Highly sensitive UHPLC-MS/MS method for the simultaneous estimation of propafenone and its metabolites 5-hydroxypropafenone and N-depropylpropafenone on human dried blood spots technique and application to a pharmacokinetic study.

A highly sensitive, rapid and selective UHPLC-MS/MS method has been developed and validated for quantification of the propafenone (PF), 5-hydroxypropafenone (5-OHPF) and N-depropylpropafenone (N-DPF) on human dried blood spot (DBS). The assay procedure involves a solid-liquid extraction of PF, 5-OHPF and N-DPF and amlodipine (internal standard, I.S.) from dried human DBS cards using water and acetonitrile. The chromatographic resolution was achieved on a BEH C18 column using a gradient mobile phase consisting of 0.1% formic acid in water and acetonitrile with 0.1% formic acid at flow rate of 0.6mL/min. The UHPLC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Total run time of analysis was 1.1min and elution of PF, 5-OHPF, N-DPF and I.S. occurred at 0.69, 0.6, 0.68 and 0.73min, respectively. A detailed method validation was performed as per the regulatory guidelines and the standard curves found to be linear in the range of 5.11-1000ng/mL for PF and 5-OHPF and 0.51-100ng/mL for N-DPF with a correlation coefficient of ≥0.99 for all the drugs. The intra- and inter-day accuracies were in the range of 95.6-107 and 93.5-103; 93.4-106 and 96.3-107 and 87.9-103 and 96.5-102%, for PF, 5-OHPF and N-DPF, respectively. The intra- and inter-day precisions were in the range of 2.50-5.52 and 3.38-5.18; 2.16-6.34 and 3.23-4.94 and 2.63-7.55 and 1.56-10.2%, for PF, 5-OHPF and N-DPF, respectively. The validated assay method was successfully applied to a pharmacokinetic study in humans. The key pharmacokinetic parameters AUC0-∞ and Cmax were 6057±1526, 2002±515 and 525±202 ng*h/mL and 653±183, 295±37.5 and 68.4±13.6ng/mL for PF, 5-OHPF and N-DPF, respectively.

Elucidating pharmacodynamic interaction of silver nanoparticle - topical deliverable antibiotics.

In order to exploit the potential benefits of antimicrobial combination therapy, we need a better understanding of the circumstances under which pharmacodynamic interactions expected. In this study, Pharmacodynamic interactions between silver nanoparticle (SNP) and topical antibiotics such as Cefazolin (CEF), Mupirocin (MUP), Gentamycin (GEN), Neomycin (NEO), Tetracycline (TET), Vancomycin (VAN) were investigated using the MIC test, Combination assay followed by Fractional Inhibitory concentration Index and Agar well diffusion method. SNP + MUP, SNP + NEO, SNP + VAN combinations showed Synergism (SN) and SNP + CEF, SNP + GEN, SNP + TET showed Partial synergism (PS) against Staphylococcus aureus. Four combinations (SNP + CEF, SNP + MUP, SNP + GEN, SNP + VAN) showed SN, SNP + TET showed PS and Indifferent effect (ID) were observed for SNP + NEO against Pseudomonas aeruginosa. SN was observed for SNP + CEF, SNP + GEN, SNP + NEO, SNP + TET and SNP + MUP showed ID, SNP + VAN showed PS against Escherichia coli. In addition, we elucidated the possible mechanism involved in the pharmacodynamic interaction between SNP-topical antibiotics by increased ROS level, membrane damage following protein release, K(+) leakage and biofilm inhibition. Thus, our findings support that conjugation of the SNP with topical antibiotics have great potential in the topical formulation when treating complex resistant bacterial infections and where there is a need of more concentration to kill pathogenic bacteria.

New Validated RP-HPLC Analytical Method for Simultaneous Estimation of Atorvastatin and Ezetimibe in Bulk Samples as Well in Tablet Dosage Forms by Using PDA Detector.

This paper describes a new RP-HPLC method for simultaneous quantification of these compounds in the bulk sample drug as well as in tablet dosage forms. The chromatographic separation was performed on an XTerra C8 (4.6 x 250 mm; 5 µm), with phosphate buffer [pH 3.5] and acetonitrile in the ratio of 40:60 (v/v) as mobile phase. The detection was carried out at 240 nm. The accuracy was found to be 99.59% and 98.98% for atorvastatin and ezetimibe respectively. The linearity was 5-25 µg/ml for both the drugs. The intra-day RSD was 0.57% and inter-day RSD was 0.13% for atorvastatin calcium and intra-day RSD was 0.56% and inter-day RSD was 0.09% for ezetimibe. The validation of method was carried out utilizing ICH-guidelines.

A rapid and sensitive liquid chromatography-tandem mass spectrometric assay for moexipril, an angiotensin-converting enzyme inhibitor in human plasma.

A simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of angiotensin-converting enzyme inhibitor, moexipril, in human plasma. Benazepril was used as an internal standard (IS). Analyte and IS were extracted from the human plasma by liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on a C18 column by using a mixture of methanol and 0.1% formic acid buffer (85:15, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.2-204 ng/mL. The multiple reaction-monitoring mode was used for quantification of ion transitions at m/z 499.4/234.2 and 425.2/351.1 for moexipril and IS, respectively. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.0 min for each sample made it possible to analyze more than 400 plasma samples per day. The proposed method was found to be applicable to clinical studies.

Liquid chromatography-tandem mass spectrometric assay for the light sensitive calcium channel antagonist lacidipine in human plasma.

A novel, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of calcium channel antagonist lacidipine in human plasma. Carbamazepine was used as an internal standard. Analyte and the internal standard were extracted from human plasma by solid-phase extraction technique. The reconstituted samples were chromatographed on a C(18) column by using a mixture of acetonitrile-ammonium acetate buffer (5 mM) (80:20, v/v) as the mobile phase at a flow rate of 1.0 mL/min. The calibration curve obtained was linear (r(2)≥0.9990) over the concentration range of 0.05-12.5 ng/mL. The multiple reaction-monitoring mode was used for quantification of ion transitions at m/z 456.2/354.2 and 237.1/194.1 for the drug and the internal standard, respectively. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.2 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

Simultaneous determination of pioglitazone and candesartan in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

A simple and rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for simultaneous quantification of pioglitazone and candesartan in human plasma. Irbesartan was used as an internal standard. The analytes were extracted from human plasma samples by solid-phase extraction technique using a Strata-X 33 µm polymeric sorbent. The reconstituted samples were chromatographed on a C18 column by using a 80:20 (v/v) mixture of acetonitrile and 0.1% formic acid as the mobile phase at a flow rate of 0.8 mL/min. The calibration curves obtained were linear (r≥0.99) over the concentration range of 15-3000 ng/mL for pioglitazone and 5-608 ng/mL for candesartan. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.7 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.