Semi Solds Flashcards
What are the semi sold pharmaceutical form
Ointments, creams and gels
Where can we apply semisolids
The skin, eye, nasally, vaginally and rectally
Why do we use unmedicated ointments
Un-medicated ones are used for their physical effects as protectants, emollients, or lubricants.
What are topical applications can be designed for
Local effects,
Systemic absorption
How are topical applications designed
Designed to deliver drug into the skin in treating dermal disorders, with the skin as the target organ.
What are transdermal projects
designed to deliver drug
through the skin (percutaneous absorption) to
the general circulation for systemic effects, with
the skin not being the target orga
What are ointments
semisolid preparations intended for
external application to the skin or mucous
membranes.
Could be medicated or un-medicated.
What are the different ointment bases
- Oleaginous bases
- Absorption bases
- Water-removable bases
- Water-soluble bases
Why do we use oleaginous bases
– On application on the skin, they have an emollient
effect and they protect against the escape of
moisture.
– They are effective as occlusive dressings as they
can remain on the skin for long periods of times
without drying out and they are immiscible with
water and are difficult to wash off.
What are some examples on oleaginous bases
petrolatum, white petrolatum, white
ointment, and yellow ointment.
Can we incorporate water/aqueous preparations in oleaginous bases
only in small amounts and with some difficulty.
What is petroleum USP
– It is a purified mixture of semisolid
hydrocarbons obtained from petroleum.
– It varies in color from yellowish to light amber.
– It melts at 36 – 60 C.
– Also known as yellow petrolatum or petroleum
jelly.
– Commercial product: Vaseline.
What is white petroleum
It is a purified mixture of semisolid
hydrocarbons obtained from petroleum than
has been wholly or nearly decolorized.
– It is used for the same purpose as petrolatum.
Because of its light color, it is considered
more esthetically pleasing by some patients
and pharmacists.
– Also known as white petroleum jelly.
– Commercial product: white Vaseline.
What is yellow ointment
– Yellow wax is the purified wax obtained form the
honeycomb of the bee Apis mellifera.
– also called simple ointment.
– It has a slightly greater viscosity than plain petrolatum
How do we prepare yellow ointment
– It has the following formula:
Yellow wax 50 g
Petrolatum 950 g
.
– It is prepared by
• Melting the yellow wax on a water bath
• Adding the petrolatum until the mixture is uniform
• Cooling and stirring until congealed.
What is white ointment
Differs from yellow ointment by substitution of
white wax (bleached yellow wax) and white
petrolatum in the formula.
What are the two types of absorption bases
Those that permit the incorporation of aqueous
solutions resulting in the formation of w/o
emulsions (e.g., hydrophilic petrolatum)
.
Those that are w/o emulsions (also known as
emulsion bases) that permit the incorporation of
additional quantities of aqueous solutions (e.g.,
lanolin)
Why are absorption bases hard to remove from the skin
the external phase of the
emulsion is oleaginous
What are absorption bases used for
useful for incorporation of small volumes
of aqueous solutions into hydrocarbon bases.
first, incorporate the aqueous solution into the
absorption base then, incorporate the mixture into
the hydrocarbon base.
What are some examples for absorption bases
Hydrophilic petrolatum
Lanolin
How do we use hydrophilic petrolatum
– It has the following formula:
Cholesterol 30 g
Stearyl alcohol 30 g
White wax 80 g
White petrolatum 860 g
– It is prepared by:
• Melt the stearyl alcohol and white wax on a steam bath
• Add the cholesterol with stirring until dissolved
• Add the white petrolatum
• Allow the mixture to cool while stirring until congealed.
What are the commercial products for hydrophilic petrolatum
Commercial product: Aquaphor has the capacity to
absorb up to three times it weight in water
What is lanolin
Obtained from the wool of sheep.
– It is a wax-like substance that has been
cleaned, deodorized and decolorized.
– It contains not more than 0.25% of water.
Additional water may be incorporated into
lanolin by mixing.
What are water removable bases
– They are o/w emulsions
– Can be easily washed from the skin with
water (often called water washable bases).
– They may be diluted with water or aqueous
solutions.
– They can absorb serous discharges.
– Hydrophilic Ointment, USP, is an example of
this type of base.
What are water soluble bases
They do not contain oleaginous
components.
– They are completely water washable and
often referred to as greaseless.
– They can not incorporate large amount of
aqueous solutions they become very soft.
– They mostly are used for incorporation of
solid substances.
Example: Polyethylene glycol ointment, USP.
How does the physical state of PEG changes
Depending on the average molecular weight:
–PEG < 600: clear colorless liquid
–600 < PEG < 1000: semisolid.
–PEG > 1000: wax-like white material
How can we use the appropriate base
– Desired release rate of the drug substance from the
ointment base.
– Desirability of topical or percutaneous drug absorption.
– Desirability of occlusion of moisture from the skin.
– Stability of the drug in the ointment base.
– Effect, if any, of the drug on the consistency or other
features of the ointment base.
– Desire for a base easily removed by washing with water
– Characteristics of the surface to which it is applied
Give examples on conditions with the right base
– An ointment is generally applied to dry, scaly
skin.
– A cream is applied to weeping or oozing
surfaces
– A lotion is applied to intertriginous areas or
where friction may occur, as between the
thighs or under the armpit
What is incorporation
The components are mixed until a uniform
preparation is obtained.
• In extemporaneous compounding (small scale): the
pharmacist often use a spatula to rub the
ingredients together on an ointment slab
How can we incorporate solids
– When preparing an ointment by spatulation the
pharmacist works the ointment with a stainless
steel spatula having a long, broad blade.
– He would periodically removes the accumulation
of ointment on the large spatula with a smaller
one.
– A metal spatula is always used unless one of the
components reacts with metal (e.g., Iodine), then
a hard rubber spatula should be used.
What are the steps for soild incorporation
• Place all solid material in a mortar
• Grind and blend the solid powders thoroughly.
• Transfer the powder to one side of the ointment
slab.
• Place the ointment base on the other side of the
slab.
• Mix one portion of the powder with a portion of
the base until uniform
• Continue mixing in a geometric dilution fashion till
the powder and the ointment base in thoroughly
and uniformly blended.
When shouldn’t we use a metal spatula
components reacts with metal (e.g., Iodine), then
a hard rubber spatula should be used.
What is levigation
mixing the solid material with a
vehicle in which it is insoluble to make smooth
dispersion (while wet)
Name some levigation agents
• Mineral oil when for oleaginous bases.
• Glycerin for hydrophilic bases.
• Or a small portion of ointment/cream base
itself
How much levigation agent should we add
About equal volume to the solid material.
Where to levigate and what are the advantages
– Where to levigate? In a mortar with a pestle or
directly on the ointment slab with a spatula.
– Advantages: reduction of particle size +
dispersion of the powder.
Consider the following case:
– You have solids (could be the drug or some additives)
that you want to incorporate in the ointment/cream
where:
• They are soluble in a common solvent.
• The solvent will affect neither the stability of the drug
nor the efficacy of the product.
You may first dissolve them in that solvent (e.g.,
water or alcohol)
• The solution is added to the ointment base by
spatulation or in a mortar and pestle.
Why do we use mortar and pestle for larger volumes
because the liquid is more
captive than on an ointment slab.
How do we incorporate gummy materials
– Place the crystals on the middle of the ointment
slab
– Add few drops of alcohol or isopropyl alcohol to
dissolve the crystals with a spatula.
– Spread the solution on the slab and allow it t
evaporate.
– Scrub the thin film from the slab with the
spatula and incorporate the powder material
into the ointment base.
How doe we incorporate methanol and camphor
• Place both of the crystalline materials on
the middle of the ointment slab
• Rub them against each other with pressure
using a metal spatula.
• This will form an eutectic mixture with a
melting point below room temperature
crystals will melt and form a liquid oily
mixture on the slab.
• Incoporate this oily liquid with a portion of
the base and continue mixing till all the
liquid is absorbed by the b
How can we incorporate liquids
– Can be added to the ointment after careful
consideration of the ointment base’s capacity to
accept the volume of liquid required.
– Aqueous solution may be incorporated into
hydrophobic bases (e.g., petrolatum) by using an
absorption base (e.g., aquaphor) or a hydrophilic
base (e.g., hydrophilic ointment, USP).
– Nevertheless, the capacity of hydrophilic bases are
limited and high quantity of liquid will result in an
ointment that is too soft or semi-liquid.
– Alcoholic solutions of small volume may be added
easily to oleaginous bases or emulsion bases.
How can we use roller mills
can be used to force
coarsely formed ointments through stainless
steel or ceramic rollers.
– This will produce ointments uniform in
composition and smooth in texture
What is the Fusion method
All or some of the components of the ointment are
combined by being melted together then cooled with
continuous stirring until congealed.
Components that are not melted are added to the
congealing mixture as it is being cooled
Heat-labile substances and volatile components
should be added last, when the temperature of the
mixture is low enough not to cause any
decomposition or volatilization
How can we conduct the Fusion method on a small scale
porcelain dish or glass beaker
What ointment bases needs the Fusion method and why
– Beeswax
– Paraffin
– Stearyl alcohol
– High molecular weight PEG
Because they don’t lend
themselves well to mixture by incorporation..
What is the melting procedure
A. The material with the highest melting points should
be heated to the lowest required temperature to
produce a melt.
B. The materials with the lowest meting point is melted
first then, the remaining components are added in
order of their melting points (form low to high) under
slow increase of temperature fusion of all
components is achieved at lower temperature than
would be expected for the highest melting point
component due to solvent action exerted by the first
melted components on the others.
C. For preparation of ointments having an emulsion base the
method of manufacture involves both melting and
emulsification.
How can we prepare ointments with the Fusion method
The water-immiscible components such as the oil and
waxes are melted together in a steam bath (70 – 75
C).
Meantime, an aqueous solution of the heat stable,
water soluble components is prepared and heated to
the same temperature as the oleaginous phase.
Add the aqueous solution slowly with continuous stirring
to the melted oleaginous mixture.
Maintain the temperature for 5-10 minutes then cool the
mixture with continuous stirring until congealed.
What are creams
They are semisolid preparation containing one or more
medicinal agents dispersed in either a w/o emulsion or
o/w emulsion or in any other type of water-washable
base.
Why are creams preferred
• Creams are preferred over ointments because they are
easier to spread and remove.
What are pastes
Pastes are semisolid preparations intended for
application to the skin. They generally contain a
larger proportion of solid material (such as 25%)
than ointments and therefore are stiffer.
How can we prepare pastes
• Pastes can be prepared in the same manner
as ointments, by direct mixing or the use of heat
to soften the base prior to incorporating the solids
Name 2 properties of pastes
• Because of the stiffness of pastes, they remain
in place after application and are effectively
employed to absorb serous secretions.
• Because of their stiffness and impenetrability,
pastes are not suited for application to hairy
parts of the body
Give an example for pastes
• Among the few pastes in use today is zinc
oxide paste , which is prepared by mixing
25% each of zinc oxide and starch with
white petrolatum.
• The product is very firm and is better able
to protect the skin and absorb secretions
than is zinc oxide ointmen
What are the types of packaging for semisolids
• Large-mouth ointment jars
• Metal or plastic tubes.
How should we store ointments
• Ointments should be stored in a closed containers to
prevent against microbial contamination.
• Ointments should be stored in a cool place to avoid
product separation by heat.
What are the sizes of the tubes
• Topical preparations are usually frequently
packaged in 5, 15, and 30 g tubes.
• Ophthalmic ointments are typically
packaged in 3.5 g tubes.
How can we fill ointments in a jar
– On a small scale in the pharmacy, ointments
jars can be filled by carefully transferring the
weight amount of ointment into the jar with a
spatula.
– The jar size should be selected so that the
ointment reach near the top of the jar but not
so high as to touch the lid when closed.
– Ointments prepared by fusion may be poured
directly into the jar to congeal in it.
What does then penetration of the skin depends on
– The physicochemical properties of the drug.
– The characteristics of the pharmaceutical vehicle.
– The condition of the skin (broken versus unbroken)
What are the layers of the skin
The skin is divided histologically into
– The stratum corneum (the outer layer, part of
the epidermis)
– The living epidermis
– The dermis
What is the stratum corneum
The stratum corneum is 10 – 15 m of flat,
partially desiccated, dead epidermal cells.
• The stratum corneum is composed of
40 % protein (mainly keratin)
40% water
20 % lipids: triglycerides, free fatty acids,
cholesterol and phospholipids.
• Hair follicles and gland ducts can provide
entry for drug molecules. But because
their relative surface area is so minute
compared to the total epidermis, they are
minor factors in drug absorption.
• The stratum corneum being a keratinized
tissue, behaves as a semi-permeable
membrane, and drug molecules can
penetrate by passive diffusion.
Ok
What does the rate of drug movement through the startum comeum depends on
– Drug concentration in the vehicle.
– The aqueous and lipid solubility of the drug
– The distribution coefficient of the drug between
the stratum corneum and the drug vehicle.
What do bases vary in
– Emollient and occlusive effects.
– Ease of application of the product
– Ease of removal of the product.
Oleaginous bases: provide higher
emollient and occlusive effects.
Creams (o/w emulsions): spread more
easily and easier to remove.
Water-soluble bases: non greasy and
easily removed.
Ok
