Transcript EQUIPMENT FOR WEIGHING, MEASURING, AND COMPOUNDING

Extemporaneous Compounding
The process by which solutions, suspensions, ointments, creams,
powders, suppositories, and capsules are prepared.
NEED FOR EXTEMPORANEOUS
COMPOUNDING
• Is the production of medication on demand
in an appropriate quantity and dose form
from pharmaceutical ingredients.
• Compounding might involve mixing a
powdered active ingredient with a diluent
powder and filling a given number of
capsules with the combined materials.
NEED FOR EXTEMPORANEOUS
COMPOUNDING
• All compounding must be performed according
to Good Manufacturing Practice (GMP).
• GMP is laboratory and industry guidelines to
ensure a suitable work environment to prepare
high quality medications.
REASONS FOR COMPOUNDING
•The Rx calls for a different dose than what is commercially
available.
•A solid form might need to be prepared in another dosage form
such as liquid.
•The commercial preparation may have unwanted ingredientspatient may have allergies.
•Patient may require customization of rate of delivery, rate of
onset, or site of action.
•Product may not be commercially available at all.
Compounding Issues
Safety Note!
• Products compounded for veterinary use
cannot be used in humans.
EQUIPMENT FOR WEIGHING, MEASURING,
AND COMPOUNDING
• Balances: Balance measurements using a
counterbalance are made using sets of
standardized pharmaceutical weights.
• A Class III balance (formerly known as a class A
prescription balance) is a two pan balance that can
weigh 120g or less with a sensitivity requirement
(SR) of 6mg.
• That means 6mg of weight will move the indicator
on the balance 1 degree.
EQUIPMENT FOR WEIGHING, MEASURING,
AND COMPOUNDING
• Forceps and Spatulas: Forceps should be
used when picking up weights so that moisture
and oils are not transferred to the weights.
• Spatulas are used in compounding tasks such as
preparing ointments and creams or loosening
material from the surfaces of a mortar and pestle.
EQUIPMENT FOR WEIGHING, MEASURING,
AND COMPOUNDING
• Compounding Slab: This is an ideal surface
for mixing compounds because of its
nonabsorbent surface.
• Mortar and Pestle: The coarser the surface of
the mortar and pestle, the finer the triturating, or
grinding, that can be done.
• Graduates and Pipettes: Graduates come in
two varieties: conical and cylindrical. A pipette is
used for measuring liquids with a volume less than
1.5 mL
EQUIPMENT FOR WEIGHING, MEASURING,
AND COMPOUNDING
• Master Formula Sheet: Prepared by the
pharmacist, this sheet indicates the amount
of each ingredient needed, lists the
procedures to follow, and provides the
labeling instructions.
Compounding Issues
Safety Note!
• Compounding should never be rushed.
TECHNIQUE FOR WEIGHING
PHARMACEUTICAL INGREDIENTS
Weighing of the product is one of the most
essential parts of the compounding process.
Weighing the exact amount prescribed is
essential in compounds for several reasons:
the product cannot be “checked” for content
once mixed, the quantities weighed out are
often very small, and a slight overage could
mean a serious overdose for the patient.
Weighing Pharmaceutical
Ingredients
1. Unlock the balance and confirm that it is
leveled, front to back and side to side, using
the leveling screws at its base. Once this is
done, the balance is ready to use. Lock the
balance once again, before transferring weight
to it.
Weighing Pharmaceutical
Ingredients
2. Place weighing papers on the two pans of
the balance. These papers should be of
exactly the same size and weight. The edges of
the paper on the left-hand pan may be folded
upward, to hold the substance to be weighed.
Do not place any materials on the weighing
pans without using weighing papers.
Weighing Pharmaceutical
Ingredients
3. Unlock the balance to confirm that the
balance is still leveled, and then lock it again.
Weighing Pharmaceutical
Ingredients
4. Add the desired weight to the right-hand
pan, using forceps to transfer the weight from
the weight container.
Weighing Pharmaceutical
Ingredients
5. Place an approximate amount of the
material to be weighed onto the left-hand pan,
using a spatula to transfer it.
Weighing Pharmaceutical
Ingredients
6. Slowly release the beam using the unlocking
device at the front of the balance, and check
the balance.
Weighing Pharmaceutical
Ingredients
7. If the amount of the substance being
weighed is too great or too small, lock the
balance again and use a spatula to add or
remove material
Weighing Pharmaceutical
Ingredients
8. Slowly release the beam using the unlocking
device and check for equilibrium.
Weighing Pharmaceutical
Ingredients
9. Once a nearly precise amount of material
has been transferred to the pan, a very small
adjustment upward can be made by placing a
small amount of material on the spatula,
holding the spatula over the left pan, and
lightly tapping the spatula with the forefinger
to knock a bit of the substance onto the pan.
This is done with the balance unlocked and
the balance beam free to move.
Weighing Pharmaceutical
Ingredients
10. Lock the balance, close the lid, and then
unlock the balance to make a final
measurement. (At this point, have the
pharmacist check the measurement.)
Weighing Pharmaceutical
Ingredients
11. Lock the balance before removing the
measured substance. Use transfer forceps to
remove the weights and return them to their
storage case.
Terms to Remember
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Class III prescription balance
counterbalance
spatulas
forceps
compounding slab
mortar and pestle
pipette
graduates
master formula sheet
TECHNIQUE FOR MEASURING LIQUID
VOLUMES
A general rule of thumb is to always select the
device that will give you the most accurate
volume. Selecting a container that will be
at least half full when measuring, or using
the smallest device that will hold the
required volume, is considered good
practice.
Measuring Liquid Volumes
1. Choose a graduate with a capacity that equals or
very slightly exceeds the total volume of the liquid to be
measured. Doing so reduces the percentage of error in
the measurement. Again, the closer the total capacity of
the graduate to the volume to be measured, the more
accurate the measurement will be.
Measuring Liquid Volumes
2. Bear in mind that the more narrow the
column of liquid in the graduate, the less
substantial any reading error will be. Thus
for very small volume measurements a
cylindrical graduate is preferable to a conical
graduate.
Measuring Liquid Volumes
3. Pour the liquid to be measured slowly into
the graduate, watching the level of the liquid
in the graduate as you do so. If the liquid is
viscous, or thick, then you should attempt to
pour it toward the center of the graduate to
avoid having some of the liquid cling to the
sides.
Measuring Liquid Volumes
4. Wait for liquid clinging to the sides of the
graduate to settle before taking a
measurement.
Measuring Liquid Volumes
5. Measure the level of the liquid at eye level
and read the liquid at the bottom of the
meniscus.
Measuring Liquid Volumes
6. When pouring the liquid out of the
graduate, allow ample time for all of the liquid
to drain. Bear in mind that depending on the
viscosity of the liquid, more or less will cling to
the sides of the graduate. For a particularly
viscous liquid, some compensation or
adjustment for this clinging may have to be
made.
Compounding Issues
Safety Note!
• Use the smallest device that will hold the
required volume when measuring a liquid.
• Always measure liquids on a solid, level
surface at eye level.
COMMINUTION AND BLENDING OF
DRUGS
• Examples of Compounding Preparations:
The following are some common examples of
compounding in the pharmacy: solutions,
suspensions, ointments and creams, powders,
suppositories, and capsules.
Compounding Issues
Safety Note!
• Regardless of their apparent stability, all
suspensions should be dispensed with an
auxiliary label reading “Shake Well.”
COMMINUTION AND BLENDING OF
DRUGS--TERMS
• Geometric Dilution Method: A way to
combine drugs using a mortar and pestle.
• Place the most potent ingredient in the mortar first
(usually the smallest amount) then add an equal
amount of the next most potent ingredient and mix
well.
• Continue in this manner adding equal amounts
each time until all ingredients are combined.
COMMINUTION AND BLENDING OF
DRUGS--TERMS
• Blending: The act of combining two substances.
• Trituration: The process of grinding a substance
to create fine particles by means of mortar and
pestle.
• Levigation: Used to reduce particle size of a solid
by combining it with a small amount of levigating
agent and grinding to reduce particle size. Usually
used in preparing ointments.
COMMINUTION AND BLENDING OF
DRUGS
• Labeling, Record Keeping, and Cleanup:
After compounding, the product must be
labeled with a prescription label, and a
careful record of the compounding
operation should be kept. Once the
compounding operation is finished, the
equipment and area should be cleaned and
everything should be returned to their
proper places in storage.
REFERENCE SOURCES FOR THE
COMPOUNDING PHARMACY
The pharmacy technician can refer to a
standard reference work on the subject, such
as Remington: The Science and Practice of
Pharmacy by Gennaro.
Discussion
Explain why using proper techniques
and weighing ingredients with
accuracy are important while
preparing special compounds in the
pharmacy.
Discussion
The art of compounding uses a whole different language,
and you have been asked to describe the following terms to a
pharmacy student who is visiting your pharmacy. Use
simple terms.
a. levigate
e. geometric dilution
b. punch method
f. meniscus
c. triturate
g. graduate
d. spatulation
h. mortar & pestle