Pharmaceutics Unit -2.pptx

Pharmaceutics
B. Pharma
1st Semester
Unit -2
Pharmaceutical calculation
Presented by – Nikita Gupta
(Assistant Professor )

Pharmaceutical calculations
There are two systems of weights and
measures
1. Imperial system
2. Metric system

1. Imperial system:- Old system of weights and measures.
• In this weight is a measure of gravitational force acting
on a body.
• It is divided into
A. Avoirdupoir system
B. Apothecories system

Avoirdupoir system:- Pound is standard unit ( Lb )
1Lb = 16oz
1 Lb = 7000 grains
So, 16 oz = 7000 grains
1 oz = 7000 / 16 = 437.5 grains

Apothecories system
Also known as troy system.
The grain is standard weight.
➢ 20 grains ( gr) = 1 scruple ( )
➢ 60 grains = 1 drachm ( )
➢ 480 grains = ounce ( )
➢ 8 drachms = 1 ounce
➢ 12 ounces = 1 pound ( Lb )
➢ 5760 grains = 1 pound

MEASURMENT OF CAPACITY IN IMPERIAL SYSTEM:-
Gallon is the standard unit.
➢ 1 gallon = 160 fluid ounces
➢ 1/4 of o gallon = quart
➢ 1/8 of o gallon = 1 pint
➢ 1/160 of o gallon = 1 fl ounce
➢ 1/8 of o fl ounce = 1 fl drachm
➢ 1/60 of o fl drachm = 1 minim

2. Metric system - 1 st April 1964,
Metric system was implemented in india in pharmacy profession. ▪
Used in Indian pharmacopoeia for weight and capacity
(i) Weight conversion
1 kilogram (kg) = 2.2 Lb ( pound )
30g = 1 ounce
450g = pound
1g = 15 grains
60mg = 1 grain

(ii) Capacity ( volume )
1000ml = 1 quart
500ml = 1 pint
30 ml = 1 fluid ounce
4ml = 1 fluid drachm
1ml = 15 minims
0.06ml = 1 minim
1l = 0.2642 gallon

Calculations involving percentage solutions
Percentage calculation:-
It is of four types-
(1) Percent w/v ( weight in volume ) solution or suspension
(2) Percent v/v ( volume in volume ) solution or syrup
(3) Percent v/w ( volume in weight ) cream or semisolid
(4) Percent w/w ( weight in weight ) powders

Weight in volume ( w/v) solution:-
Impirial system
Q.1= calculate the quality of dextrose required to
prepare 1fl.oz of a 10% solution.
Calculation:-
1oz = 100 fl. Oz
(Solid) (liquid)

1oz = 437.5 gr
So, 100 fl oz = 437.5 gr.
Means- 1 fl oz ( 4.375 gr.) = 1% w/v solution
So, 10% w/v solution = 4.375 × 10 gr. = 43.75 gr.
So, 43.75gr of dextrose when dissolved in water to make 1
fl oz produce 10% w/v solution.

Metric System
Q.2:- calculation the quantity of solution chloride required to make
500ml of a 0.5% solution.
Calculation:-
1% solution = 1g of sodium in 100ml water.
0.5% w/v solution = 1×0.5g of solution chloride in 100ml water
= 0.5g of sodium chloride in 100ml water.
So, for 500ml of 0.5% solution = 0.5 x 500 = 2.5g
100
So, 2.5g of sodium chloride is dissolved in water to produce 500ml of
a 0.5% solution.

Weight in weight ( w/w) solution:-
Q.1:- Prepare 100ml of phenol glycerine
I.P. CALCULATION:-
IP Formula is.
Phenol 160g
Glycerin 840 g
1000g

Weight per ml glycerine = 1.257g
= 1.26g
So, 100ml of phenol glycerin require glycerin = 100 x 1.26 = 126g
1000 g phenol glycerin contain = 160g phenol
So, 100 g phenol glycerin contain = 160 x 100 = 16% w/w
1000
So, Quality of phenol required = 160 x 126 = 24 g
840

So New formula for 100ml is –
Phenol 24 g
glycerin 126 g

Volume in volume ( v/v ) solutions:-
Q.1 :- Prepare 200ml of 5% solution of chloroform in 90% alcohol.
Sol. –
1ml chloroform dissolved in 100ml of alcohol = 1% v/v solution
5ml chloroform dissolved in 100 ml of alcohol = 5% v/v solution
5 x 2 (10 ml ) ml chloroform dissolved in 200ml of alcohol = 5% v/v
solution

Alcohol Dilutions
Dilute alcohols are made from
95% alcohol = 95 parts alcohol
05 parts of water
When alcohol get mixed with water following changes take place
(1) Rise in temperature
(2) Contraction in volume
(3) Turbid appearance due to solubility of air is more in alcohol than
in water.
So, dilution will be done at about 20°c

Example :- Calculate the amount of 95% alcohol required to prepare
400ml of 45% alcohol
Calculation:-
Volume of stronger alcohol to be used = volume required x percentage
required
Percentage used
= 400 x 45 = 18000
95 95
= 189.47ml = 190ml
So, 190ml 95% alcohol is diluted with water to produce 400ml resulting
alcohol is 400ml 45% alcohol.

Alligation Method:-
When calculation involves mixing
of Two or more similar preparations of different strength
To produce a preparation of intermediate strength.

Proof spirit and Isotonic solutions based on freezing point
and molecular weight.
Isotonic solutions:- Solution having the same osmotic pressure are
called iso-osmotic or isotonic solution.
If a red blood cell is in contact with a solution that has the same
osmotic pressure as that of blood plasma. The cell wall neither
swell nor shrink.

The solutions which are not roving same osmotic
pressure are called – paratonic.
Have greater pressure called hypertonic.
Have less pressure called hypotonic.

The main contribution of osmotic pressure is due to 0.88% of
inorganic salts mainly sodium chloride present in blood plasma.
So a solution containing 0.9% NaCl is.. Practically isotonic
with blood plasma.
A Solution Containing. More than 0.9% NaCl. Called
Hypertonic ( causes shrinkage of RBC )
Less than 0.9% NaCl Called Hypotonic ( causes swelling of
RBC )

Calculations for adjustment to isotonicity:-
1) Based on freezing point method :-
Percentage w/v of adjusting = 0.52 – a
substance needed b
Where, a = freezing point of unadjusted solution
b = freezing point a 1% w/v solution of the adjusting
substance.

2) Based on molecular concentration:-
Percentage w/v of adjusting
substance needed = 0.03 M
N
Were, M = Gram molecular weight of the substance.
N = Number of ions which the substance is ionised

Example:- Find the concentration of sodium chloride required to
produce a solution iso-osmotic with blood plasma.
Calculation:-
Molecular weight of sodium chloride ( NaCl ) = 23 + 35.5 = 58.5
Sodium chloride is ionising substance and it gets dissociate into 2 ions.
Hence, the following formula is used.
W = 0.03 M = 0.03 x 58.5
Or, W = 0.88 g per 100 ml

Powder
Syllabus
• Definition
• Classification
• Advantages and disadvantages,
• Simple & compound powders – official preparations
• Dusting powders
• Effervescent
• Efflorescent and Hygroscopic powders
• Etectic mixtures.
• Geometric dilutions.

Powders: Power are solid dosage form which contain mixture of
powdered substance intended for both internal and external use.

Advantages of powder
1. Powders are convenient to prescribe, compound and
administer.
2. Powders are more stable than liquids.
3. Powders can be easily swallowed and large quantities can be
administered with foods or drinks.

4. Powders provide accuracy of dose.
5. There are less chances of chemical reactions in the
ingredient because of absence of moisture.
6. Powders are available in a very fine state, hence
provide rapid dissolution and absorption

Disadvantages of powder
1.Certain drugs are sensitive to atmospheric conditions
like air moisture and light, are not suitable for
dispensing in the form of powder.
2. Drugs which are bitter, nauseous, corrosive and
unpalatable are not suitable for dispensing in powder
form.

3. Manufacturing of powders requires operations like
milling sieving, mixing, drying, etc. Hence, it is time
consuming.
4. Powders are not suitable when they contain volatile,
deliquescent, hygroscopic or oxygen sensitive substance.

Simple & compound powders – official preparations
Simple Powder - In simple powder contains only one
ingredient either in crystalline form or amorphous form.
If powder present in crystalline form then it is reduced to fine
powder, weighed the powder & divided into number of doses
& wrapped as individual dose.

E.g. Dispensed six powders of Aspirin each powder
contains 300 mg of aspirin
Rx, Aspirin 300 mg
Procedure: powder the aspirin & weigh the required
quantity of aspirin. Weigh 300 mg of aspirin for each
powder & wrap each powder in individual powder paper.

Compound powders - Compound powders contains two or
more than two substances which are mixed together .
Then divided into desired number of individual doses. Then
dispensed into each powder paper.

E.g Dispense eight powder of A.P.C each powder
contains 500mg of A.P.C
Rx, Aspirin300 mg Paracetamol150 mgCaffeine50 mg
Procedure: weigh accurately of each powder & mix
them as per ascending order of their weight. Weigh 500
mg of the mixed powder for each powder & wrap each
dose individual in powder paper

Dusting powders
Dusting
Powder
Surgical
Medical

Surgical dusting powders are used mainly in body cavities
and on burns and umbilical cords of infants as a result of
major wounds, whereas medical dusting powders are used
on superficial skin conditions.
In contrast, medical dusting powders must be free of
pathogenic microorganisms while surgical dusting powders
must be sterilized before use.

It is generally possible to prepare dusting powders by
mixing two or more ingredients, of which starch, talc, or
kaolin must be one element.
The most common materials used are talc and kaolin
because they are chemically inert. These ingredients are
prone to contamination by pathogenic bacteria, however, so
before using them they must be sterilized by dry heat
method (160 degrees for 2 hours).

Effervescent
In effervescent powders, acids and carbonates or hydrogen
carbonates are generally combined with water to release
carbon dioxide when exposed to it.
The powders may be single-dose or multi-dose prepared.
Water is usually used to dissolve or disperse these drugs
before administration.

Storage - Powder effervescent should be stored tightly
closed in a container.
Upon combining organic food acid with carbonate, it forms
potassium, sodium, calcium or magnesium salts of the acid,
which buffer the pH of the solution to make it easier on the
stomach.
Studies have demonstrated that ingredients in a variety of
effervescent products can penetrate the bloodstream as
quickly as 15 minutes after application.

Efflorescent powder :- In the chemical world,
efflorescent powders are crystallized powders containing
water of hydration or crystallization, such as alums, atropine
sulphate, citric acid, caffeine, and codeine.
When exposed to a low humidity environment, this water can
be liberated either through manipulation or when exposed to
manipulation, Powders will become pasty and sticky if this
happens, or may even liquefy.

In an anhydrous salt form of the drug, it is possible to keep in
mind the differences between its potency during its anhydrous
form and during its hydrated form.
Solids with efflorescent properties can spontaneously lose
water when exposed to hydrated salts.

Hygroscopic Powders - The term hygroscopic means that
these substances can absorb or adsorb water from their
surroundings.
Those substances that adsorb or absorb water from the
surroundings are known as hygroscopic substances.
The water molecules in hygroscopic substances are absorbed
into the crystal structure when water vapor is absorbed.
As a consequence, the size of the substance increases.
A change in hygroscopic properties can be seen in colour,
boiling point, viscosity and others due to hygroscopic nature.

Eutectic Mixtures - Eutectic mixture is defined as a
mixture of two or more components which usually do not
interact to form a new chemical compound but, which at
certain ratios, inhibit the crystallization process of one
another resulting in a system having a lower melting point
than either of the components

Example – 1. In metallurgy and other areas, there are many
examples of eutectic mixture or eutectoids. These mixtures
usually have beneficial properties that no other constituent
material has.
2. The eutectic point of an ethanol-water mixture is almost pure
ethanol. The value indicates that distillation will achieve a full
proof or purity of alcohol
3. Minerals may create eutectic mixtures in igneous rocks,
resulting in distinctive intergrowth textures such as those seen
in granophyre.

4. Soldering is mostly done with eutectic alloys. By mass, a
standard formulation contains 63% tin and 37% lead.
5. Corrosion tolerance and hardness are exceptional in
eutectoid glassy metals.
6. Printer with inkjet technology. Since the ink is a eutectic
blend, it can be printed at a low temperature.
7. Galinstan is a liquid metal alloy made up of gallium,
indium, and tin that is used as a mercury substitute with low
toxicity.

Geometric dilution –
Geometric dilution is the process of diluting something
based on its measured size.
Most often, scientists and doctors employ this method
when combining fine powders of unequal amounts to
ensure equal distribution.

Bakers sometimes use geometric dilution to equally
combine the dry ingredients in a mixture
The UNC Eshelman School of Pharmacy explains that
geometric dilution methods include triturating powders
and mixing powders into ointments.

Liquid dosage forms
Syllabus
• Liquid dosage forms
• Advantages and disadvantages of liquid dosage forms.
• Excipients used in formulation of liquid dosage forms.
• Solubility enhancement technique

Liquid Dosage Forms
Liquid Dosage Forms are useful because some people have
the problem of swallowing solid dosage forms.
For the preparation of liquid dosage form, a lot of additive
ingredients are needed. Such as vehicles, stabilizers,
preservatives, suspending agents, emulsifying agents,
solubilizers, colours, flavours, etc
The liquid form of a drug dose for administration or
consumption. Route of administration may be oral,
intravenous, intramuscular, cutaneous, subcutaneous, etc.

Advantages:
• Very useful for those patients who have trouble swallowing.
• The rate of absorption of the liquid dosage form is so faster
than the solid dosage form.
• Liquid dosage forms are flexible to take a proper those than
solid dose.

Disadvantages:
• It needs a lot of special storage conditions.
• Affected by microorganisms: Due to the presence of
sweetening and flavoring agents.
• Less stable than other doses.
• The problem of container breakage.

Excipients used in formulation of liquid dosage forms
Along with the active drug substance, liquid dosage forms contain
excipients.
These serve a variety of pharmaceutical purposes.
The amount of these excipients is usually greater than the amount
of the drug substance since the drug substance comprises the bulk
of the formulation.
To ensure that liquid dosage forms are made of chemically and
physically compatible components, all of the excipients that are
used in the preparation should be compatible with every other
component.

Types of additives used in the liquid dosage forms
1. Vehicles :- Vehicles are those materials that are chemically
inert and don't have any therapeutic value.
But these are used in the formulation of liquid dosage forms to
improve the stability, patient acceptability, function of the
dosage form.
Examples of aqueous vehicles: Water, glycerin, alcohol,
Propyl glycol, Polyethylene glycol etc.
Examples of oily vehicles: Vegetable oils, mineral oils, organic
oily bases, and emulsified bases.

2. Stabilizers :- Stabilizers are those materials used to increase
the stability of material or formulation by preventing
degradation of the product.
According to the material, it varies.
3. Preservatives :- Preservatives are those ingredients used for
the preservation or for the protection of the formulation from
the attack of microorganisms.
Examples of preservatives: benzoic acid, sorbic acid, sodium
benzoate.

4. Suspending Agents :- Suspending agents are those
excipients, which are useful to help active pharmaceutical
ingredients to stay suspended into the formulation and prevent
the cake formation under the container of the formulation.
Suspending agents are using in the preparation of the
suspension.
5. Emulsifying Agents :- Emulsifying agents are those surface-
active ingredients used in the formation of the emulsion.
It's useful to adsorb the water-oil droplet interface.
Examples of emulsifying agents: Gun acacia, Tragacanth.

6. Solubilizers :- Solubilizers are those materials used to
increase the solubility of a material to improve bioavailability.
Example of solubilizers: Polysorbate.
7. Colouring agents :- Colouring agents are used in the liquid
dosage form to improve the acceptance of consumers.
Examples of natural colours: Titanium dioxide, carotene, ferric
oxide, etc.
Examples of Synthetic colours: Erythrosine, Tetrazine, etc.

8. Flavouring Agents :- Flavouring agents are used to
overcoming the unpleasant smell of a formulation.
Examples of flavouring agents: Apple, ginger, clove, rose,
etc.
9. Sweetening Agents :- Sweetening agents are used to
overcoming the unpleasant taste of the formulation.
Examples of sweetening agents: Sucrose, fructose,
saccharine, sorbitol.

10. Co-solvents - Essentially, co-solvents are designed to
increase the water solubility of drugs that do not contain ionic
groups and their water solubility cannot be increased by
adjusting the pH.
11. Surfactants - Microparticles in aqueous media can be
described as dynamic aggregates with defined polar
(hydrophilic) and nonpolar (hydrophobic) regions, called
surfactants or surface-active agents.

12. Viscosity/suspending agents - Excipients such as
viscosity modifiers and suspending agents, which act as
energy barriers and minimize particle attachment and
aggregation are known as viscosity modifiers and
suspending agents, respectively.

Suspension
A mixture in which small particles of a substance are dispersed
throughout a gas or liquid.
If a suspension is left undisturbed, the particles are likely to
settle to the bottom.
The particles in a suspension are larger than those in either a
colloid or a solution.
Muddy water is an example of a suspension.

Examples of Suspensions
❖ Mud in Water
❖ Turpentine oil in paint dyes
❖ Chalk in water
❖ Slaked lime for whitewashing
❖ Milk of magnesia
❖ Sand particles suspended in the water
❖ Kimchi suspended on vinegar

Heterogeneous mixtures occur when there is nonuniformity
with the substances present in a given mixture.
soapy water is a great example.
When you add soap to water and shake it up to mix, a
uniform, bubbly solution forms.
Two individual substances (water and dish soap) evenly
distribute and do not separate in this homogeneous solution.

Heterogeneous mixtures occur when there is nonuniformity
with the substances present in a given mixture.
In other words, heterogeneous mixtures contain different
substances that physically remain separated from one
another

Emulsion
An emulsion is a mixture of two or more liquids that are normally
immiscible (unmixable or unblendable) owing to liquid-liquid phase
separation.
emulsion should be used when both phases, dispersed and continuous,
are liquids. In an emulsion, one liquid (the dispersed phase) is
dispersed in the other (the continuous phase).
Examples of emulsions include homogenized milk, liquid
biomolecular condensates, and some cutting fluids for metal working.

Emulsion types
❖ Oil-in-water (o/w)
❖ Water-in-oil (w/o)
❖ Oil-in-water-in-oil (o/w/o)
❖ Water-in-oil-in-water (w/o/w)

Solubility Enhancement Techniques
❖Particle size reduction
❖Crystal engineering
❖Salt formation
❖Solid dispersion
❖Use of surfactant.

Pharmaceutics Unit -2.pptx

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Pharmaceutics Unit -2.pptx