Bioavailability study of triamterene and xipamide using urinary pharmacokinetic data following single oral dose of each drug or their combination

Ultra-Performance Liquid Chromatographic and Densitometric Methods for Sensitive Determination of Xipamide and Triamterene in Pure and Pharmaceutical Dosage Forms

BACKGROUND

Validated UPLC method and TLC densitometric method were prescribed for determination of antihypertensive components. Objectives: To establish and validate rapid and accurate Ultra performance liquid chromatographic (UPLC) and TLC densitometric methods for determination of Xipamide and Triamterene in pure and dosage forms.

METHODS

The first method; UPLC method, depended on using Agilent Zorbax Eclipse Plus C8 (50 mm × 2.1 mm, 1.8 μm), as the column, mobile phase composed of (acetonitrile-water) (70 + 30, v/v) adjusted by acetic acid to obtain (pH 3), 0.2 mL/min flow rate and UV detection at 231.4 nm. The second method was a thin layer chromatography (TLC) densitometric method, separation was achieved by using toluene-methanol-ethyl chloride-acetic acid (7 + 2 + 1 + 0.2, v/v/v) as the mobile phase, pre coated silica gel plates as the stationary phase and UV detection at 300.0 nm.

RESULTS

The obtained results were validated and statistically compared with official and reported methods. The obtained results showed high accuracy and reproducible results with excellent mean recoveries for both drugs.

CONCLUSIONS

The UPLC method showed shorter retention time for both Xipamide (0.88 min) and Triamterene (0.63 min), lower detection limit less than 0.055 µg/mL for both drugs with high selectivity, decreased injection volume (1 µL) and lower flow rate other than any HPLC method. Both proposed methods were sensitive, selective, and effectively applied to pure and dosage forms (Epitens®).

HIGHLIGHTS

Unprecedented sensitive, rapid, and reproducible UPLC and TLC methods were developed for selective determination of mixture of Xipamide and Triamterene with LOD less than 0.076 µg/mL for both drugs.

Sensitive Inexpensive HPLC Determination of Novel Anticancer Combination in Nanoparticles and Rat Plasma: Pharmacokinetic Application

Two high-performance liquid chromatography-diode array detection methods have been developed and validated for the simultaneous quantification of genistein (GNS) and all trans retinoic acid (ATRA) as a novel anticancer combination therapy in their co-formulated nanoparticles and in rat plasma. Separation was performed on C18 column (250 × 4.6 mm, 5 μm) using celecoxib as internal standard. A mobile phase containing acetonitrile and water adjusted to pH 3 using 1% trifluoroacetic acid was delivered in gradient elution modes with time programmed UV detection. For extraction of the drugs and the internal standard from rat plasma, liquid- liquid extraction was applied. The proposed methods were validated as per International Conference on Harmonisation (ICH) guidelines (in the range 0.1-10 μg/mL for analysis of GNS and ATRA in nanoparticles) or according to Food and Drug Administration (FDA) guidance on bioanalytical method validation (in the range 0.025-20 μg/mL for analysis of GNS and ATRA in rat plasma). Pharmacokinetic study in six rats was performed following intravenous (IV) administration of a single dose of 0.5 mg/Kg of GNS and ATRA. The drugs' concentrations were measured up to 24 hours, and different pharmacokinetic parameters were calculated. The obtained parameters were comparable with the reported values for IV administration of each drug alone in rats. This confirms the applicability of the proposed method in monitoring the levels of the two drugs in vivo following their coadministration and indicating that the two drugs could be coadministered as a promising novel combination therapy for the treatment of lung cancer without great alteration in their pharmacokinetic parameters compared with their individual IV administration.

Preparation and characterization of triamterene complex with ascorbic acid derivatives

The purpose of this study was to prepare solid dispersions of triamterene (TRT) with ascorbic acid (AA) or ascorbic acid 2 glucoside (AA2G) and to evaluate their physical properties. Solid dispersions were prepared by dissolving each sample in an organic solvent and evaporation (EVP). Powder X-ray diffraction (PXRD) revealed a halo pattern for EVP1 (AA/TRT = 1/1) and EVP2 (AA2G/TRT = 1/1). In differential scanning calorimetry (DSC), endothermic peaks due to the melting of TRT and AA disappeared for EVP1 (AA/TRT = 1/1), and the melting peaks of TRT and AA2G disappeared for EVP2 (AA2G/TRT = 1/1). Fourier transform infrared (FT-IR) spectroscopy revealed broadened peaks for EVP1 (AA/TRT = 1/1) and EVP2 (AA2G/TRT = 1/1) due to the hydroxyl groups (-OH) of AA and the amino groups (-NH2) of TRT and also revealed a peak shift due to the pteridine skeleton (C = N) of TRT. In near-infrared absorption (NIR) spectroscopy, peaks due to the hydroxyl groups (-OH) of AA and AA2G were found for EVP1 (AA/TRT = 1/1) and EVP2 (AA2G/TRT = 1/1), respectively. A peak due to the amino groups (-NH2) was evident. This suggested the formation of an evaporation, in which TRT interacted with AA or AA2G. In the dissolution test, the dissolved fraction of TRT alone after 3 min was 30%, whereas the fractions were enhanced to approximately 90% for EVP1 (AA/TRT = 1/1) and EVP2 (AA2G/TRT= 1/1). Results confirmed that dissolution properties were improved as a result of complex formation. The above findings indicated improvement the dissolution properties of TRT.

Robust Chromatographic Methods for the Analysis of Two Quaternary Mixtures Containing Paracetamol, Codeine, Guaifenesin and Pseudoephedrine or Phenylephrine in their Dosage Forms

Two simple validated and highly selective methods for analysis of paracetamol, codeine, guaifenesin and pseudoephedrine or phenylephrine quaternary mixtures were developed. The first method is a high performance liquid chromatography with diode array detection method where separation was successful using Agilent C18 (150 × 4.6 mm) column, gradient elution of phosphate buffer pH 3, methanol and acetonitrile and diode-array detection at 210 nm. The second method is a HPTLC method followed by densitometric measurement of the spots at 257 nm. Separation was carried out on Merck HPTLC aluminum sheets of silica gel using methylene chloride: methanol: glacial acetic acid: ammonia (17.8: 1.68: 0.4: 0.12, v/v) mobile phase. The methods were applied successfully for analysis of both quaternary mixtures in laboratory-prepared tablets and also validated in regards to linearity, precision, accuracy, sensitivity and stability.

A novel HPLC-DAD method for simultaneous determination of febuxostat and diclofenac in biological samples: pharmacokinetic outcomes

Aim: To develop a simple HPLC-DAD method for simultaneous determination of febuxostat (FEB) and diclofenac (DIC) in biological samples to assess pharmacokinetic outcomes of their coadministration. Methodology & results: Sample preparation was performed by liquid–liquid extraction. Drugs analysis was done on C18 column using methanol-formic acid pH 2.1 (76:24, v/v) as mobile phase and time-programmed UV detection. Lower limits of quantitation for FEB and DIC were 10 and 20 ng/ml, respectively. Baseline pharmacokinetics were similar to published data on either drug alone. Coadministration led to more than twofold increase in FEB Cmax and AUC together with a reduced hepatic uptake in rats. Conclusion: DIC interfered with initial distribution and terminal clearance of FEB potentially due to reduced FEB hepatic uptake.

Validated spectroscopic methods for the estimation of triamterene in bulk powder and capsule form via derivatization reactions

Sensitive, simple and specific spectrophotometric and spectrofluorimetric methods were developed for the determination of triamterene in bulk powder and pharmaceutical dosage form. The spectrophotometric method (Method A) is based on the formation of an ion-pair complex with eosin Y in acetate buffered solution of pH 3.7 followed by measuring the absorbance at 545 nm. The absorbance-concentration plot is rectilinear over the range 3.0-15.0 μg/mL with a limit of detection (LOD) of 0.429 μg/mL and a limit of quantitation (LOQ) of 1.031 μg/mL. The spectrofluorimetric method (Method B) is based on the reaction of triamterene with 7- chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in basic solution (pH 10) to form a product with high fluorescence measured at 546 nm after being excited at 438 nm. The plot of fluorescence versus concentration is linear within the range 2.0-10.0 μg/mL. The suggested methods were applied for the analysis of commercial capsules containing the studied drug with successful results. The results obtained from the proposed method were statistically compared with those of a reported one and revealed good agreement. The presented methods are useful in routine analysis of triamterene in laboratories of quality control.

Simultaneous determination of methocarbamol and aspirin in presence of their pharmacopeial-related substances in combined tablets using novel HPLC-DAD method

Objective and Significance: Methocarbamol (MET) and aspirin (ASP) are widely used as a muscle relaxant combination. The USP reports guaifenesin (GUA) and salicylic acid (SAL) as related substances and hydrolytic products of MET and ASP, respectively. This work aimed at developing and validating a simple and sensitive RP-HPLC method for the determination of both drugs as well as their related substances (at their pharmacopeial limits) in their bulk powders, laboratory prepared mixtures, and MET-ASP combined tablets. Methods and Results: Chromatographic separation was achieved in less than 9 min with the required resolution, peak symmetry, and accuracy on C₁₈ column using isocratic elution system of diluted acetic acid (pH 3.2): acetonitrile at the ratio of 79: 21, v/v, at a flow rate of 1 mL/min. Detection was achieved with photodiode array at 233 nm for MET, GUA, and SAL and at 273 nm for ASP. The developed method has been validated as per ICH guidelines and the calibration plots were linear over the concentration ranges of 2-150, 0.4-30, 25-450, and 0.2-27 μg/mL for MET, GUA, ASP, and SAL, respectively. Conclusion: The optimized method proved to be specific, robust and precise for the quality control of the studied drugs in pharmaceutical preparations to ascertain that their related substances are not exceeding the permitted pharmacopeial limits.

Two liquid chromatographic approaches for the simultaneous determination of xipamide and its degradation product (2,6-xylidine) using time-programmed fluorescence detection

A study of the performance of reversed-phase chromatography with a programmable multiwavelength fluorimetric technique using either conventional hydro-organic or micellar eluent is established for the determination of xipamide (XIP) in the presence of its degradation product, 2,6-xylidine (XY). In conventional liquid chromatography (CLC), the analyses were carried out on a Promosil ODS 100 Å column (250 mm × 4.6 mm i.d., 5 μm) using a mobile phase consisting of methanol/0.1 M phosphate buffer (65: 35, v/v) at pH 4.0. For micellar liquid chromatography (MLC), a short Spherisorb column (150 mm × 4.6 mm i.d., 5 μm) was employed in conjunction with a greener mobile phase (pH 5.0) containing 0.1 M sodium dodecyl sulfate and 15% n-propanol. CLC proved to be superior to MLC in terms of sensitivity for the determination of the degradation product because it could detect trace amounts down to 10.0 ng/ml of XY as a degradation product in XIP. However, MLC represents an eco-friendly approach for the simultaneous determination of XIP and XY. In addition, the opportunity for the direct introduction of biological matrices into the chromatographic system is one of the distinctive benefits of MLC. The proposed methods were applied for the determination of XIP in its tablets, human urine and content uniformity testing. The results of the proposed methods were statistically compared with those obtained using the comparison fluorimetric method, revealing no significant differences in the performance of the methods regarding accuracy and precision.