Current Pharmaceutical Analysis - Volume 5, Issue 4, 2009

The majority of enantiomeric separations for purity analysis and quality control continue to be performed by normal phase liquid chromatography (LC) and supercritical fluid chromatography (SFC). Yet, analysts perform over ninety percent of their routine work using reversed phase systems. When given the opportunity, reversed phase chiral methods are preferred by analysts for they do not require the complex system rinses needed when changing a reversed phase system to a normal phase setup. Because the pharmaceutical industry relies heavily on column screening for chiral method development, the viability of these screens has been studied. Using polysaccharide, macrolide and Pirkle based stationary phases in the reversed phase mode has been evaluated and compared to traditional normal phase screening capabilities. Depending on the screen and compounds applied, a reversed phase screen achieves chiral recognition 60-95% of the time making them a viable alternative to traditional normal phase chiral screens. The results of these investigations are reported.

Nano-Drug Delivery Systems have emerged as an effective means of targeting therapeutic agents such as drugs, peptides and proteins to various target sites. The unique advantages and potential targeting capability of this approach have claimed it as the drug delivery system of the future. Various analytical methodologies have been used for the evaluation of this delivery system both in vitro and in vivo. This review will attempt to describe the various in vitro methods used for this purpose, their importance and limitations. The in vitro methods include particle sizing, zeta potential, microscopy, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, X-ray diffraction, in vitro release characteristics, determination of drug loading, encapsulation efficiency and loading efficiency. In vitro cell culture has also been utilized in cellular uptake, transmission electron microscopy, MTT assays, flow cytometry, and cellular transport studies. In summary, this in-depth review will provide the basic understanding, as well as the pros and cons of commonly used analytical methods currently utilized to evaluate this emerging drug delivery system.

Generally, some drugs are present in our body for quite long time at nano or femto gram level and accumulate in body tissues, causing many side effects. Therefore, in the absence of the techniques capable to detect at nano or low level the absence of these drug residues is assumed. Besides, small biological samples such as blood of infants, some hormones and enzymes in our body need detection techniques of nano levels. Pharmaceutical analysis is an integral part in pharmacokinetics and pharmacodynamics studies, which needs accurate analyses of drugs. The analytical techniques should be capable to detect drugs and pharmaceutical at nano or low detection limits. The detection at nanogram level is becoming more important and scientists and other regulatory authorities are searching for data on the detection at nanogram level. Therefore, the present article describes state-of-art of nano analysis by using Nano Liquid Chromatography (NLC). Besides, attempts have been made to discuss applications, optimization and comparison of analyses.

In the past decade, monolithic columns consisting of one piece of an organic polymer or silica with flowthrough pores have been reported in the literature. These materials provide better stability and more important, higher performance than conventional columns packed with particles. This paper summarizes recent applications of monolithic stationary phase in the liquid phase separation, including the separation of enantiomers, bioparticles, herbal extracts, biological specimen.

The combination of flexible and robust immunoassay technology with the sensitivity of DNA as a signal amplification template is realized in Immuno-PCR (“IPCR”). Classical ELISA is converted to IPCR by exchange of antibodyenzyme detection conjugates with antibody-DNA conjugates. The value of ultra-sensitive analytics deriving from this for pharmaceutical R&D is threefold: (I) Deeper understanding of biomolecular interactions for the development of new compounds. (II) Monitoring of compounds at very low concentrations in toxicokinetic and pharmacokinetic clinical studies. (III.) Control of compound functionality and therapeutic effects by surveillance of characteristic biomarkers and/or immunogenicity reactions. This review summarizes background information about general selection of IPCR targets, actual standard assay procedures and work with biological matrices. Quantitative real-time detection as well as optimized reagents and protocols revealed a typically 100-10,000-fold increase in sensitivity and a broad dynamic range compared to ELISA. Case studies are discussed for (I) the analysis of biomolecular interaction with proximity ligation technologies and IPCR, (II) pharmacokinetic studies of novel drugs with validation data for assay precision and recovery and (III) biomarker profiling, including cytokine multiplex assays and polyplex trace analysis in extremely small sample volumes. In a survey of results from recent innovations, the potential of this emerging field of applications is evaluated for novel pathways in study design and analytics.

New chromatographic-densitometric method for determination of clopamide and impurities (4-chlorobenzoic and 4-chloro-3-sulfamoylbenzoic acids) in tablets was developed. Silica gel TLC plates as a stationary phase and nbutanol- 2-propanol -water- methylene chloride (10:7:2:5:3 v/v/v/v/v) as a mobile phase were used for separation. Densitometric measurements were done at λ = 235 nm. Favourable retention parameters (Rf, Rs, k, α) were obtained under developed conditions, which guarantee good separation of studied components. Whereas, results that were obtained from validation method confirm specificity, high sensitivity, linearity in a range of studied concentrations, repeatability and good accuracy of this method.

The elecrochemical behavior of ornidazole was investigated using various voltammetric methods. The number of electrons transferred and diffusion coefficient were calculated by using cyclic voltammetry and bulk electrolysis techniques. It is determined that ornidazole is adsorbed on the hanging mercury drop electrode (HMDE) by using cyclic voltammetric data. Therefore, sensitive adsorptive stripping voltammetric methods for the determination of ornidazole at HMDE were developed. A systematic study of various experimental conditions was examined by using differential pulse adsorpive stripping voltammetry (DPAdsSV) and square wave adsorptive stripping voltammetry (SWAdsSV). This electroanalytical procedure enabled to determine ornidazole in the concentration range 8.0x10-7-1.0x10-5 molL-1 for both DPAdsSV and SWAdsSV. The detection and quantification limits were found to be 7.6x10-8 and 2.6x10-7 for DPAdsSV and 3.4x10-8 and 1.3x10-7 mol L-1 for SWAdsSV, respectively. The methods were applied to three different commercial pharmaceutical capsule preparations.The data obtained from commercial preparations were compared with those from a published spectrophotometric method. No difference was found statistically.

Clopidogrel, being a potent platelet aggregation inhibitor, is used widely around the world to reduce cardiovascular risks in patients with stroke, myocardial infarction, and atherosclerosis. The aim of this review firstly focuses on a comprehensive update of chromatography determination of clopidogrel and its metabolites as well as in human plasma, Wistar rat plasma, and in pharmaceutical preparations. It has been described using TLC, HPLC/MS, RP-HPLC, and GC/MS methods. Secondly to localize the chromatography conditions for separation and quantification, this review provides detailed information on separation conditions for clopidogrel and its metabolites. A new HPLC method adjusted to our laboratory conditions was developed for the evaluation of assay and purity of clopidogrel in film-coated tablets.

In this work, a simple spectrophotometric methodology based on the competitive aggregation in a dyesurfactant- drug system is described for the determination of pharmaceutical compounds. This is a modification of recently established surfactant to dye binding degree method. Eriochrome Blue Black R (EBBR) and Didodecyldimethylammonium bromide (DDABr) were the dye and surfactant used, respectively. In the proposed method, the anions of EBBR bind to the cationic DDABr molecules to form dye-surfactant aggregates. Upon adding an amphiphilic drug to the mixture, the drug competes with the dye to interact with the surfactant, which results in a decrease in dye-surfactant aggregates formation. This causes a change in UV-Vis absorption properties of the dye. The measurement parameter is the difference between the absorption of the dye in the presence and absence of the drug. In the appropriate experimental conditions the absorbance differences are directly proportional to the drug concentration. Piroxicam and folic acid are used as two model drugs to develop the methodology. The influence of variables such as pH, concentrations of buffer, EBBR and DDABr on the measurement parameter was studied. Under the optimum conditions, the calibration graphs were linear up to 1.6 and 2.7 ig ml-1 for piroxicam and folic acid, respectively, with the corresponding detection limits of 0.05 and 0.09 ig ml-1. The method was applied to the determination of the drugs in pharmaceutical formulations.

Resistance is also an increasing problem for antibiotic based therapy of Helicobacter Pylori infection. A paradigm shift in the treatment of infectious disease may be useful to prevent the further emergence of antibiotic resistance. Some daily-consumed food and beverages, including tea, lactobacillus, alcohol and garlic, have anti-helicobacter activities in-vitro. In epidemiological studies consumption of tea was associated with decreased risk of Helicobacter Pylori infection. Supplementation of Lactobacillus improved the tolerance of antibiotic based Helicobacter eradication therapy. However, few controlled clinical trials have been published and most are methodologically weak. Controlled trial had shown that lactobacillus alone was not effective in eradicating Helicobacter Pylori infection. Otherwise, controlled trial of plant extracts or non-antibiotic based therapy for Helicobacter Pylori infection has not been available yet. Overall, currently available evidences concerning these alternative strategies are still scanty, but promising. Further investigations, especially randomised controlled trials, are needed to investigate the role of these alternative strategies in preventing Helicobacter Pylori infection, and find out how these food or beverages should be used to augment the efficacy of antibiotic based therapies.