Page 104 - Interactive Theoritical Notes of Bioharmaceutics and pharamcokinetics.docx compressed

PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

❑ The dissolution of drugs can be described by the Noyes-Whitney Equation.

❑ This equation describes the rate of dissolution of spherical particles when the

dissolution process is diffusion controlled and involves no chemical reaction :

where :

.
▪ dC/dt: rate of dissolution of the drug particles
▪ D: diffusion coefficient of the drug in solution in the GIT fluids
.
.
▪ A: effective surface area of the drug particles in contact with the GIT fluids
▪ h: thickness of the diffusion layer around each drug particle
.
▪ Cs: saturation solubility of the drug in solution or concentration of drug in the
.
diffusion layer
.
▪ C: concentration of the drug in the bulk GI fluid in bulk layer

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