Controlled-release properties

Leonard M, Boisseson MRD, Hubert P et al (2004) Hydrophobically modified alginate hydrogels as protein carriers with specific controlled release properties. J Control Release 98 395 105... 

As a general rule, do not divide sustained/controlled release medications as they may lose their controlled release properties. However, there may be some exceptions to this rule. For example, Calan SR 240 tablets which are to be given once daily can be split to administer 120 mg (or A tablet) twice daily. Therefore, unless specifically suggested by the manufacturer, controlled release tablets should not be crushed or broken. 

Native starches are used as disintegrants, diluents, and wet binders. However, their poor flow and high lubricant sensitivity make them less favorable in direct compression. Different chemical, mechanical, and physical modifications of native starches have been used to improve both their direct compression and controlled-release properties (Sanghvi, 1993 van Aerde and Remon, 1988). Schinzinger and Schmidt (2005) used potato starch as an excipient and compared its granulating behavior with a-lactose-monohydrate and di-calcium phosphate anhydrous in a laboratory fluidized bed granulator using statistical methods. 

Safety and efficacy are two more general pharmaceutical product requirements, as is reproducibility of performance. This last-named requires that the product produces the same response on multiple administrations of the same batch or from batch to batch and to some extent implies there is uniformity of content and reproducibility. The same implication applies to products that have some form of controlled release properties the inference is that the rates of release of the incorporated drug are similar under all circumstances. 

Mesoporous silica containers can be used as inhibitor hosts with controlled release properties triggered at the beginning of the corrosion process in response to local pH changes. For instance, mesoporous silica nanoparticles covered with polyelectrolyte layers can be loaded with an inhibitor (2-(benzothiazol-2-ylsulfanyl)-succinic acid) prior to introduction into a hybrid zirconia-silica sol-gel film. This hierarchical design avoids spontaneous release of the inhibitor by the formation of a polyelectrolyte shell over the container s outermost surface. 

The pH sensitivity of halloysite can be enhanced by using retardant polymers, a cationic coating for the formation of a pH-sensitive polyelectrolyte shell on the nanotubes after their saturation with corrosion inhibitor. To equip the halloysite nanotubes with controlled release properties, the surface of the nanotubes was first loaded with benzotriazole and subsequently modified by LbL deposition of two polyelectrolyte bilayers, thus blocking the tubes openings with polyelectrolytes. 

Tuning the properties of each generation to complement those of particular guest molecules makes it possible to bind those guests and then let them dissociate at a known rate. This controlled release property makes dendrimers potential candidates as drug delivery agents as illustrated in Fig. 7.8 [23],... 

Niosomal antigens are potent stimulators of the cellular and humoral immune response. The formulation of antigens as a niosome in W/O emulsions further increases the activity of antigens. The controlled-release property of these types of emulsion formulations is responsible for enhancing the immunological responses. 

Fabrication of protein nanotubes has the potential to lead food science and engineering to new heights. However further studies need to be conducted to fulfill the promise in many potential food applications. Interactions of nanotubes with the materials to be encapsulated— their structures, characteristics and controlled release properties—should be studied using the model or actual food systems. Another important area of future research is the investigation of the self-assembly characteristics of other food proteins that can be used for similar purposes. 

Do not break or chew( XR tablets as this will alter controlled release properties... 

Paroxetine CR tablets not scored, so chewing or cutting in half can destroy controlled release properties... 

Tardi C, Brandi M, Schubert R (1998) Erosion and controlled release properties of semisoHd vesicular phospholipid dispersions. J Control Release (2-3 ) 261-270... 

Granulates Flavour emulsion sprayed on nucleus agglomeration in fluid bed dryer optionally caoting of particles. Dry, free-flowing product Good oxidative stability of encapsulated flavour Intermediate particle size Limited controlled release properties (coatings)... 

Fat encapsulation Flavour composition adsobed by Uquid of solid tat tat dispersed or solidified into small particles No significant protection of encapsulated flavour Particles sensitive to mechanical forces and temperature Flexible particle size Limited controlled release properties... 

This technique could be extremely important for assessing the controlled-release properties of a solid oral dosage form. The homogeneity and quality of the manufacturing process could be determined. Also, this technique could be applied to the analysis of the surface of beads, tablets, and granulations, allowing the chemical composition of more than one layer to be evaluated. 

Principally, encapsulation of proteins within the aqueous lumen of polymersomes can benefit from the extended circulation kinetics and controlled release properties of polymersomes. Neutral diblock (PEO-PDB, PEO-PEE), charged triblock (PEO-... 

NLC have been proposed as the SLN of a new generation, with higher drug loadings and controlled release properties [75,76], Several structures were proposed, including the presence of oil droplets in a solid lipid matrix (which should combine... 

For food applications of inclusion complexes, a controlled release property is of importance. This is true for many food products, such as microwave entrees, snacks, and desserts. The pharmaceutical industry has also utilized the technique as a drug delivery system. However, the release kinetics of guest compounds from the inclusion complex powders has not yet been fully understood. 

Figure 1.24a shows the retention of AITC included in a-, p-, and y-CD against the release time at 50°C and 15% RH. The AITC included in a-CD exhibited an extended release. After 25 h, 60% of the initial amount of AITC still remained in the powder at such a high temperature and humidity. On the other hand, the AITC included both in P- and y-CD released significantly during the initial period of release, showing a quantitatively similar release behavior in both cases. This implies that the AITC included in a-CD had good controlled released properties. Qualitatively similar results are observed for D-limonene included in the native CDs, as shown in Figure 1.24b. These results imply that the release characteristics of included flavors in CDs depend on the combination of the types of flavors and CDs.

Microencapsulation (Chapter 5, [B.33, B.67, B.97]) is another one of the methods to obtain products vfith controlled release properties. It allows to isolate an active component from external media by forming a polymeric network or differently structured... 

Alvarez-Lorenzo, C., Concheiro, A., and Dubovik, A.S. 2005. Temperature-sensitive chitosan-poly(N-isopro-pylacrylamide) interpenetrated networks with enhanced loading capacity and controlled release properties. J Control Release. 102 629-641. 

Liu, W., Wu, W.D., Selomulya, C., and Chen, X.D. Facile spray-drying assembly of uniform microencapsulates with tunable core-shell structures and controlled release properties. Langmuir 21(21) (2011) 12910-12915. 

Fluid Bed Coating Is Commonly Used to Achieve a Controlled-Release Property for an Ingredient in the Core or Coating... 

Moustafine, R.I. Bukhovets, A.V. Sitenkov, A.Y. Kemenova, V.A. Rombaut, R Van den Mooter, G. Eudragit E PO as a complementary material for designing oral drug delivery systems with controlled release properties Comparative evaluation of new interpolyelectrolyte complexes with countercharged Eudragit LlOO copolymers. Mol. Pharm. 2013,10 (7), 2630-2641. 

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