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Determination of sapropterin dihydrochloride in solid dosage forms by visible spectroscopy

Arabacı, Burak
TSapropterin Dihydrochloride is the synthetic form of tetrahydrobiopterin (BH4) which is cofactor of phenylalanine hydroxylase (PAH) enzyme. For people with phenylketonuria (PKU), oral administration of sapropterin dihydrochloride decrease phenylalanine level in blood by converting it to tyrosine. The purpose of this study is to develop an analytical method for the determination of this active ingredient in order to follow the production of the generic drug development of Kuvan®. Fourier-Transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), inductively coupled plasma/mass spectrometry (ICP-MS), chloride content and high-performance liquid chromatography with UV detector HPLC/UV analysis were used in order to investigate purity and to ensure specifications of Sapropterin Dihydrochloride (SAP). Because of high selectivity and sensitivity of HPLC/UV analysis were used as a reference method for the quantitative analysis of SAP. The study continued with UV/Visible Spectroscopy (UV/VIS) analysis. A method from the literature with Folin-Coicalteu (FC) reagent was studied and compatible results were obtained with respect to HPLC/UV method. By using cyclic voltammetry, oxidation and reduction potentials of SAP was calculated and with this oxidation potential CuSO4 was selected as coloring agent for UV/CuSO4 method of quantitative analysis. This method worked very well for the determination of sapropterin concentration for 5 to 65 ppm. without having any interference from the other ingredients present in the drug. Square wave voltammetry also used as an assay method at the potential value of 0.27 V. In this thesis, reliable, precise and easy-to-use methods were successfully developed and validated for the assay investigation of Sapropterin dihydrochloride. An analysis method with paper sensor was developed and linearity of method was studied but further investigation was needed to use this method for pharmaceutical dosage forms.