Study Set Content:
Found in pharmaceutics including homomeric crystals and heteromeric crystals
solvates, salt crystals and cocrystals
when a solvent is incorporated into the lattice
Solvates
- lattice accommodate other molecules, such as acids and bases, toformsalts
Salt Crystals
In the solid, the two ionized compounds will interact in the lattice to forma crystallinesalt.
Salt Crystals
A homogeneous, multicomponent phase of fixed stoichiometry where the chemical entities are held together in a crystal lattice by intermolecular forces
Cocrystal
Solid material is referred to as amorphous, when there is no long-range order over many molecular units to produce a lattice or crystalline structure.
Amorphous Solid
These solids are referred to as glasses (nonequilibrium solid form) or possibly as
supercoiled liquids
(a viscous equilibrium liquid form)
(a viscous equilibrium liquid form
These solids are referred to as glasses (nonequilibrium solid form) or possibly as supercoiled liquids (a viscous equilibrium liquid form) because of the random order of arrangement and the distortion of the shape under pressure.
Amorphous Solid
exhibit similar properties in all directions (amorphous and cubic crystals)
Isotropic
– showing different characteristics (electric conductance, refractive index, rate of solubility) in various directions along the crystal
Anisotropic
– appears to be amorphous, assume crystalline arrangement when heated and then allow to cool slowly)
(beeswax and paraffin
contains both crystalline and amorphous
Petrolatum
– crystalline form/amorphous form
Antibiotic (Novobiocin acid)
Do not possess a melting point but are defined by a glass transition (Tg) temperature, which is the temperature where amorphous material converts from a glass to a supercooled liquid upon heating
Amorphous Materials
Because of the relative weakness of the interactions between its molecule, amorphous materials are less physically stable than crystalline materials
Amorphous Materials
are large molecules formed by the covalent assembly of smaller molecules (monomers) into a chain or network of repeating structural units
Polymers
– rubber, polypeptides and cellulose
a. Natura
– plastics used in packaging and devices (polyvinylchloride, polyethylene, and polystyrene) and those used in controlled release devices
Synthetic and Semisynthetic
uses of Polymers
a) Help stabilize the amorphous drug in the solid state and may help prevent crystallization upon dissolution.
b) The drug: polymer ratio is an important consideration when making dispersion and can be influenced by the polymer used.
c) Used as excipients in solid, semisolid, and liquid formulations.
