A sensitive HPLC-UV method for quantifying vancomycin in biological matrices: Application to pharmacokinetic and biodistribution studies in rat plasma, skin and lymph nodes

Preparation, in vitro and in vivo evaluation of a novel mitiglinide microemulsions

This study aimed to prepare an o/w mitiglinide microemulsion (MTGME) to improve the drug solubility and bioavailability. The formulation of o/w MTGME was optimized by the solubility study of drug, pseudo-ternary phase diagram and Box-Behnken design successively. MTGME was characterized by dynamic laser light scattering (DLS), zeta potential and transmission electron microscopy (TEM), moreover, the storage stability, pharmacodynamics and pharmacokinetics were investigated. The optimal prescription for MTGME consisted of Maisine 35-1 (oil), Cremophor EL (surfactant) and propylene glycol (PG, cosurfactant). MTGME with a spherical dimension of 58.1 ± 5.86 nm was stable when stored at 4 °C for 3 months. The blood glucose levers (BGL) of diabetic mice were uniformly and significantly decreased by intragastric (i.g.) administration of 1-4 mg/kg MTGME, in which BGL (i.g. 4 mg/kg MTGME) was reduced by 69% during 24 h. The pharmacokinetics study of MTGME (i.g., 20 mg/kg) in Wistar rats showed higher plasma drug concentration (Cmax, 2.9 folds), larger area under curve (AUC, 4.6 folds) and oral bioavailability than those of MTG suspensions. Generally, the MTGME (o/w) showed good effect on controlling hyperglycemia. Therefore, microemulsion can be used as an effective oral drug delivery system to improve the bioavailability of MTG.

Fluorimetric monitoring of vancomycin using an allosteric probe-initiated sensing platform

Vancomycin is the first-line drug for infections of methicillin-resistant Staphylococcus aureus (MRSA) and multi-drug-resistant bacteria. The effective therapeutic concentration range of vancomycin is narrow, so it's essential to implement vancomycin therapeutic drug monitoring. However, conventional detection methods have disadvantages of expensive equipment, complicated operation, or poor reproducibility. Herein, a fluorescent sensing platform initiated by an allosteric probe was constructed for simple and sensitive monitoring of vancomycin at a low cost. The key point of this platform is the well-designed allosteric probe, which comprises an aptamer and a trigger sequence. When vancomycin exists, the combination of vancomycin and the aptamer will lead to a conformational change of the allosteric probe, thus exposing the trigger sequence. The trigger can react with the molecular beacon (MB) to generate fluorescent signals. In addition, the allosteric probe combined with hybridization chain reaction (HCR) was applied to develop an amplified platform, the linear range is from 0.5 μg mL^-1 to 50 μg mL^-1 with the limit of detection (LOD) of 0.26 μg mL^-1. Most importantly, this allosteric probe-initiated sensing platform shows good detection ability in human serum samples, and it also indicates great correlation and accuracy compared with HPLC. The present simple and sensitive allosteric probe-initiated platform has the potential to support the therapeutic drug monitoring of vancomycin, which is of great significance to promote the rational use of antibiotics in clinics.

Validation of spectrophotometric method to quantify chloramphenicol in fluid and rat skin tissue mimicking infection environment: Application to in vitro release and ex vivo dermatokinetic studies from dissolving microneedle loaded microparticle sensitive bacteria

Cellulitis is a common dermis/subcutaneous tissue skin infection and shared global disease burden, with a higher incidence for males and people aged 45-64 years. Application therapy of chloramphenicol (CHL) has been hindered because of its toxicity and limited penetration into the skin. In this research, CHL was developed into a bacterially sensitive microparticles which were further incorporated into a microneedle system to increase penetration. To support this formulation, in this study, UV-vis spectrophotometry method was validated in methanol, polyvinyl alcohol (PVA) 1%, phosphate buffered saline (PBS), tryptic soy broth (TSB) (fluid-mimicking infection), and skin tissue to quantify amount of CHL. The developed analytical method was subsequently validated according to ICH guidelines. The results obtained showed that the correlation coefficients were linear ≥0.9934. The values of LLOQ inside the methanol, PVA 1%, PBS, TSB, and skin tissue were 7.20 µg/mL, 4.40 µg/mL, 8.18 µg/mL, 387.48 µg/mL, and 7.27 µg/mL, respectively. The accuracy and precision of the developed method were prominent. These methods were successfully applied to quantify the amount of CHL in microparticle and microneedle system in fluid and tissue skin infection. The result showed the high drug release microparticle sensitive bacteria, and high drug retention in ex vivo dermatokinetic evaluation in rat skin tissue containing bacterial infection. This was due to the presence of Staphylococcus aureus bacteria culture that produced lipase enzymes, playing a role in lysing microparticle matrix to develop selectively delivery antimicrobials. A further analytical method needs to be matured to quantify CHL inside the in vivo studies.

A combined qualitative and quantitative method development and validation of vancomycin hydrochloride injection formulation by HPLC and UV involving quality by design

A selective, specific, precise, linear, accurate and robust analytical method was developed and validated for the assay of vancomycin HCl in vancomycin hydrochloride injection. Comparative UV spectrophotometric and reverse-phase HPLC were used to develop the quantitative determination. Acetonitrile and pH 2.2 phosphate buffer in the ratio 20:80 v/v were used as the mobile phase, and a flow rate of 1.0 ml/min with a 20 min run time. The detection was carried out at 235 nm with a Nucleosil C₁₈ (250 × 4.6 mm) 10 μm column, and the ambient column temperature was maintained. The method uses a 20 μl injection volume and diluent as a blank solution in this connection. The method was validated as per the current regulatory guidelines. The linearity of this method was found to be linear in the range of 50-150% of the working concentration, and the correlation coefficient was >0.999. The method's accuracy was within the acceptable range, which was 98.1-101.5%. The method's precision was within an acceptable range of about 0.32% RSD. The analytical solution was stable for up to 48 h at room temperature. The method's robustness was proved by utilizing quality design tools. Stress studies demonstrated the method's stability-indicating nature.

HPLC-UV method validation for quantification of β-carotene in the development of sustained release supplement formulation containing solid dispersion-floating gel in situ

Despite the health benefits of β-carotene, its activity has been hampered by poor aqueous solubility and low oral bioavailability. Therefore, it is crucial to develop a new approach to overcome these problems. In this study, we developed a dry powder supplement comprising a combination approach of solid dispersion and floating gel in situ of β-carotene to enhance the solubility and achieve sustained release behavior. Here, we validated an HPLC method to quantify β-carotene as per the guidelines from ICH. The analytical method was validated in methanol and Fasted-State Simulated Gastric Fluid (FaSSGF) to determine β-carotene in recovery and in vitro release studies, respectively. A simple HPLC method using Xselect CSH™ C18 column (Waters, 3.0 × 150 mm) with the particle size of 3.5 µm was validated with 100% acetonitrile as the mobile phase. The calibration curves were found to be linear with LLOQ values < 3 ng/mL. Importantly, the method was accurate and precise without a carry over effect and successfully applied to determine the β-carotene concentration in the content analysis of the compound and in vitro drug release from floating gel in situ laden with solid dispersion formulations. The sensitivity of the method obtained here offers a wide potential use in various applications in drug delivery systems.

Surface molecularly imprinted solid-phase extraction for the determination of vancomycin in plasma samples using HPLC-MS/MS

Vancomycin is a glycopeptide antibiotic used to treat infections caused by Gram-positive bacteria. Due to the narrow therapeutic index of vancomycin, it is necessary to develop a sensitive and reliable analytical method to monitor the drug concentration in plasma. A novel method based on surface molecularly imprinted solid-phase extraction combined with liquid chromatography-tandem mass spectrometry for the determination of vancomycin in plasma sample was developed. The plasma sample was cleaned up through the solid-phase extraction process before the analysis. The calibration standard of vancomycin in plasma ranged between 1 and 100 ng/mL, and the correlation coefficient (r) was 0.9993. The average recoveries were from 94.3 to 104.0%, and the precision was less than 10.5%. The limit of detection and limit of quantification were 0.5 ng/mL and 1 ng/mL, respectively. The method validated was successfully used for the detection of vancomycin in mice after oral administration.

Validation of spectrophotometric method to quantify cabotegravir in simulated vaginal fluid and porcine vaginal tissue in ex vivo permeation and retention studies from thermosensitive and mucoadhesive gels

Cabotegravir (CAB) is an antiretroviral therapy (ARV) used for Human Immunodeficiency Virus (HIV) treatment. CAB has low solubility, which affects its bioavailability in oral therapy. Moreover, the injection form of CAB has difficulty in the administration process. Therefore, it is essential to develop a new drug delivery system for CAB. Vaginal drug delivery system offers many advantages such as a large surface area, increased drug bioavailability, and improved drug delivery. CAB was developed in thermosensitive and mucoadhesive vaginal gel preparations that provided optimal distribution in the vaginal mucosa. To support the process of formulation development, in this study, UV-visible spectrophotometry method was validated in methanol, simulated vaginal fluid (SVF) and vaginal tissue to quantify the amount of CAB in the gel preparations, in vitro, and ex vivo studies, respectively. The developed analytical method was subsequently validated according to ICH guidelines. The calibration curves in these matrices were found to be linear with correlation coefficient values (R²) ≥ 0.998. The LLOQ values in methanol, SVF and vaginal tissue were 2.15 µg/mL, 2.22 µg/mL, and 5.13 µg/mL, respectively. The developed method was found to be accurate and precise without being affected by dilution integrity. These methods were successfully applied to quantify the amount of CAB in gel preparations, in vitro, and ex vivo studies, showing uniformity of drug content and controlled release manner in the permeation profile for 24 h for both thermosensitive and mucoadhesive vaginal gels. Further analytical method is required to be developed for the quantification of CAB in in vivo studies.

Surface molecularly imprinted solid-phase extraction for the determination of vancomycin and norvancomycin in milk by liquid chromatography coupled to tandem mass spectrometry

A simple and sensitive method based on surface molecularly imprinted solid-phase extraction (SMISPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to determine the residues of vancomycin (VCM) and norvancomycin (NVCM) in milk samples. The imprinted polymer prepared with teicoplanin as a virtual template can specifically recognize VCM and NVCM. The samples were purified with SMISPE and analyzed by LC-MS/MS in positive ionization mode. The results showed that the VCM and NVCM had a good linear correlation in the range of 0.5 μg/kg to 50 μg/kg. The recoveries of target analytes were from 83.3% to 92.1%, and the limits of quantification were both 1.0 μg/kg. The matrix effects of VCM and NVCM were -11.0% and -3.43%, respectively. The proposed method can efficiently eliminate the interference from matrix compounds and reduce baseline noise, which is useful for the monitoring of the residues of VCM and NVCM in milk samples.

Utility of Silver-nanoparticles for Nano-fluorimetric Determination of Vancomycin Hydrochloride in Pharmaceutical Formulation and Biological Fluids: Greenness Assessment

Vancomycin hydrochloride (VANH) is a glycopeptide antibiotic commonly employed in the prophylaxis and therapy of various gram-positive bacterial life-threatening infections. Due to the narrow therapeutic window of VANH, its serum levels should be well-monitored to avoid its toxicity and to optimize its therapy. Herein, an innovative silver-nanoparticles enhanced fluorescence technique was designed for VANH rapid analysis in its pharmaceutical formulation and biological fluids. This technique is based on reinforcement of VANH fluorescence intensity with silver-nanoparticles that were synthesized by a redox reaction between VANH and silver nitrate in NaOH alkaline medium using polyvinylpyrrolidone as a stabilizer. The produced silver-nanoparticles were characterized by using UV-visible spectroscopy where they have an intense absorption maximum at 415 nm and transmission electron microscope (TEM) micrograph where they are spherical in shape with smooth surface morphology and size of 10.74 ± 2.44 nm. The fluorescence intensity was measured at 394 nm after excitation at 259 nm. Under optimum conditions, a good linear relationship was accomplished between the VANH concentration and the fluorescence intensity in a range of (1-36) ng/mL with a limit of detection of 0.29 ng/mL. Greenness assessment was performed using two assessment tools namely; eco-scale scoring and green analytical procedure index revealing excellent greenness of the proposed technique. The proposed technique was validated according to the International Conference on Harmonisation (ICH) recommendations and statistically compared with the reported HPLC method revealing no significant difference concerning accuracy and precision at p = 0.05. The proposed technique depended primarily on water as a cheap and eco-friendly solvent.

Development and validation of a high-performance liquid chromatography method for levothyroxine sodium quantification in plasma for pre-clinical evaluation of long-acting drug delivery systems

Levothyroxine (LEVO) sodium is an FDA-approved drug that is used to treat underactive thyroid (hypothyroidism) and other conditions. It is generally used as a thyroid-stimulating hormone administered orally. However, this approach has some drawbacks such as this drug should be taken every day 30 min to 1 h prior to breakfast with an empty stomach, moreover, some food interactions must be monitored. Thus, alternative innovative approaches capable of providing sustained LEVO release should be developed. Our research was designed to establish a simple quantitative determination method for LEVO in rat plasma for pre-clinical evaluation of long acting formulations using a high-performance liquid chromatography method, to validate the analytical method according to ICH guidelines and to characterise its pharmacokinetic behavior in rats. After simple protein precipitation with acetonitrile, LEVO was eluted on a Xselect CSH™ C18 column (Waters, 3.0 × 150 mm) with a particle size of 3.5 μm using a mobile phase of water and acetonitrile at a ratio of 65 : 35% v/v, including 0.1% v/v of trifluoracetic acid. The calibration standards used for plasma ranged between 0.5-1000 ng mL^-1 with a correlation coefficient (r²) of ≥0.998. The limit of detection was 0.44 ng mL^-1 and the lower limit of quantitation was 1.33 ng mL^-1. The extraction recovery of LEVO in rat plasma samples by this method was between 80 and 85%. The method was selective, sensitive, accurate and precise for detecting and quantifying LEVO in a pharmacokinetic study carried out in rats for pre-clinical evaluation of long acting formulations. The validated HPLC method meets the ICH established requirements and therefore offers a wide range of potential applications in pre-clinical therapeutic drug monitoring, pharmacokinetics and toxicology.

Copper nanocluster-based sensor for determination of vancomycin in exhaled breath condensate: A synchronous fluorescence spectroscopy

A synchronous fluorescence spectroscopy (SFS) nanoprobe is developed for the determination of vancomycin in exhaled breath condensate (EBC) samples. The synthesized nanoprobe is copper nanoclusters (Cu NCs) and its SFS peak is located at 405 nm with Δλ = 80. The affinity of Cu NCs to complex formation with vancomycin results in blocking non-radiative e^-/h⁺ recombination defect sites on the surface of NCs and consequently enhancing the SFS signal intensity. Central composite design and response surface methodology is used for the optimization of reaction conditions. Under the optimized conditions, a linear relationship is found between the SFS intensity and the concentration of vancomycin in the range of 0.1-8 μg/mL. The validated method is applied for the determination of vancomycin in EBC of newborns receiving vancomycin treatment.

A systematic review on chromatography-based method validation for quantification of vancomycin in biological matrices

A fully validated bioanalytical methods are prerequisite for pharmacokinetic and bioequivalence studies as well as for therapeutic drug monitoring. Due to high pharmacokinetic variability and narrow therapeutic index, vancomycin requires reliable quantification methods for therapeutic drug monitoring. To identify published chromatographic based bioanalytical methods for vancomycin in current systematic review, PubMed and ScienceDirect databases were searched. The selected records were evaluated against the method validation criteria derived from international guidelines for critical assessment. The major deficiencies were identified in method validation parameters specifically for accuracy, precision and number of calibration and validation standards, which compromised the reliability of the validated bioanalytical methods. The systematic review enacts to adapt the recommended international guidelines for suggested validation parameters to make bioanalysis reliable.

Development, Evaluation, and Pharmacokinetic Assessment of Polymeric Microarray Patches for Transdermal Delivery of Vancomycin Hydrochloride

Methicillin-resistant Staphylococcus aureus (MRSA) can cause harmful and potentially deadly infections. Vancomycin remains the first-line antibiotic treatment for MRSA-derived infections. Nevertheless, as a peptide drug, it is poorly absorbed when administered orally because of its high molecular weight and low permeability in the gastrointestinal tract and is therefore administered intravenously for the treatment of systemic diseases. In order to circumvent some of the many drawbacks associated with intravenous injection, other routes of drug delivery should be investigated. One of the strategies which has been employed to enhance transdermal drug delivery is based on microarray patches (MAPs). This work, for the first time, describes successful transdermal delivery of vancomycin hydrochloride (VCL) using dissolving MAPs (DMAPs) and hydrogel-forming MAPs (HFMAPs). VCL was formulated into DMAPs and reservoirs [film dosage forms, lyophilized wafers, and compressed tablets (CSTs)] using excipients such as poly(vinyl pyrrolidone), poly(vinyl alcohol), sodium hyaluronate, d-sorbitol, and glycerol. In this study, HFMAPs were manufactured using aqueous blends containing poly(methylvinyl ether-co-maleic acid) cross-linked by esterification with poly(ethylene glycol). The VCL-loaded CSTs (60% w/w VCL) were the most promising reservoirs to be integrated with HFMAPs based on the physicochemical evaluations performed. Both HFMAPs and DMAPs successfully delivered VCL in ex vivo studies with the percentage of drug that permeated across the neonatal porcine skin recorded at 46.39 ± 8.04 and 7.99 ± 0.98%, respectively. In in vivo studies, the area under the plasma concentration time curve from time zero to infinity (AUC_0-∞) values of 162.04 ± 61.84 and 61.01 ± 28.50 μg h/mL were achieved following the application of HFMAPs and DMAPs, respectively. In comparison, the AUC_0-∞ of HFMAPs was significantly greater than that of the oral administration control group, which showed an AUC_0-∞ of 30.50 ± 9.18 μg h/mL (p < 0.05). This work demonstrates that transdermal delivery of VCL is feasible using DMAPs and HFMAPs and could prove effective in the treatment of infectious diseases caused by MRSA, such as skin and soft tissue infections, lymphatic-related infections, and neonatal sepsis.