RATIOS OR…TIME TO GRAB THOSE CALCULATORS……

PERCENTAGES Represent a portion of a whole (100) Used in compounding Used to calculate markup on prices, payment discounts, net profits, gross profits

RATIOS Also called proportion or formula method –Can be considered as parts or fractions –A concentration of 1:1000 means there is 1 part to 1000 parts or 1 g of drug in 1000 ml of solution

RATIOS 90% of the orders you will encounter in the pharmacy will be ratio/proportion equations This is three-step process: 1)Filter out the unnecessary information 2)Find what strength you have in stock and what strength you need 3)Set up an equation and double-check the calculations

RATIO METHODS 1)Method A: (have = need or ratio/ proportion) 2)Method B: D / H x Q = Medication to give D = desired dose H = have in stock Q = quantity needed If there are 30 ml in 1 ounce, the ratio is 30:1, written as 30ml/1oz.

PROPORTIONS A proportion is an equation that links two equivalent ratios __a__ = __c__ or a:b = c:d b d It is solved by b x c = a x d

PROPORTIONS EXAMPLE: Ecotrin tabs are labeled 324 mg. How many grains of Ecotrin are in each tablet? We know 1 grain = 60 mg. Method #1: _60mg_ = _1 grain_ 324 mg X Method #2: _60 mg_ = _324 mg__ 1 grain X To solve: (324 mg) (1 gr) = (60 mg) (X gr) X = 324 ÷ 60 X = 5 grains

ANOTHER RATIO TO TRY How many ounces are in 120 ml? _30 ml_ = _120 ml_ 1 oz X X = 120 oz ÷ 30 X = 4 oz.

LAST RATIO TO TRY How many pints are in 12 gallons? _8 pts_ = __X__ 1 gal 12 gal X = 96 pts ÷ 1 X = 96 pts

DETERMINING WEIGHT Because all manufacturers provide proper dosing regimens based on kilograms, it is necessary to convert pounds into kilograms There are 2.2 pounds per kilogram –2.2 pounds = 1 kg –16 ounces = 1 lb To determine how many kg in 1 lb, divide To determine how many lbs in 1 kg, multiply

EXAMPLES Example #1 The patient weighs 183 lbs. How many kg is this? 183 ÷ 2.2 = kg Example #2 The patient weighs 12.4 kg. How many lbs. is this? 12.4 X 2.2 = lbs