Evaluation of a TLC Densitometric Method for Analysis of Azole Antifungal Agents

TLC-smartphone in antibiotics determination and low-quality pharmaceuticals detection

Thin layer chromatography (TLC) is a powerful and simple technique for screening and quantifying low quality and counterfeit pharmaceutical products. The detection methods used to detect and quantify separate analytes in TLC ranges from the densitometric method to mass spectrometric or Raman spectroscopic methods. This work describes the development and optimization of a simple and sensitive TLC method utilizing a smartphone CCD camera for verification of both identity and quantity of antibiotics in dosage form, namely ofloxacin and ornidazole. Mixtures of ofloxacin and ornidazole were chromatographed on a silica gel 60 F₂₅₄ plate as a stationary phase. The optimized mobile phase is n-butanol : methanol : ammonia (8 : 1 : 1.5 by volume). Iodine vapor has been used as a "universal stain" to visualize the spots on the TLC plates in order to obtain a visual image using the smartphone camera and a desk lamp as an illumination source, thus eliminating the need for a UV illumination source. The recorded images were processed to calculate the R _f values (R _f values for ofloxacin and ornidazole were 0.12 and 0.76, respectively) which provide identity of the drugs while spot intensity was calculated using a commercially available smartphone app and employed for quantitative analysis of the antibiotics and "acetaminophen" as an example of a counterfeit substance. The smartphone TLC method yielded a linearity of ofloxacin and ornidazole in the range of 12.5-62.5 μg/band and 500-1000 μg/band, respectively. The limit of detection was found to be 1.6 μg/spot for ofloxacin and 97.8 μg/spot for ornidazole. The proposed method was compared with the bench top densitometric method for verification using a Camag TLC Scanner 3, the spot areas were scanned at 320 nm. The R _f value of ofloxacin and ornidazole was calculated to be 0.12 and 0.76, respectively. The densitometric method yielded a linearity of ofloxacin and ornidazole in the range of 5-40 μg/band and 5-50 μg/band, respectively. The limit of detection was found to be 0.8 μg/spot for ofloxacin and 1.1 μg/spot for ornidazole. The proposed method has been successfully applied for the determination of ofloxacin and ornidazole present in more than one pharmaceutical dosage form and was comparable to the densitometric method.

A chiral enantioseparation generic strategy for anti-Alzheimer and antifungal drugs by short end injection capillary electrophoresis using an experimental design approach

The present study describes a generic strategy using capillary electrophoretic (CE) method for chiral enantioseparation of anti-Alzheimer drugs, namely, donepezil (DON), rivastigmine (RIV), and antifungal drugs, namely, ketoconazole (KET), Itraconazole (ITR), fluconazole (FLU), and sertaconazole (SRT) in which these drugs have different basic and acidic properties. Several modified cyclodextrins (CDs) were applied for enantioseparation of racemates such as highly sulfated α, γ CDs, hydroxyl propyl-β-CD, and Sulfobutyl ether-β-CD. The starting screening conditions consist of 50-mM phosphate-triethanolamine buffer at pH 2.5, an applied voltage of 15 kV, and a temperature of 25°C. The CE strategy implemented in the separation starts by screening prior to the optimization stage in which an experimental design is applied. The design of experiment (DOE) was based on a full factorial design of the crucial two factors (pH and %CD) at three levels, to make a total of nine (3² ) experiments with high, intermediate, and low values for both factors. Evaluation of the proposed strategy pointed out that best resolution was obtained at pH 2.5 for five racemates using low percentages of HS-γ-CD, while SBE-β-CD was the most successful chiral selector offering acceptable resolution for all the six racemates, with the best separation at low pH values and at higher %CD within 10-min runtime. Regression study showed that the linear model shows a significant lack of fit for all chiral selectors, anticipating that higher orders of the factors are most likely to be present in the equation with possible interactions.

Photostability of triazole antifungal drugs in the solid state

The publication is devoted to photostability assessment of four triazole antifungal drugs: fluconazole, itraconazole, posaconazole and voriconazole. The compounds were exposed in the solid state using the whole spectrum of UV-Vis radiation. The analyses were performed using high performance thin layer chromatography (HPTLC) technique with densitometric detection. The results indicates considerable degradation of structurally similar itraconazole and posaconazole which could be clinically significant. After 72 hours of itraconazole irradiation there remain less than 25%, and 60% in case of posaconazole. To a lesser extent photodegradation concern two other compounds with a separate chemical structure: fluconazole and voriconazole. After 72 hours of irradiation there left 75% and 82% of these substances, respectively. The strict dependence between compound photostability and its chemical structure was observed.

HPTLC methods to assay active ingredients in pharmaceutical formulations: a review of the method development and validation steps

High-performance thin-layer chromatography (HPTLC) is still increasingly finding its way in pharmaceutical analysis in some parts of the world. With the advancements in the stationary phases and the introduction of densitometers as detection equipment, the technique achieves for given applications a precision and trueness comparable to high-performance liquid chromatography (HPLC). In this review, the literature is surveyed for developed and validated HPTLC methods to assay active ingredients in pharmaceutical formulations published in the period 2005-2011. Procedures and approaches for method development, validation and quantitative assays are compared with the standard ways of conducting them. Applications of HPTLC in some other areas are also briefly highlighted.