Solutions 2

• What does the Intrinsic Dissolution Rate (IDR) measure?

  Rate of dissolution independent of variables

  
• What factors affect the rate of dissolution?

  Agitation, particle size, viscosity, pH, temperature
• Under what conditions is the IDR measured?

  When surface area and agitation are constant
• What is the formula for the intrinsic dissolution rate?

  $\frac{dm}{dt} =$$D \frac{A(C_s - C)}{h}$
• What does the variable 'k' represent in the dissolution equation?

  Intrinsic dissolution rate constant
• What are the units of the intrinsic dissolution rate constant, k?

  cm/s
• How do you calculate the intrinsic dissolution rate constant, k?

  Using the modified dissolution equation
• What is the significance of sink conditions in dissolution studies?

  Ensures accurate measurement of dissolution rate
• How do you calculate the diffusion coefficient, D?

  D = k × h
• How do you determine if sink conditions apply?

  Check if C is less than 10% of Cs
• What does the Hixson-Crowell Cube Root Law assume about drug particles?

  Particles are uniformly sized
• What does the Hixson-Crowell Cube Root Law describe?

  Dissolution based on cube root of weight
• What is the process to find the cube root dissolution rate constant (k)?

  1. Monitor dissolution over time
  2. Record concentration in solution
  3. Calculate mass dissolved and undissolved
  4. Plot cube root mass undissolved against time
  5. Determine gradient for k

  
• How can you verify the accuracy of the cube root dissolution rate constant?

  Check if intercept cubed equals initial mass

  
• Why is the measurement of Intrinsic Dissolution Rate important?

  • Depicts dissolution rate of a drug
  • Screens drug candidates
  • Understands solution behavior under conditions
  • Determines batch-to-batch chemical equivalency