# WEIGHTS AND MEASURES.pptx

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```					 WEIGHTS AND MEASURES:

BY
Zubair Latif
DEPARTMENT OF PHARMACOLOGY
AND TOXICOLGY
UNIVERSITY OF VETERINARY AND
ANIMAL SCIENCES
LAHORE
POSOLOGY:

 It is the science of determining and understanding
drug dosage.

 To a limited or extensive degree, Posology may be
studied by anyone who wants to become a doctor,
nurse, pharmacist, veterinarian, or pharmacologist.
WEIGHTS:

 It is a measure of the gravitational force acting on
the body.
 Weight is directly proportional to the body mass.
 The mass is constant everywhere and based on
inertia where as weight varies slightly with altitude,
temperature and pressure.
 The effects of these factors are not considered unless
very precise weighing and large quantity are
involved.
MEASURES:

 It is the determination of the volume or extent of a
body.
 Temperature and pressure have pronounced effect,
especially on gases and liquids.
 These factors are therefore considered when making
precise measurements.
THE METRIC SYSTEM

 Metric systems of units have evolved since the
adoption of the first well-defined system in France in
1795.
 Multiples and submultiples of metric units are
related by powers of ten and their names are formed
with prefixes.
 Relationship is compatible with the decimal system
of numbers and it contributes greatly to the
convenience of metric units.
THE METRIC SYSTEM:

 In the early metric system there were two
fundamental or base units, the metre for length and
the gram for mass.

 The other units of length and mass, and all units of
area, volume, and compound units such as density
were derived from these two fundamental units.
BASIC UNITS OF METRIC SYSTEM:

Meter:
o It is the unit of length upon which the other units of
the metric system are based.
o One meter is equal to 1/40,000,000 of the earth’s
polar circumference.
o One meter is equal to 39.37 inches.
o It is abbreviated as “m”.
BASIC UNITS OF METRIC SYSTEM:

Liter:
o It is the basic unit of volume used to measure liquids.
o One liter is equal to the volume of one cubic
decimeter of water at 4°C.
o It is abbreviated as “l”(small L).
BASIC UNITS OF METRIC SYSTEM:

Gram:
 The gram is the basic unit of weight used to weigh
solids.
 One gram is equal to the weight of one milliliter of
distilled water at 4°C.
 It is abbreviated as “g or Gm”.
DETAIL OF THE METRIC SYSTEM:

 In 1944 the council on pharmacy and chemistry of
the American Medical Association adopted the
metric system exclusively.

 In many experimental procedures, including some in
the pharmaceutical sciences, very small quantities
(and occasionally very large) of the weight, length,
volume, time or radioactivity are measured.
DETAIL OF THE METRIC SYSTEM:

 To avoid the use of various numbers with many zero
in such cases, the NIST recognized prefixes to be
used to express fractions or multiple of the
International System of Units.
 This was established in 1960 by the General
Conference on Weights and Measures .
 He recognized prefixes, which are used adjoined to
an appropriate unit (as, for example, in such
quantities as nanogram, picomole, microcurie,
microsecond, or, megavolt)
INTRODUCTION TO METRIC SYSTEM:

S.NO   FACTI   PREFI   SYMB   MULTI   PREFI   SIMBL
ONS     X       OL     PLE     X       E
1      10-1    deci    d      10      deca    da
2      10-2    centi   c      102     hecto   h
3      10-3    milli   m      103     kilo    k
4      10-6    micro   µ      106     miga    M
5      10-9    nano    n      109     giga    G
6      10-12   pica    P      1012    tera    T
7      10-15   femto   F      1015    peta    P
8      10-18   atto    a      1018    exa     E
INTRODUCTION TO METRIC SYSTEM:

S.NO   METRIC WEIGHT       EQUAL TO   EQUIVALENT
WEIGHT
1      1 microgram µg      =          0.000001g
2      1 milligram   mg    =          0.001g
3      1 centigram   cg    =          0.01g
4      1 decigram    dg    =          0.1g
5      1 gram         g    =          1g
6      1 decagram     dag =           10g
7      1 hectogram    hg   =          100g
8      1 kilogram     kg   =          1000g
INTRODUCTION TO METRIC SYSTEM:

S.NO   UNIT      INCHES MM       µM      NM       A

1      1 inch    1        25.4   25400   2.54×107 2.54×108

2      1mm       0.0394   1      1000    106      107

3      1µm       3.94×10- 10-3   1       1000     10000
5

4      1nm       3.94×10- 10-6   10-3    1        10
8

5      1A(Angstr 3.94×10- 10-7   10-4    0.1      1
om)       9
INTRODUCTION TO METRIC SYSTEM:

S.NO     METRIC          LEQUID EQUIVALENT
MEASURES
1       1 microliter(µL)        0.000001L
2       1 milliliter(mL)     0.001L
3       1 centiliter(cL)     0.01L
4       1 deciliter(dL)      0.1L
5       1 liter(L)           1L
6       1 dekaliter(dL)      10L
7       1 hectoliter(hL)     100L
8       1 kiloliter(kL)      1000L
THE ENGLISH SYSTEM:

 This system grew out of the creative way that people
measured for themselves.

 Familiar objects and parts of the body were used as
measuring devices. For example, people measured
shorter distances on the ground with their feet.

 The ancient "digit," "palm," "span" and "cubic" units
of length slowly lost preference to the length units
"inch," "foot," and "yard."
THE ENGLISH SYSTEM:

 Roman contributions include the use of 12 as a base
number (the foot is divided into 12 inches) and the
words from which we derive many of our present
measurement unit names.

 For example, the 12 divisions of the Roman "pes," or
foot were called unciae. Our words "inch" and
"ounce" are both derived from that Latin word.
THE ENGLISH SYSTEM:

 The "yard" as a measure of length can be traced back
to early Saxon kings (rulers arose in England).

 They wore a sash or girdle around the waist that
could be removed and used as a convenient
measuring device.

 The word "yard" comes from the Saxon word "gird"
meaning the circumference of a person’s waist.
THE ENGLISH SYSTEM:

 In English system of measurement, avoirdupois
and apothecary system of weight measurement are
used in handling medicine.

 It must be emphasized that pharmacist may buy
their drugs by avoirdupois weight.
AVOIRDUPOIS SYSTEM:

 The word avoirdupois is from Anglo-Norman
(French rulers) aveir de peis literally "goods of
weight".

 This term originally referred to a class of
merchandise: aveir de peis, "goods of weight", things
that were sold in bulk and were weighed on large
steelyards or balances.
AVOIRDUPOIS SYSTEM:

 There are two major theories regarding the origins of
the avoirdupois system.

 The older theory is that it originated in France.

 A newer theory is that it is based on the weight
system of Florence (capital of the Italian region).
AVOIRDUPOIS SYSTEM:

 The avoirdupois weight system is thought to have come
into use in England circa 1300. It was originally used for
weighing wool.

 In the early 14th century several other specialized weight
systems were used, including Troy weights (used by
goldsmiths) and the weight system of the Hanseatic
League (lower Germans) with a 16-ounce pound of 7200
grains and an 8-ounce mark.

 However, the main weight system, used for coinage and
for everyday use, was based on the 12-ounce Saxon
pound of 5400 grains, also known as the Tower pound.
AVOIRDUPOIS SYSTEM:

 From the 14th century until late 16th century, the
avoirdupois pound was also known as the wool
pound or the avoirdupois wool pound.

 The basic unit of weight in the avoirdupois system is
the grain (gr). The larger units are the ounce (oz)
and the pound (lb).
AVOIRDUPOIS SYSTEM:

Grain:
o The grain is a unit of measurement of mass that is
nominally based upon the mass of a single seed of a
cereal.
o From the Bronze Age (iron and stone age) into the
Renaissance (14-16 century) the average masses of
wheat and barley grains were part of the legal
definition of units of mass.
AVOIRDUPOIS SYSTEM:

Ounce:
 It is a unit of mass with several definitions, the most
commonly used of which are equal to approximately 28
grams.

 Its size can vary from system to system.

 The most commonly used ounces today are the
international avoirdupois ounce and the international
troy ounce.
 The avoirdupois ounce is the most commonly used ounce
today.
AVOIRDUPOIS SYSTEM:

 It is defined to be one sixteenth of an avoirdupois
pound which is equal to 7,000 grains.

 One ounce is therefore equal to 437.5 grains.

 On January 1, 2000, it ceased to be a legal unit of
measure within the United Kingdom for economic,
health, safety or administrative purposes, but
remains a familiar unit, especially amongst older
people.
AVOIRDUPOIS SYSTEM:

 The troy ounce is equal to 480 grains. It is equal to
exactly 31.1034768 grams.

 There are 12 troy ounces in the troy pound which is
equal to 5760 grains.
AVOIRDUPOIS SYSTEM:

Pound:
 The avoirdupois pound, also known as the wool
pound, first came into general use.

 It was initially equal to 6992 troy grains.

 It is also equal to 16 ounces.

 During the reign of Queen Elizabeth, the avoirdupois
pound was redefined as 7,000 grains.
AVOIRDUPOIS SYSTEM:

 In 1963 a new Weights and Measures Act defined for
the first time as a mass equal to 0.45359237 kg to
match the definition of the international pound
agreed in 1959.

 To convert from the avoirdupois system to the metric
system, one must know the conversion factors, which
are 1 gr = 65 mg, 1 g = 15.4 gr, 1 oz = 28.4 g and 1 kg
= 2.2 lb.
APOTHECARY SYSTEM

 The apothecary system is one of the oldest systems of
measurement used when calculating drug dosages.

 This system originated in Greece, and eventually
made its way to England where it was used during
the late 1600s, being brought by the colonist to
America where it evolved and became a modified
APOTHECARY SYSTEM

 The basic unit of measurement used for weight in the
apothecary system is the grain (gr).

 One pound contains 12 ounces (℥), an ounce
contains 8 drachms, and a drachm (ʒ) contains 3
scruples or 60 grains.
APOTHECARY SYSTEM

 Care should be taken not to confuse the ounce and
pound of the apothecary system with their
counterparts in the avoirdupois system.
APOTHECARY SYSTEM

 In the United States, the apothecary system remained
official until it was abolished in 1971.

 This system also contains units for fluid measurement.
The basic unit of measurement used for volume is the
minim (m). A minim is equal to the quantity of water in
a drop that also weights 1 grain.

 A fluid dram is equivalent to 60 minims and a fluid
ounce is equal to eight fluid drams and 16 fluid ounces
in one pint; two pints equals one quart; and, there are
four quarts in one gallon.
COMMON WEIGHTS USED
IN PHARMACY
THE RELATIONSHIP OF WEIGHT AND MEASURE (PRACTICAL EQUIVALENT)

LINEAR MEASURE:        LIQUID MEASURE:       WEIGHT:
1 meter= 39.4 inches   1 milliliter=16.2m    1 kilogram=2.20 lb avoir
1 inch=2.54cm=25.4mm   1 fluidounce=29.6ml   1 pound avoir=454g
1micrometer=1/1000mm   1 pint=473ml          1 ounce avoir= 28.4g
=10-6m                 1gallon=3790ml        1 ounce apothecary=
31.1g
1pound                in
apothecary=373g
1gram=15.4 gr
1grain=64.8 mg
THE RELATIONSHIP OF WEIGHT AND MEASURE (APPROXIMATE MEASURES)

S.   HOUSEHOLD           APOTHECARY      METRIC VOLUME
N    MEASUREMENTS        NOTATION
O
1    1 tumblerful        8 Fluidounces   240ml
2    1 teacupful         4 Fluidounces   120ml
3    1 wineglassful      2 Fluidounces   60ml
4    2 tablespoonfuls    1 Fluidounces   30ml
5    1 tablespoonful     3 Fluidounces   15ml
6    1 dessertspoonful   2 Fluidounces   8ml
7    1 teaspoonful       1 Fluidounces   5ml
8    ½ teaspoonful        Fluidounces    2.5ml

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