Pharmacy technician training- Unit 2, lessons 15-21

Amount of cream or ointment used per application

500 mg or 1 g (1g for calculations unless application area is known)

Amount of eye and ear drops per mL

20 drops/mL

Standard package size for insulin ins 10 mL

Fried’s Rule

Dosed based on infant age in months divided by 150 times the adult dose

Young’s rule

Calculating doses for 1-12 year olds, not used often

Age/age+12 x adult dose

Clark’s rule

Assumes adults weigh 150 pounds, phased out since average adult is over 150 pounds

Child’s weight/150 x adult dose

Alligation

Using proportions of two or more components with different concentrations needed to create a mixture of a desired concentration when needed concentration is not commercially available

1. Dilute stock solution

2. Combine 2 solutions of different concentrations of active ingredient

Alligation ratio calculations

Subtract the desired concentration from the higher concentration Subtract the lower concentration from the desired concentration. These differences represent the parts of each concentration needed. 

• HC ratio (parts of LC) = DC - LC 

• LC ratio (parts of HC) = HC - DC 

Add the HC ratio and LC ratio to find the total number of parts. 

Divide the individual ratio by the total parts and multiply by the desired total quantity to find the amount of each concentration needed

Another method:

Subtract required from higher conc

Subtract lower from required

Number results in ratio for each conc

Total parenteral products

Solutions administered by IV, includes IV admixtures, infusions, TPN, and chemotherapy

Drop factors

Refers to specific drop rate, usually 10 or 60 gtts/mL, but sometimes 15 or 20

Total parenteral nutrition (TPN)

Supplies all body needs, including fluids, nutritional needs, lipids, and electrolytes