JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Pharmacy II Year PHYSICAL PHARMACEUTICS-II Previous Question Paper (March-2022 - R17)
Answer any five questions. All questions carry equal marks.
Main
Define oxidation and list out four antioxidants used in pharmaceutical products?
Answer
Oxidation is a chemical process involving the loss of electrons from a molecule, atom, or ion, often resulting in the degradation of pharmaceutical substances through interaction with oxygen, light, or metal catalysts. Four common antioxidants used in pharmaceutical products are Butylated Hydroxyanisole (BHA), Butylated Hydroxytoluene (BHT), Ascorbic acid, and Sodium metabisulfite.
List out the various factors influencing the chemical degradation of pharmaceutical products. Discuss about the dielectric constant and temperature.
Answer
Factors influencing the chemical degradation of pharmaceutical products include temperature, pH, moisture (hydrolysis), light (photolysis), oxygen (oxidation), dielectric constant, and the presence of impurities or metal ions.
Dielectric Constant: The solvent's dielectric constant significantly affects the rate of reactions involving polar molecules. A change in the dielectric constant of the solvent system can alter the reaction rate constant, particularly for reactions where the transition state has a different polarity than the reactants. Decreasing the dielectric constant often stabilizes drugs prone to hydrolysis.
Temperature: Temperature is the most critical factor in chemical stability. According to the Arrhenius relationship, an increase in temperature increases the kinetic energy of molecules, leading to a higher frequency of effective collisions and thus accelerating the rate of degradation reactions. Generally, the rate of reaction doubles or triples for every 10°C rise in temperature.
Write the Arrhenius equation and elaborate the terms therein.
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Give the reasons for the following with reference to degradation and stability:
i) Preservation of drugs in air tight containers.
ii) Storing medicines in colored/ambered bottles.
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Write role of ionic strength on reaction rate.
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Discuss in brief about specific acid base catalysis.
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What are the limitations of cup and bob viscometer? Suggest alternative method for preventing the same along with its principle and working.
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Write the pharmaceutical applications of a thixotropic substances.
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Write a note on viscoelastic measurement based on the mechanical properties of materials.
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Define kinematic viscosity and rheopexy?
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Discuss the principle and working of falling sphere viscometer.
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A formulation scientist has developed a new pain killer ointment and subjected the same to rheological analysis at 25 degrees using a cone and plate viscometer. The instrument has a constant of C of 6.277 cm-3. At a cone velocity of 100rpm the torque reading was 1285.0 dynes.cm. The torque (Tf) at the shearing stress was found to be 65 dynes.cm. Calculate the plastic viscosity at 25 degrees.
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Define emulsion? Discuss in detail about the formulation of the same.
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With the help of a diagram discuss in detail about the DLVO theory.
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What do you understand by Brownian movement?
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Discuss about the various sedimentation parameters along with the equations.
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Calculate the sedimentation volume of 7%(w/v) antiacid suspension in water. The initial volume is 100 ml and the final volume is 42 ml. If the degree of flocculation is 1.4, calculate the deflocculated sedimentation volume.
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Write a note on Coalescences and phase inversion with reference to emulsions.
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Write a note on surface free energy.
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Discuss one method used for the determination of surface tension along with its advantages and disadvantages.
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What do you understand about the concept of insoluble monolayer and film balance?
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How colloidal dispersion differ from coarse dispersions.
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Discuss in detail about the association colloids.
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List out the various optical properties of colloids. Write about light scattering.
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