This is PPT file for Pharmacy

1. INCOMPATIBILITIES
PRESCRIPTIONS
Prepared by : Bushra F. Deshpande
Dept: Pharmaceutics
K.Y.D.S.C.T’S COP Sakegaon.
BHUSAWAL

2. DEFINITION
It is the result of prescribing or mixing
two or more substances which are antagonist
in nature and an undesirable product is formed
which may affect the safety, purpose or
appearance of the preparation.

3. TYPES OF INCOMPATIBILITY

4. A. PHYSICAL INCOMPATIBILITY
Two or more than two substances are
combined together a physical change take place
and an unacceptable Product is formed.
The physical incompatibilities may be corrected using
Any one or more of the following
1) Change the order of mixing of ingredients of the prescription
2) Emulsification
3) Addition of suspending agent
4) Change in the form of ingredients
5) By addition, substitution

5. EXAMPLES OF PHYSICAL IN COMPATIBILITIES AND THEIR METHODS OF CORRECTION:
A) Immiscibility
B) Insolubility
C) Precipitation
D) Liquefaction
A) Immiscibility:
Oil and water are immiscible with each other. They
can be made miscible with water by emulsification.
eg:
℞
Castor oil 15ml
water 60ml
make an emulsion
In this prescription castor oil is immiscible with water. To overcome
this incompatibility an emulsifying is used to make a good emulsion.
W/O , Water is not soluble in oil
B) Insolubility:
Insolubility means the inability of material to dissolve in a particular solvent system.
The majority of physical incompatibilities are due to insolubility of the inorganic as well as organic compound in a
particular solvent

6. Eg:
℞
Phenacetin 3g
Caffeine 1g
Orange syrup 12ml
Water upto 90ml
Make a mixture
In this phenacetin is an in diffusible substance. Compound power of tragacanth or mucilage of tragacanth is used
as a suspending agent to make a stable suspension.
C) Precipitation:
Drug in solution may be precipitation the solvent in which it is insoluble is added to the solution is added
to the solution.
Eg:
Prepare and dispense 100ml of the following lotion.
Tincture benzoin compound 5ml
Glycerin 15ml
Rose water in sufficient
Quantity to make
Tincture benzoin compound contain resin. The change in solvent
system result in an unavoidable precipitate. Addition of tincture with rapid
stirring yield a fine colloidal dispersion.

7. d) Liquefaction:
• It means that when two solid substance are mixed together, conversion to a liquid state take place.
• It happens through the following method:
Formation of liquid mixture
When the solid substance is soluble in another solid substance which lead to decrease of its melting point and conversion
to liquid in certain ratios.
Eg :
Menthol Camphor Convert in to liquid Powder
℞
Menthol 5g
Camphor 5g
Ammonium chloride 30g
light magnesium carbonate 60g
Make an insufflation
The menthol, camphor and ammonium chloride get liquefied on mixing with each other. To dispense menthol,
camphor and ammonium chloride are triturated together to form a liquid. Add light magnesium carbonate and mix it thoroughly
to make free flowing powder.

8. B. CHEMICAL INCOMPATIBILITY
Reaction between two or more substance
which lead to change in chemical properties
of pharmaceutical dosage form. As a
result of this a toxic or inactive or product
may formed
Two types of Chemical incompatibility
Tolerated Adjusted

9.  Tolerated incompatibility :
In tolerated incompatibilities, the chemical interaction can be
minimized by changing the order of mixing or mixing the solution in
dilute forms but no alteration is made in the formulation.
 Adjusted incompatibility :
In adjusted incompatibilities the chemical interaction can be
prevented by addition or substitution of one of the reacting ingredients of a
prescription with another of equal therapeutics value.
E.g:
Substitution of caffeine citrate with caffeine in sodium salicylate and
caffeine Citrate mixture.

10. Precipitate yielding interactions:
 The precipitates so formed may be diffusible or in diffusible. The method A or B is followed in dispensing the
Prescription yielding diffusible precipitates respectively.
 The preparation should contain a thickening agent if the precipitates respectively.
 The preparation should contain a thickening agent if the precipitate is non-diffusible.
Method A
 The method is followed when diffusible precipitates are formed in large quantity.
 Divide the vehicle into two equal portions.
 Dissolve one reactants in separate portions and mix the second portions by
slowly by adding one into other with rapid stirring
Method B
The method is followed when diffusible precipitates are formed in large quantity.
Divide the vehicle into two equal portions.
Dissolve one of the reacting substance in one portion.
Weigh suitable quantity of tragacanth powder
And transfer in a mortar and use second portion. To produce smooth mucilage
Than mix one and second portions add slowly with rapid stirring

11. Example of chemical incompatibilities and methods of their corrections
A. Alkaloid incompatibility
1. Alkaloidal salts with alkaline substance
2. Alkaloidal salts with soluble iodides
3. Alkaloidal salt with tannins
4. Alkaloidal salt with salicylates
5. Alkaloidal salts with soluble iodides and bromides
B. Soluble salicylates incompatibilities
1. Soluble salicylates with ferric salt
2. Soluble salicylates with alkali bicarbonates
3. Soluble salicylates and benzoates with acids
C. Soluble iodides incompatibility
1. Oxidations of iodides with ferric salts
2. Oxidation of iodides with potassium chloride
3. Oxidation of iodides with quinine sulphate
D. Chemical incompatibilities causing evolution of carbon dioxide gas
1. Sodium bicarbonate with soluble calcium or magnesium salts
2. Bismuth subnitrate and sodium bicarbonate
3. Borax with sodium bicarbonate and glycerin
E. Miscellaneous chemical incompatibility
1. Soluble barbiturates with ammonium bromide
2. Potassium chlorate with oxdisable substance
3. Incompatibility of emulsifying agents
4. Color stability of dyes
5. Incompatibilities of liquorice extract

12. C. THERAPEUTIC INCOMPATIBILITY
Therapeutic incompatibility is a result of
prescribing certain drug to a patient with the
intention to produce a specific degree of
pharmacological action.

13.  The following reasons of therapeutic incompatibly
Error of Dosage
Drug Interaction
Synergistic and
Antagonistic
drug
Contra
Indicated drug
Wrong Dosage
BFD

14. ERROR IN DOSAGE
 Many therapeutic incompatibility result from error in writing or interpreting the prescription
Order.
 The most serious type of the dosage error in the dispensing is overdose of a medication
E.G
℞
• Atropine sulphate 0.006g
• Phenobarbitone 0.015g
• Aspirin 0.300g
 Cause:
In this prescription, the quantity of the atropine sulphate in each capsule is more than its recommended dose.
 Remedy
The prescription is referred back to the prescriber to correct the overdose of the atropine sulphate.

15. WRONG DOSE OR DOSAGE FORM
 There are certain drug which have quite similar names and there is always
a danger of dispensing the wrong drug.
E.G
℞
Prednisone and Prednisolone
Digoxin and Digtoxin
 Some times many drugs are available in the different dosage for and hence, if
the dosage forms is not clearly mentioned on the prescription, it becomes
necessary to seek clarification from the prescribe

16. PRESCRIBING CONTRA – INDICATE DRUGS
 There are certain drugs which may be contra- indicated in a particular
disease or particular patient who is allergic to it.
E.G:
Corticosteroids are contra – indicated in the patient having an active
peptic ulcer. The penicillin and sulphar drugs are contra – indicated to
the patient who are allergic to it.
E.G
℞
Sulphadiazine 250mg
Sulphamerazine 250mg
Ammonium chloride 500mg
 Cause:
Ammonium chloride is a urinary acidifier. It cause the deposition of the sulphonamide crystals in the kidney.
 Remedy:
Before prescribing such substances a doctor must be carful.
BFD

17. SYNERGISTIC AND ANTAGONISTIC DRUGS
Synergistic
When two drugs are prescribed together, they tend to increase the activity of each
other which is known as SYNERGISM.
Antagonistic
When two drugs are prescribed together they tend decrease the activity each other
which is known as ANTAGONISM.
E.G
 A combination of aspirin and paracetamol increases the analgesic activity.
E.G
℞
Amphetamine sulphate 20mg
Ephedrin sulphate 100mg
Syrup up to 100ml
 Cause :
In this combination of two sympathomimetic drugs with additive effect.
 Remedy:
the prescription should be referred back to the prescriber

18. DRUG INTERACTIONS
The effect of one drug is altered by the simultaneous administration of another
drug. The drug interaction can usually be corrected by the proper adjustment of
dosage if the suspected interaction is detected .
E.G
℞
Tetracycline hydrochloride 250mg
 Cause:
Tetracycline is inactivated by calcium present in milk.
so, it should not be take milk
 Remedy:
In this therapeutic incompatibility is unintentional.
The prescription should be referred back to the prescribe