pharm calc

• add active ingredient
• admixture with a like preparation of greater strength
• evaporation of vehicle (if liquid)

• add diluent
• admixture with a like preparation of lesser strength

elderly or young

• -diluent=increase concentration
• +diluent=decrease concentration

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

percentage or ration strength decreases

percentage or ratio strength increases

C1Q1=C2Q2

• concentrated solutions of active or inactive sibstances (increase concentrated)
• used as a convenience to prepare solutions of lesser concentrations

need to subtract amount already present from amount found in Q1C1=Q2C2 equation

arithmetical method of solving problems that involves the mixing of slutions or mixtures of solids possessing different percentage strengths

• 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

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

• strength of a mixture (desire) must lie somewhere between the strengths of its components
• stronger than its weakest component
• weaker than its strongest component

• reduce or enlarge formulas for pharmaceutical preparations
• offical formulas are based on the preparation of 1000 mL or 1000g

reduce formula

• enlarge formula
• maintain the correct proportion of one ingredient to another

Determine the factor that defines the multiple (enlarge) or the decimal fraction(refuce) of the amount of formula to be prepared

quantity of formula desired/quantity of formula given

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

indicate the relative proportion of each of the ingredients in the formula either by eright or volume