Identification And Quantification Of Phosphodiesterase-5 Inhibitors As Adulterants In Dietary Supplements Marked For Sexual Enhancement In The Lebanese Market

Objective: Ultraviolet Visible spectrophotometric was adopted to identify and quantify any adulteration with PDE-5 inhibitors (Sildenafil and Tadalafil) in selected dietary supplements used for sexual enhancement in the Lebanese market Methods: Nine dietary supplements, randomly collected from Lebanese pharmacies, were screened for Sildenafil and Tadalafil using UV-spectrophotometry for both qualitative and quantitative detection. Results: Tadalafil was detected in one sample at a dose of 59 mg/dosage unit, with the maximal recommended dose being 20 mg. Sildenafil was detected in five samples at doses ranging from 11.7 to 188.2 mg/dosage unit, with the maximal recommended dose being 100 mg. Conclusion: This study demonstrates that regular analysis of supposed dietary supplements is needed for more effective quality control and health promotion. The method described for the extraction, identification and quantification of Tadalafil and Sildenafil would be useful for regulatory detection of adulterations.

Rp-Hplc And Chemometric Methods For The Determination Of Two Anti-Diabetic Mixtures; Metformin Hydrochloride-Canagliflozin And Metformin Hydrochloride-Gliclazide In Their Pharmaceutical Formulation

Objective: To develop and validate novel more sensitive analytical methods for the concurrent quantification of metformin-canagliflozin and metformin-gliclazide in their bulk forms and in their pharmaceutical preparations. Methods: Two methods were developed based on several chemometric assisted spectrophotometric methods and a Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC). The first method applies different spectrophotometric chemometric assisted methods, including ratio difference, derivative ratio and extended ratio subtraction method, while the second method describes a RP-HPLC separation of metformin hydrochloride-canagliflozin and metformin hydrochloride-gliclazide binary mixtures using a C18 column with a mobile phase consisting of acetonitrile: potassium dihydrogen phosphate (adjusted to pH 3) with sodium lauryl sulphate as additive in the ratio of 30:70 (%v/v) in isocratic elution mode at 1 ml/min. Results: The proposed methods were able to quantify each of the studied drugs in their binary mixtures with high percentage recoveries in both methods. The spectrophotometric methods were able to quantify each of metformin, canagliflozin and gliclazide in the ranges of 2.0-20.0 μg/ml, 1.5-40.0 μg/ml and 2.0-30.0 μg/ml, respectively. The RP-HPLC method produced well-resolved peaks at a retention time of 3.92, 6.92 and 9.10 min in the concentration ranges of 50.0-300.0 μg/ml, 5.0-50.0 μg/ml and 10.0-100.0 μg/ml for metformin, canagliflozin and gliclazide, respectively. The proposed methods were optimized and validated in accordance to the International Conference of Harmonisation (ICH) guidelines in terms of linearity, LOD, LOQ, precision and accuracy. Conclusion: The developed methods were found to be sensitive and reproducible methods for the simultaneous determination of anti-diabetic binary mixtures; metformin hydrochloride-canagliflozin and metformin hydrochloride-gliclazide. And thus were successfully employed for the quality control analysis of the pharmaceutical formulations of the studied binary mixtures.

Novel Selective Spectrophotometric Methods For The Determination Of Methimazole In Pure Form And In Pharmaceutical Formulation

Objective: To develop and validate new, selective spectrophotometric colorimetric analytical methods for the quantification of methimazole in its pure form and in its pharmaceutical preparations. Methods: Method A is based on the oxidation of methimazole with potassium permanganate in alkaline medium, the manganate ion produced was measured at λmax= 610 nm. Method B is a kinetic determination of methimazole using fixed-time method based on the oxidation of methimazole using known excess of cerium (IV) nitrate in acidic medium and assessing the unreacted Ce (IV) by adding a fixed amount of methyl orange and measuring the absorbance of the resultant solution at λmax=507 nm which is equivalent to the unreacted methyl orange. The reaction conditions and analytical parameters are investigated and optimized. Method validation was carried out according to ICH guidelines in terms of linearity, LOD, LOQ, precision, and accuracy. Results: Beer’s law is obeyed in the range of 1.50–15.00 μg/ml for method A and 0.25–3.00 μg/ml for method B. The developed methods were subjected to the detailed validation procedure. The proposed spectrophotometric methods were applied for the determination of the methimazole in its pure form and in its pharmaceutical formulation. The percentage recoveries were found to be 100.82 % and 99.85 % in the pharmaceutical formulation for the two proposed methods, respectively. Conclusion: Both developed spectrophotometric methods, considered as green analytical chemistry, were found to be novel, highly selective and can be applied for the quality control of methimazole in its pure form and in its pharmaceutical formulation based on the simplicity, applicability of the parameters, accessibility of the reagents employed and reasonably low time of analysis.

Development And Validation Of Analytical Spectrophotometric And Rp-Hplc Methods For The Simultaneous Estimation Of Hydroquinone, Hydrocortisone And Tretinoin Ternary Mixture In Topical Formulation

Objective: Development and validation of spectrophotometric and RP-HPLC methods for the simultaneous determination of Hydroquinone (HQ), Hydrocortisone (HC) and Tretinoin (TRT) ternary combination in pharmaceutical preparation. Methods: The proposed spectrophotometric method was able to determine TRT directly from its absorption spectrum at 362 nm, however, HQ and HC from their first derivative spectra at 284 nm and 252 nm, respectively, without any separation step. The RP-HPLC method was developed using a C18 Sunfire© waters column with a mobile phase composed of acetonitrile: phosphate buffer (adjusted to pH 6.1 using ortho-phosphoric acid) in the ratio of 30:70 %, v/v, respectively at a flow rate of 0.8 ml/min. Quantification was based on measuring peak areas at 260 nm. Results: The spectrophotometric method was able to selectively quantify each of HQ, HC and TRT in the ranges of 10-50 µg/ml, 2-10 µg/ml and 0.5-5 µg/ml, respectively. The RP-HPLC method was able to produce well-resolved peaks after 3.0, 8.2 and 20.2 min, in the ranges of 2-10 µg/ml, 0.1-1 µg/ml and 0.05-2 µg/ml, for HQ, HC and TRT, respectively. The obtained A, D1 or peak areas values plotted against the concentration of each of the three components showed linear response in the stated ranges. Both methods were validated in terms of linearity, LOD, LOQ, precision, accuracy and selectivity. Conclusion: Both developed proposed methods were applied for the determination of the active ingredients in the pharmaceutical formulation and the common excipients did not interfere in the analysis. The RP-HPLC method proved to be more sensitive when compared to the applied spectrophotometric method. However, the applied spectrophotometric methods, considered as green analytical chemistry, is a simple, time-saving method that requires minimal use of a hazardous solvent.