Pharmacy Powder Preparations

Powder Triturate

• A powder triturate is a mixture of a small amount of dye and a large amount of lactose.
• It's used as a starting point for other preparations like powders and capsules.
• The purpose is to practice mixing powders effectively.

Powder Preparations

Bulk Powder

• Sifter cans are common containers for bulk topical powders.
• Topical powders are usually labeled as percent weight per weight.

Divided Powders

• Divided powders are sometimes called "charts" (an older term).

Preparing Divided Powders

• Calculate for one extra chart to account for potential loss during processing.
• Processing loss is common, especially for topical products.
• Ideal powder per chart is 200-500 mg.
  • This range prevents excessively small or large doses, aiding handling and minimizing taste issues.

Preparing Powder Mixtures

• After calculation, prepare powder mixtures, including powder triturate.
• Comminute (grind) powders if needed; this is done in a mortar.
• Blend powders using:
• Spatulation: - Use ointment paper (parchment paper). - This method is less effective for comminuting coarse particles. - Mix ingredients of similar size for optimal flow. - Keep powders in a confined area to prevent loss. - Mix from side to side, pressing with spatula.
• Trituration in mortar: - Ideal for comminution and mixing. - Use a high-quality, crack-free mortar, ensuring the porcelain interior isn't excessively smooth (glass should be smooth and shiny). - Geometric dilution can be used if mixing unequal quantities, adding the larger amount to the smaller amount in equal increments and mixing thoroughly each time. - Use circular motions, keeping powder low in the mortar and applying light pressure. (Use more force for comminution). Avoid embedding powders by using diluents with powders.

Important Points About Mixing Powders

• Achieving complete homogeneity is often challenging in powder mixtures.
• Minimize stratification by reducing all ingredients to similar particle sizes.
• Geometric dilution is crucial for mixing powders of similar colors.
• Thoroughly mix at each stage of geometric dilution to ensure even mixing.
• Geometric dilution is especially important when combining powders in unequal quantities.
• For complete mixing, mix in all dimensions (up and down).

Packaging Divided Powders

• Weigh each dose of divided powder individually.
• Packaging methods include:
• Folded powder paper: Traditional, but less moisture-resistant than other methods.
• Plastic Ziploc bags: More practical, creating a moisture barrier by sealing bags in vials.

Beyond-Use Dating for Powders

• Beyond-Use dates for powders are based on stability information for each ingredient (e.g. drug).
• Be mindful of factors like photo-oxidation, hydrolysis, and hygroscopicity.
• Use the latest USP dating (180 days at controlled room temperature) if stable or a shorter date if necessary. (Use the shortest stability date of the ingredients and excipients, including containers.)

Working Safely with Hazardous Powders

• USP Chapter 800 covers safe handling of hazardous drugs (NIOSH list).
• Hazardous drugs have potential hazards including various types of toxicity.
• NIOSH list should be checked for updates.

Compounding Capsule Preparations

Capsule Selection

• Choose appropriate capsule size and color for the patient.
• Record the size and color in the records.

Determine Fill Weight

• Fill weight is based on capsule volume and powder density.

Packing Capsules

• Use capsule-filling machines or hand-packing.

Procedures for Filling Capsules

• Calculate for 2 extra capsules for loss.
• Record capsule size/color in the record.
• Separate caps and bodies.
• Capsule-filling machine methods:
  • Place bodies in machine holes, followed by powder, tamping. Rejoin caps and clean the capsules.
• Hand-packing methods:
  • Mix formulation on a hard surface.
  • Shape into a square pile. Wear gloves
  • Insert formulation into capsule body, then flip, scrape.
  • Snap caps, check weight (tare with empty), proceed.

Importance of Weighing Capsules Properly

• Two methods exist for accounting for capsule shell weight:
  • Subtract empty capsule shell weight.
  • Use empty shell as tare (be mindful of the balance and avoid double taring.)

Quality Control for Capsules

• Capsule-filling machine methods:
  • Accurately weigh capsules, determine if any deviate, calculate mean, standard deviation, and relative standard deviation (target < 6%).

Beyond-Use Dating for Capsules

• Beyond-use dates are based on stability data and ingredient expiration dates.
• USP recommends a beyond-use date of 180 days at controlled room temperature.

Oral Liquids

Oral Solutions

Preliminary Work

• Investigate drug solubility in the vehicle (often water).
• Confirm solubility data for correct drug form. (e.g. acid or salt form).
• Carefully review stability.

Procedures for Preparing Oral Solutions

• Calculate for 2-3 extra solutions due to loss.
• Dissolve ingredients (accelerate by trituration or levigation with a water miscible agent carefully).
• Add vehicle to a graduate, add washings to transfer the entire substance, reach final volume, and mix thoroughly with a stir rod.
• Inspect for clarity and absence of undissolved matter.
• Dispense into appropriate bottle, with labeling for refrigeration if needed.

Potentially Useful Tips

• Dissolve the ingredients in water (if viscous vehicle) first, then add the remaining solution.
• Add high-viscosity liquids to low-viscosity liquids with constant stirring.
• For elixirs, dissolve alcohol-soluble and water-soluble components separately, then combine.
• Solutions should be clear and crystal-free, with pH checked.

Oral Suspensions

Preliminary Work

• Determine the drug's solubility in the vehicle.
• Verify solubility data for the specific drug form and include potential hydrates.
• Record viscosity, particularly for suspending agents like methylcellulose.

Procedures for Preparing Oral Suspensions

• Add extra volume to account for loss (e.g. 30%).
• Mix powders and levigate if needed.
• Mix with vehicle incrementally , transferring the mortar washings.
• Bring to final volume and mix thoroughly.
• Fill an appropriate bottle, ensuring headspace for shaking if necessary.
• Label for refrigeration and shaking.

Quality Control for Suspensions

• Assure dosage uniformity.
• Visually assess viscosity (viscous or non-viscous, noting thixotropy).
• Check and record the pH.
• Make extra batches to check settling or caking if needed.
• Avoid extreme temperatures to prevent Ostwald ripening.

Beyond-Use Dating for Oral Liquids

• Beyond-use dates depend on ingredient stability and expiration dates.
• USP recommends 14 days refrigerated, or 35 days if preservatives are present.

Suppositories

Preliminary Work

• Drug powder is preferred.
• Note physical-chemical properties (solubility).
• Select the appropriate base from the prescription.
• Prepare and calibrate the mold.

Mold Choices

• Aluminum molds are commonplace (cavities around 2 mL, pediatric sizes around 1.3 mL).

Calibration of Molds

• Calibration is important for determining the amount of base required and to monitor dosage accuracy (consider the volume occupied by non-base ingredients).
• If the drug dose is small, the pharmacist can assume the volume is negligible.
• If the base and drug densities are equal, the total weight of drug can be subtracted from the total weight of the base.

Double Casting Technique

• Useful for suppositories made only once or a limited number of times without calibrating the mold
• Steps involve a two-stage melting process to result in a homogenous mix

Procedures for Making Suppositories

• Base Preparation:*
• Use a water bath at ~60°C to control heat and limit temperature overshooting for stability.
• Use the least heat possible to prevent ingredient degradation and increase the melting point. Viscosity should be manageable
• Drug/Excipient Preparation:*
• Reduce powders to uniform particle size, without agglomeration.
• Mixing:*
• Mix drug, excipients, and base thoroughly (use levigation if necessary to prevent agglomeration).
• Molding:*
• Fill cavities completely or add a slight excess for contraction.
• Pour mixture close to its solidification point.
• Cooling & Finishing:*
• Place in refrigerator (avoid freezing for brittle suppositories);
• Trim excess base (warm spatula if needed).
• Dispensing and Labeling:*
• Wrap suppositories individually as needed.
• Label packages with instructions such as moistening if needed, method (rectal, vaginal).

Storage and Beyond-Use Dating for Suppositories

• Store at controlled room temperature or refrigerated.
• Fatty-acid base suppositories are usually refrigerated.
• USP allows 180 days at controlled room temperature or refrigeration. (Pharmacies might make a decision to have a shorter date for other precautions).

This quiz covers essential concepts in powder preparations, focusing on triturates, bulk powders, and divided powders. It also emphasizes the importance of calculations and handling techniques in pharmacy practices. Test your knowledge on mixing, measuring, and preparing various powder forms.