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What are the two main types of solid phases?
Crystalline and amorphous
Define crystalline solids.
Solids with particles arranged in a regular, repeating lattice structure
Define amorphous solids
Solids with no long-range molecular order, leading to a more random particle arrangement
Why is solubility important in pharmaceutics?
Poor solubility leads to poor absorption, reduced bioavailability, and increased drug development costs
What are unit cells?
The smallest repeating structure in a crystal lattice
Name the most common types of unit cells in pharmaceutics.
Triclinic, monoclinic, and orthorhombic
What are the characteristics of crystalline solids?
Thermodynamically stable, sharp melting points, and low solubility
Provide an example of a crystalline solid used in pharmaceuticals.
Sodium chloride
What is the glass transition temperature (Tg)?
The temperature at which an amorphous solid transitions from a brittle state to a rubbery state
Why are amorphous solids often used in drug formulations?
They exhibit higher solubility, faster dissolution rates, and improved bioavailability
What are common examples of amorphous materials?
Glass, rubber, and certain polymers
What is polymorphism?
The ability of a solid to exist in more than one crystalline form with different physical and chemical properties
Provide an example of a drug affected by polymorphism.
Ritonavir, where polymorphic changes caused solubility and bioavailability issues
How does polymorphism affect drug properties?
It influences solubility, stability, melting point, and bioavailability
What is the significance of Form I and Form II in polymorphism?
Form I is typically the most stable, while Form II may exhibit higher solubility but lower stability
How do crystalline and amorphous solids differ in stability?
Crystalline solids are more thermodynamically stable, while amorphous solids are less stable and prone to crystallization
Compare the solubility of crystalline and amorphous solids.
Amorphous solids generally have higher solubility than crystalline solids
Which solid type is preferred for drugs with poor water solubility?
Amorphous forms are preferred to enhance bioavailability
What is a disadvantage of using amorphous solids in formulations?
They are less stable and may revert to crystalline forms over time
How does the solubility of a drug affect its bioavailability?
Higher solubility improves absorption and bioavailability
What is the impact of poor solubility during drug development?
It can lead to rejection in clinical trials, increasing costs and development time
Why is flowability important in drug formulation?
It affects the manufacturability and quality of solid dosage forms
How can polymorphism influence drug manufacturing?
Different polymorphs may have varied flow properties and compressibility
What is dissolution rate, and why is it important?
The speed at which a drug dissolves, critical for its absorption
How does solubility depend on pH?
Drugs may have pH-dependent solubility, affecting absorption at physiological pH
What factors influence solubility in polymorphs?
Packing efficiency, intermolecular interactions, and Gibbs free energy
Why is the most stable polymorph often used in formulations?
It minimizes the risk of conversion to other forms during storage
How can metastable polymorphs benefit drug formulations?
They may enhance solubility and bioavailability despite lower stability
How did polymorphism affect the development of Ritonavir?
A less soluble polymorph (Form II) appeared post-market, leading to reduced bioavailability and financial losses
What are the challenges of using polymorphs in bioequivalence?
Different polymorphs can result in varying dissolution rates and therapeutic efficacy
