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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5320_Библиотеки_им_академика_М_И_Перельмана
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306
17.2.3 Multiple Emulsions
Pharmaceutical Dosage Forms and Drug Delivery
-
philic drugs.
17.2.4 Microemulsions
17.2.4.1 Self- Emulsifying Drug Delivery Systems and Self- Microemulsifying Drug
Delivery Systems
in vivo
®),
-
sporine (Sandimmune®
17.3 Quality Attributes
1. Uniformity of content
emulsion.
2. Separation volume or creaming: Once an emulsion has been left undisturbed for some time, it
creaming
creamed
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Emulsions
the emulsion.
3. Dispersed phase size distribution
4. Drug concentration
Palatability
-
erations, of course, are not pertinent for parenteral emulsions. Regarding parenteral emulsions,
6. Redispersability
of the container.
7. Absence of phase separation: Coalescence leading to phase separation is irreversible. Although
using the right surfactants in an appropriate concentration.
8. Deliverability
9. Flow
10. Lack of microbial growth
11. Physical integrity
12. Adhesion to the package: Preferential adsorption or adhesion of one phase or component of the
13. Leachables and extractables
14. Chemical stability
impurities.
307
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308
Pharmaceutical Dosage Forms and Drug Delivery
Drug release: Since an emulsion contains the drug in the dispersed phase, the release of the drug
from the dispersed phase into an aqueous solution in an appropriate dissolution vessel is quanti-
semisolid emulsions.
is not needed.
17.4 Formulation Considerations
thermodynamically unstable due to the differences in the molecular forces of
collapse of the dispersed phase.
17.4.1 Minimization of Interfacial Free Energy
interfacial area of the globules is much greater than the minimum surface area of that liquid in a phase-
interfacial tension
Adding a surfactant to an emulsion leads to preferential translocation of the surfactant molecules to
17.4.2 Optimum- Phase Ratio
phase ratio)
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309
combination results in a poor emulsion.
17.4.3 Size, Viscosity, and Density: Stoke’s Law
Chapter 16
1.
2.
3.
-
lation of the dispersed phase in a particular direction.
17.4.4 Zeta Potential
zeta potential (see
Chapter 16) on the surface of the droplets causes the dispersed- phase droplets to repel each other and
occulation is facilitated over coalescence.
17.5 Emulsification
17.5.1 Mechanisms of Emulsification
1. Reduction of interfacial tension.
2.
dispersed- phase granules.
3.
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TABLE 17.1
Pharmaceutical Dosage Forms and Drug Delivery
A. Protective w/ o Emulsion of Calamine
Ingredients Amount Role
Calamine 1 g Protective
1 g Protective
Olive oil
Internal phase
B. Benzoyl Benzoate o/ w Emulsion
Drug and internal phase
2 g
TABLE 17.2
Type Examples
Surfactants
Sorbitan oleate (Span 80)
Anionic Potassium laurate
Cationic
Hydrophilic Colloids
Acacia
Phospholipids
Sterols Cholesterol
Finely Divided Solid Particles
Bentonite
17.5.2 Surfactants
monomolecular lms
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zeta potential
17.5.2.1 Ionic and Nonionic Surfactants
Surfactants could be anionic (containing anionic or acidic, functional groups, such as sulfates and
Ka), cationic (containing
than their pKa
-
nium ion bear a permanent positive charge.
17.5.2.2 Hydrophile– Lipophile Balance Value
17.5.3 Hydrophilic Colloids
multilayer lms around
17.5.4 Finely Divided Solid Particles
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17.6 Manufacturing Process
Pharmaceutical Dosage Forms and Drug Delivery
capsule.
17.7 Stability
17.7.1 Physical Instability
Figure 17.2. Flocculation is discussed in the chapter on
suspensions.
FIGURE 17.2
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Emulsions
17.7.1.1 Creaming and Sedimentation
313
Creamingsedimentation,
Section 17.4.3.
17.7.1.2 Aggregation, Coalescence, Creaming, and Breaking
most stable emulsion.
17.7.1.3 Phase Inversion
stearate.
17.7.2 Chemical Instability
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Pharmaceutical Dosage Forms and Drug Delivery
17.7.3 Microbial Growth
separation of the phases. Preservatives must be added in adequate concentrations in the formulations to
Review Questions
17.1
A
the medium
B
C
D All of the above
17.2
be in the
A Continuous phase
B Discontinuous phase
C Aqueous phase
D Oil phase
E
17.3
A
B Creaming and sedimentation
C Coalescence and aggregation
D
E Multiple emulsions and microemulsions
F SEDDS and SMEDDS
17.4
17.6
17.7
17.8
17.9
(SEDDS or SMEDDS):
A
B
C
D
E
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17.10
A
B
C
D
E
F
17.11
A
B
C
D
E
F
FURTHER READINGS
The Art, Science, and Technology of Pharmaceutical Compounding
Physicochemical Principles of Pharmacy 4th ed.,
(Eds.) Modern Pharmaceutics
Pharmaceutical Dosage Forms: Disperse
Systems
Int
J Pharm 345
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