Antimicrobials B.Pharm PIC 1st Sem Unit-3

Pharmaceutical
Inorganic Chemistry
………………..
Unit – 3 Part III
Gastrointestinal Agents
Antimicrobials
…………………..
By
Himanshu Sharma
SmartConnect Pharmacy

01
03
02
Table of contents
04
Classification Mechanism
Assays Iodine
Boric acid, Hydrogen peroxide*,
Chlorinated lime*
Iodine & its Preparation

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Introduction &
Classification
01

Antimicrobials
 An antimicrobial is an chemical agent that is used to kills or inhibit the growth of
pathogenic microorganisms. Such as Bacteria, Fungi or Protozoa.
 These are normally ineffective in the sporing state of micro-organisms.
 It is broadly classified into six categories (via mode of action):
Antimicrobial
Antiseptic Disinfectant Germicides Bacteriostatic Sterilization Sanitizers

Antimicrobials
• The most common targets for antimicrobial drug actions fall into 5 basic
categories:
i. Inhibition of Cell Wall Synthesis
ii. Inhibition of Protein Synthesis
iii. Inhibition of Nucleic Acid Synthesis
iv. Effects on cell membrane sterols (antifungal agents)
v. Inhibition of unique metabolic steps
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Antiseptic
● Antiseptic(s) (from Greek anti: "against" and sēptikos:
"putrefactive").
● These are the type of antimicrobial substances that are
applied to living tissue/skin to reduce the possibility of
infection, sepsis, or putrefaction.
● These type of agents prevents the growth of action of
microorganism.
● Ex- Phenol, Iodine, etc

Disinfectants
• Disinfectants are antimicrobial agents that are applied to the surface of
non-living objects to destroy microorganisms that are living on the
objects.
• Disinfection does not necessarily kill all microorganisms, especially
resistant bacterial spores; it is less effective than sterilization.
• Ex- These are used in rooms, hospitals, surgery equipment's, etc.
• All disinfectants are bactericidal in nature.

Requirements for antiseptics and disinfectants
● 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.

Germicides
• These are the substance or agents which kills microorganism.
• These agents acts by oxidation of bacterial protoplasm by denaturation of bacterial
enzymes & their proteins.
• Ex- Bactericide (Against Bacteria), Fungicides (Against Fungi), etc.
Bacteriostatic
• These are the substance or agents which primarily functions by inhibiting the growth of
bacteria.
• These do not kills bacteria but stops their growth and other activities.

● It is a process of rendering the sanitary by reducing the number of
bacterial contaminants.
● These are disinfectant used to maintain public health and called as
sanitizers.
● Sanitation is mainly concerned with cleaning or washing away the
organism.
Sanitizers

Sterilization
• Sterilization is the process of complete destruction of all living microorganism,
including bacterial spores.
• It is mainly done by physical method i.e., Application of heat or radiation.
• It can also be done using a chemical means (use of chemical disinfectant.
• A recent investigation by the author has shown that the aerobic mesophilic
bacterial sporeformers, such as Bacillus subtilis and Bacillus coagulans,
are the most resistant among several species of sporeforming bacteria to dry
heat sterilization.

Mechanism of Action
• Ideally an antibacterial is expected to affect microbes sporing the host cells and
many organic compounds. E.g., Antibiotics.
• However, the action of inorganic antibacterial is mostly non- specific.
• These agents affects all the protein in similar manner and in higher concentration
affects host protein as well as microbial protein.
• They mainly acts by Oxidation, Halogenation or Protein precipitation, alter the
molecular shape (Confirmation) of the proteins or important enzyme surfaces.

Mechanism of Action
1. Oxidation Mechanism
• Reducing groups present in the most proteins get oxidized by oxidizing agents.
• E.g., 2 Sulfhydryl group, -SH forms a disulphide bridge –S-S-.
• Thus alters the molecular shape of the protein, ultimately leading to the
destruction of proteins.
• Generally, non-metals, certain anion, hydrogen peroxide act by this mechanism.

Mechanism of Action
2. Halogenation Mechanism
• Most of the enzymes are protein in nature.
• Primary and Secondary amide group present in protein at peptide linkage undergo
Chlorination with change in molecular shape and ultimately leading to the
destruction of proteins.
• Generally hypothalites or hypochlorites act by this mechanism.

Mechanism of Action
3. Protein Precipitation
• Many cations exhibits protein binding or protein precipitation.
• The interaction with protein occurs through polar group which acts as ligands and
metal cation as Lewis acid.
• The complex formed may be strong chelate leading to inactivation of protein.
• E.g., Boric acid, Borax, etc.

Boric acid
• Synonym: Dioxidane;
Oxidanyl;
Perhydroxic acid
• Chemical formula: H2O2
• Mol. Weight: 34 g/mol
• It is clear colorless liquid.
• It is odorless having bitter acidic taste.
• It is miscible in water.

• Preparation:
Boric acid may be prepared by reacting borax (sodium tetraborate
decahydrate) with a mineral acid, such as hydrochloric acid:
Na2B4O7·10H2O + 2HCl H3BO3 + 2NaCl + 5H2O
It is also formed as a byproduct of hydrolysis of boron trihalides and
diborane
B2H6 (diborane) + 6H2O 2B(OH)3 + 6H2
BX3 + 3H2O B(OH)3 + 3HX
(boron
trihalides)
Boric acid

Boric acid
1. Boric acid can be used as an antiseptic for minor burns or cuts. it is also used as weak
bacteriostatic, fungistatic and astringents.
2. Boric acid is applied in a very dilute solution as an eye wash.
3. Dilute boric acid can be used as a vaginal douche to treat bacterial vaginosis due to
excessive alkalinity.
4. It is also used as mouth washes, skin lotion for local anti-infective action.
5. It is used as an insecticide.
6. The boric acid-borate system can be useful as a primary buffer system.
7. It is also used in preservation of grains such as rice and wheat.
 Uses

Hydrogen Peroxide*
• Synonym: Dioxidane;
Oxidanyl;
Perhydroxic acid
• Chemical formula: H2O2
• It is clear colorless liquid.
• It is odorless having bitter acidic taste.
• It is miscible in water.

• Preparation:
When aqueous cream of barium peroxide treated with cold dilute
sulphuric acid forms hydrogen peroxide:
BaO2 + H2SO4 BaSO4 + H2O2
When carbon dioxide is passed slowly through ice-cold paste of
barium peroxide, then hydrogen peroxide produced:
BaO2 + H2O + CO2 BaCO3 + H2O2
Hydrogen Peroxide*

Hydrogen Peroxide*
1. Hydrogen peroxide used as an antiseptic, germicidal and disinfectant.
2. Hydrogen peroxide can be used for the sterilization of various surfaces, including surgical tools and may
be deployed as a vapor (VHP) for room sterilization.
3. H2O2 demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores. In
general, greater activity is seen against Gram-positive than Gram-negative bacteria.
4. Hydrogen peroxide was used for disinfecting wounds.
5. Diluted H2O2 (between 1.9% and 12%) mixed with ammonium hydroxide is used to bleach human hair.
6. Hydrogen peroxide is also used for tooth whitening. It can be found in most whitening toothpastes.
7. Hydrogen peroxide has been used for creating organic peroxide-based explosives
 Uses

Chlorinated lime*
• Synonym: Hypochlorous acid;
Bleaching powder;
Calcium oxychloride;
Calcium hypochlorite;
• Chemical formula: Ca(ClO)2
• Mol. Weight: 142.98 g/mol
• It is white/grey powder.
• It has strong odor of chlorine.
• on exposure to air it becomes moist and rapidly decomposes to
release Hypochlorous acid.

• Preparation:
Calcium hypochlorite is produced industrially by treating slaked lime
[Ca(OH)2] with chlorine gas:
2Cl2 + 2Ca(OH)2 Ca(OCl)2 + CaCl 2 + 2H2O
Chlorinated lime*
 Uses
1. Calcium hypochlorite has rapid bactericidal action. It kills most of
bacteria, some fungi, yeast, algae, viruses and protozoa.
2. Calcium hypochlorite is commonly used to sanitize public swimming
pools and disinfect drinking water.

Chlorinated lime*
3. Calcium hypochlorite is also used in kitchens to disinfect surfaces and equipment.
4. Other common uses include bathroom cleansers, household disinfectant sprays,
algaecides, herbicides, and laundry detergent.
 Uses
 Storage
1. Calcium hypochlorite is stored dry and cold.
2. It is stored away from any organic material and metals.
3. The hydrated form is safer to handle.

Iodine
• Iodine was discovered by Bernard Courtois in 1811.
• Iodine is not found in free state in nature. In the combined state, it
is found in the form of iodides.
• In sea weeds it is found as iodides of sodium and potassium. Sea
grass and tree plants are called sea weeds.
• Chemical formula: I2
• Its vapors are purple in color.
• It is practically insoluble in water but soluble in alcohol.
• It occurs as heavy, bluish-black rhombic plates with metallic luster.

• It is freely soluble in chlorine and ether.
• It melts at higher temperature.
• Common Methods for Making Iodine
Iodine is formed by adding bromine liquid to an aqueous solution of
potassium iodide or passing chlorine gas:
2KI + Br2 2KBr + I2
2KI + Cl2 2KCl + I2
Iodine
Preparation:

Iodine
• Chile saltpeter (Caliche):
Chile saltpeter mainly contains sodium nitrate but it also contains sodium
iodate (NaIO3) in some amount. After dissolving caliche in water and
concentrating the aqueous solution, most of the sodium nitrate gets
separated in the form of crystals.:
2NaIO3 + 5NaHSO3 2NaHSO4 + 2Na2SO4 + H2O + I2
Preparation:

Iodine
1. Tincture of iodine is obtained by dissolving I2 in aqueous solution of KI and adding rectified
strite (95% ethyl alcohol) to it. Due to the yellowish brown color of KI3, the color of tincture
iodine also remains yellowish brown. This solution is used as a bactericidal to clean
wounds.
2. Iodoform is used as a bactericide.
3. Iodine is also used to make iodex. iodex is used to treat swelling, pain, and sprains.
4. The use of iodine containing salt has now become common. Deficiency of iodine causes
many diseases related to thyroid gland.
5. Iodine is used to make many other important organic compounds in inorganic compounds.
6. It is also used as a reagent in the laboratory.
 Uses

Iodine
5. Iodine is used to make many other important organic compounds in inorganic
compounds.
6. It is also used as a reagent in the laboratory.
7. It is used by quantitative analysis to determine the concentrations of many substances in
solutions.
8. It is also used in making colors, in color photography and in making dyes.
 Uses

Solution of Iodine
Iodine is insoluble in water but in presence of Sodium or potassium
iodide it is soluble due to formation of poly-iodides.
The followings are the solution preparations containing iodine.
1. Strong Iodine Solution (10% W/V Solution of Iodine)
2. Weak Iodine Solution (2% W/V Solution of Iodine)
3. Aqueous Iodine Solution (5% W/V Solution of Iodine)
4. Iodine tincture USP
5. Mandl’s paint

Solutions of Iodine
1. Strong Iodine Solution (Strong tincture of Iodine): Contains 10% W/V solution of
iodine and 6% W/V solution of potassium iodide in alcohol.
2. Weak Iodine Solution (Weak tincture of Iodine): Contains 2.5% W/V solution of iodine
and 2.5% W/V solution of potassium iodide in alcohol.
3. Aqueous Iodine Solution (Lugal’s Solution): Contains 5% W/V solution of iodine and
10% W/V solution of potassium iodide in water.
4. Iodine tincture USP: Contains 2% W/V solution of iodine and 2.4% W/V solution of
potassium iodide and 50 ml alcohol and water up to 100 ml. (External use only)
5. Mandl’s paint: Contains 1.25% W/V solution of iodine in glycerin. Glycerin is used to hold
the iodine in the applied area (throat).
*Note: All above solutions are used as antiseptics & disinfectants.

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Reference
1. https://www.slideshare.net/RevathyRevss/antimicrobial-agents-248327371
2. https://ajptonline.com/HTMLPaper.aspx?Journal=Asian%20Journal%20of%20Ph
armacy%20and%20Technology;PID=2017-7-1-2
3. https://www.pharmaguideline.com/2021/10/antimicrobials.html
4. https://www.researchgate.net/publication/321938398_PHARMACEUTICAL_INO
RGANIC_CHEMISTRY_Antimicrobial’s

Antimicrobials B.Pharm PIC 1st Sem Unit-3

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