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 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].
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 the ritger Peppas equation?
The previously (Ritger and Peppas, 1987) introduced exponential relation Mt/M∞ = ktn may be used to describe the Fickian and non-Fickian release behavior of swelling-controlled release systems which swell to a moderate equilibrium degree of swelling and are prepared by incorporation of a drug in a hydrophilic.
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 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 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.
How does pH affect drug solubility?
Increase in pH led to decrease in solubility and percentage of unionized form of weakly basic drug and an increase in its distribution coefficient. The effect of solubility and partition coefficient on skin permeability is a well-documented phenomenon.
Which form of a drug has greater celebrity?
Which form of a drug has greater solubility? Explanation: Anhydrous form of a drug has a greater aqueous solubility than the hydrates.
How does Fick’s law affect diffusion?
Fick’s Law describes the relationship between the rate of diffusion and the three factors that affect diffusion. It states that ‘the rate of diffusion is proportional to both the surface area and concentration difference and is inversely proportional to the thickness of the membrane’. ∝ means ‘is proportional to’.
What is Hixson Crowell’s cube root equation?
Join ResearchGate to ask questions, get input, and advance your work. Hixson Crowell’s cube root equation is a mathematical model used to describe powder dissolution or drug release from specific formulations. The shape (drug particles , drug dosage form…) is spherical and size will decrease as the system dissolves.
What is Hixson and Crowell 1931a?
Hixson and Crowell, 1931a, Hixson and Crowell, 1931b, Hixson and Crowell, 1931c specifically addressed the fact that the surface of a dissolving substance often changes with time in practice, e.g. if spherical particles dissolve in well-agitated bulk fluids the radius of the spheres continuously decreases.
Does Hixson-Crowell equation apply to tablets?
Thus, the Hixson–Crowell equation applies to pharmaceutical dosage forms such as tablets, considering that dissolution occurs in planes parallel to the surface of the active agent if the tablet dimensions decrease proportionally, but with maintenance of the geometrical characteristics. 5.6. Ritger–Peppas and Korsmeyer–Peppas model (Power law)
What is Hixson and Crowell’s Noyes-Whitney modification?
Hixson and Crowell proposed a modification of Noyes–Whitney (Equation (5.7) ): (5.10) d W d t = K S C s − C where W is the amount of drug soluble on time t, d W /d t is the ratio of the solute passing to the solution on time t, S is the surface of dissolution, and K the constant of proportionality.