Dispensing Pharmacy - Quick Reference Notes

Section I — Ensuring Good Dispensing Practices

  • Dispensing: preparing and giving medicine to a named patient based on a prescription; interpret prescriber wishes; accurate preparation and labeling.
  • Dispensing Environment:
    • Clean, hygienic, uncontaminated; organized for accuracy and efficiency.
    • Staff: good personal hygiene; uniform; restricted access to dispensing area.
    • Surroundings: dust/ dirt minimized; protect from road pollution; access restricted to authorized personnel.
  • Stocking, Shelving & Storage:
    • Regular cleaning; spills wiped immediately; food/drink kept out; refrigerator for medicines only.
    • Temperature monitoring: target usually 2−8∘C2-8^\circ C; take corrective actions if out of range.
    • Labeling & organization: stock containers clearly labeled; alphabetic order; grouped by dosage form; regular expiry checks.
    • Stock rotation: use first-in/first-out (FIFO) or first-expiry/first-out (FEFO).
  • Equipment & Packaging:
    • Use appropriate tools for measuring liquids, weighing solids, counting tablets/capsules.
    • Prevent cross-contamination: clean equipment between products and at day end.
    • Fast movers placed in accessible locations for efficiency.
  • Dispensing Personnel:
    • Knowledge of medicines (uses, correct dose, precautions, interactions, storage).
    • Good calculation and arithmetic skills; ability to assess quality.
    • Cleanliness, accuracy, honesty; effective communication with patients.
  • Dispensing Process (six major activities):
    1) Receive and validate the prescription
    2) Understand and interpret the prescription
    3) Prepare and label items for issue
    4) Make a final check
    5) Record the action taken
    6) Issue medicine to the patient with clear instructions/advice
  • Standard Operating Procedures (SOPs): formalize the dispensing steps to improve consistency and training.
  • Packaging & Labeling:
    • After collecting products, package to protect quality and attach clear labels.
    • Containers must preserve medicine quality; liquids require clean bottles and secure caps; never mix two liquid medicines.
    • Reminder/dose-accuracy aids are increasingly used for complex regimens.
    • Label content should include: product name, strength, quantity, patient name space, dosage regimen; avoid abbreviations; include batch number and expiry where possible; consider pictorial labels for illiteracy; pretest readability.
  • Designated labeling practices (examples):
    • External-use-only warnings where applicable.
    • Small auxiliary labels (e.g., "Shake well before use", cautions).
  • Quick SOP reference (Dispensing Cycle):
    • Receive/Validate → Interpret → Prepare/Label → Final Check → Record → Issue with Instructions

Section II — Pharmaceutical Calculations

  • Dose terminology:
    • Minimum dose: lowest dose that achieves the desired therapeutic effect.
    • Maximum dose: highest dose usually tolerated without undesired effects.
    • Toxic dose: dose causing marked functional derangement.
    • Lethal dose: smallest dose known to cause death.
    • Prophylactic dose: dose to prevent disease onset.
    • Therapeutic dose: dose to treat an established disease.
    • Loading dose: higher-than-maintenance dose to rapidly achieve therapeutic plasma levels.
    • Maintenance dose: dose to maintain therapeutic level.
  • Pediatric dose calculations:
    • Pediatric groups: Neonate (birth–1 mo), Infant (1 mo–1 yr), Early/Late childhood, Adolescence, Adult; Premature defined as birth before 37 weeks.
    • Factors: age, weight, health status, organ function (hepatic/renal).
    • BSA-based dosing:BSA=height (cm)×weight (kg)3600\text{BSA} = \frac{\text{height (cm)} \times \text{weight (kg)}}{3600}
    • Child dose formulas:
    • Child dose=BSAchild×Adult dose1.73\text{Child dose} = \frac{\text{BSA}_{\text{child}} \times \text{Adult dose}}{1.73}
    • Child dose=Weight (lb)×Adult dose150\text{Child dose} = \frac{\text{Weight (lb)} \times \text{Adult dose}}{150}
    • Child dose=Age (yr)×Adult doseAge+12\text{Child dose} = \frac{\text{Age (yr)} \times \text{Adult dose}}{\text{Age} + 12}
  • Other considerations:
    • Adjust for disease state, severity, and organ function.
    • Pharmacokinetics vs. Pharmacodynamics: see Section VIII notes for definitions.
  • Quick prompts (conceptual):
    • Pharmacokinetics: how the body handles a drug (ADME: Absorption, Distribution, Metabolism, Excretion).
    • Pharmacodynamics: how the drug affects the body (mechanism of action, effect at target sites).
  • Example problem types (exam style): converting doses, adjusting for weight/age, pediatric dosing, and determining maintenance vs loading doses.

Section III — Powders

  • Practical No. 3: Dusting powders (composition for 100 g)
    • Camphor 10 g; Menthol 10 g; Ammonium chloride 20 g; Light magnesium carbonate 60 g.
    • Method: triturate camphor, menthol, ammonium chloride separately; mix camphor+menthol then add ammonium chloride; add 40 g magnesium carbonate; add 20 g of the mixture to remaining carbonate; geometric mixing; blend to uniform powder; package and label.
    • Uses: local anesthetic; emollient; counter-irritant.
    • Roles: Menthol (local analgesic); Camphor (astringent); Ammonium chloride (soothing); Magnesium carbonate (adsorbent/base).
    • Container: Sifter-top container; Storage: cool, dry place.
    • Labeling/label content and storage considerations (temperature, cleanliness).
  • Quick quiz prompts:
    • Define powder; classify types; clinical uses; qualities of an ideal powder.
  • Problem-based learning themes:
    • Two basic methods to dispense powders; alternative applications; infection risks; advantages and disadvantages; hygroscopic powder packaging options.

Section IV — Creams & Lotions

  • Practical No. 4: Sodium Bicarbonate Spray Lotion (100 ml)
    • Ingredients: NaHCO3 1.5 g; Borax 1.5 g; Phenol 0.15 g; Glycerin 25 g; Water to 100 ml.
    • Procedure: pre-dissolve NaHCO3 and borax in water; avoid gas buildup by using an open container; add glycerin and phenol; adjust volume with water.
    • Uses: antiseptic; external use only; container: spray bottle.
  • Practical No. 5: Vanishing Cream (100 g)
    • Ingredients: Stearic acid 20 g; KOH 1.5 g; Phenol 0.1 g; Glycerin 4 g; Water 74 g; Perfume.
    • Procedure: prepare two phases; saponify oils with KOH/NaOH; combine phases; cool; add perfume/phenol; container: wide-mouth jars or collapsible tubes; label: external use only.
  • Practical No. 6: Calamine Lotion (300 ml)
    • Ingredients: Calamine 150 g; Zinc oxide 50 g; Bentonite 30 g; Sodium citrate 5 g; Liquid phenol 5 ml; Glycerol 50 ml; Water 10 ml.
    • Procedure: triturate solids with sodium citrate solution; add liquids; mix; use as soothing/astringent.
    • Container: fluted bottles; direction: external use only; shake before use; apply with cotton swab.
  • Labeling protocol (external use only; keep for external use reminders).

Section V — Emulsions

  • Practical No. 7: Castor Oil Emulsion (60 ml)
    • Castor oil 8 ml; Acacia gum 2 g; Water to 60 ml.
    • Method: make mucilage from acacia in water; add oil dropwise with continuous trituration to form creamy paste; transfer and bring to 60 ml.
    • Uses: laxative/constipation relief.
    • Role: Castor oil (active); Acacia gum (emulsifying agent); Water (vehicle).
  • Emulsion-related concepts (test prompts):
    • How emulsions are prepared; creaming vs sedimentation; phase inversion; ideal emulsifying agent properties; vehicle selection for topical use.

Section VI — Sprays

  • Practical No. 9: Menthol Nasal Spray (100 ml)
    • Menthol 1 g; Liquid paraffin to 100 ml.
    • Procedure: dissolve menthol in small amount of liquid paraffin; make final volume with paraffin.
    • Container: fluted spray bottle; use: nasal decongestant; container: For nasal use only.

Section VII — Cosmetics

  • Practical No. 10: Sunblock (775 ml)
    • Zinc oxide 320 g; Calcium hydroxide 0.45 g; Oleic acid 5 ml; Arachis oil 320 ml; Wool fat 30 g; Water qs.
    • Procedure: form paste with zinc oxide and calcium hydroxide; add oleic acid and oils; gradually add water to required volume.
    • Uses: protects skin from UV rays; roles: physical blocker (ZnO), emulsifiers/bases, vehicle.
    • Container: appropriate cosmetic containers; labeling: external use only; non-irritating writing.
  • Practical No. 11: Shaving Cream (100 ml)
    • Stearic acid 38.8 g; Coconut oil 9.7 g; KOH 8 g; NaOH 1.6 g; Glycerol 11.6 g; Water 30.3 ml; Phenol 0.01 g; Perfume.
    • Procedure: saponify oils with alkali; create oil and aqueous phases; emulsify to creamy paste; adjust temperature; add preservative and perfume; container: collapsible tubes or wide-mouth jars; use: lubricating shaving cream; external use only.
  • Practical No. 12: After Shave Cream (175 ml)
    • Potash alum 2 g; White soft paraffin 50 g; Emulsifying wax 30 g; Liquid paraffin 20 ml; Glycerin 10 ml; Tween 80 0.5 ml; Methyl paraben 0.18 g; Propyl paraben 0.02 g; Rose oil 0.5 ml; Water qs.
    • Procedure: prepare oil and aqueous phases; heat to ~60-70°C; combine phases with stirring; add rose oil; allow to congeal; container: collapsible tubes or wide-mouth jars; use: astringent.

Section VIII — Drug Incompatibilities

  • Definition: incompatibility is an undesired reaction between a drug and a solution, container, or another drug; may occur during compounding, dispensing, or administration.
  • Types:
    • Pharmaceutical incompatibility:
    • Physical incompatibility: visible physical change; causes include insolubility, immiscibility, liquefaction, adsorption, complexation.
    • Chemical incompatibility: chemical interactions (color change, precipitation, effervescence) due to oxidation, hydrolysis, polymerization, isomerization, decarboxylation, CO2 absorption, insoluble complex formation.
    • Therapeutic incompatibility: errors in writing/interpretation; improper doses; antagonistic combinations; contraindicated drugs; toxic products from incompatibility.
  • Practical examples (illustrative): examples show how incompatibilities may manifest in prescriptions (e.g., incompatible combinations or dose miswrites).
  • Quick comparison:
    • Incompatibility vs. interaction: incompatibility is a formulation/administration issue; interactions are pharmacodynamic/pharmacokinetic interactions between drugs in therapy.

Glossary (selected terms)

  • Active Ingredient: component responsible for pharmacologic activity.
  • Emulsion: oil-in-water preparation for internal use or topical use depending on context.
  • Cream: semi-solid emulsion for topical use (oil-in-water or water-in-oil).
  • Dusting powder: fine powders applied to intact skin.
  • Lotion: liquid preparation for topical use without friction.
  • Shaving cream / After shave cream: cosmetic/therapeutic topical preparations with specific bases.
  • Sunblock: preparation that protects skin from UV rays; SPF relates to sun protection.
  • Excipients like emulsifying wax, glycerin, Tween 80, parabens, rose oil, etc., are used to stabilize, preserve, and enhance texture.

Notes and exam-style prompts to practice:

  • Explain six major steps in the dispensing cycle and give an SOP example for one step.
  • Distinguish between FIFO and FEFO with a practical example.
  • Calculate a pediatric dose using BSA, weight-based, and age-based formulas; indicate which method is most appropriate in a given scenario.
  • Describe the preparation and labeling requirements for a dispensed medicine, including external-use-only warnings and pictorial labeling considerations.
  • Outline the key differences between physical, chemical, and therapeutic drug incompatibilities with concise examples.