Clinical calculations Number systems: –Arabic –Roman

Systems used for Drug adminstration Metric system Apothecary system Household system

METRIC SYSTEM DECIMAL SYSTEM THREE BASIC UNITS –GRAM –LITER –METER

CONVERSIONS WITHIN METRIC SYSTEM LARGER to smaller: multiply smaller to LARGER: divide *Eliminate unnecessary “0” *PRECEDE decimal with “0”

APOTHECARY SYSTEM Roman numerals Fractions Name precedes number

Conversions within apothecary system Larger to smaller unit, multiply Smaller to larger unit, divide (By constant value)

CONVERSIONS WITHIN THE HOUSEHOLD SYSTEM LARGER TO SMALLER UNIT SMALLER TO LARGER UNIT (By constant value)

CONVERSIONS WITH THE THREE SYSTEMS Metric and apothecary equivalents are approximations Unequal values should be rounded to nearest whole number You must memorize

memorize 1 gr = 60 mg 1 g = 15 gr 1 L = 32 oz 1 oz = 30 mL 2 T = 30 mL 3 t = 1 T

OTHER DRUG RELATED INFO ABBREVIATIONS Drug forms Drug measurements Routes of administration Times of administration

METHODS OF CALCULATIONS BASIC FORMULA D = desired dose H = on-hand dose V = vehicle (form and amt that drug comes)

Ratio and proportion H and V: left side, known quantities D and X: right side, desired dose and unknown (means & extremes, solve for “X”)

Fractional equation –Similar to ratio/proportion –Written as fraction –Cross multiply, solve for “X”

Dimensional Analysis 1.Drug dose form (V) 2.Equivalency in units (H) 3.Conversion factor (C) 4.Drug order factor (D)

Individualizing doses Dosing by actual body weight Convert pounds to kilograms Determine dose per body weight

remember I kg = 2.2 pounds 2.2 pounds = 1 kg

BASICS TO REMEMBER Cc = mL 30 mL = 1 oz 2 T = 6 t 5 mL = 1 t Gr 1 = 60 mg Gr xv = 1 g QD BID TID QID Qh NPO STAT PRN