Which equation describes the rate of dissolution of the drug from the pills?

According to the USP, a drug is believed to dissolve rapidly when at least 85% of the claimed amount of the molecule dissolves within 30 minutes, using the USP-I apparatus at 100 rpm or 50 rpm min for USP-II device. , in a volume of 900 ml or less in any media, such as 0.1 n HCl, pH 4.5 buffer, pH 6.8 buffer.

Dissolution Rate Equation

dw/dt= ks (Csat-Csol)

Where

dw/ dt = are the rate of dissolution

k = a dissolution constant

S = area of ​​the solid

C sat = concentration of a saturated solution

C sol = the concentration at a given time