Equations and Calculations Flashcards
Clark’s Rule
[weight (lbs) × average adult dose] / 150 = children’s dose
Young’s Rule
[Age (yr) × average adult dose] / [Age (yr) + 12] = children’s dose
Fried’s Rule
[Age (months) × average adult dose] / 150 = infant’s dose
Mg/kg/day
mg dose / kg of patient weight / over 24 hour period
A form of daily dose. Use as conversion factor for determining patient dose based on their weight.
Temperature Conversion
°F = (1.8°C) + 32
°C = (°F - 32) / 1.8
% mark up
[mark up ($) / item cost ($)] × 100%
Selling price
[number of items x item cost ($)] + [number of items × % mark up ($)]
% gross profit
[markup ($) / selling price ($)] × 100%
Net profit
Selling price ($) - [item cost ($) - overhead ($)]
% concentration and dilution
(old vol) × (old %) = (new vol) × (new %)
Allegation Alternate Method
High % ___________ High Parts (Parts of higher % needed for product)
________ Desired % ___________
Low % ____________ Low Parts (Parts of lower % needed for product)
High Parts = Desired % - Low %
Low Parts = High % - Desired %
Total Parts = High Parts + Low Parts
High Volume = [High Parts/Total Parts] x Volume of Final Product = volume of higher % required to make desired volume of desired %
Low Volume = [Low Parts/Total Parts] x Volume of Final Product = volume of lower % required to make desired volume of desired %
Flow rate
(Volume to be infused) / (amount of time being infused)
% (w/w)
for solid drug in solid vehicle. Units in numerator and denominator must match. What those units are is not set.
% (v/v)
for liquid drug in liquid vehicle. Units in numerator and denominator must match. What those units are is not set.
% (w/v)
for solid drug in liquid vehicle. Units of numerator are always grams of solid drug and denominator is always milliliters of liquid vehicle.
x% (w/w) product to ratio
x parts solid drug and 100 parts solid vehicle, or x:100
x% (v/v) product to ratio
x parts liquid drug and 100 parts liquid vehicle, or x:100
x% (w/v) product to ratio
x parts solid drug and 100 parts liquid vehicle, or x:100.
Allegation Medial Method
Amount of A Used x Concentration of A = result of multiplication for A
Amount of B Used x Concentration of B = result of multiplication for B
Amount of C Used x Concentration of C = result of multiplication for C
Sum of Amounts = Amount of A + Amount of B + Amount of C
Sum of Results = Result for A + Result for B + Result for C
Sum of Results / Sum of Amounts = Average Strength of Mixture of A, B, and C (often in percent)
This can be used to check answers for allegation alternate method.
Monovalent Milliequivalents (mEq)
Used for electrolytes. 1 mEq = # mmols of H+ or OH- that reacts with 1 mmol of Ion in molecule.
Monovalent: 1 mEq = Atomic Weight (AW) or Molecular Weight (MW)
NaCl has MW of 58.5, so 1 mEq = 58.5 mg. Dissociates into 1 mEq of Na+ and 1 mEq of Cl-
Divalent Milliequivalents (mEq)
Used for electrolytes. 1 mEq = # mmols of H+ or OH- that reacts with 1 mmol of Ion in molecule.
Divalent: 1 mEq = Atomic Weight (AW) or Molecular Weight (MW) / 2
CaCl2 has MW of 111, so 1 mEq = 111 / 2 = 55.5 mg. Dissociates into 1 mEq of Ca2+ and 2 mEq of Cl-
Trivalent Milliequivalents (mEq)
Used for electrolytes. 1 mEq = # mmols of H+ or OH- that reacts with 1 mmol of Ion in molecule.
Trivalent: 1 mEq = Atomic Weight (AW) or Molecular Weight (MW) / 3
Al(OH)3 has MW of 78, so 1 mEq = 78 / 3 = 26 mg. Dissociates into 1 mEq of Al3+ and 3 mEq of OH-
If solution has 10g of KCl, how many mEq of K+ does it have? AW K+ = 39 and AW of Cl- = 35.5
MW of KCl = [1 x 39] + [1 x 35.5] = 74.5
mEq = 74.5 / 1 (K+ is monovalent) = 74.5 mg
10g KCl x [1000 mg / 1 g] = 10,000 mg KCl
10,000 mg KCl x [1 mEq / 74.5 mg] = 134 mEq of KCl
Solution with 10 g KCl has 134 mEq of K+ and 134 mEq of Cl-
Vial label says “Add 9.2ml diluent to get 10ml of 100 mg per ml solution.” How many ml of recon sol would provide 250mg dose?
[250 mg / 1 dose] x [1 ml / 100 mg] = 2.5ml / 1 dose
