Pharmacy Calculations Flashcards

Insulin Calculation

• 1 ML of insulin equals 100 units.
• Example: HUMULIN N U-100 with a sig of 35 units SQ daily.
• Quantity of insulin provided is 10 ML (or 1000 units).
• Calculation for days supply: 1000 units / 35 units per day results in 28 days.

Ear/Eye Drop Calculation

• 20 drops are equivalent to 1 ML.
• Example: SIG indicates 5 drops in each ear (AD) four times a day (QID) for 7 days.
• Quantity provided is 10 ML.
• Calculation for days supply: 10 ML x 20 drops/ML = 200 drops total; 200 drops / 20 drops (sig) gives 10 days.

Inhaler Actuation Calculation

• Inhalers can vary in the number of actuations.
• Example: ATROVENT contains 200 actuations with a sig to inhale twice every 12 hours (Q12H).
• Calculation for days supply: 200 actuations / 4 (2 actuations every 12 hours) equals 50 days.

Liquid Medication Calculation

• Liquid doses can vary.
• Example: A sig states 1 teaspoon (i TSP) four times a day (QID) as needed (PRN) for cough and cold.
• Quantity provided is 4 ounces (120 ML).
• Calculation involves: 5 doses daily (1 TSP = 5 ML) leading to 5 x 4 = 20 ML consumed daily; thus, 120 ML / 20 ML gives 6 days.
• Determine appropriate bottle size by dividing quantity by 30 (120 ML / 30 = 4 oz bottle).

Ointment/Cream Calculation

• Day supply for ointments/creams can vary based on application frequency and tube size.
• Example: NYSTATIN skin ointment at 100,000 units per gram with a sig to apply QID.
• Day supply is an estimate; commonly, ointments last around 30 days.

Tablets/Capsules Calculation

• Day supply can differ based on dosage regimen.
• Example: SIG indicates ii tablets orally in the morning (QAM) and ii tablets at night (QHS).
• Quantity provided is 60 tablets.
• Calculation for days supply: Patient takes a total of 4 tablets daily; therefore, 60 tablets / 4 tablets results in 15 days of supply.