pharm calc

  1. changing the strength of a pharmaceutical preparation
    • add active ingredient
    • admixture with a like preparation of greater strength
    • evaporation of vehicle (if liquid)
  2. changing the strength
    • add diluent
    • admixture with a like preparation of lesser strength
  3. provide a product strength more suitable for use by a particular patient
    elderly or young
  4. same amount active ingredient
    • -diluent=increase concentration
    • +diluent=decrease concentration
  5. Strengteh and total quantity
    if the amount of active ingredient remains constant, any change in the quality of a solution or mixture of solids is inversely proportional to the percentage or ration strength
  6. increase quantity
    percentage or ration strength decreases
  7. decrease quantity
    percentage or ratio strength increases
  8. Relationship between total quantity and strength
  9. Stock solutions
    • concentrated solutions of active or inactive sibstances (increase concentrated)
    • used as a convenience to prepare solutions of lesser concentrations
  10. "should be added to"
    need to subtract amount already present from amount found in Q1C1=Q2C2 equation
  11. Alligation
    arithmetical method of solving problems that involves the mixing of slutions or mixtures of solids possessing different percentage strengths
  12. Alligation Medial
    • percentage strength of each component is multiplied by its corresponding quantity
    • sum of the products is divided by the total quantity of the mixture
    • resultant decimal fraction is multiplied by 100 to give percentage strength of mixture
  13. Alligation Alternate
    calculate the number of parts of 2 or more components of a given strength when they are mixed to prepare a mixture of desired strength
  14. Alligation Alternate
    • strength of a mixture (desire) must lie somewhere between the strengths of its components
    • stronger than its weakest component
    • weaker than its strongest component
  15. reducing and enlarging formulas
    • reduce or enlarge formulas for pharmaceutical preparations
    • offical formulas are based on the preparation of 1000 mL or 1000g
  16. Smaller quantity
    reduce formula
  17. greater quantity
    • enlarge formula
    • maintain the correct proportion of one ingredient to another
  18. Step 1
    Determine the factor that defines the multiple (enlarge) or the decimal fraction(refuce) of the amount of formula to be prepared
  19. Factor=want/have
    quantity of formula desired/quantity of formula given
  20. Step 2
    Multiply the quantity of each ingredient in the formula by the factor to determine the amount of each ingredient required in the reduced or enlarged formula
  21. Formulas that specify proportional parts
    indicate the relative proportion of each of the ingredients in the formula either by eright or volume
Card Set
pharm calc
altering product strengths