Calculation of Dosage & Metric System
Kaleem ul Haq
Raees Ajaib
Asad Mehmood
Percentage Solutions
• Percentage w/w express the number of grams of active substance in 100g of solution .
• Percentage w/v express the number of grams of active substance in 100ml of solution.
• Percentage v/w express the number of ml of active substance in 100g of solution .
• Percentage v/v express the number of ml of active substance in 100ml of solution.
Percentage strength to millimoles Per Liter
• Let C=Percentage w/v strength of a salt.
• W=milligrams of salt containing 1 millimole of the specified ion
• 100 milliliter of solution contain C grams of salt
• 1L of solution contain 10x C grams of salt=10,000C milligrams
• Millimoles per liter = 10,000C/w
Calculation of doses
• We have following formulas for calculation of doses
• Young’s Formula
• Dilling’s Formula
• Cowling’s Formula
• Fried’s Formula
• Bastedo’s formula
• Clark’s Formula
• Gaubin’s formula
• Young’s Formula :-
• Dose for Child = Age (years )/Age +12 x Adult dose
• This formula is used for children under 12 years of age
• Dilling’s Formula :-
• Dose for Child = Age (years)/20 x adult dose
• The fraction age/20 approx close to weight curve between the ages 4 -20 so more than 10 years of age
• Cowling’s formula :-
• Dose of child = Age (Years )+1/ 24 x Adult dose
• Fried’s formula :-
• Dose of child = Age(months)/150 x Adult dose
• Bastedo’s formula :-
• Dose of child = Age (years )+3/30 x Adult dose
• Clark’s formula :-
• Dose of child = weight (pounds )/150 x Adult dose
Gaubin’s formula
Age(years) Dose for children with respect to adult dose
under 1 1/12
1-2 1/8
2-3 1/6
3-4 1/4
4-7 1/3
7-14 1/2
14-20 2/3
21- 60 full adult dose
60-70 4/5
70-80 3/4
over 90 1/2
Square Meter Surface Area Method
• Child dose = Body Surface area of child x Adult dose
Body Surface area of child
• The average body surface area for an adult has been given as 1.73meter square .
Reduction & Enlargement of Recipe
• The following rules are used in converting the recipe from one system to another
• Rule 1 :-
• To convert the recipe in imperial system to metric system
• Write grams in place of grains
• Divide the minims by 1.1 and write result in millimeters (for small scale )
• Write grams in in place of ounce & milliliters in place of fluidounce (for large scale)
• Rule 2 :-
• To convert a recipe in metric system to imperial system
• Write grains in place of grams
• Multiply the milliliter by 1.1 and write the result in in minims (small scale )
• Write ounce in place of grams & fluid ounce in place of milliliters .
Calculation by Alligation
• Simple arithmetical method for calculation of resulting strength after mixing solutions or other substances .
Metric System
• The use of metric system of weights and measures was legalized in 1897 by the weights and measures (Metric System ) .
Length
• Basic unit = 1 meter (m)
• 1 decimeter (dm) = 1/10th part of 1 meter
• 1 centimeter (cm) = 1/100th part of 1 meter
• 1 millimeter (mm) = 1/1000th part of 1 meter
• 1 micrometer (um) = 1/1000th part of 1 cm
• 1 nanometer (nm) = 1/1000th path of 1micron`
Mass
• The international kilogram is the weight in vacuum of platinum- iridium cylinder preserved at the international Bureau of Weights and Measurers
• Basic unit = 1 kilogram (kg)
• 1 gram (g) = 1/1000th part of a kg
• 1 milligram (mg) = 1/1000 part of a gram
• 1 micrograms (ug) = 1/1000 part of milligram
Capacity
• The 1 Liter is the volume occupied by a cube with side of 1 decimeter
• Basic unit = 1 liter
• 1 milliliter = 1/1000th part of a liter
• 1 ml is equal to 1 cubic centimeter.