This document discusses pharmaceutical impurities. It defines impurity as unwanted foreign particles other than the active drug. Impurities can come from raw materials, reagents, manufacturing processes, storage conditions, or deliberate adulteration. The types and amounts of impurities depend on factors like purity of starting materials and purification methods. Limit tests are used to detect and limit specific impurities like chlorides, sulphates, and iron according to pharmacopeia limits. The tests use reactions like precipitation or color changes to compare a sample to a standard of a known impurity level. Maintaining low impurity levels is important for safety, efficacy, and stability of pharmaceutical products.
Limit tests, Introduction, Definition,
Limit Test For Chlorides
Limit Test For Sulphates
Limit Test For Iron
Limit Test For Lead
Limit Test For Arsenic
Semisolid dosage forms: Definitions, classification, mechanisms and factors influencing dermal penetration of drugs. Preparation of ointments, pastes, creams and gels. Excipients used in semi solid dosage forms. Evaluation of semi solid dosages forms
Impurities in pharmaceutical substancesShaliniBarad
Impurities definition
Sources of impurities
Effect/ type of impurities
Limit test definition
Limit test Importance,
Principle & procedure of Limit test for iron, chloride, sulphate, arsenic & heavy metals.
Limit tests, Introduction, Definition,
Limit Test For Chlorides
Limit Test For Sulphates
Limit Test For Iron
Limit Test For Lead
Limit Test For Arsenic
Semisolid dosage forms: Definitions, classification, mechanisms and factors influencing dermal penetration of drugs. Preparation of ointments, pastes, creams and gels. Excipients used in semi solid dosage forms. Evaluation of semi solid dosages forms
Impurities in pharmaceutical substancesShaliniBarad
Impurities definition
Sources of impurities
Effect/ type of impurities
Limit test definition
Limit test Importance,
Principle & procedure of Limit test for iron, chloride, sulphate, arsenic & heavy metals.
Quality control drugs and pharmaceuticalsSHIVANEE VYAS
The term quality control is the most important in pharmaceutical industries. It is essential that a good quality product should be available to the doctors for treating patient or for the actual users. The term quality is applied to drugs and drug products which contributing directly or indirectly to the purity, safety & effectiveness of the products.
INTRODUCTION TO PHARMACEUTICAL CHEMISTRY AND LIMIT TESTSUJATA WANKHEDE
INTRODUCTION TO PHARMACEUTICAL CHEMISTRY, INTRODUCTION TO LIMIT TESTS, LIMIT TEST OF IRON, CHLORIDE, SULPHATE, ARSENIC AND THERE DIAGRAMS WITHTHE PRINCIPAL AND PROCEDURE OF ALL THE LIMIT TEST WITH THEIR RESULTS
Definition of Impurity
Types of Impurities
Sources of Impurity
foreign unwanted matter present in a compound which are differ from the actual molecular formula.
According to ICH “An impurity in a drug of the new drug substance that is not the substance”.
Chemically a compound is impure if it contains undesirable foreign matter i.e. impurities. Thus chemical purity is freedom from foreign matter
Impurities can have unwanted pharmacological or toxicological effect that seriously impact product quality and patient safety.
The International Conference on Harmonization (ICH) has formulated a workable guideline regarding the control of impurities.
Impurities in pharmaceutical are the unwanted chemicals that remains with the active pharmaceutical ingredient (API’s), or develop during formulation or upon aging of both API and formulated API’s to medicine.
The presence of the unwanted chemicals, even in small amount , may influence the efficacy and safety of pharmaceutical product
Impurities in pharmaceuticals are the unwanted chemicals that remain with the active pharmaceutical ingredients (APIs), or develop during formulation, or upon aging of both API and formulated APIs to medicines.
Types and Sources of impurities.pptx Pharmaceutical Inorganic chemistry UNIT-...Ms. Pooja Bhandare
Types and Sources of impurities. Pharmaceutical Inorganic chemistry UNIT-I (Part-II) Impurities:
Impure Chemical Compound
Pure Chemical Compound.
Types of impurities: Organic Impurity, Inorganic impurity, Residual solvent, Sources of Impurities in Pharmaceuticals
The different sources of impurities in pharmaceuticals are listed below:
Raw material used in manufacture
Reagents used in manufacturing process
Method/ process used in manufacture or method of manufacturing
Chemical processes used in the manufacture
Atmospheric contamination during the manufacturing process
Intermediate products in the manufacturing process
Defects in the manufacturing process
Manufacturing hazards
Inadequate Storage conditions
Decomposition of the product during storage
Accidental substitution or deliberate adulteration with spurious or useless materials.
Test for purity: Pharmacopoeia prescribes the “Test for purity” for pharmaceutical substances to check their freedom from undesirable impurities.
Pharmacopoeia will decide and fix the limit of tolerance for these impurities.
For certain common impurities for which pharmacopoeia prescribes the test of purity are:
Colour, odour, taste
Physicochemical constants (Iodine value, saponification value, melting point, refractive index etc.)
Acidity, alkalinity, pH
Humidity (Estimation of moisture)
Cations and anions
Insoluble Constituent or Residue.
Ash, Water insoluble ash
Arsenic or lead
Loss on drying
Loss on ignition.
Effect of Impurities
Introduction to limit tests, the limit test is a semiquantitative test, limit test for chlorides, limit test for sulfates, limit test for iron, limit test for heavy metals, limit test for arsenic, Gutzeit apparatus
Limt test Pharmaceutical Inorganic chemistry UNIT-I (Part-III) Limit Test.
Limit tests:- Factors affecting limit tests:
Specificity of the tests
Sensitivity
Control of personal errors (Analyst errors)
Test in which there is no visible reaction
Comparison methods
Quantitative determination
Limit test for Chloride: Principle, Procedure, observation and result.
Limit test for Sulphate: Principle, Procedure, observation and result
Limit test for Iron: Principle, Procedure, observation and result.
Limit test for Heavy metal: Principle, Procedure, observation and result.
Limit test for Lead: Principle, Procedure, observation and result.
Limit test for Arsenic: Principle, Gutzet test Procedure, detail in Gutzet Apparatus. observation and result.
Modifies Limit test for Chloride: Principle, Procedure, observation and result.
Modified Limit test for sulphate: Principle, Procedure, observation and result.
Sources of impurities, raw materials as a source of impurity, manufacturing methods as a source of impurity, reagents, solvents and reaction vessels as a source of impurity, manufacturing hazards as a source of impurity, physical and chemical stability of pharmaceuticals during storage, the reaction of pharmaceuticals with containers or storage vessels, thermal decomposition of pharmaceuticals, the use of water in the pharmaceutical industry, atmospheric contamination as a source of impurity, intermediate compounds as a source of impurity, cross-contamination of pharmaceutical powders, contamination of drugs by microbes, contamination of pharmaceuticals by particulate matter, errors in the manufacturing process as a source of impurity, storage of pharmaceuticals in amber-colored bottles, storage of drugs in a cool temperature, rubber closures as a source of impurity, natural sources of drugs, animal sources of drugs, plant sources of drugs, microorganism as a source of drugs, minerals as a source of drugs, effect of arsenic in human body, effect of excess of chlorine, iron and sulphate in human body, types of impurity.
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2. PHARMACEUTICAL IMPURITY
Impurity Means presence of unwanted foreign particle other than
active drugs which may be or may not be toxic and is found in
pharmaceutical substances
3. 1. Raw Material Employed in Manufacture
2. Reagents used in the Manufacturing Process
3. Methods/Process used in Manufacture
4. Intermediate products in manufacturing process
5. Atmospheric contamination during the
Manufacturing Process
6. Decomposition of the Product during Storage
7. Accidental substitution & Deliberate
Adulteration
Type and Amount of impurity present in the chemicals or
pharmaceutical substances, depends on factors
4. Sources of Impurities in Pharmaceuticals
Substances used in pharmaceutical field should be Almost pure.
Purity of the substances varies with different factors such as,
their methods of manufacture and
Types of their purification etc.
Impurities may be toxic or non-toxic even if it is non-toxic it may be used
intentionally as adulterant to increase the weight of the active ingredient and
reduce the activity of the drug, so that one must avoid impurities in
pharmaceuticals, cannot eliminate all the impurities.
Official pharmacopoeias prescribe limits for particular impurities like sulphate,
chloride, iron, heavy metals and arsenic.
5. Four types of Impurities
1. Impurity which produce toxic effect on the body is present beyond the
limit
Eg: Impurities of lead and arsenic
2. Impurities which are harmless but, if present beyond the prescribed limit
in Pharmaceutical substance will change the effect of active ingredient.
Eg: Impurities of Na and K salts
3. Impurities which present beyond the limit will affect the storage
property of pharmaceuticals.
Eg: presence of moisture leads to decompose the product (LOD)
4. Impurities will alter the colour, odour and taste
Eg: Phenolic impurities present in sodium salicylate will alters the
color of the solution.
6. Factors Which Are Responsible For Pharmaceutical
Impurities
1. Raw Material Employed in Manufacture
• The raw materials, from which these are prepared, often contain
impurities.
• It is therefore necessary to employ pure chemicals and substances as
raw materials.
E.g:
• 1. Presence of tin, lead, silver, copper, cobalt and gold in bismuth salts.
• 2. Rock salt contains small amounts of calcium sulphate and magnesium
chloride. So sodium chloride prepared from rock salt will almost contains
trace of calcium and magnesium compounds as impurity.
7. 2. Method used in Manufacture
Some impurities get incorporated into the materials during the manufacturing
process.
A) INTERMEDIATES
For certain drugs a multiple-step-synthesis procedure is involved, which
produces intermediate compounds. The purification of the intermediates is essential,
otherwise impurities present in the intermediates will get into the final product.
(e.g.) Potassium iodide is prepared by treating potassium hydroxide with
iodine. The intermediate potassium iodate (KIO3) formed is reduced to iodide. If the
iodide is not reduced completely, the final product potassium iodide, will contain
traces of potassium iodate as impurity.
8. B) Reagents used in the Process
The final product may contain unreacted reagents as impurities, if it is
not washed properly.
E.g.,
1. Lead as an impurity may result from the sulphuric acid used as reagent.
2. Soluble alkali may be an impurity in calcium carbonate if the calcium
carbonate is made by reacting calcium chloride and sodium carbonate and not
properly washed.
9. C) Solvents
• Water is a common solvent in large scale manufacturing of pharmaceuticals.
• This can give rise to trace impurities such as sodium, calcium, magnesium,
carbonate, chloride and sulphate ions.
• These impurities can be avoided by using purified water.
D) Catalyst
• Generally, catalysts are used to induce the reaction.
• There may be possibility of incorporation of traces of catalyst in the final
products.
E.g.,
1. Presence of palladium catalyst in phenanthrene.
2. Presence of copper chloride in the synthesis of phenol.
10. E) The Reaction Vessels
• The vessels used in manufacturing process are made of metals like
copper, iron, aluminium, zinc, tin though these days many of these
metals are replaced by stainless steel. Traces of these metal ions may
contaminate the final products.
• Glass vessels may give rise to traces of alkali to the product.
• Metal particles of aluminium containers may contaminate the products
like ointments and pastes stored in it.
11. F) Atmospheric contaminants
• Dust, sulphur dioxide, hydrogen sulphide, arsenic and water vapour from
atmosphere may affect a drug.
• Presence of carbon dioxide, carbon monoxide and hydrogen cyanide
from environment also affect the drug products if it is not manufactured
under controlled conditions.
12. G) Decomposition of the Product during Storage
• Many drugs undergo changes due to improper storage conditions.
• If the drugs are not stored properly, they will expire before the date of expiry.
• These decomposition may be due to light, water vapour, air, carbon dioxide and
metallic ions.
E.g,
1. Ferrous sulphate slowly changed into insoluble ferric oxide by air and moisture.
2. Solutions of potassium hydroxide absorbs carbon dioxide on exposure to air.
3. Bismuth carbonate turns black on exposure to sunlight for a long period.
13. • Therefore, the products which are prove to decompose due to environmental
factors should be stored in well-closed containers.
• If the products are prone to decompose due to light should be stored in light-
resistant containers like amber colour bottles for liquids and opaque
packaging for solid dosage forms.
14. H) Deliberate Adulteration:
A drug may be deliberately adulterated with cheaper and inert materials for
the sake of more profit.
This will reduce the potency of the active ingredient present in the
formulation quantitatively.
These practices are prevented by central and state drug control
departments.
16. LIMIT TESTS
• Limit tests are quantitative tests or semi-quantitative tests which are
designed to detect and limit / control small quantities of impurities
present in the substance.
• All the limit tests that are prescribed in the pharmacopoeias are based
on the comparison of standard turbidity or colour with that of the
sample under test.
• Usually the limits are prescribed in parts per million (PPM).
17. • For the preparation of standard turbidity or colour the
pharmacopoeias prescribe the limit of particular impurities for
particular substances and it varies for different compounds.
• The amount of test samples to be taken is mentioned in the
individual monograph of the pharmacopoeias.
18. 3 TYPES
Test in which
there is no
visible Reaction
• Testing as prescribed, there is no color, opalescence
or precipitate Negative test indicate the
absences of Large impurity
Comparison
Methods
• Compare the amount of impurity in the substance
with a standard of known concentration and
determine whether impurity is within or the
excess of the limit prescribed`
Quantitative
Determination
• Amount of impurity present in actually
determined and compared with the numerical
limit given in Pharmacopoeia
19. Quantitative Determination
1. Limits of soluble matter
2. Limits of Insoluble matter
3. Limits of non-volatile matter
4. Limits of moisture and volatile matter
5. Limits of residue on ignition
6. Loss on ignition
7. Ash values.
20. 1. Limit Test for Chlorides
• A solution of the substance is acidified with nitric acid, diluted to definite
volume and treated with silver nitrate and the opalescence so produced is
compared with that of standard opalescence containing known amount of
sodium chloride solution.
Cl- + AgNO3 → AgCl + NO3-
• Presence of nitric acid prevents the precipitation caused by silver carbonate or
silver hydroxide which may result due to alkaline impurities in the solution.
21. Principle
• Limit test for chloride is based on the well-known reaction
between silver nitrate and soluble chlorides forming
precipitate of silver chloride which is insoluble in nitric
acid.
• The test solution becomes turbid, the extent of turbidity
depending upon the amount of silver chloride produced
which in turn depends upon the amount of chloride present
in the test sample.
• The opalescence produced depends upon the amount of
chloride present in the given sample.
22. • It is compared with the opalescence produced in a
standard solution containing the prescribed quantity of
chloride similarly treated if the opalescence in the
sample is less that in standard. Its passes the test.
24. 2. Limit Test for Sulphate
• It depends upon the precipitation of the sulphate with
barium chloride in the presence of hydrochloric acid,
ethyl alcohol and traces of potassium sulphate.
• The turbidity produced is compared with that of
turbidity produced by addition of the above reagents
to a standard solution containing a definite quantity
of potassium sulphate.
SO4− + BaCl2 → BaSO4 + 2Cl−
25. • The potassium sulphate increases the sensitivity of the test by
giving ionic concentrations in the reagent which just exceed the
solubility product of barium sulphate.
• Presence of alcohol helps to prevent super saturation.
Hydrochloric acid is added to prevent precipitation due to barium
carbonate which is also sparingly soluble in water.
26. 3) Limit Test for Iron
• Specified amount of the drug is dissolved in water and treated with citric acid
and thioglycolic acid. It is made alkaline with dilute ammonia solution.
• The purple colour produced is compared with that of standard ferric
ammonium sulphate treated in the same way as the test solution.
• Ferric ion is reduced to ferrous ion by the thioglycolic acid.
• Citric acid is added to prevent precipitation of the iron by the ammonia (citric
acid forms a soluble complex).
27. • Ammonia is added to make alkaline the solution, and the purple colour
is stable in alkaline medium. Purple colour is due to the formation of co-
ordination compound, ferrous thioglycollate.
28. 4. Limit Test for Heavy Metals
• All metals like Copper, Bismuth, Lead, Mercury, Arsenic, Antimony, Silver, etc
(except alkali metals and alkaline earth metals) are coloured by sulphide ions
(H2S or Na2S) under specified conditions.
• Depends upon the quantity of the metal the colour varies from brown to black.
• There are three methods are prescribed in I.P to determine the presence of
heavy metals. Method A and B are carried out in acid conditions with hydrogen
sulphide reagent and method C involves alkaline medium with the use of sodium
sulphide reagent.
29. • Method A
A solution of substance is adjusted to a pH 3 to 4 (by adding
ammonia (or) acetic acid) and hydrogen sulphide reagent is mixed
with this and comparison of black colour produced with a standard
colour containing a known amount of lead.
• Method B (For Organic Compounds)
The substance is ignited well in presence of conc. sulphuric
acid and treated with mixture of nitric and sulphuric acids. The
resulting solution is digested with dilute hydrochloric acid. Then
extracted with hot water and proceeded as in method A.
Pb++ + H2S → PbS + 2 H+
30. • Method C
The solution of the substance is treated
with sodium hydroxide solution and sodium
sulphide reagent. Then it is compared with that
a standard colour.
Pb++ + Na2S → PbS + 2Na+
31. 5. Limit Test for Arsenic
• In this test arsenic impurities if at all present is converted in to arsine gas
(ASH3) which when contact with a mercuric chloride paper produces yellow
stain.
• The intensity of the stain is proportional to the amount of arsenic present. A
standard stain produced from a definite amount of arsenic is used for
comparison.
• Apparatus used for arsenic limit test is called Gutzeit apparatus. A drug
solution is prepared and placed in wide monthed bottle, potassium iodide, zinc
dust, hydrochloric acid, stannous chloride are added into it and the apparatus is
set up as given in the figure 2.
32. • Hydrogen gas is generated in the solution by the presence of
stannous chloride, hydrochloric acid (stannated hydrochloride)
and potassium iodide on arsenic free granulated zinc.
• Stannous chloride and potassium iodide are acts as a reducing
agents so that any pentavalent arsenic is reduced to the trivalent
state. The presence of stannous chloride and hydrochloric acid
ensures rapid reaction between acid and potassium iodide and
produces nascent hydrogen gas.
34. The arsine gas produced in the bottle escapes through the tube and
the lead acetate impregnated cotton wool kept in the centre of the tube
entraps the hydrogen sulphide if any from the arsine gas.
The gas escapes through glass tube and reacts with mercuric chloride
paper kept in the clips and produces yellow stain. The reaction is
allowed to proceed for forty minutes maintained at 400C.