Antidotes and it's classification | B pharmcy pharmaceutical chemistry notes

Antidotes :

1.  Antidotes is the substance which counteracts the effect of poision.
2.  It acts either by neutralizing the poision and its toxic effect or chemically converting them in to non toxic or less toxic form.

Example-  sodium nitrite, sodium thiosulphate, activated charcol.

Classification :

(1)  Physiological
(2)  Chemical
(3)  Mechanical

(1)  Physiological antidote :

The antidote that counteract the effect of poision by producing the effect opposite to that of poision .
Ex -  Adriline is the physiological antidote of histamine.

(2)  Chemical antidote :

The antidote that changes the chemical nature of poision by combining with its.
Ex -  Sodium thiosulphate is the chemical antidote of cyanide which convert toxic cyanide in to non toxic thiocyanate.

(3)  Mechanical antidote :

The antidote that prevents absorption of poision in to the body by expelling out the poison by emisis or elimination through urine.
Ex -  Activated charcoal which absorbe the poision before its absorption across the intestinal wall.

Poison :

(1)  Poison is a substance that is harmful to our body which is capable of causing illness or death of a living organism when introduced or absorbe intentionally or accidentally in body .
(2)  Poisoning of the body is occurs due to various resion, it can be due to -
-  The presence of heavy metal like lead mercury etc.
-  Insecticides and pesticides used in our daily life.
-  Cyanide poisoning due to ingestion of soluble cyanide solution, seesds of apricot and apple etc.

Cyanide poisoning :

(1)  Cyanide poisoning normally occur accidentally or when cyanide is taken intentionally or suicidal purpose.
(2)  Cyanide poisoning is usually fatal in nature. If it is not treated immediately.
(3)  In cyanide poisoning cyanide ion combined with ferric ion of cytochrome oxidase which prevents electron transfer. This leads to stopage cellular respiration and metabolic process.

Treatment :

(1)  In cyanide poisoning sodium nitrite and sodium thiosulphate injection are given to counteract the effect of cyanide poisoning.
(2)  Sodium thiosulphate react with cyanide ion and convert it in to sodium thiocyanate which is less toxic than cyanide.
(3)  When sodium nitrite react with ferrous ion of haemoglobin it get oxides to form ferric ion of  methaemoglobin . Thus reduce the concentration of cyanide ion.

Sodium nitrite :

Properties :

Colour - Colourless and slightly yellowish crystals.
Odour - Odourless
Taste - Mild iodine taste
Solubility  - Soluble in water and slightly soluble in alcohol.

Storage :

It is stored in airtight container.

Uses :

-   It is used as antidote in cyanide poisoning.
-   Sodium nitrite is added to aqous disinfection solution to prevent the rusting of surgical instruments.
-   It is also used as a preservative in food industries.



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