Pharmaceutical Compounding

Non-sterile compounding produces medications for oral, topical, or inhalation use that do not require sterilization: creams, ointments, capsules, powders, liquids, and suppositories. Work is done on a clean counter with standard pharmacy tools; risk of contamination is lower because the final product will not enter the bloodstream. Non-sterile compounding is used for: (1) pediatric dose customization (smaller tablet), (2) flavor masking (mixing bitter drug in chocolate), (3) allergen-free formulations (dye-free, lactose-free), (4) combination medications not available commercially. Sterile compounding produces injectables (IV, IM, subcut), ophthalmic drops, and irrigants that require aseptic technique and must be sterile and pyrogen-free (free of endotoxins that cause fever). Work is done in a laminar flow hood with strict asepsis: sterilized tools, alcohol-prepped vials, and documented technique. Contamination risk is high; a bacterial particle can cause a life-threatening infection. Sterile compounding requires more training, certification, and regulatory oversight (USP <797> standards). Choose non-sterile when possible; sterile only when the route demands it.

Beyond-use date (BUD) is the date after which a compounded medication should not be used. Unlike manufactured drugs with 2–5 year shelf lives, compounded medications degrade faster because they lack preservatives and stability data. BUD depends on storage conditions and the formulation: (1) Non-sterile formulations (creams, ointments) in airtight containers at room temperature: 30 days to 6 months depending on ingredients (less stable if water-based or contains essential oils). (2) Non-sterile aqueous solutions: 7–14 days refrigerated (water supports bacterial growth). (3) Sterile formulations (IV): 24 hours at room temperature, or up to 7 days refrigerated, per USP <797> standards (shorter if not compounded in a certified facility). Calculate BUD conservatively: if you are unsure, assume 14 days non-sterile or 24 hours sterile. Check the stability of each ingredient (some drugs degrade in light or heat; store accordingly). Document the BUD on the label and in the pharmacy record. A compounded medication past its BUD should never be dispensed.

Accuracy depends on the tool: (1) Analytical balance: weighs down to 0.001 grams (most accurate); always balance to zero before weighing, use weighing papers (never pour directly into the pan), and measure the net weight (weight of ingredient minus paper). (2) Graduated cylinder: measures volume (mL) to the nearest 1 mL; read at eye level at the bottom of the meniscus (curved surface of the liquid), not the top. (3) Syringe: accurate to 0.5 mL or smaller; use tuberculin or insulin syringes for precise small volumes. Common errors: (1) Using a balance that is not zeroed or calibrated (you get 5 mg too much or too little). (2) Reading a graduated cylinder at the wrong level (top vs. bottom of meniscus). (3) Rounding too early (calculating 15.3 mL as 15 mL instead of 15.3, accumulating error over multiple steps). (4) Confusing weights (grams, milligrams, grains — an old unit; 1 gram ≈ 15 grains). Always double-check your calculation and measurement with a colleague; a second pair of eyes catches errors. Use SI units (grams, mL) exclusively; avoid old apothecary units (grains, drams, minims).

Aseptic technique is the practice of preventing microbial contamination during the preparation of sterile medications. Key steps: (1) Preparation: hand hygiene (wash with soap and water for 30 seconds), don clean garb (gown, gloves, cap, mask), and disinfect the laminar flow hood with 70% isopropyl alcohol, wiping from back to front and side to side. (2) Workspace: keep the hood's work area clean, organized, and traffic-free; do not reach over the hood opening (air particles drop in). (3) Aseptic handling: use sterilized needles and syringes (never reuse), alcohol-prep vial caps and ampule tops before drawing (wait 30 seconds for alcohol to dry), and use a new needle for each vial. (4) Technique: hold a vial upright, inject air equal to the volume of drug you will withdraw (prevents a vacuum), then withdraw the dose with the needle angled and the bevel under the surface of the liquid. (5) IV admixture: use a closed-system admixture kit (reduces contamination) and label clearly with drug, dose, patient name, date, and your initials. (6) Inspection: visually inspect for particulates, cloudiness, or discoloration before dispensing. A single breach in aseptic technique can introduce bacteria or fungi; these are invisible but can cause sepsis or meningitis. USP <797> standards require annual media fill testing (simulated compounding with sterile media to verify your technique is truly aseptic).

A suspension is a mixture of a solid drug in a liquid; an emulsion is a mixture of two liquids that don't normally mix (oil in water). Both are unstable and tend to separate over time. Suspensions: (1) Use a suspending agent (tragacanth, methylcellulose, or xanthan gum) to thicken the liquid and keep the solid particles dispersed. (2) Shake before each use to redistribute settled particles. (3) Store in an airtight container away from light and heat. Common failure: forgetting the suspending agent = particles settle to the bottom within hours, patient gets wrong dose. Emulsions: (1) Use an emulsifying agent (lecithin, polysorbate, or gum arabic) to stabilize the oil-water interface. (2) Mix in the correct order: usually oil into water (never water into oil). (3) Add the emulsifier slowly while mixing to prevent phase separation. Common failure: adding water too quickly or mixing oil into water (reverse order) = the emulsion 'breaks' and separates into distinct oil and water layers. Test for stability: prepare a small batch, store it as directed, and observe daily for 7–30 days; if it separates or grows mold, adjust the formula (more suspending agent, different preservative, shorter BUD). Instability = medication failures and patient complaints ('My suspension separated'). Stability testing is tedious but essential.

Children often refuse bitter or sour medications; flavoring and sweetening masks the taste. Strategies: (1) Use liquid flavoring agents (cherry, strawberry, grape, bubble gum) — add 2–5% of the total volume; too much flavoring makes the suspension thick and unpleasant. (2) Add sweetener (sucrose, sorbitol, or aspartame) in 10–50% concentration; sucrose is most common but risks cavities, while sorbitol is better for diabetic children. (3) Layer the flavoring: first add the suspending agent and drug, then add flavor and sweetener last, to avoid degrading the drug or affecting viscosity. (4) Test with an older child or parent to ensure palatability before finalizing. (5) For very bitter drugs (e.g., doxycycline), consider enteric-coated capsules or suggest the child swallow whole rather than crushing and mixing into suspension. (6) Educate parents: 'Refrigerate and shake well; the flavor may separate if stored too long.' Palatability is often the difference between a child taking the full course and a parent giving up after dose 2. A five-minute flavor and sweetening step dramatically improves adherence.

A powder for reconstitution is a dried formulation (powder or granules) that the patient mixes with water or another liquid before taking, creating a liquid dose (usually a suspension). Examples: antibiotics (amoxicillin powder), antivirals, and other drugs unstable in liquid form. Advantages of powder: (1) longer shelf life (powder is more stable than aqueous solution; BUD can be 6–12 months vs. 7–14 days for liquid), (2) smaller package (easier to mail or carry), (3) patient re-hydrates as needed (reduces waste if only a portion is used). Disadvantages: (1) patient must mix correctly (some add too much or too little water, affecting dosing), (2) risk of non-adherence if mixing is burdensome. Compounding a powder for reconstitution: (1) weigh and mix the active drug and suspending agents (e.g., methylcellulose, tragacanth) on an analytical balance, (2) add a flow agent (silica, maltodextrin) to prevent caking, (3) sieve to ensure uniform particle size, (4) package in an airtight container, and (5) include clear directions ('Add water to the line marked on the bottle, shake well'). Labeling must state the final concentration after reconstitution (e.g., '125 mg/5 mL when reconstituted'). This is more complex than dispensing a pre-mixed liquid but often preferred for pediatric antibiotics and other unstable drugs.

Quality control is a multi-step process: (1) Pre-compounding: verify the prescription is legible and correct, check for drug allergies and interactions, confirm the dose is appropriate for the patient (especially pediatric or elderly), and verify you have the correct ingredients (check labels three times). (2) During compounding: measure carefully (use a balance or graduated cylinder appropriate to the volume), mix thoroughly (homogeneity ensures uniform dosing), and follow the SOP (standard operating procedure) for each formulation. (3) Post-compounding: visually inspect the final product (color, consistency, odor) — does it match the expected appearance? Compare to a reference standard if available. (4) Labeling: verify the label includes patient name, drug name, dose, directions, date compounded, BUD, your initials, and any warnings (e.g., 'Shake well' or 'Keep refrigerated'). (5) Documentation: record the prescription, ingredients used, weights/measures, compounder initials, and pharmacist who checked it. (6) Verification: another pharmacist reviews the prescription, the final product, and the label before dispensing. (7) Patient counseling: educate on how to store and use the medication, how to measure doses, and when to call if it separates or smells odd. A single error (wrong dose, contamination, mislabeling) can cause patient harm and legal liability. Compounding is high-risk; never rush or skip verification steps.