Okay I found some references and the equation I am after is(adsbygoogle = window.adsbygoogle || []).push({});

Q = 2 * C * (D * t / ∏)^(1/2)

where Q is the weight of drug released per unit area (hence unit is mg/cm^2)

C is the initial drug concentration

D is the diffusion coefficient (unit of cm^2 min^-1)

and t is release time in min.

What I am not sure about is the units.

Logically the concentration of drug would be in g/L.

but when I merge all the units together, I get something else.

This is my working.

The units on the right hand side should equals to Q.

= 2 (constant) * C (g/L) * [D (cm^2 * min^-1) * t (min) / ∏ (constant)]^(1/2)

only considering units (ie discard constants)

= [g * cm^[2*(1/2)] * min^(1/2)] / [L * min^(-1 * 1/2)]

= g * cm * min^(1/2) / L * min^(-1/2)

= g * cm * min^(1/4) / L

which does not equals to unit of Q (mg/cm^2).

The units given are all correct but is there something I am missing here?

Breaking rules of powers perhaps?

Thank you!!!!

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# Homework Help: Spontaneous drug release rate equation

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