What is the diffusion coefficient of a drug?

The diffusion coefficient (also known as diffusivity) of an active pharmaceutical ingredient (API) is a fundamental physicochemical parameter that affects passive diffusion through biological barriers and, as a consequence, bioavailability and biodistribution.

How do you find self diffusion coefficient?

The self-diffusion coefficient is given by g · a2 times the number of jumps per sec that the diffusing particles make. Gm is the free enthalpy for a jump, i.e. the free enthalpy barrier that must be overcome between two identical positions in the lattice.

What are the dimensions of the diffusion coefficient?

The various diffusion coefficients Diffusion coefficients have the dimension Length2 Time −1. In the international system of units they are expressed in m 2 s −1 The CGS system (cm 2 s −1) is still widely used. We will show now which experimental situations correspond to these various coefficients.

How are diffusion coefficients measured in NMR spectroscopy?

Diffusion coefficients in a sample are measured by NMR spectroscopy using the pulsed-field-gradient spin-echo (PGSE) pulse sequence [41, 42, 89]. The magnetic field gradient is applied in a single direction to encode the location of spins in this method.

How is the diffusivity of a substance determined?

The diffusivity of one particular substance to another is typically identified through experimenting. Diffusion coefficients can be computed in liquids, gases and multiple media that usually involve factors such as changes in temperature and pressure.

What is the diffusion coefficient of sulfuric acid?

It is quite evident that Eq. (6.72) gives a relation for sulfuric acid binary diffusion in a nonporous medium. In a porous medium the value should be corrected according to the Brugmann relation, that is, Eq. (6.84). A. Kayode Coker, in Ludwig’s Applied Process Design for Chemical and Petrochemical Plants (Fourth Edition), Volume 1, 2007