Abstract
Simple, rapid and sensitive spectrophotometric methods were developed and validated for the microdetermination of terazosin HCl, doxazosin mesylate and pioglitazone HCl drugs in pure and pharmaceutical dosage forms. These methods are based on ion-pair formation reaction between these drugs and a chromogenic reagent Rose Bengal (RBeng). These reactions were studied under various conditions and the optimum parameters were selected. The spectrophotometric microdeterminations have been done at λmax=570 nm for terazosin HCl and pioglitazone HCl and at λmax=575 nm for doxazosin mesylate. Under proper conditions the suggested procedures were successfully applied for microdetermination of these drugs in pure and in pharmaceutical dosage forms. The values of SD, RSD, recovery %, LOD, LOQ and Sandell sensitivity refer to the high accuracy and precession of the applied procedures. The results obtained were compared with the data obtained by the official methods, referring to confidence and agreement with rose bengal procedure results. The solid drugs-reagent ion-pairs were prepared, separated and their structures were investigated using elemental analysis, FT-IR, 1H-NMR and thermal analyses and the results confirm the structures proposed by the stoichoimetric ratio in the solution work. The biological activities of the drugs and their solid ion-pairs against some types of (G-) and (G+) bacteria and fungai were studied and compared with each other. It is found that terazosin-RBeng and pioglitazone-RBeng reaction products have antibacterial effect higher than the parent drugs, but doxazosin-RBeng reaction product has almost the same antibacterial effect of the parent drug.
Highlights
Terazosin (TRZ) HCl dihydrate has an IUPAC name (1-(4-amino-6, dimethoxyquinazoline-2-yl)-4-[[(2RS)-tetrahydrofuran-2-yl]carbonyl] piperazine hydrochloride dihydrate [1]) and structure given in Figure 1. mass=459.9It has a general g.mol-1. formulaC19H25N5O4.HCl.2H2O, and moleDoxazosin (DOX) mesylate has an IUPAC name (1-(4-amino-6, 7-dimethoxy-2- quinazolinyl)-4-[(2, 3-dihydro-1, 4-dioxin-2-yl) carbonyl] piperazine methanesulphonate) [2] and structure given byC23H25N5O5.CH3SO3H, and mol TRZ HCl dihydrate and DOX mesylate both are highly selective potent alpha-1 adrenoreceptor antagonists used in the treatment of hypertension [3] and benign prostatic hyperplasia [4,5]
Studying the effect of time (0-60 min.) on the formation of the three products at the selected conditions shows that the three reaction products are stable over one hour and the time has no significant effect on their stabilities
For DOX-Rose Bengal (RBeng) reaction product an extra ethanol had to be added to prevent any formation of precipitates, but this addition affects the absorbance, so ethanol volume effect was studied and the results show that the absorbance remains constant at 1.5 and 2 mL of ethanol, so ethanol volume of 2 mL is chosen as the optimum volume for the microdetermination
Summary
Carbonyl] piperazine hydrochloride dihydrate [1]) and structure given in Figure 1. mass=459.9. A number of studies were described for the determination of DOX in pure, pharmaceutical and biological samples These methods include reversed phase (RP)-HPLC [9], liquid chromatography (LC)-mass spectrometry (MS) [10], spectrophotometric methods [11] and voltammetry [12]. All chemicals used were of analytical reagent grade (AR), and of highest purity available They included PIOG HCl, an authentic sample was kindly supplied by Elrazy Pharmaceutical Co, Ismailia (Egypt), TRZ HCl dihydrate and DOX mesylate, and authentic samples were. Solution of 1×10-3 M RBeng disodium salt was prepared by dissolving the accurately weighed amount in the appropriate volume of distilled water and the volume completed to 250 mL volumetric flask.
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