Incompatibilities in prescription, types-physical, chemical, therapeutic

1. INCOMPATIBILITIES
In
PRESCRITION
Parag Jain
Assistant Professor
Chhattrapati Shivaji Institute
of Pharmacy
Durg, Chhattisgarh
Presented by

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. INCOMPATIBILITIES OCCURS DURING:
• Compounding
• Formulation
• Manufacturing
• Packaging
• Dispensing
• Storage
• Administration of drugs
• The incompatibilities may be detected by changes in the
physical, chemical, and therapeutic qualities of the
medicine.

4. TYPES OF INCOMPATIBILITIES
• The incompatibilities occur when the
components of a medicine interact in such a
way that properties of that medicine are
adversely affected.
• Incompatibility can be classified into three
groups-
• Physical incompatibility
• Chemical incompatibility
• Therapeutic incompatibility

5. PHYSICAL INCOMPATIBILITY:

6. PHYSICAL INCOMPATIBILITY
• Interaction between two or more substances
which lead to change in color, odor, taste,
viscosity and morphology.
• A visible physical change takes place
• An unacceptable, non-uniform, unpalatable
product is formed.
• Difficult to measure an accurate dose.
• Can be corrected by applying pharmaceutical
skill.

7. MANIFESTATIONS OF PHYSICAL
INCOMPATIBILITY:
• Insolubility of prescribed agent in vehicle
• Immiscibility of two or more liquids
• Liquification of solids mixed in a dry state

8. 1. Insolubility:
• The following factors affect the solubility of prescribed agent in vehicle
and may render it less soluble:
• Change in pH
• Milling
• Surfactant
• Chemical reaction
• Complex formation
• Co-solvent
• Example of insolubility:
• Benzalkonium chloride
• Sodium lauryl sulfate

9. 2. Immiscibility of two or more liquids:
• Incomplete mixing
• Example: Flavoring agent such as orange oil,
lemon oil or their alcoholic solution are
added in aquous preparation they may not
mix well and droplets of the oils may b float
on the water surface. They make the
solution turbid, having a hazy appearance.

10. 3. LIQUIFICATION OF SOLIDS MIXED IN A DRY
STATE:
• It means that when two solid substances are mixed
together, conversion to a liquid state take place.
• Example: Certain low melting points solids when
mixed together liquefy due to formation of eutectic
mixtures, they form a soft mass when mixed
together thus the physical integrity of the
preparation may be lost. Ex- menthol, thymol,
aspirin form eutectic mixture when two of them are
mixed together.

11. CHEMICAL INCOMPATIBILITY:

12. CHEMICAL INCOMPATIBILITY
• Chemical changes which occur due to the interaction of the
prescribed substances leading to the formation of a harmful or
dangerous product
• They often occur by
• OXIDATION – REDUCTION
• HYDROLYSIS
• COMBINATION OF BOTH

13. Oxidation – reduction
1. Oxidation -Loss of electrons
2. Reduction - Gain of electrons
Oxidization of prescriptions
• On exposure to air
• Higher storage conditions
• Light
• Over dilution
• Incorrect pH adjustments
• Presence of catlysis

14. • Trace metal ion catalysis - complexing agents
like disodium edetate , sodium calcium edetate
• Autooxidation of fats and
oils ,phenols,aldehydes,vitamins - antioxidants
like propyl gallate,
thymol,BHT,BHA,hydroquinone
• Light Reduces siver,mercury,gold salts to metallic
form

15. HYDROLYSIS
DRUGS PRONE TO HYDROLYSIS :
Procaine
Sulphonamides
Chlorothiazide
Barbituric acid
Aspirin
Alkaloids
Penicillin
ADDITIVES PRONE TO HYDROLYSIS :
GELATIN- SUCROSE
FLAVORING OILS
CHLOROBUTANOL
Hydrolysis promoters :
• Heat catalysts
• Hydrogen ions
• Hydroxyl ions
Ex: ESTERS, AMIDES, METALS like Zn, Fe

16. Complexation
• The medicaments or excipients get bound to or
trapped inside the macromolecules
• The complexes are too large to penetrate cell
membranes
• Reversible complexation is useful
• POVIDONE – IODINE Complex : useful to reduce
the irritancy and stability of the drug

17. THERAPEUTIC INCOMPATIBILITY:

18. THERAPEUTIC INCOMPATIBILITY
• Therapeutic incompatibilities are unintentional
pharmacodynamic or pharmacokinetic interactions that take
place in vivo after administration of medicinal products.
• Example: Amine containing drugs are incompatible with mono
amino-oxidase inhibitors.
CAUSES:
• It may be due to the administration of :
• Overdose or improper dose of a single drug.
• Improper Dosage form.
• Contraindicated drug.
• Synergistic and antagonistic drugs

19. DOSAGE ERROR
• Dispensing of an overdose of prescription
• Any experienced pharmacist should be able to detect
such an error while checking the prescription
• Ex: Atropine sulphate-0.06gm
• Phenobarbital-0.015gm
• Asprin-0.300gm

20. Wrong dose or dosage form
• Possibility of dispensing the wrong drug because of
confusingly similar names
• Ex: Prednisone and prednisolone
• Protamine and protamide
• Digoxin and disgitoxin

21. Contraindicated drugs
• Certain drugs are contraindicated in a particular
disease or when a particular patient is allergic to it
• Corticosteroids-contraindicated to patients having
peptic ulcer
• Morphine,barbiturates-dangerous in severe asthma
• Pencillin and sulphur drugs - allergic to patients
• Vasoconstrictors-should not be given to hypertensive
patients

22. Synergistic or antagonistic drugs
• Synergistics:
• Penicillin derivatives+probenicid
• Aspirin +paracetamol
• Antagonistics:
• Amphetamine X barbiturate
• Stimulants X sedatives
• Cholinergic drugs X anticholinergic drugs
• Purgatives X antidiarrhoeals
• Antacids X antibiotics

23. Website: www.probecell.com Email: probecellinfo@gmail.com
Ph: 7415211131
Office: Smriti Nagar, Bhilai, Chhattisgarh - 490020
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