A: Infrared Absorption 197K.

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

Citrate buffer— Prepare a degassed solution containing 5.82 mg of anhydrous dibasic sodium phosphate and 16.7 mg of citric acid monohydrate in water. Adjust to a pH of 3.0.

Medium: Citrate buffer; 900 mL.

Apparatus 2: 50 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C38H50N6O5 dissolved by employing UV absorption at the wavelength of maximum absorbance at about 240 nm on filtered portions of the solution under test, suitably diluted with Dissolution Medium, in comparision with a Standard solution having a known concentration of USP Saquinavir Mesylate RS in the same Medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C38H50N6O5 is dissolved in 45 minutes.

Triethylamine phosphate solution, Mobile phase, System suitability solution, and Chromatographic system— Proceed as directed in the Assay under Saquinavir Mesylate.

Standard solution— Use the Standard preparation, prepared as directed in the Assay under Saquinavir Mesylate.

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 20 µL) of the Test solution and the Standard solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity in the portion of Capsules taken by the formula: in which F is a response factor, and is equal to 2 for a peak, if present, at a retention time of 0.32 relative to saquinavir, to 0.5 for peaks, if present, at relative retention times of about 0.38 and 0.53, and to 1 for all other peaks; 670.86 and 766.96 are the molecular weights of saquinavir and saquinavir mesylate, respectively; C is the concentration, in mg per mL, of USP Saquinavir Mesylate RS in the Standard solution; W is the weight, in mg, of Capsule contents taken for the Test solution; ri is the peak response for each impurity obtained from the Test solution; and rS is the peak response for saquinavir obtained from the Standard solution: not more than 0.2% of any individual impurity is found, and not more than 1.0% of total impurities is found.

(Official January 1, 2007)

Triethylamine phosphate solution, Mobile phase, System suitability solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Saquinavir Mesylate.

Assay preparation— Empty and combine the contents of not fewer than 10 Capsules. Transfer an amount of Capsule contents, equivalent to about 22 mg of Saquinavir, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of saquinavir (C38H50N6O5) in the portion of Capsules taken by the formula: in which 670.86 and 766.96 are the molecular weights of saquinavir and saquinavir mesylate, respectively; C is the concentration, in mg per mL, of USP Saquinavir Mesylate RS in the Standard preparation; and r U and r S are the peaks obtained from the Assay preparation and the Standard preparation, respectively.