amount of drug(A)= conc of std/ Abs of. std x Abs. of sample/ 1000 x vol of dissolution media x dilution factor
%drug release = A / label claim x 100
I s this formula is correct? and suitable for calculation of ophthalmic in-situ gel formulation? term 1000 used for?
Hello dear Kore Priyanka
If you want to know more about the amount of drug release, I referred you to read the monograph (724) of USP2016.
In your equation, you should calculate the amount of drug release using the standard curve of spectrophotometric analysis.
The concentration of the drug = (Conc. std. *Abs. sample) / Abs. std.
The unit of the concentration is depended on the unit of standard concentration in your standard curve.
So the amount of drug was obtained by multiplying the concentration by the volume of dissolution media.
The amount of the drug = (Sample concentration * Dissolution media)
If you used dilution the sample before scanned the absorbance, dilution the sample before scanned the absorbance, you should use the dilution factor. And the term 1000 may associate to the unit of the concentrations.
For drug release
Plot calibration curve [concentration in mcg vs absorbance] use following eq.
Drug released in mcg = [Abs + intercept] / slope
Amount of drug released =
[Conc. in mcg x dilution factor x volume of disso or diffusion medium] / 1000
Drug release = [Amount released x 100] / labelled claim
The term 1000 is used to convert microgram to mg.
Very good and practical question!
From these answers, the mug says that much help in everyday practice!
Thanks and Regards
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