Discussion on the 2 kinds of Disperse Systems 1. Suspensions 2. Emulsions. The principles of emulsification, types and examples of emulsifying agents used.

1. Chapter 14:
DISPERSE SYSTEMS
Asst. Prof. MA. LOURDES L. MOJARES, R. Ph
Faculty
CEU School of Pharmacy

2. DISPERSE SYSTEMS:
COMPONENTS
 DISPERSED PHASE
The undissolved or immiscible drug
(suspensoid) distributed
throughout the liquid vehicle.
Also called the
“internal phase”

3. DISPERSE SYSTEMS:
COMPONENTS
 DISPERSION MEDIUM
The liquid vehicle, to which the
insoluble drug is distributed.
Also called
“external phase”

4. DISPERSE SYSTEMS:
COMPONENTS
 DISPERSING /SUSPENDING
AGENT
Stabilizes the suspension,
maintains the homogeneity of
the internal and external
phases, after agitation of the
contents.

5. DISPERSE
SYSTEMS
Remember the
“Shake Well”
instruction
before
administering
suspensions /
emulsions.

6. DISPERSE SYSTEMS
PARTICLE SIZES
 Colloidal dispersions – 1 nm to
0.5 nm
 Coarse dispersions
(suspensions and emulsions) –
10 um to 50 um
 Fine dispersions ( magmas and
gels) – 0.5 um to 10 um

7. SUSPENSIONS: DEFINITION
 Disperse systems containing
finely divided, insoluble drug
particles (“suspensoids’)
distributed somewhat uniformly
throughout a liquid vehicle.

8. SUSPENSIONS: DEFINITION
 Ready to use liquid form
(antacids and analgesics)
Labeled as “Oral Suspension”
 Dry powders for Reconstitution
(antibiotics and other drugs that
are unstable in liquid form for
longer time)

9. REASONS for SUSPENSIONS
1. For improving product stability
2. Ease of administration and
flexibility in administration of a
range of doses
3. For masking unpleasant taste of

10. Features desired in
Pharmaceutical Suspension
1. Particles should settle slowly and
should be readily re-dispersed
upon shaking of the container.
2. The particle size of the
suspensoid should remain fairly
constant throughout long periods
of undisturbed standing.
3. The suspension should pour
readily and evenly from its

11. DISPERSED PHASE:
PHYSICAL FEATURES
 Particle diameter is 1 to 50 m
 Particle size reduction is
accomplished by:
 Micropulverization – 10-50 m
 Fluid energy grinding (jet milling
or micronization) – under 10 m

12. SUSPENDING AGENTS:
TYPES AND EXAMPLES
1. HYDROPHILIC COLLOIDS
 Increase the viscosity of water by binding
water molecules
 Support the growth of microorganisms
 Mostly anionic, except methylcellulose
(neutral) and chitosan (cationic)
 Incompatible with quaternary antibacterial
agents

13. HYDROPHILIC COLLOIDS:
EXAMPLES
 Acacia –used as 35% mucilage;
form colored complex with organic
compounds due to peroxidase
 Tragacanth – used as 5%
dispersion in water; does not
contain peroxidase
 Methylcellulose (MC)
 Carboxymethylcellulose (CMC)

14. SUSPENDING AGENTS:
TYPES AND EXAMPLES
2. CLAYS
 Silicates that are anionic in
aqueous dispersion
 Strongly hydrated
 Exhibit thixotropy
Bentonite (as 5% magma), Veegum

15. SUSPENDING AGENTS:
TYPES AND EXAMPLES
3. OTHER AGENTS
 Agar
 Chondrus(carrageenan)
 Gelatin
 Pectin
 Gelatinized Starch

16. TYPES OF SUSPENSION
1. ORAL SUSPENSIONS
 Ready to use
 Dry powders for reconstitution
 Uses: Antacid,Anthelmintic,
Antibacterial
(see table 14.1 pp.390-391)

17. TYPES OF SUSPENSION
2. SUSPENSIONS FOR INJECTION
 Particles must exhibit
“SYRINGEABILITY”
The product must have the ability
to be successfully administered
by a syringe and appropriate
needle.

18. TYPES OF SUSPENSION
3. OPHTHALMIC SUSPENSIONS
 Particle size must not exceed 10
microns

19. TYPES OF SUSPENSION
4. SUSPENSIONS FOR TOPICAL USE
 Fine particles (impalpable) are
desired to avoid grittiness when
applied to the skin
 The smaller the particle size, the
greater the covering and protective
power of the preparation.

20. TYPES OF SUSPENSION
3. OPTHALMIC SUSPENSIONS
 Particle size must not exceed 10
microns
 Particles must be “impalpable”

21. TYPES OF SUSPENSION
4. SUSPENSIONS FOR TOPICAL USE
 Fine particles are desired to avoid
grittiness when applied to the skin
 The smaller the particle size, the
greater the covering and protective
power of the preparation.

22. TYPES OF SUSPENSION
5. RECTAL SUSPENSIONS
 Barium Sulfate for
Suspension, USP
 May be employed orally or
rectally for diagnostic
visualization of the GIT.

23. TYPES OF SUSPENSION
 MesalamineSuspension (Rowasa)
 For the treatment of Crohn’s
disease, distal ulcerative colitis,
proctosigmoiditis, and proctitis.
 No longer commercially available
but is compounded by
pharmacist.

24. PREPARATION OF
SUSPENSIONS
I. WETTING OF PARTICLES
 Wetting agents are employed for
hydrophobic (non-wetting) powders
II. BLENDING OF ALL THE INGREDIENTS
 All soluble components must have
been dissolved in the dispersion
medium

25. CLASSES OF SUSPENSION
1. LOTIONS
2. GELS
3. MAGMAS AND MILKS
4. MIXTURES

26. LOTIONS
 Suspensions for external
application.
 A low to medium viscosity, topical
product, intended to be applied on
“unbroken” skin.
 Lotions have lower viscosity than
Creams and Gels.

27. LOTIONS
 Prepared by:
(1) Trituration method
(2) By chemical reaction method

28. TYPES of LOTIONS
 MEDICATED LOTIONS
1. Kwell (Lindane) Lotion
- scabicide
2. Calamine Lotion
- antipruritic
- protective

29. TYPES of LOTIONS
 NON MEDICATED LOTIONS
1. Jergen’s Lotion
- emollient
2. Aveeno Lotion
- moisturizer

30. EMULSIONS: DEFINITION
 A dispersion in which the
dispersed phase is composed
of small globules of liquid
distributed throughout another
liquid, in which it is immiscible.
 A two-phase system in which
one immiscible liquid is
intimately dispersed in another
liquid (as droplets).

31. PHASES OF EMULSIONS
DISPERSED PHASE
– the liquid droplet, internal phase, or
discontinuous phase.
DISPERSION MEDIUM
– the liquid vehicle, external phase,
or continuous phase

32. TYPES OF EMULSIONS
 W/O emulsion
- water is the internal phase
- oil is external phase
 O/W emulsion
- oil is the internal phase
- water is external phase

33. EMULSIFYING AGENTS
 Any compound that lowers the
interfacial tension and forms a film
at the interface
TYPES:
1. Natural emulsifying agents –
acacia, tragacanth, agar, pectin,
gelatin, methylcellulose
2. Synthetic emulsifying agents –
anionic, cationic, or nonionic

34. SYNTHETIC EMULSIFIERS
 ANIONIC AGENTS – include
sulfuric acid esters, sulfonic acid
derivatives, and soaps
Alkali soaps – form O/W emulsion
Metallic soaps – form W/O
emulsion
Monovalent and Polyvalent soaps
– form W/O emulsion

35. SYNTHETIC EMULSIFIERS
 CATIONIC AGENTS
Used as surfactant in 1%
concentration
Example: Benzalkonium chloride

36. SYNTHETIC EMULSIFIERS
 NONIONIC EMULSIFIERS
Resistant to the addition of acids and
electrolytes
Examples:
Sorbitan esters – SPANS, hydrophobic,
low HLB values, form W/O emulsions
Polysorbates – TWEENS, hydrophilic,
high HLB values, form O/W emulsions

37. HLB SYSTEM
 HYDROPHILE – LIPOPHILE BALANCE
 Used to classify non-ionic surfactants
 All NON –IONIC surfactants have an
HLB value.
 The higher the HLB number, the more
hydrophilic
 The lower the HLB number, the more
lipophilic

38. HLB SYSTEM
HYDROPHILIC SURFACTANTS
 High HLB values (>10)
 Form O/W emulsion
LIPOPHILIC SURFACTANTS
 Low HLB values (1-10)
 Form W/O emulsion

39. Application of Surfactants
HLB VALUE SURFACTANT
RANGE APPLICATION
1–3 Antifoaming agents
4–6 Water-in-Oil
emulsifiers
7–9 Wetting agents
8 – 18 Oil-in-Water
emulsifiers
13 – 15 Detergents
10 – 18 Solubilizing agents

40. METHODS OF PREPARATION
1. WET GUM METHOD
(English method)
4:2:1 of oil : water : gum
Formation of Primary Gum as the
nucleus of the emulsion.

41. METHODS OF PREPARATION
2. DRY GUM METHOD
(Continental method)
4:2:1 ratio of oil: water: gum
Formation of Primary Mucilage as
the nucleus of the emulsion

42. METHODS OF PREPARATION
3. BOTTLE METHOD – (Forbes
Bottle method or 2:2:1 method)
2:2: 1 ratio of oil : water : gum
Applicable to emulsions
containing Volatile Oils.

43. METHODS OF PREPARATION
4. NASCENT SOAP METHOD
 The soap is formed first by mixing
equal volumes of oil and alkali
 The soap acts as emulsifying
agent
 A 50:50 ratio of oil to water
ensures sufficientemulsion

44. THEORIES OF EMULSIFICATION
1. SURFACE-TENSION THEORY
Initially, when oil and water are
mixed it becomes immiscible due
to the presence of surface
tension.
The use of surfactants result in
the lowering of interfacial tension
between two immiscible liquids.

45. THEORIES OF EMULSIFICATION
2. ORIENTED WEDGE THEORY
This theory assumes
monomolecular layers of
emulsifying agent curved around a
droplet of the internal phase.

46. THEORIES OF EMULSIFICATION
3. PLASTIC FILMOR INTERFACIAL
FILM THEORY
This theory places the emulsifying
agent at the interface between the
oil and water, surrounding the
droplets of the internal phase as a
thin layer of film adsorbed on the
surface of the drops.

47. THEORIES OF EMULSIFICATION
4. VISCOSITY THEORY
The final product will exhibit
increased viscosities.
When the contents are agitated, it
will have a thick, creamy
consistency which will make the
emulsion acceptable for use.

48. METHODS OF DETERMINING
THE TYPE OF EMULSION
 DYE SOLUBILITY TEST
Uses methylene blue or brilliant
blue
If the dye is dissolve and uniformly
diffuse – O/W
If the particle of the dye lie in
clumps on the surface – W/O

49. METHODS OF DETERMINING
THE TYPE OF EMULSION
 DILUTION TEST
If freely mixes with water – O/W
If not diluted with water – W/O

50. METHODS OF DETERMINING
THE TYPE OF EMULSION
 ELECTRIC CONDUCTIVITY TEST
O/W conducts electric current
W/O do not conduct electric
current

51. MICROEMULSION
 Thermodynamically stable system
 Optically transparent isotropic
mixture of a biphasic O/W system
stabilized with surfactants

52. MICROEMULSION
 Diameter of particle:
100 Å (10 mμ) to 1000 Å (Angstrom)

53. AEROSOLS
 Pressurized dosage forms
designed to deliver drug
systemically or topically with the
aid of a liquefied or propelled gas
(propellant).
 A dispersion of solid, liquid or gas
forms of a drug in gas.

54. AEROSOLS:COMPONENTS
 Product concentrate
 Propellant
Compressed gases – CO2, N2, NO
Liquefiable gases – saturated
HC’s, CFC’s, dimethyl ether, and
HFC’s

55. AEROSOL CONTAINER

56. ADVANTAGES
 Convenience of application
 Stability
 Wide range of products to be
dispensed as sprays, foams, or
semisolids
DISADVANTAGES
 Environment hazard
 Inadvertent inhalation of the gas

57. FILLING METHODS of
AEROSOLS
I. Cold Filling Method
 Product concentrate and
propellant are cooled at -34.5
to -40°C
 Dry ice and Acetone are the
cooling systems used.

58. FILLING METHODS of
AEROSOLS
II. Pressure Filling Method
1.Product concentrate is
quantitatively placed in the
aerosol container.
2.Valve assembly inserted and
crimped in place.
3. Liqiefied gas (under pressure) is
metered into the valve system.

59. ACTUATOR MOUNTING CUP WITH
FLOWED-IN GASKET
STEM
HOUSING
SPRING
DIP TUBE
GASKET
59

60. PARTS of the VALVE ASSEMBLY
ACTUATOR
MOUNTING
CUP
SPRING
GASKET
HOUSING

61. Types of Aerosols
1. Inhalational aerosols – MDI’s
2. Topical aerosols
 Tolnaftate (antifungal)
3. Vaginal aerosols
 Nonoxynol- 9 (contraceptive foam)
4. Rectal aerosols
 Proctofoam

62. METERED DOSE INHALERS
(MDI’s)
 These devices allow a drug to be
inhaled as a fine mist of drug or
drug-containing particles for
systemic or pulmonary delivery
 Use special metering valves to
regulate the amount of formulation
and the drug that is dispensed in

63. METERED DOSE INHALERS
(MDI’s)
 Commonly employed in asthma
therapy