The document discusses key concepts related to dosage form design and drug delivery including states of matter, binding forces between molecules, particle size analysis, powder flow properties, and properties of solutions. It defines terms such as solute, solvent, solution, and solubility. It also describes the process of dissolution and factors that influence dissolution rates.

1. PHA311 – MOT 2
Scientific principles of dosage form design and
drug delivery

2. Contents
• States of matter
• Definition of terms
• Binding forces between molecules
• Particle size analysis
• Powder flow properties
• Properties of Solutions
• Dissolution and solubility
• Solutions of Electrolytes and Non-electrolytes

3. Contents (continued)
• Introduction to dissolution and solubility
• Definition of terms
• The Process of Dissolution
• Dissolution Rates of Solute in Liquids
• Solubility

4. States of Matter
Solids, liquids, & Gases

5. States of Matter: one of the forms that
matter takes, such a solid, liquid or gas.

6. MATTER
ChemicalProperties PhysicalProperties
all matter has
Mass
Volume
states
Solid
Liquid
Gas
flammability
oxidation
reactivity
toxicity
Density
Solubility
Volume
Melting Point
Freezing Point
can undergo
ChemicalChanges PhysicalChanges
identified by

7. State of matter: one of the forms that
matter takes, such as solid, liquid, or gas.
Solid: matter that has a fixed volume and
a fixed shape.
Liquid: matter that has a fixed volume but
not a fixed shape.
Gas: matter that has no fixed volume or
fixed shape.
Definition of terms

8. Phase Motion of Particles
How would you describe the movement
of these particles?
Speed of Particles
How would you describe the speed
of these particles?
Solid Particles vibrate in
place and are tightly
packed
Slow
Can we
act this
out?

9. We can look at these 3 properties to figure
out which state of matter an object is:
SHAPE … does it have a definite shape?
MASS … does it have a definite amount
of matter?
VOLUME … does it take up a definite
amount of space?

10. Phase Motion of Particles
How would you describe the movement
of these particles?
Speed of Particles
How would you describe the speed of
these particles?
Liquid Particles are close,
but can slide past
one another
Medium
Can we
act this
out?

11. Predictions anyone?
LIQUID
Definite
SHAPE?
Definite
MASS?
Definite
VOLUME?
YES
YES
NO

12. Phase Motion of Particles
How would you describe the movement
of these particles?
Speed of Particles
How would you describe the speed of
these particles?
Gas Particles are
constantly
expanding and far
apart
Fast
Can we
act this
out?

13. Predictions anyone?
GAS
Definite
SHAPE?
Definite
MASS?
Definite
VOLUME?
YES
NO
NO

14. A gas will spread out to fill all the
space in whatever container it is in.

15. Review
SOLID LIQUID GAS
Definite
SHAPE?
Definite
MASS?
Definite
VOLUME?
YES
YES
YES
YES
YES
YES
NO NO
NO

16. Review
Phase Motion of
Particles
Speed of
Particles
Solid
Liquid
Gas
Particles are close,
but can slide past
one another
Particles vibrate in
place and are tightly
packed
Particles are
constantly
expanding
Fast
Medium
Slow

17. Binding forces between molecules
•Repulsive and attractive forces
•Intramolecular forces
•Intermolecular forces
• Van der Waals forces
• Ion - ion interactions
• Hydrogen Bonds
•Bond energy

18. Repulsive and Attractive Forces
Repulsive and Attractive Forces
•For molecules to exist as aggregates in gases, liquids, and solids,
intermolecular forces must exist
•These intermolecular forces involve both attractive and repulsive
forces.
•These forces must be balanced in an energetically favoured
arrangement for the molecules to interact.

19. Intramolecular forces
• Atoms within a molecule are attracted to one another by sharing of
electrons, it can be categorized into:
1. Ionic bonding: between positively and negatively charged ions(metals and
non-metals).
2. Covalent bonding: between atoms that share the outer shell of electrons.
3. Metallic bonding: between positively charged ions and delocalized outer
electrons of metal elements, it is weaker than both ionic and covalent bonding.

20. Intermolecular forces
Intermolecular forces occur between molecules. It can be divided into:
1. Van der waals forces
2. Ion–dipole interaction
3. Ion–induced dipole interaction
4. Hydrogen bonds

21. Intermolecular forces
Van der Waals Forces
• Van der Waal interactions are weak forces that involve the dispersion
of charge across a molecule called a dipole.
Van der Waal interactions can be classified into:
• A. Dipole–dipole interaction, orientation effect, or Keesom force
• B. Dipole-induced dipole interaction, induction effect, or Debye force
• C. Induced dipole–induced dipole interaction, dispersion effect, or London
force

22. PARTICLE SIZE
• Particle size is characterized using these terms :
i. Very coarse (#8)
ii. Coarse (#20)
iii. Moderately coarse (#40)
iv. Fine (#60)
v. Very fine (#80)
2022/11/10 22

23. PARTICLE SIZE
• Particle size can influence variety of important factors :
- Dissolution rate
- Suspendability
- Uniform distribution
- Penetrability
- Lack of grittiness
2022/11/10 23

24. Methods to Determine Particle Size
• Sieving
• Microscopy
• Sedimentation rate method
• Light energy diffraction
• Laser holography
• Cascade impaction
2022/11/10 24

25. Methods to Determine Particle Size cont.
1. Sieving method :
• Range : 50 – 150 μm
• Simple, inexpensive
• If powder is not dry, the apertures get
clogged.
2022/11/10 25

26. Methods to Determine Particle Size cont.
2. Microscopy :
• Range : 0.2 – 100 μm
• Particle size can be determined by the use of
calibrated grid background.
• Most direct method.
• Slow & tedious method.
2022/11/10 26

27. 3. Sedimentation method :
• Range : 1 - 200 μm
• Andreasen pipette is used.
• Particle size is calculated by stoke’s law :
dst = √ {18 η0 h/(ρs-ρ0) gt}
dst = √ 18 η0 h
(ρs -ρ0) gt
Where,
h = distance of fall in time, t
no = viscosity of the medium
ρs = density of the particles
2022/11/10 27

28. Methods to Determine Particle Size cont.
4. Light energy diffraction :
• Range : 0.5 – 500 μm
• Particle size is determined by the reduction in light reaching the sensor as the
particle, dispersed in a liquid or gas, passes through the sensing zone.
• Quick & fast.
5. Laser holography :
• Range : 1.4 – 100 μm
• A pulsed laser is fired through an aerosolized particle spray & photographed in
three dimensional with holographic camera, allowing the particles to be
individually imaged & sized.
2022/11/10 28

29. POWDER FLOW PROPERTIES
• Powder flow properties can be affected by change in particle size, shape
& density.
• The flow properties depends upon following-
1. Force of friction.
2. Cohesion between one particle to another. ,
• Fine particle posses poor flow by filling void spaces between larger
particles causing packing & densification of particles.
• By using glident (gliding agent) we can alter the flow properties. e.g.
Starch
2022/11/10 29

30. Flow properties cont.
• Angle of Repose
• Determination Of Powder Flow Properties is done by determining
Angle Of Repose.
• A greater angle of repose indicate poor flow. 
• It should be less than 30°
• It can be determined by the following equation. tan θ = h/r. where, θ
= angle of repose. h=height of pile. r= radius.
• Angle Of Repose (In degree) Type Of Flow <25 Excellent 25-30 Good
30-40 Passable >40 Very poor
2022/11/10 30

31. 2022/11/10 31

32. 2022/11/10 32

33. Bulk characteristics
c) Densities
The ratio of mass to volume is known as density
Types of density:
(i) Bulk density: It is obtained by measuring the volume of known mass of powder that
passed through the screen.
(ii)Tapped density: It is obtained by mechanically tapping the measuring
cylinder containing powder.
(iii)True density: It actual density of the solid material.
(iv)Granule density: may affect compressibility, tablet porosity, disintegration,
dissolution
2022/11/10 33

34. Bulk characteristics
• d) compressibility
"Compressibility" of a powder can be defined as
the ability to decrease in volume under pressure
and "compactability as the ability of the powdered
material to be compressed into a tablet of specified
tensile strength.
• It can be used to predict the flow properties based
on density measurement.
• Carr’s index=Tapped density – pored density * 100
Tapped density
2022/11/10 34

35. Determination Of Powder Flow Properties
• Carr’s Index Type of flow
5-15 Excellent
12-16 Good
18-21 Fair To Passable
23-35 Poor
33-38 Very Poor
>40 Extremely Poor
2022/11/10 35

36. Introduction to Solubility and Dissolution
Solubility
• Solubility is a drug physical property that is crucial for therapeutic activity and
efficiency
• The drug is to be dissolved first for it to be absorbed
• Insoluble drugs are depicts erratic and incomplete absorption
• The solubility of acidic and basic compound are pH dependent D
Dissolution
• Dissolution refers to the prosess of a drug being disolved in the body fluids at the
site of absorption
• Dissolution when slow will be the absorption rate limiting parameter and in this
manner will influence drug bioavailability

37. Definition of terms
• Solution
• Solvent
• Solute
• Dissolved
• Dissolution
• Extent of dissolution
• Solubility
• Equilibrium
• Saturation
• Miscibilty

38. Definition of terms
• Solute-the substance being dissolved
• Solvent-the substance doing the dissolving (the larger amount)
• Solution- a homogeneous mixture of the solute and the solvent
• Solution= solvent + solute
• Aqueous (aq)= water solution
• Tincture= alcohol solution
• Amalgam= Mercury solution
• Electrolytes- A substance that when dissolved in water produces a
solution that can conduct an electric current
• Non-electrolyte - A substance that when dissolved in water produces a
solution that can not conduct an electric current

39. Expressions of Concentration
• Quantity per quantity
• Percentage
• Parts
• Molarity
• Molality
• Mole fraction
• Milliequivalents
• Normal solutions

40. The process of dissolution
• States of matter
• Condensed masses
• Molecules are not in kinetic motion
• Unlike in gaseous phase where molecules are in constant movement
independently within the confines of the container
• Condensed phases form crystal lattices
• During dissolution these are broken down
• Bonds are broken down and the crystal lattice is dismantled