This post is writing during the teaching of the professors from The University of Manchester.
2A Molecules to Materials and Medicines
Surfaces and Shape
- flow properties, important in manufacturing Including tableting and capsule production: The shape of particles affects the flowability of powders, which is critical during the manufacturing process. Spherical particles generally offer better flow properties compared to irregularly shaped particles.
- rate of dissolution: The surface area of a drug particle directly affects its dissolution rate. This can enhance bioavailability.
Crystallinity
- Product stability: A crystal is generally the most stable form of the medicine
- Alter (reduce) dissolution rate
Ritonavir (Norvir)
protease inhibitor used for HIV patients, used in combination therapy
has a crystal in product
found to be a new (lower energy) crystal form (form II) with lower dissolution rate
reduce the energy
Packing of Molecules
- crystals more stable form, better for formulation
- amorphous material will convert into crystalline material over time
Chemical Composition
hard gelatin capsules
- made of gelatin, sugar and water
- can be clear, colourless, and essentially tasteless
- can be coloured with various dyes e.g. FD&C and D&C and made opaque by agents such as titanium dioxide
- most commercially available capsules contain a combination of colorants and/or opaquants to make them distinctive
soft gelatin capsules
- made from gelatin (增塑剂) to which glycerin or polyhydric alcohol (non-volatile plasticizer) such as sorbitol has been added
- contain more moisture than hard capsules
- may contain a preservative, e.g. methylparaben and/or propylparaben, to retard microbial growth.
Reproducibility
Ideal Viscosity Behaviour
‘Custard’ is a viscous, weak gel that flows freely under little stress, becoming almost solid under high stress, i.e. its viscosity is not constant. It is known as a shear thickening (or thixotropic) fluid. 切变稠化
Possess a non-newtonian viscosity, which is dependent upon stress, becoming less viscous upon shaking, i.e. shear thinning. 非牛顿流体 剪切稀化
Increasing viscosity can increase residence time of eye drops. It also can cause discomfort and blurring. The ideal formulation should be viscous at low shear rates, such as when the eyes are opened, to prevent removal of the lubricants from the eye surface.
2B Pre-formulation
Pre-formulation
API: Active Pharmaceutical Ingredients
Rheology
glass is liquid
