Weights

Weight

is a unit of measurement for the force of gravity applied to a body that is inversely correlated with mass.. Or the weight of an object is usually taken to be the force on the object due to gravity

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Measures

Finding out the size, amount, or degree of (something) by using an instrument or device marked in standard units is called measures. Or

A standard unit used to express the size, amount, or degree of something.

System of Measurement

A system of measurement is a set of units of measurement which can be used to specify anything which can be measured

There are two Systems of weights and measures

1. The Imperial System
2. The Metric System
3. Imperial System

A system of weights and measures originally developed in England.

Example of Imperial measures:

Length: inches, feet, yards

Area: square feet, acres

Weight: pounds, ounces,

Volume: fluid ounces, gallons

The Imperial System has been replaced by the Metric System in most countries (including England). We will discuss only the metric system in detail

Metric System

The most commonly used system of weights and measures in pharmacy is the metric system. Understanding of the metric system is important to perform calculations in the pharmacy.

The three basic units of the metric system are the meter, the gram, and the liter The names of the other units are formed by adding a prefix to one of the basic values of Prefixes in the Metric System

Units. Each prefix has a numerical value as indicated below.

Prefix Values

Micro (mc) 1/1,000,000

Milli(m) 1/1,000

Centi(c)=1/100 times the basic unit.

Deci - (d) 1/10 Deka - (dk)=10

Hecto - (h)=100 times the basic unit.

Kilo (k) = 1000

Standard Unit of Weight in the Metric System Used in the Pharmacy

Common measures of weight in metric system

(a) 1~kg=1000~g

(b) 1~g=1000~mg

(c) 1~mg=1000~mcg

Whereas

Kg = kilogram

g = gram

mg = milligrams

mcg = microgram

The gram (g or gm) is the basic unit of weight used to weigh solids in the pharmacy.

1 kilogram (kg)=1000gm

1 hectogram (hg)=100gm

1 decagram (dag)=10gm

1 gram (gm) = 1000 milligrams (mg)

1 decigram (dg)=0.1gm or 100mg

1 centigram (cg)=0.01gm or 10mg

1 milligram (mg)=0.001gm or 1mg

Standard Unit of Volume in the Metric System

1 kiloliter (kl)=1000 liters

1 hectoliter (hl) = 100 liters

1 decaliter (dal) = 10 liters

1 liter (1) = 1,000 milliliters (ml)

1 deciliter (dl)=0.10~L or 100ml

1 centiliter (cl)=0.01~I or 10ml

Domestic measures

drop-0.06ml nea spoonfull= 5ml desert spoonful omil table spoonful-15ml sea cupifal 120ml Dand ounce =30ml

Measurement of Temperature

Centigrade or Celsius temperature scale Celsius temperature scale also called centigrade emperature scale, is the scale based on 0 for the freezing point of water and 100 for the boiling point of water.

Fahrenheit temperature scale

Falhrenheit temperature scale is a scale based on 32 for the freezing point of water and 212 for the boiling point of water.

Conversions of Temperature

The following formula works for converting both ways, that is, conversions can be made from Fahrenheit to Centigrade or from Centigrade to Fahrenheit using this formula:

SF-9C+160

Calculation

Density

Density is defined as the mass of a substance per unit volume. Density is defined as mass divided by volume Density mass/volume.

Volume

Vohome is the measure of space occupied by an object. Volume system unit of volume is liter (L), on the other hand, one liter is the Volume weight/density volume of a 10-centimetre cube, 1 liter = (10 cm)3

Percentage

Percent means "parts per hundred" and is expressed in the following manner.

Or

Percentage is the rate, number, or amount in each hundred.

Percentage number of parts/100 parts

Percentage Preparations

There are three types of percentage preparation

1. Weight in volume (W/V)
2. Weight in weight (W/W)
3. Volume in volume (V/V)

Weight in Volume (W/V)

W/V of Weight/Volume percent is defined as the number of grams in 100 milliliters of solution.

Example

(10% w/v solution of NaCl) A 10 percent (w/v) sodium chloride (NaCl) solution would contain 10 grams of sodium chloride in every ery 100 milliliters of water.

Weight in Weight (W/W)

W/W percent or Weight/Weight percent is defined as the number of grams in 100 grams of a solid preparation.

Example

(5% w/w boric acid ointment)

One hundred grams of boric acid would contain five grams of boric acid in a five percent (w/w) boric acid ointment.

Volume in Volume (V/V)

The volume/volume percent, often known as V/V percent, is the amount of liquid in milliliters per 100 milliliters of solution.

Example

(70% v/v solution of alcohol)

A 70% (v/v) alcoholic solution would contain 70 milliliters of alcohol in every 10 ml of solution.