Extemporaneous Compounding The process by which solutions suspensions

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 120 g or less with a sensitivity requirement (SR) of 6 mg. • That means 6 mg 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 m. L

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 • • • 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