Pharmaceutical Dosage Form I - Lecture 5: Formulation Work A

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Questions and Answers

What is the purpose of controlled flocculation in pharmaceutical dosage forms?

  • To increase the zeta potential of particles
  • To induce the formation of a cake
  • To prevent the formation of compact sediment (correct)
  • To disperse the particles evenly

How is controlled flocculation usually achieved?

  • Addition of surfactants only
  • Use of extreme heat and pressure
  • Combination of particle size control, use of electrolytes, and addition of polymers (correct)
  • Mechanical agitation only

What is the role of electrolytes in converting a suspension from a deflocculated to a partially flocculated state?

  • Alter the zeta potential and reduce the electric barrier between particles (correct)
  • Increase the repulsion force between particles
  • Cause further deflocculation
  • Stabilize the suspension

What do polymers termed as 'polyelectrolytes' do in controlled flocculation?

<p>Become ionized in an aqueous solution and act both electrostatically and sterically (D)</p> Signup and view all the answers

How do electrolytes act as flocculating agents?

<p>By reducing the electric barrier between particles and decreasing the zeta potential (A)</p> Signup and view all the answers

What are the most widely used electrolytes for flocculation?

<p>Sodium salts of acetates, phosphates, and citrates (B)</p> Signup and view all the answers

What effect does a decrease in zeta potential have on suspended particles?

<p>It leads to a decrease in repulsion force and the formation of a bridge between adjacent particles (A)</p> Signup and view all the answers

Which type of surfactants can cause flocculation by neutralizing the charge?

<p>Anionic surfactants (D)</p> Signup and view all the answers

How do optimum concentrations of surfactants reduce the surface tension between liquid medium and solid particles?

<p>By reducing the surface tension (C)</p> Signup and view all the answers

What effect do non-ionic surfactants have on the charge density of a particle?

<p>They have a negligible effect on the charge density (C)</p> Signup and view all the answers

How do polymeric flocculating agents promote flocculation?

<p>By forming bridges between projected parts of the polymer chains (A)</p> Signup and view all the answers

What is the purpose of structured entrapping vehicles in relation to flocculated particles?

<p>To increase physical stability of suspension by retarding sedimentation rate (A)</p> Signup and view all the answers

Which type of polymers are examples of structured entrapping vehicles?

<p>Non-Newtonian polymers with thixotropic behavior (D)</p> Signup and view all the answers

1

<p>What type of methods can be applied after adding wetting agent and dispersion medium to particles? (A)</p> Signup and view all the answers

What are structured vehicles used to increase in suspensions?

<p>Viscosity (C)</p> Signup and view all the answers

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