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PHARMACEUTICS GPAT SHORT NOTES I



Every year 1-2 questions are asked in the GPAT exams from these general topics of Pharmaceutics.


1. Terms of solubility

Descriptive term
Volume of solvent in ml per gm of solute
Very soluble
Less than 1
Freely soluble
1 to 10
Soluble
10 to 30
Sparingly soluble
30 to 100
Slightly soluble
100 to 1000
Very slightly soluble
1000 to 10,000
Practically insoluble
More than 10,000

2. Flow characteristics of materials

  
PROPERTY
CHARACTER
TYPE OF LIQUID
Newtonian
Follows Newton’s law
Liquids with simple molecules and solid dispersion.
Non- newtonian
       Dilatancy or shear thickening
Shear dependent viscosity.
Increase in apparent viscosity with increase in rate of shear.
Suspensions with high solid content of small deflocculated particles.
      Pseudoplasticity or shear thinning
Shear dependent viscosity.
Decrease in apparent viscosity with increase in rate of shear.
Polymer or macromolecule solution.
       Plastic or Bingham body
Shear dependent viscosity. No apparent response to low level stress, flow after yield value.
Suspensions with flocculated particles.
        Thixotropy
Time dependent viscosity.
Shear thinning but not immediate recovery when rate of shear is lowered.
Gel-sol transformation.
        Antithixotropy
Time-dependent viscosity.
Shear thickening.
Sol-gel transformation.

3. Temperature conditions

Sr. No.
Term
Temperature condition
1
Store in cool place
8-25°C
2
Cold
2-8°C
3
Room temperature
Temperature of working area.
4
Excessive heat
Above 40°C
5
Storage under non-specific condition
Storage under protection from moisture, freezing and excessive heat.


4. Evaluation of tablet granules

  • Carr’s index: Relationship between flow and compressibility of a powder.
  • Compressibility: Property of a stable intact mass when pressure is applied
Carr's index= Tapped density-Bulk density/ Tapped density * 100



Carr’s index
Types of flow
5-15
Excellent
12-16
Good
18-21
Fair
23-25
Poor
33-38
Very poor
More than 40
Extremely poor


  • Hausner ratio
Hausner ratio= Tapped density/Bulk density

Hausner’s ratio
Interpretation
Equivalent Carr’s index
1.25
Good flow
20 %
> 1.25 (1.25-1.50)
Poor flow
33 %

  • Angle of repose: Angle of the free surface of a pile of a powder to the horizontal plane. 

Angle of repose
Indication of type of flow
< 25
Excellent
25-30
Good
30-40
Passable (may improve with glidant)
> 40
Very poor





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