What is Hixson Crowell equation?
the initial effective surface area can be expressed by using the specific surface area (Ssp= 6/ρlo ) as： So = SspMo. dm/dt = (1/V ) k Ssp Mo (M /Mo)2/3 ( Ms – m ) can be rewritten as. -dM/dt = (1/V ) k Ssp Mo1/3 M 2/3 {Ms – (Mo- M ) } 1) sink condition ( Mo << Ms ) the cube root law equation ( ’89)
What is Hixson Crowell model?
Hixson–Crowell model. Hixson and Crowell (1931) discovered that a group of particles’ regular area is proportional to the cube root of its volume.
What is the Hixson Crowell cube root law?
The Hixson-Crowell cube root law describes the release from system where there is a change in surface area and diameter of the particles or tablets [15,16]. The applicability of all of these equations was tested in this work. The dissolution data obtained for all formulations at pH.
What is Higuchi equation?
Simplified Higuchi model describes the release of drugs from insoluble matrix as a square root of time dependent process based on Fickian diffusion Equation. Q = KH t1/ 2. The data obtained were plotted as cumulative percentage drug release versus square root of time.
What is korsmeyer Peppas model?
Korsmeyer-Peppas was a simple model known as “Power law” describing drug release from a polymeric system. Korsmeyer-Peppas model (1) describe some release mechanisms simultaneously such as the diffusion of water into the matrix, swelling of the matrix and dissolution of the matrix [12].
How do you calculate release kinetics?
ft = Q = A √D(2C с Cs) Cs t (7) where Q is the amount of drug released in time t per unit area A, C is the drug initial concentration, Cs is the drug solubility in the matrix media and D is the diffusivity of the drug molecules (diffusion coeffi- cient) in the matrix substance.
Which form of drug has greater solubility?
11. Which form of a drug has greater solubility? Explanation: Anhydrous form of a drug has a greater aqueous solubility than the hydrates. This is because the hydrates are already in interaction with the water and therefore have less energy for crystal breakup.
How do you calculate N in korsmeyer Peppas model?
One is to do the calculations manually Y = log(y) and X = log(x). A plot of Y vs X gives a slope m = n and an intercept b = log(k). The second way is to plot log(y) vs log(x). When you fit a straight line to this plot, the same results are returned for m = n and b = log(k).
What is fickian and non fickian diffusion?
The main difference between Fickian and Non Fickian Diffusion is the presence or absence of boundaries; there are no boundaries in Fickian diffusion whereas non Fickian diffusion has a sharp boundary separating the highly swollen region from a dry, glassy region.
What is N value in korsmeyer-Peppas?
in model Korsmeyer-Peppas the value of n characterizes the release mechanism of drug as described in Table 1.
Which form of drug imparts good solubility Mcq?
Which form of a drug has greater solubility? Explanation: Anhydrous form of a drug has a greater aqueous solubility than the hydrates.
How does cosolvent increase solubility?
This process is known as cosolvency, and the solvents used to increase solubility are known as cosolvent. Cosolvent system works by reducing the interfacial tension between the aqueous solution and hydrophobic solute. It is also commonly referred to as solvent blending.