A new spectrophotometric method for the determination of finasteride in tablets

Synchronous fluorescence as a green and selective method for the simultaneous determination of finasteride and tadalafil in dosage form and spiked human plasma

Finasteride and tadalafil are combined in a pharmaceutical capsules called Entadfi™, that has received FAD approval. It was indicated for the management of male benign prostatic hyperplasia-related urinary tract issues. In the current study, finasteride and tadalafil concentrations in raw form, laboratory prepared mixtures, pharmaceutical preparation and spiked human plasma were all quantitatively estimated using a sensitive synchronized fluorescence spectroscopic approach united with first derivative. When excited at 260 nm, finasteride display its emission at 320 nm. Yet, when excited at 280 nm, tadalafil displayed its emission at 340 nm. The application of micellar surfactant as sodium dodecyl sulphate (SDS) significantly increased the fluorescence intensity.The overlapping of the fluorescence spectra was entirely eliminated by derivatizing the synchronous spectra to the first derivative, which also made it possible to simultaneously quantify the cited drugs. Without interfering with one another, the first-order synchronous spectra of tadalafil and finasteride at 320 and 330 nm, respectively. The approach revealed linearity alongside an acceptable correlation coefficient for finasteride and tadalafil concentrations over the range of 10 -50 ng/mL. That approach was utilized to estimation of the cited drugs in dosage forms, simultaneously with %recoveries for tadalafil and finasteride of 99.62 ± 0.78 and 100.19 ± 0.60, respectively. Also, four various tools, the national environmental method index, the AGREE evaluation method, the green analytical procedure index and the analytical eco-scale were used to evaluate how environmentally friendly the given approach was. With regard to the metrics of the greenness aspects, the proposed approach appeared to be better than the previously published spectrophotometric methods and HPLC.

Simultaneous spectrophotometric determination of finasteride and tadalafil in recently FDA approved Entadfi™ capsules

Entadfi™ is a recently FDA approved pharmaceutical combination capsule of finasteride and tadalafil. It was prescribed for the treatment of urinary tract disorders caused by benign prostatic hyperplasia in men. This paper introduced the first spectrophotometric methods for simultaneous determination of finasteride and tadalafil in the pure form and in the pharmaceutical capsules. UV absorption spectra of finasteride and tadalafil exhibited overlap hindered the direct simultaneous determination of the cited drugs. The UV absorption spectra of finasteride and tadalafil were transformed to the second order derivative. Finasteride could be determined selectively at 230.80 nm without interference from tadalafil. Moreover, tadalafil could be determined selectively at 292 nm without interference from finasteride. The ratio spectra of the studied drugs were derived and the derived ratio spectra of each drug were transformed to the first order derivative. Finasteride could be determined selectively at 218.80 nm without interference from tadalafil. Moreover, tadalafil could be determined selectively at 289.60 nm without interference from finasteride. The methods showed linearity with an excellent correlation coefficient in the concentration range of 10-140 µg/mL for finasteride and 3-40 µg/mL for tadalafil. The methods were validated following ICH guidelines for accuracy, precision, robustness, limit of detection, limit of quantification, and selectivity. The methods were found to be sensitive with LOD values for finasteride and tadalafil of 2.406 µg/mL and 0.876 µg/mL using the second derivative with zero crossing method and 2.229 µg/mL and 0.815 µg/mL using the first derivative of ratio spectra method. The methods were successfully applied for the determination of the studied drugs in their laboratory prepared mixtures, with mean percent recovery for finasteride and tadalafil of 99.37% and 99.17% using the second derivative with zero crossing method and 99.74% and 99.56% using the first derivative of ratio spectra method. Furthermore, the described methods were successfully applied for determination of the studied drugs in Entadfi™ capsules without interference from excipients. Based on the proposed results, the described methods could be utilized as simple method for the quality control of the studied drugs.

Stability Study of Finasteride: Stability-Indicating LC Method, In Silico and LC-ESI-MS Analysis of Major Degradation Product, and an In Vitro Biological Safety Study

Stability studies of the pharmaceutically important compound finasteride were conducted in order to evaluate decomposition of the drug under forced degradation conditions. A simple stability-indicating liquid chromatography method was developed and validated for the evaluation of finasteride and degradation products formed in pharmaceutical preparations and the raw material. Isocratic LC separation was achieved on a C18 column using a mobile phase of o-phosphoric acid (0.1% v/v), adjusted to pH 2.8 with triethylamine (10% v/v) and acetonitrile (52:48 v/v), with a flow rate of 1.0 mL min-1. The alkaline degradation kinetics of the drug were also evaluated and could be best described as second-order kinetics under the experimental conditions applied for the tablets and raw material. Based on in silico studies and molecular weight confirmation, a comprehensive degradation pathway for the drug and the identity of its major product could be suggested without complicated isolation or purification processes. Furthermore, a biological safety study was performed to evaluate the effect of the degraded sample in relation to the intact molecule. The results showed that the degraded sample affected the cell proliferation. Therefore, these studies show that special care must be taken during the manipulation, manufacture and storage of this pharmaceutical drug.

Optimization and validation of spectrophotometric methods for determination of finasteride in dosage and biological forms

Aim and Background:

Three simple, accurate and sensitive spectrophotometric methods for the determination of finasteride in pure, dosage and biological forms, and in the presence of its oxidative degradates were developed.

Materials and Methods:

These methods are indirect, involve the addition of excess oxidant potassium permanganate for method A; cerric sulfate [Ce(SO4)2] for methods B; and N-bromosuccinimide (NBS) for method C of known concentration in acid medium to finasteride, and the determination of the unreacted oxidant by measurement of the decrease in absorbance of methylene blue for method A, chromotrope 2R for method B, and amaranth for method C at a suitable maximum wavelength, λ_max: 663, 528, and 520 nm, for the three methods, respectively. The reaction conditions for each method were optimized.

Results:

Regression analysis of the Beer plots showed good correlation in the concentration ranges of 0.12–3.84 μg mL_–1 for method A, and 0.12–3.28 μg mL_–1 for method B and 0.14 – 3.56 μg mL_–1 for method C. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were evaluated. The stoichiometric ratio between the finasteride and the oxidant was estimated. The validity of the proposed methods was tested by analyzing dosage forms and biological samples containing finasteride with relative standard deviation ≤ 0.95.

Conclusion:

The proposed methods could successfully determine the studied drug with varying excess of its oxidative degradation products, with recovery between 99.0 and 101.4, 99.2 and 101.6, and 99.6 and 101.0% for methods A, B, and C, respectively.