it gives you a brief description that how oxidation can affect the stability of drug and causes degradation

1. OXIDATION
PRESENTED TO: MAM MARIA
PREPARED BY: SAMAWIA IQBAL

2. OUTLINE
 Introduction
 Definition
 Forms of oxidation
 Drug susceptible to oxidation
 Drug metabolism
 Protection from oxidation
 Conclusion

3. INTRODUCTION
Degradation pathway:
The incapability of any particular formulation in a specific
container to remain within a particular chemical and physical
specification.
Decomposition of active ingredients in liquids , solid ,
semisolids dosage forms can occur through:
 Hydrolysis

4. Cont…
 Oxidation
 Racemization
 Decarboxylation
 Ring cleavage
 photolysis

5. DEFINITION
Oxidation is defined as the removal of electropositive atom ,
radical , an electron or the addition of an electronegative atom
or radical
 It occurs when exposed to atmospheric oxygen.
 It is controlled by environment i.e. light trace elements ,
oxygen and oxidizing agents.
 Either the addition of oxygen or the removal of hydrogen or
the removal of electrons.

6. OXIDATION
Upon exposure to oxygen pharmaceuticals that are not in their
oxidized form may decompose.
The oxidative decomposition of pharmaceutical compounds is
responsible for the instability of considerable number of
pharmaceuticals.

7. FORMS OF OXIDATION
There are two forms of oxidative decomposition:
 Auto oxidation
 Photo oxidation
AUTO OXIDATION:
Autoxidation is a reaction of material with molecular oxygen
that occurs spontaneously and involves a free radical chain
process.

8. Cont…
The autoxidation of an organic substance RH by a free radical
chain process can be simply described as follows;
Initiation :
RH R. + H
Propagation :
R + O2 RO2
RO2 + RH ROOH + R.

9. Cont…
Hydro peroxide decomposition :
ROOH RO. + OH.
Termination :
RO2. + X inactive products
RO2 + RO2 inactive product

10. PHOTOXIDATION
Oxidation in which removal of electrons is involved in the
absence of oxygen.
This type of oxidation is less frequently encountered.
EXAMPLE :
It occurs in adrenaline , riboflavin and ascorbic acid.

11. DRUGS SUSCEPTIBLE TO OXIDATION
Steroids and sterols are subjected to oxidative degradation
through the process of carbon –carbon double bonds , others
include ;
 Polyunsaturated fatty acids.
 Vitamins
 Antibiotics
 Hormones

12. DRUG METABOLISM - OXIDATION
Drug metabolism involves a wide range of chemical reactions
including oxidation , reduction , hydrolysis etc. It has two
phases;
 PHASE I
 PHASE II

13. PHASE-I OXIDATION
 Phase-I reactions involve the formation of a new or modified
functional group or a cleavage by the addition of oxygen or
the removal of hydrogen.
 These are non synthetic reactions.
 EXAMPLE :
Oxygenation , hydroxylation

14. PHASE-II OXIDATION
 Phase-II oxidation reactions involve conjugation with
endogenous compounds (sulfate , glycine ) to form polar
highly ionized organic acids.
 These involve synthetic reactions.
 EXAMPLE :
N-acetyl conjugation include ; histamine , dapsone
Sulfate conjugation include ; paracetamol.

15. STABILIZATION OF DRUGS AGAINST
HYDROLYSIS AND OXIDATION
There are a few factors on which the stabilization of drugs
against the process of hydrolysis and oxidation is based :
 Temperature
 Light
 Humidity
 Oxygen
 Chelating agents
 solvents

16. PROTECTION FROM OXIDATION
 Choice of suitable pharmaceutical dosage form which
reduces the possibility of oxidation process.
 Maintenance of PH by using buffers solution.
 Choice of suitable solvents.
 Storage in low temperature.
 Protection from air.
 Low oxygen contents.

17. ANTIOXIDANTS
 They are the reducing agents which are added to the drugs
or the other pharmaceuticals to prevent their oxidation
through oxidative processes.
 Antioxidants undergo oxidation more readily than the
drugs or other pharmaceuticals with which they are
present.
 Antioxidants are mainly used in pharmaceuticals
preparation containing readily oxidisable substances to
prevent them in their original form.

18. OXIDATION-IN OUR BODY
 Oxidation basically occurs all over the body and at
cellular level. There is an oxidation reaction theory
that states that oxygen reacts within the body and
produces by-products called free radicals . A free
radical is an oxygen molecule that has lost an
electron over time these radicals build up and aging
occurs.

19. CONCLUSION
pharmaceutical dosage forms are meant to maintain their
physical , chemical , therapeutic and microbiological stability in
their specification within the stated shelf life . However they do
undergo chemical , physical degradation that results in toxicity ,
failure and loss of esthetics of drugs . Thus the formulator must
consider these factors during manufacturing , packaging ,
storage and transport of the drugs.

20. THANKS