part 7: SOLIDS

1. Strong intermolecular forces of attraction

2. Have little kinetic energy

3. Incompressible

4. They possess fixed/definite shape

5. Translational motion is little

1. Strong intermolecular forces of attraction

2. Have little kinetic energy

3. Incompressible

4. They possess fixed/definite shape

5. Translational motion is little

Characteristics of Solids

1. Crystalline Solids

2. Amorphous

3. Polymeric

3 types of Solids

Crystalline Solids

• Arranged in repetitious three-dimensional lattice units

• Definite melting points

Unit cells

There are 7 common lattice units or ___________

Anisotropic

Unidentical/different properties for different directions (DIRECTIONAL)

Lattice point

Each point in Crystal Lattice

1. Cubic

2. Tetragonal

3. Orthorhombic

4. Rhombohedral/Rhombic

5. Hexagonal

6. Monoclinic

7. Triclinic

7 Crystal Systems for Crystalline Solids

Sodium chloride

Unit cell: Cubic

Urea

Unit cell: Tetragonal

Ritonavir (form II)

Unit cell: Orthorhombic

Iodine

Unit cell: Rhombohedral/Rhombic

Iodoform

Unit cell: Hexagonal

Sucrose

Unit cell: Monoclinic

Boric acid

Unit cell: Triclinic

Glasses or Supercooled liquids

Amorphous solids are also known as?

Amorphous Solids

• Randomly arranged constituent particles and have no ordered long-range structure

• Do not have definite melting points

Isotropic

Identical properties in any direction

1. Glass

2. Wood

3. Plastics

Example of Amorphous Solids

Polymers

Polymeric Solids are also known as?

Polymeric Solids

Large molecules formed by the covalent assembly of smaller molecules (Monomers) into a chain or network of repeating structural units

1. Molecular weight

2. Size

The number of repeating units in the polymer determines its __________and ___________

1. Natural polymers

2. Synthetic and Semisynthetic polymers

Types of Polymers

1. Rubber (Polyisoprene)

2. Polypeptides

3. Cellulose (Polysaccharide)

Natural Polymers

1. PVP

2. PE

3. PS

Synthetic and Semisynthetic Polymers

Polymers

Are used as excipients in solid, semisolid, and liquid formulations

1. Grade

2. Molecular weight

The properties of a polymer will change depending on the ____________ or ____________ of the polymer

Low molecular weight PEG

Co-solvent for solution formulations

High molecular weight PEG

Ointment and suppository bases

Polymorphism

• Ability to exist in more than one crystalline form due to changes in the:

  • Intermolecular bonding patterns

  • Molecular orientation difference

  • Two forms: Dimorphic

  • Three forms: Trimorphic

• Different properties:

  • Solubilities

  • Stability

  • Melting point

  • X-ray diffractions

• Different drug outcomes:

  • Drug efficacy

  • Bioavailability

  • Toxicity

1. Unstable gamma

2. Alpha

3. Beta prime

4. Beta stable

Polymorphic forms of Cocoa Butter

18°C

Cocoa Butter polymorphic form: Unstable gamma

22°C

Cocoa Butter polymorphic form: Alpha

28°C

Cocoa Butter polymorphic form: Beta prime

34.5°C

Cocoa Butter polymorphic form: Beta stable

Beta stable

Polymorphic form of Cocoa Butter that is used as a suppository base

1. Tamoxifen citrate

2. Famotidine

3. Phenytoin

4. Indomethacin

Drugs studied for Polymorphism

2

Number of Polymorphic form of Tamoxifen citrate

3

Number of Polymorphic form of Famotidine

2

Number of Polymorphic form of Phenytoin

3

Number of Polymorphic form of Indomethacin

Form B

Bioavailable form of Tamoxifen citrate

II

Bioavailable form of Famotidine

I

Bioavailable form of Phenytoin

I and II

Bioavailable form of Indomethacin

1. Enantiotropic

2. Monotropic

Types of Polymorphism

Enantiotropic

• Reversible change (One polymorph can be reversibly changed into another by varying either Temperature or Pressure

• Metastable ⇄ Stable

• More than one polymorph is stable under different conditions

Monotropic

• Irreversible change

• Metastable → Stable

• Only one polymorph is thermodynamically stable

Aspirin

Example of Enantiotropic Polymorphism

Cocoa Butter

Example of Monotropic Polymorphism

Beta

Most stable polymorphic form of Cocoa Butter

a. Gamma

b. Alpha

c. Beta

d. Omega