Drug release from pellets

A popular theory with azo materials is that their degradation products are always aromatic amines, like azo dyes. Ueda and co-workers observed that the azo bonds in segmented polyurethenes were reduced to hydrazo intermediates after incubation with human feces, since no decrease in the molecular weight was observed [73]. It was then theorized that drug release from pellets coated with these azo polymers was due to both a conformational change and a breakdown of the film structure. Other studies also concluded that the polymers were reduced to hydrazo intermediates or were completely degraded to aromatic amines depending upon their hydrophilic/ hydrophobic nature. 

Husson, I., Leclerc, B., Spenlehauer, G., Veillard, M., and Couarraze, G. (1991), Modeling of drug release from pellets coated with an insoluble polymeric membrane, J. Controlled Release, 17,163-173. 

Lippold, B.H. Sutter, B.K. Lippold, B.C. Parameters controlling drug release from pellets coated with aqueous ethyl cellulose dispersions. Int. J. Pharm. 1989, 54, 15-25. 

Sadeghi F, Ford JF, Rubinstein MH, Rajabi-Siahboomi AR. Study of drug release from pellets coated with surelease containing hydroxypropylmethylcellulose. Drug Dev Ind Pharm 2001 27(5) 419 30. 

There are several approaches to identifying the mechanism of drug release from pellets. For example, O Connor and Schwartz (130) applied the approach of Higuchi (131) to show that for a series of pellet formulations, they behaved as an inert matrix with a linear... 

Bodmeier R, Guo X, Pacratakul O. Process and formulational factors affecting the drug release from pellets coated with the ethylcellulose-pseudolatex aquacoat. In McGinity JW, ed. Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms. 2nd ed. New York Marcel Dekkcr, Inc., 1997 55-80. 

Serratoni, M., Newton, M., Booth, S., Clarke, A., 2007. Controlled drug release from pellets containing water-insoluble drugs dissolved in a self-emulsifying system. Eur. J. Pharm. Biopharm. 65, 94—98. 

Farag Y, Leopold CS. Investigation of drug release from pellets coated with different shellac... 

A reported application of canonical analysis involved a novel combination of the canonical form of the regression equation with a computer-aided grid search technique to optimize controlled drug release from a pellet system prepared by extrusion and spheronization [28,29]. Formulation factors were used as independent variables, and in vitro dissolution was the main response, or dependent variable. Both a minimum and a maximum drug release rate was predicted and verified by preparation and testing of the predicted formulations. Excellent agreement between the predicted values and the actual values was evident for the four-component pellet system in this study. 

The physical properties of pellets have been widely used to determine an acceptable yield of pellets. These include shape indices, size and size distribution, densities, pore volume and distribution, flow properties, and friability. Of course, drug release from the pellets is a critical parameter to be monitored in order to ensure potency and uniformity of drug distribution. 

Hellen L, Yliruusi J. Process variables of instant granulator and spheroniser III. Shape and shape distributions of pellets. Int J Pharm 1993 96 217-223. Chapman SR, Rowe RC, Newton JM. Characterization of the sphericity of particles by the one plane critical stability. J Pharm Pharmacol 1988 40 503-505. Rowe RC, Sadeghnejad GR. The rheology of mcc powder/water mixes-measurement using a mixer torque rheometer. Int J Pharm 1987 38 227-229. O Connor RE, Schwartz JB. Spheronization II Drug release from drug-diluent mixtures. Drug Dev Ind Pharm 1985 11 (9-10) 1837-1857. 

Fig. 2 Change in drug release from theophylline pellets coated with Eudragit RS 30 D containing 5% Pharmacoat 606 and either (A) 20% triethyl citrate or (B) 30% triethyl citrate after storage at 40°C/50% relative humidity. For (A) ( ) initial (A) 2 hr (T) 6 hr ( ) 24hr (x) 3 days ( ) 7 days (A) 10 days. For (B) ( ) initial (A) 3 hr ( ) 6 hr (0) 12 hr. (From Ref> l)...

Wesshng, M. Bodmeier, R. Influence of plasticization time, curing conditions, storage time, and core properties on the drug release from aquacoat-coated pellets. Pharm. Dev. Technol. 2001, 6 (3), 325-331. 

Factors Affecting Drug Release from Sustained-Release Film-Coated Pellets Using Acrylic Aqueous Dispersions, 6th International Conference on Pharmaceutical Technology, June, 2, 1992. 

Heng PW, Hao JS, Chan LW, Chen SH. Influence of osmotic agents in diffusion layer on drug release from multilayer coated pellets. Drug Dev Ind Pharm 2004 30(2) 213-220. 

Blanque D. Stemagel H, Podczeck F el al. Some factors Influencing the formation and in vitro drug release from matrix pellets prepared by extrusion/spheronizatton. Int J Pharm 1995 119 203-11. 

R. O. Williams III, M. Sriwongjanya, J. Liu, An in vitro metbod to investigate food effects on drug release from film-coated beads, Pharm Dev Technol 2 1-9 (1997). G. M. Clarke, J. M. Newton, Gastrointestinal transit of pellets of differing size and density, Int J Pharm 700 81-92 (1993). 

Koerber, M., Hoffart, V., Walther, M., Macrae, R.J., Bodmeier, R. Effect of unconventional curing conditions and storage on pellets coated with Aquacoat ECD. Drug Dev. Ind. Pharm. 2010, 36(2), 190-199. Muschert, S., Siepmann, R, Leclercq, B., Carlin, B., Siepmann, J. Simulated food effects on drug release from ethylcellulose PVA-PEG graft copolymer-coated pellets. Drug Dev. Ind. Pharm. 2010, 36(2), 173-179. 

In vitro drug release from double coated pellets is 66.6% at 7 hr of dissolution which increases to 100.2% when drug release is studied in the presence of enzymes. 

H. Kranz, K. Jurgens, M. Pinier, and J. Siepmann, Drug release from MCC- and carrageenan-based pellets Experiment and theory, Eur. J. Pharm. Biopharm., 73 (2), 302-309,2009. 

Y. Karrout, C. Neut, D. Wils, F. Siepmann, L. Deremaux, M.-P. Flament, L. Dubreuil, P. Desreumaux, and J. Siepmann, Novel polymeric film coatings for colon targeting Drug release from coated pellets, Eur. J. Pharm. Sci. 37 427-433, 2009. 

A. Ghaffari, M.R. Avadi, H.R. Moghimi, M. Oskoui, K. Bayati, M. Rafiee-Tehrani. Mechanistic analysis of drug release from theophylline pellets coated by films containing pectin, chitosan and Eudragit RS. Drug Dev Ind Pharm. 34 (4) 390-402,2008. 

J.A. (2009) Monitoring the film coating thickness and drug layer uniformity on in-vitro drug release from sustained-release coated pellets a case study using terahertz pulsed imaging. /. Pharm. Sci, 98 (12), 4866-4876. 

Amylose, another natural polysaccharide, prepared under appropriate conditions, is not only able to produce films, but is also found to be resistant to the action of pancreatic a-amylase while remaining vulnerable to the colonic flora [82]. However, incorporation of ethylcellulose was necessary to prevent premature drug release through simple diffusion [83], In vitro release of 5-aminosalicylic acid from pellets coated with a mixture of amylose-ethylcellulose in a ratio of 1 4 was complete after 4 hr in a colonic fermenter. By contrast, it took more than 24 hr to release only 20% of the drug under conditions that mimic that of the stomach and of the small intestine. 

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