MAKAUT/SEM 1/ PHARMACEUTICAL INORGANIC CHEMISTRY/ UNIT 3/GASTROINTESTINAL AGENTS_ANTIMICROBIAL BY KUNAL DATTA ASSISTANT PROFESSOR B.PHARM , M.PHARM NETAJI SUBHAS CHANDRA BOSE INSTITUTE OF PHARMACY

1. PT 103 PHARMACEUTICAL INORGANIC
CHEMISTRY(THEORY)
KUNAL DATTA
UNIT III : Gastrointestinal Agents
Antimicrobial Agents

2. Antimicrobial Agents

3. Defination :
Any agents which either kills or inhibit the growth
of microbes i.e bacteria, fungi , protozoa etc.
Classification of agents:
Antiseptic
Disinfectants
Germicides
Keratolytics
Chemotherapeutics

4.  Agents which prevent infection , by killing or
inhibiting the growth of micro-organism when
applied topically at damaged tissue.
The drugs like phenol , iodine , chloroxylenol ,
Boric acid , zinc oxide, cetrimide are the examples
of antiseptics.
Antiseptic

5. Disinfectants
Disinfectants are antimicrobial agents that are
applied to the surface of non-living objects to destroy
microorganisms that are living on the objects.
Commonly used disinfectants include cresol , phenol.

6. These are the agents which kills microbes.
Sub classification:
Bactericidal agents- those kill bacteria
Fungicidal- those kill fungus
Germicides

7. These are the agents which are applied on the skin
to soften the keratin.
Eg: Sulphur, Aluminium oxide
Use : They are used to treat acne and other skin infection
Keratolytic Agents

8. These are the chemical agents which are used in
clinical application of antimicrobial agents to treat
infection diseases.
Chemotherapeutics Agents

9.  Must have a broad spectrum of action;
 Rapid onset of action;
 Should have a small latency period;
 Should have a high activity;
 Must be chemically resistant;
 High availability and low cost;
 Lack of local irritant or allergic effects on tissues;
 Minimal absorption from the place of their application;
 Low toxicity ;
Characteristics of antimicrobials Agents

10. • Microorganism contain many important ‘protein
structure’ (e.g enzyme) to survive.
• If there is minute changes in protein structure , the
protein becomes non functioning and inactive.
• There are three types of mechanisms for changing
their protein structure.
Oxidation
Halogenation
Precipitation of Protein
Mechanism of action : Antimicrobial Agents

11. • Oxygen liberating compound (Oxidizing agents) like
peroxide and peroxyacids , permanganate give action by this
mechanisms.
• These antimicrobial agents cause oxidation of active
functional group present in protein or enzymes and
inactivate them.
Mechanism of Action : Oxidation

12. • The halide and hypohalide (Iodine and Hypochlorite)
compounds give action by this mechanisms.
• This category of agents act on peptide linkage present in
protein or enzymes and there by changing the
conformational structure of protein.
Mechanism of Action : Halogenation

13. • Metal containg (e.g., mercury, arsenic and antimony)
compounds give action by this mechanisms.
• Metal binds with important group present in protein. This
protein metal complexation (Chelation) inactivates the
protein or enzymes.
Mechanism of Action : Precipitation of Protein

14. Classification of Antimicrobial agents according to
their MOA

15. Some Commonly Used
Antimicrobial agents

16. Potassium permanganate
Molecular formula
KMnO4
Molar mass
158.034 g/mol
Synonym
Condy's crystals; Permanganate of potash

17. Physical Properties
• Appearance : purplish-bronze-gray needles
• Odor: Odourless
• Taste: Bitter with metalic taste
• Density : 2.703 g/cm3
• Melting point: 240 °C
• Solubility: Freely soluble in water and alcohol

18. Chemical Properties
• Solid potassium permanganate decomposes when
heated :
• Potassium acts as strong oxidizing agents. KMnO4
oxidizes potassium iodide to iodine in acidic medium.
2KMnO4 → K2MnO4 + MnO2(s) + O2
2KMnO4 + 10KI + 8H2SO4 → 6K2SO4 + 2MnSO4 + 5I2 + 8H2O

19. Preparation
On a large scale, potassium permanganate is
prepared by mixing a solution of KOH with
powdered manganese oxide and potassium
chlorate. The mixture is boiled and evaporated to
yield the residue which is heated in iron pans until
it has acquired a paste like consistency.
KOH + 3MnO2 + KClO3→ K2MnO4 + KCl + 3H2O

20. Preparation
 Potassium manganate when treated with Hydrochloric acid
3 K2MnO4 + 4 HCl → 2 KMnO4 + MnO2 + 2 H2O + 4 KCl
 Potassium manganate when treated with Carbon dioxide
3 K2MnO4 + 2 CO2 → 2 KMnO4 + 2 K2CO3 + MnO2

21. Assay
 Its assay is based upon the oxidation - reduction reaction.
 Potassium permanganate is a strong oxidizing agent so it will be titrated
against oxalic acid which is a reducing agent.
 An accurately weighed amount of about 0.8 g of sample is dissolved in
water.
 Then it is diluted with water to 250 ml and titrated with 25 ml of 0.1 N
oxalic acid which is mixed with 25 ml of water and 5 ml of sulphuric acid.
 This solution is maintained at about 70°C temperature throughout the
entire titration.
5H2C2O4 + 2H2O + 2KMnO4 + 3H2SO4 → K2SO4 + 2MnSO4 + 18H2O + 10CO2

22. Uses
 Antiseptics in mouth wash preparation
 wounds and skin infection
 Oxidizing agents
 urethritis
 water treatment
 Bleaching agent
 1-5% hydro alcholic solution of potassium permanganate used
as wet dressing.

23. Storage
 Store in well closed container and kept
in a cool place.

24. Boric Acid
Molecular formula:
H3BO3
Molar mass:
61.83 g/mol
Synonym :
Hydrogen borate

25. Physical Properties
• Appearance : White crystalline solid or granular
• Odor: Odourless
• Taste: Sweet
• Density : 1.435 g/cm3
• Melting point: 170.9 °C
• Solubility: Sparingly soluble in water, Slightly soluble in
Alcohol and Freely soluble glycerine.

26. Chemical Properties
• Boric acid is soluble in boiling water. When heated
above 100°C, it dehydrates, forming metaboric acid
(HBO2) .
• When metaboric acid heated at 160°C it converted
into tetraboric acid or pyroboric acid (H2B4O7)
• When pyroboric acid is heated above 200°C it
decompose into boron trioxide (B2O3).

27. Preparation
Na2B4O7·10H2O + 2HCl → 4H3BO3 + 2NaCl + 5H2O
Boric acid may be prepared by reacting borax
(sodium tetraborate decahydrate) with a mineral acid,
such as hydrochloric acid.
In the laboratory, boric acid is obtained by adding a
mixture of conc. H2SO4 and water to a boiling solution
of borax.
Na2B4O7 + H2SO4 + 5H2O → Na2SO4 + 4H3BO3

28. Assay
• It is assayed by a titrimetric methods.
• An accurately weighed quantity of boric acid is
dissolved in a mixture of 50 ml of water, and 100 ml
glycerine.
• Now this solution is titrated with 1 N NaOH
solution using phenolphthalein as an indicator.

29. Uses
 Boric acid can be used as an antiseptic for minor burns or
cuts.
 Boric acid is applied in a very dilute solution as an eye wash.
 It is also used as mouth washes, skin lotion for local anti-
infective action.
 It is also used in preservation of grains such as rice and wheat.
 Its use as an insecticide.

30. Storage
• Store in well closed container and kept in
a cool place.

31. Hydrogen peroxide
Molecular formula
H2O2
Molar mass
34 g/mol
Synonym
Dioxidane; Oxidanyl; Perhydroxic acid

32. Properties
• Hydrogen peroxide is a colourless and odourless liquid
having a slightly acidic taste.
• Hydrogen peroxide is a strong oxidising agent and is
miscible in water.
• The solution decomposes when it comes in contact with
oxidisable matter or when made alkaline.
2H2O2 → 2H2O + O2

33. Preparation
• From Barium peroxide:
When aqueous cream of barium peroxide treated
with cold dilute sulphuric acid forms hydrogen
peroxide.
BaO2 + H2SO4 → BaSO4 + H2O2
• From Sodium Peroxide:
Sodium peroxide decomposed by addition of cold
dilute sulphuric acid forms hydrogen peroxide.
Na2O2 + H2SO4 → Na2SO4 + H2O2

34. Assay
Assay of hydrogen peroxide depend on the
oxidation reduction titration.
10 ml the H2O2 is diluted with 10 ml distilled water,
then add 10 ml of 5N Sulphuric acid and then
titrated with 0.1N potassium permanganate
solution, until a faint pink color is obtained.
2 KMnO4 + 3H2SO4 + 5 H2O2 → K2SO4 + 2 MnSO4 + 8 H2O + 5 O2

35. Uses
• It is a strong oxidising agent.
• It is used for bleaching.
• It acts as an antiseptic and a germicide and hence it
is used for cleaning cuts and wounds.
• It is an effective antidote for phosphorus and cyanide
poisoning.
• It also finds use for cleaning ears and during removal
of surgical dressings.

36. Iodine Solution
Molecular formula
I2
Molar mass
126.9 gm/mol

37. Preparation
• From Sea Weed Ash
• Sea water contains iodine as salts forms
• These salts are absorbed by seaweeds
• These seaweeds are dried , burnt and ash is collected
which is called kelp.
• Aqueous solution of kelp is prepared and
concentrated (Where the sulphates and chloride of
sodium and potassium crystallize out).

38. Preparation
• Crystals are removed by filtration
• The solution contains only salts of iodides of sodium
and potassium.
• Then the solution is treated with sulphuric acid and
then the manganese dioxide and heated.
• Synthesized iodine is purified and collected.
2NaI + 3H2SO4 + MnO2 → MnSO4 + 2NaHSO4 + I2 + 2H2O

39. Physical Properties
• Iodine is in the form of heavy, bluish-black,
rhombic prism or plate having a metallic lustre.
• It has a peculiar odour and is volatile at ordinary
temperature.
• It is insoluble in water but soluble in alcohol.
• It is freely soluble in chloroform and solvent ether
and in aqueous solution of iodides.

40. Assay
 It may be assayed by involving the oxidation - reduction
titration method.
 About 0.5 gm of iodine is first dissolved in a solution of 1 gm
of potassium iodide (1 gm potassium iodide in 5 ml water) in
an iodine flask. It is diluted with 50 ml of water and acidified
with 1 ml of acetic acid.
 Then the resulting solution is titrated with standard sodium
thiosulphate, using starch solution as an indicator.
2Na2S2O3 + I2 → Na2S4O6 + 2NaI

41. Uses
• Iodine is used in medicine mainly as a counter irritant and
disinfectant.
• It is used as a local germicide.
• Used for preparation of various iodine solution.
• In the treatment of goitre iodine is supplied to the body either
in the elemental form or in the form of sodium or potassium
iodide.

42. Official Preparation Of Iodine solution
• Aqueous Iodine solution (Lugol’s Solution)
• Weak Iodine Solution (tincture of Iodine)
• Strong Iodine solution

43. Aqueous Iodine Solution

44. Weak Iodine Solution

45. Strong Iodine Solution

46. Storage
• It is preserved in glass stoppered, amber
coloured bottles and kept in a cool place.

47. THANK YOU