Calculation of dosage & metric system

1. Calculation of Dosage & Metric System Kaleem ul Haq

2. 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.

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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 .

9. 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)

10. 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 .

11. Calculation by Alligation Simple arithmetical method for calculation of resulting strength after mixing solutions or other substances .

12. Metric System The use of metric system of weights and measures was legalized in 1897 by the weights and measures (Metric System ) .

13. Length Basic unit = 1 meter (m) 1 decimeter (dm) = 1/10 th part of 1 meter 1 centimeter (cm) = 1/100 th part of 1 meter 1 millimeter (mm) = 1/1000 th part of 1 meter 1 micrometer (um) = 1/1000 th part of 1 cm 1 nanometer (nm) = 1/1000 th path of 1micron`

14. 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) = 1/1000 th part of a kg 1 milligram (mg) = 1/1000 part of a gram 1 micrograms ( ug ) = 1/1000 part of milligram

15. Capacity The 1 Liter is the volume occupied by a cube with side of 1 decimeter Basic unit = 1 liter 1 milliliter = 1/1000 th part of a liter 1 ml is equal to 1 cubic centimeter.