Cyclodextrins Essay

1605 Words 7 Pages
Cyclodextrins are enzymatically modified starches composed of glycopynanose units which form a ring of either six (α-cyclodextrin), seven (β-cyclodextrin) or eight (γ-cyclodextrins) units. Characteristics of β-cyclodextrins include:
• Glucose unit: 07
• Molecular weight: 1135
• Solubility =1.85g/100ml
• Cavity diameter = 6.4 Ǻ
• Diameter of outer periphery = 15.4 Ǻ
• Approx. volume of cavity = 262 (Ǻ)3
Cyclodextrins have a cylindrical shape with central axial cavity and resembles the shape of a truncated cone. The outer surface of the ring is hydrophilic and the inner cavity of the ring is hydrophobic. Lipophilic molecules fit into the ring to form soluble inclusion complexes. The ring of β-cylcodextrin is the correct size for the majority
…show more content…
Why is it considered one of the most widely applied processing technique in the pharmaceutical industry? Use an example to illustrate your point.
Melt granulation is an alternative to the traditional wet granulation; this is where we find thermosetting polymers being used to form granules. It is also a size enlargement process were a thermosetting material (hot-melt binder) is used to bind the primary powder particles into granules. Melt granulation also translates to the absence of water therefore, it is a water-free alternative to wet granulation. The binder/granulating agent is a semi-solid or solid hydrophilic polymer or a hydrophobic wax. (Michael E. Aulton,
…show more content…
When pressure is relieved, crystallization will taker place, binding the particles together.
• hardening binders: common pharmaceutical mechanism in wet granulations. This is when an adhesive is included in the granulating solvent. The liquid forms liquid bridges while the adhesive will harden or crystallize on drying to form solid bridges to bind the particles. Adhesives such as polyvinylpyrrolidone, the cellulose derivatives (such as carboxymethylcellulose) and pregelatinized starch function in this way.
• Crystallization of dissolved substances: when the granules dry, crystallisation of this material takes place and the dissolved substance acts as a hardening binder. Any material in the granulating liquid will function in the manner, e.g. lactose incorporated into powder blends granulated with water. The size of the crystals produced in the bridge will be in influenced by the rate of drying of the granules; the slower the drying time, the larger the particle size. Therefore, it is important that the drug not dissolve in the granulating liquid and recrystallize, as this may adversely affect the dissolution rate of the

Related Documents