Drug product assay

The label claim for drug product ensures each vial meets a minimum concentration specification on the label. Label claim can be determined as follows:

where
C_DP	Concentration of UV-pure material in Drug Product (mg/ml)
C_sample	Concentration of UV-pure material in sample (mg/mL)
MSP_sample	Purity of FLP as determined in section (X) by UV purity
PF_sample	Preparation factor for sample (see below)
CF	Conversion Factor - ratio of sodiated to free acid form of the molecule

where
C_DP	Concentration of UV-pure material in Drug Product (mg/ml)
LC_sample	Label claim (mg/mL)

Preparation Factor

The preparation factor for the sample is determined by whether the sample volume is determined gravimetrically (that is, sample volume is weighed on analytical balance) or volumetrically (that is, sample is measured using pipette or similar dispenser).

The gravimetric factor is determined by:

where
PF_sample	Preparative factor – gravimetric
V_sample	Volume of sample (mL)
Wt_sample	Weight (g) of sample
D_sample	Density (g/mL) of sample reported to two decimal places

The volumetric factor is determined by:

where
PF_sample	Preparative factor – volumetric
V_final	Final volume of sample (mL)
V_sample	Volume of sample (mL)