Pharmaceutical Powders Flashcards
Pharmaceutical powders
- Dusting powder
- Oral powder sachet
- Powder for reconstitution
- Inhalation products
- Bulk powders for tablets and capsules
Crystalline
- Sucrose molecules align and
form large ‘lattices’ of
molecules, with a regular
repeating structure (high stable) - Cool slowly to below melting point
- Melt ↔ freeze
Amorphous
- Molecules of a different size and shape get in the way of the sucrose molecules and stop crystals forming
- Rapid solidification
- Increase solubility and dissolution rate
- Glassy ↔ rubbery
Polymorphism
- Different molecular packing
arrangements in crystal lattice - Form I - staggered
- Form II - linear
X-ray diffraction
- Each crystal has a characteristic pattern of diffraction angles and
intensity of the diffracted
beam
Comparison of x-ray differaction amorphous vs crystalline vs polymorphic
- High intensity narrow peaks for crysalline
- Lots of peaks and dips for polymorphic
- Low intensity broad peak for amorphous
What happens when water is present in crystal lattice
hydrated
- Due to small molecular size
of water and multidirectional hydrogen bonding capability of water - Anhydrous = no water
What happens when If solvents are present in
the crystal lattice
- DMSO
- Ethanol converting into ethanolate
Hydrate example
- Each tablet contains lisinopril dihydrate equivalent to 10 mg anhydrous lisinopril
Salt form effect on solubility
- Increase solubility and dissolution rate of acidic and basic drugs
Salt form example
- Amlodipine besilate
equivalent to 10 mg of amlodipine
Co-crystals
- Two or more molecules within the same
crystal lattice - Definite stoichiometric ratio which is not based on covalent bond
Example of co-crystals
- Sidenafil and aspirin combination treatment of both erectyle disfunction and antiplatelet
Primary power properties
- Particle size surface area and shape
- Content uniformity, dissolution rate and flow mix rate
Secondary powder properties
- Density determines size of tablet
- Porosity - compressiblity and perameablity
- Flowability and compressability
Diameter measurement
- Feret diameter draw two tanget and measure
- Martins diameter diagonal measurement
- Sieve measure can it pass through the sieve
Stokes diameter
- Density does it settle at the same rate velocity
Aerodynamic diameter
- Same terminal velocity measure in air or some other relevant fluid as the particle
What particle measure ment would you use for arosol deposition
- Aerodynamic diameter
Which particle diameter measurement for sedimentation
- Strokes diameter
Particle shape
- Solid irregular
- Porous irregular - more surface area exposed for absorption in water
One dimensional shape of particle
- Acicular
- Rod shaped - increase mechanical strength of tablet interlock
Two dimentional shapes
- Flaky - Stay cohesive stick together due to large SA
- Dendric
Three dimentional shape
- Porus
- Angular
- Spherical
- Rounded - Easier to mix and combine together
Specific surface area per weight
- Weight specific surface are = surface area/weight
- Lots of small cubes absorbtion SA/V ratio
Surface area measurement:
Brunauer–Emmett–Teller theory
- Powder is filled into a
vacuum-sealed
chamber - Small amounts of nitrogen gas are added to the chamber
- The nitrogen molecules adsorb to
the surface of the powder and entire surface covered - Amount of gas adsorbed from
which the surface area can be
calculated
