Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

In vitro evaluation of trimethoprim and sulfamethoxazole from fixed-dose combination generic drugs using Spectrophotometry: Comparison of flow-through cell and USP paddle methods

Raúl Medina¹ , Maximiliano Miranda¹, Marcela Hurtado¹, Adriana M Dominguez-Ramirez¹, Octavio Reyes¹, Juan C Ruiz-Segura^1,2

¹Departamento de Sistemas Biológicos, UAM-Xochimilco Mexico; ²Departamento de Química Analítica, Fac. de Química UNAM Mexico.

For correspondence:- Raúl Medina Email: rmlopez@correo.xoc.uam.mx

Received: 6 August 2014 Accepted: 3 September 2015 Published: 29 November 2015

Citation: Medina R, Miranda M, Hurtado M, Dominguez-Ramirez AM, Reyes O, Ruiz-Segura JC. In vitro evaluation of trimethoprim and sulfamethoxazole from fixed-dose combination generic drugs using Spectrophotometry: Comparison of flow-through cell and USP paddle methods. Trop J Pharm Res 2015; 14(11):2061-2069 doi: 10.4314/tjpr.v14i10.16

© 2015 The authors.
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Abstract

Purpose: To develop a first-order derivative spectrophotometric method for the determination of trimethoprim (TMP) and sulfamethoxazole (SMX) from fixed-dose combination generic products using a flow-through cell technique.

Methods: Absorbance measurement was achieved at 247.8 and 257.9 nm for trimethoprim and sulfamethoxazole, respectively. USP Apparatus 4 with 22.6 mm cells, laminar flow at 16 ml/min, and 0.1 N HCl at 37 °C as dissolution medium, were used. Dissolution profiles were compared with model-dependent and independent methods.

Results: All the products met the pharmacopeial dissolution criterion (Q ≥ 70 %, at 60 min), except SMX in two products (SC 400 mg and SB1 800 mg) using the flow-through cell (53.62 and 49.74 % dissolved, respectively). Using both USP apparatuses, significant differences in mean dissolution time and dissolution efficiency values were found (p < 0.05).All products were in line with Weibull’s kinetics and significant differences in derived parameters (Td) values were found (p < 0.05).

Conclusion: Determination of TMP and SMX by derivative spectrophotometry can easily be employed for dissolution studies using the flow-through cell technique. However, it would be necessary to determine correlation with in-vivo test results in order to assure safe interchangeability.

Keywords: Trimethoprim, Sulfamethoxazole, Flow-through cell method, First-order derivative spectrophotometry, Fixed-dose combination generic drugs