet-air temperature was found to be the most critical process variable for all the three response variables studied. A correlation was observed between the drug release rate and the microindentation hardness of the applied polymeric coat in the case of untreated coated tablets. The 3-D response surface plots indicated that lower rates of drug release from the coated tablets may be obtained by using high inlet-air temperature and low spray rate of the polymeric dispersion during coating.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 10 (1993), S. 810-815 
    ISSN: 1573-904X
    Keywords: ethylcellulose ; Surelease ; dibutyl sebacate ; glyceryl tricaprylate/caprate ; cast films ; mechanical properties ; tensile strength ; work of failure ; elastic modulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Free films of two commercially available formulations of aqueous ethylcellulose dispersion differing only in plasticizer content (Surelease/E-7-7050 without silica and E-7-7060 containing dibutyl sebacate and glyceryl tricaprylate/caprate as plasticizers, respectively) were cast and coalesced at temperatures ranging between 30 and 70°C. Mechanical properties of these films were measured using tensile stress analysis. Three mechanical parameters, namely, tensile strength, work of failure, and elastic modulus, were computed from the load-time profiles of these films. The results showed that the tensile strength and elastic modulus values of the films cast from both formulations increased with the corresponding increase in coalescence temperature up to 60°C, beyond which no significant differences were observed. In the case of work of failure, however, the difference between the two formulations was observed above 60°C. The films cast from Surelease/E-7-7050 formulation without silica (dibutyl sebacate as the plasticizer) were relatively softer than those from Surelease/E-7-7060 formulation (glyceryl tricaprylate/caprate as the plasticizer). At coalescence temperatures above 50°C, the films cast from both formulations exhibited temperature-dependent plastic deformation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 9 (1992), S. 1351-1358 
    ISSN: 1573-904X
    Keywords: powdered solution technology ; powdered solutions of drugs ; flowable liquid-retention potential (Φ value) ; carrier material ; coating material ; excipient ratio (R) ; liquid layer ; mono- and multilayer coating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The concept of powdered solutions can be used to formulate liquid medications in dry, nonadherent, free-flowing, and readily compressible powders. The technique is based on simple admixture of drug solution or liquid drug with selected carrier and coating materials. Improved drug release profiles are exhibited by such delivery systems even for poorly water-soluble drugs. Previous work using this method has rendered its industrial application impractical because of the unsatisfactory flow properties of the powder admixtures. This article presents a theoretical model based on the principles and mechanism of powdered solutions and introduces a new physical property of powders termed the flowable liquid-retention potential (Φ value). Mathematical expressions are derived that can be used to calculate the optimum amount of excipients required to yield powder admixtures with acceptable flowability. The validity and applicability of these expressions have been verified experimentally using clofibrate and prednisolone as test materials. The proposed model is shown to be superior to previously reported studies in optimizing the amount of excipients needed to prepare powdered solutions with acceptable flow properties.
    Type of Medium: Electronic Resource
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