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Full Factorial Experimental Design for Development and Validation of a RP-HPLC Method for Estimation of Letrozole in Nanoformulations

[ Vol. 14 , Issue. 3 ]

Author(s):

Aswathi R. Hegde, Renuka S. Managuli, Anup Naha, Kunnatur B. Koteshwara, Meka Sreenivasa Reddy and Srinivas Mutalik*   Pages 320 - 330 ( 11 )

Abstract:


Background: Letrozole (LTZ) is a potent aromatase inhibitor which blocks estrogen synthesis in post-menopausal women. Suitable analytical methods are required to quantify letrozole in bulk and its nanoformulations. Hence a sensitive and robust reverse-phase high performance liquid chromatographic method (RP-HPLC) was developed for the estimation of LTZ.

Methods: The method was developed using Kinetex C18 column (250 mm×4.6 mm; 5µ) and mobile phase comprising acetonitrile (ACN): acetate buffer (pH 4.5) mixture (50:50% v/v) was used to affect the chromatographic separation at 0.8 mL/min flow rate. The responses were measured at 240 nm. Force degradation studies were done by exposing LTZ to acid- and alkali-induced hydrolysis, oxidation (H2O2), thermal and photolysis. Two-level factorial design was used to validate the method as per ICH Q2 (R1) using Design-Expert® software. The effects of independent variables on flow rate, pH, acetonitrile content and column temperature were recorded as responses.

Results: Method was linear over the concentration range of 5-2500 ng/mL with a correlation coefficient (R2) of 1.000. Force degradation studies revealed that LTZ was stable to all stress agents except the basic conditions. The inter-day precision results were reproducible with relative standard deviation (% RSD) of 0.078. The peak area RSD and mean recovery of LTZ was found to be <1.0% and 99-102% in drug solution and <1.0% and 98-106% in nanoformulations respectively. Deliberate changes in independent chromatographic parameters analyzed using analysis of variance (ANOVA) indicated that the model was significant (p<0.0001).

Conclusion: The developed analytical method was successfully utilized to quantify LTZ in bulk and its nanoformulations.

Keywords:

Optimization, validation, high performance liquid chromatography, factorial design, letrozole, nanoformulations.

Affiliation:

Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State

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