A rapid and sensitive UPLC–MS/MS method for determination of HZ08 in rat plasma and tissues: Application to a pharmacokinetic study of liposome injections

In Vitro and In Vivo Activities, Absorption, Tissue Distribution, and Excretion of OBP-4, a Potential Anti-Clostridioides difficile Agent

Clostridioides difficile infection (CDI) is considered a major concern of the health care system globally, with an increasing need for alternative therapies. OBP-4, a new oxazolidinone-fluoroquinolone hybrid with excellent in vitro activities and good safety, shows promising features as an antibacterial agent. Here, we further evaluated the in vitro and in vivo activities of OBP-4 against C. difficile and its absorption (A), distribution (D), and excretion (E) profiles in rats. In vitro assays indicated that OBP-4 was active against all tested C. difficile strains, with MICs ranging from 0.25 to 1 mg/liter. In addition, OBP-4 showed complete inhibition of spore formation at 0.5× MIC. In the mouse model of CDI, 5-day oral treatment with OBP-4 provided complete protection from death and CDI recurrence in infected mice. However, cadazolid (CZD) and vancomycin (VAN) showed less protection of infected mice than did OBP-4 in terms of diarrhea and weight loss, especially VAN. Subsequently, ADE investigations of OBP-4 with a reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method showed extremely low systemic exposure and predominantly fecal excretion, resulting in a high local concentration of OBP-4 in the intestinal tract-the site of CDI. These results demonstrated that OBP-4 possesses good activity against C. difficile and favorable ADE characteristics for oral treatment of CDI, which support further development of OBP-4 as a potential anti-CDI agent.

Development of an UPLC-MS/MS Method for Quantitative Analysis of Clotrimazole in Human Plasma Samples

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the quantification of clotrimazole (CTZ) plasma levels after intravaginal administration of the drug given at approved dosages. Plasma samples were extracted by liquid–liquid extraction and a single chromatographic run could be completed within about 2 min. The method was linear over the investigated range (0.488–250 ng/mL) with all the correlation coefficients, R2, greater than 0.9903. All data were in the range of ±15.0% with respect to the nominal concentration for high QC and medium QC, and in the range ±20% with respect to the nominal concentration for low QC. This rapid and sensitive method was validated and could be applied to human plasma samples from a healthy volunteer, showing that the assay is able to detect plasma concentrations of CTZ in the range of those found after the administration of the drug at approved dosages in the clinical setting.

A Validated HPLC-MS/MS Assay for 14-O-[(4,6-Diaminopyrimidine-2-yl)thioacetyl] Mutilin in Biological Samples and Its Pharmacokinetic, Distribution and Excretion via Urine and Feces in Rats

14-O-[(4,6-Diaminopyrimidine-2-yl)thioacetyl] mutilin (DPTM), a novel pleuromutilin candidate with a substituted pyrimidine moiety, has been confirmed to possess excellent antibacterial activity against Gram-positive bacteria. To illustrate the pharmacokinetic profile after intravenous (i.v.), intramuscular (i.m.) and oral (p.o.) administrations with DPTM, as well as tissue distribution and excretion via urine and feces in vivo, a specific, sensitive and robust HPLC-MS/MS method was first developed to determine DPTM in rat plasma, various tissues, urine and feces. The plasma, tissues, urine and feces samples were treated by protein precipitation with acetonitrile using tiamulin fumarate as an internal standard (IS). This method which was achieved on an HPLC system detector equipped with an ESI interface, was sensitive with 5 ng/mL as the lower limit of detection and exhibited good linearity (R² > 0.9900) in the range of 5⁻4000 ng/mL for plasma, various tissues, urine and feces, as well as intra-day precision, inter-day precision and accuracy. The matrix effects ranged from 94.2 to 109.7% with RSD ≤ 9.4% and the mean extraction recoveries ranged from 95.4 to 109.5% in plasma, tissue homogenates, urine and feces (RSD ≤ 9.9). After i.v., i.m. and p.o. administrations, DPTM was rapidly absorbed and metabolized in rats with the half-life (t1/2) of 1.70⁻1.86, 3.23⁻3.49 and 4.38⁻4.70 for 10, 25 and 75 mg/kg doses, respectively. The tissue distribution showed that DPTM was diffused into all the tested tissues, especially into the intestine and lung. Excretion via urine and feces studies demonstrated that DPTM was mainly excreted by feces after administration.

Improved Oral Bioavailability of Total Flavonoids of Dracocephalum moldavica via Composite Phospholipid Liposomes: Preparation, in-vitro Drug Release and Pharmacokinetics in Rats

Background:

Dracocephalum moldavica L is a traditional Uygur medicine for centuries, total flavonoids extracted from Dracocephalum moldavica are the major active ingredients of herbs, which possesses significant medicinal values to treat coronart disease and hypertension, due to the glycosyl group on the ring, total flavonoids of Dracocephalum moldavica has low hydrophilic and poorly absorbed after oral administration, so one way is the formulation of poorly water soluble and permeabledrugs with lipids containing formulations such as Composite phospholipid liposomes to improve the absorption profile of drug.

Objectives:

To prepare composite phospholipid liposome (CPL) encapsulatetotal flavonoids extract from Dracocephalum moldavica (TFDM), determine its physicochemical properties, investigate its in-vitro release and evaluate the pharmacokinetics in Sprague-Dawley (SD) rats to increase the bioavailability of TFDM-CPL.

Material and Methods:

The TFDMCPL was prepared by the method of ammonium sulfate transmembrane gradients. The CPL and TFDM were separated by Sephadex-G50 chromatography. The concentration of TFDM in the CPL was detected by HPLC, then the entrapment efficiency (EE) was evaluated. And the shape, particle size, zeta potential, drug release in vitro of TFDMCPL were investigated, and the pharmacokinetics was evaluated by rat jugular vein intubation tube in SD rats.

Results:

The EE of TFDM was 84.17±2.2%, mean size of TFDMCPL was 136.2±3.7nm, polymey disperse index (PDI) was 0.158±0.015 and zeta potential was -19.8±1.2mV. TFDM-CPLwere found to enhance the release of drugs more effectively than TFDM based on the in vitro model and Following oral administration of TFDM, the plasma exposures of TFDM-CPL was significantly extended, and the mean concentration of TFDM-CPL was significantly higher compared to TFDM-solution. TheC_max, t_1/2, AUC_{0-12 h} values of TFDM for group of TFDM-CPL were siginificantly increased.

Conclusion:

The method of ammonium sulfate transmembrane gradients is suitable for preparingTFDM-CPL. And TFDM-CPL have potential to be used to improve the bioavailability of poorly soluble drugs after oral administration.

SUMMARY

For the first time, composite phospholipid liposomes (CPL) containing total flavonoids of Dracocephalum moldavica (TFDM) were developed by method of ammonium sulfate transmembrane gradients.

The TFDM-CPL was a significant improvement in bioavailability compared to the TFDM-solution, with a 10-fold increase in relative bioavailability in vivo.

The TFDM-CPL was still stable during storage at 4oC for 6 months.

Abbreviations Used: CPL: composite phospholipid liposome.; TFDM: Total Flavonoids Extract from Dracocephalum moldavica; SD:Sprague-Dawley; EE:entrapment efficiency; PDI: polymey disperse index; TFDM-CPL: Total flavonoid extract from Dracocephalum moldavica – composite phospholipid liposome; DM: Dracocephalum moldavica L.; SPC: Soybean phospholipid; HSPC: Hydrogenated soya phosphatide; PBS: phosphate buffered saline; HPLC: high performance liquid chromatography; TEM: transmission electron microscopy; CMC-Na: Carboxy Methyl Cellulose-Natrium; AUC: area under the curve

Pharmacokinetics and tissue distribution study of prucalopride in rats by ultra high performance liquid chromatography with tandem mass spectrometry

A sensitive, reliable and high throughput ultra high performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of prucalopride in rat plasma and various tissues (including heart, liver, spleen, lung, kidney, stomach,small intestine, large intestine, cecum, cerebrum, cerebellum, and ovary). The plasma and tissues samples were treated by protein precipitation with acetonitrile using carbamazepine as an internal standard (IS). Chromatographic separation was performed on a Waters ACQUITY UPLC^® HSS C18 column (2.1mm×50mm, 1.8μm) with a gradient mobile phase consisting of acetonitrile-water (containing 0.1% formic acid) as mobile phase at a flow rate of 0.2mL/min. The quantification was performed by multiple reactions monitoring mode with m/z 367.99→195.89 for prucalopride and m/z 236.97→194.04 for carbamazepine on a Waters Xevo TQD mass spectrometry equipped with electrospray ionization (ESI) source. The calibration curve was linear in the range of 0.1-100ng/mL for plasma and various tissues (r≥0.99) with a lower limit of quantification of 0.1ng/mL. The recoveries obtained for prucalopride were more than 85%. The validated method was successfully applied to the pharmacokinetics and tissue distribution study of prucalopride after oral administration to rats. The pharmacokinetic parameters were demonstrated as followed: the time to reach peak concentration (T_max) was 1.0h, and the peak concentration (C_max) was 21.71±4.28ng/mL, the half-life (t_1/2) was 18.21±0.69h, and the area under the curve (AUC) was 59.30±9.43ngh/mL. Tissue distribution showed the highest level was observed in stomach and intestine, then in liver, which indicated that prucalopride was absorbed firstly in stomach and intestine, and mainly accumulated in liver. It was also the first study to investigate the tissue distribution of prucalopride in rats following oral administration.

Principle, Instrumentation, and Applications of UPLC: A Novel Technique of Liquid Chromatography

The key focus of the pharmaceutical or chemical industries is to reduce the cost involved in the development of new drugs and to improve the selectivity, sensitivity, and resolution for their detection. The purpose can now be solved by the separation method called UPLC which is the modified HPLC method comprising high pressure and small sized particles (less than 2 µm) used in the column, so the length of the column decreases leading to time saving and reduction in the consumption of solvent. The underlying principle of UPLC is based on van Deemter statement which describes the connection between linear velocity with plate height. UPLC contributes to the improvement of the three areas: speed, resolution, and sensitivity. This is a new advanced category of the HPLC which has the same basic principle and methodology with improved chromatographic performance. This review is an effort to compile the principle, instrumentation, and applications of UPLC.

Optimization of the process variables of tilianin-loaded composite phospholipid liposomes based on response surface-central composite design and pharmacokinetic study

Tilianin is attracting considerable attention because of its antihypertensive, anti-atherogenic and anticonvulsive efficacy. However, tilianin has poor oral bioavailability. Thus, to improve the oral bioavailability of tilianin, composite phospholipid liposomes were adopted in this work as a novel nanoformulation. The aim was to develop and formulate tilianin composite phospholipid liposomes (TCPLs) through ethanol injection and to apply the response surface-central composite design to optimize the tilianin composite phospholipid liposome formulation. The independent variables were the amount of phospholipids (X1), amount of cholesterol (X2) and weight ratio of phospholipid to drug (X3); the depended variables were particle size (Y1) and encapsulation efficiency (EE) (Y2) of TCPLs. Results indicated that the optimum preparation conditions were as follows: phospholipid amount, 500 mg, cholesterol amount, 50mg and phospholipid/drug ratio, 25. These variables were also the major contributing variables for particle size (101.4 ± 6.1 nm), higher EE (90.28% ± 1.36%), zeta potential (-18.3 ± 2.6 mV) and PDI (0.122 ± 0.027). Subsequently, differential scanning calorimetry techniques were used to investigate the molecular interaction in TCPLs, and the in vitro drug release of tilianin and TCPLs was investigated by the second method of dissolution in the Chinese Pharmacopoeia (Edition 2015). Furthermore, pharmacokinetics in Sprague Dawley rats was evaluated using a rat jugular vein intubation tube. Results demonstrated that the Cmax of TCPLs became 5.7 times higher than that of tilianin solution and that the area under the curve of TCPLs became about 4.6-fold higher than that of tilianin solution. Overall, our results suggested that the prepared tilianin composite phospholipid liposome formulations could be used to improve the bioavailability of tilianin after oral administration.

Pharmacokinetics and tissue distribution study of ginkgolide L in rats by ultra-high performance liquid chromatography coupled with tandem mass spectrometry

An ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) approach was developed and validated for the determination of ginkgolide L (GL) in rat plasma and tissues using diazepam as internal standard (IS). Detection was performed on a triple quadrupole MS system using multiple reaction monitoring (MRM) mode in positive mode. Sample preparation was carried out through a liquid-liquid extraction with ethyl acetate. The chromatographic separation was achieved by using an Agilent ZORBAX SB-Aq column with a mobile phase of 0.5% aqueous formic acid (A) and methanol (B). The monitored transitions were set at m/z 391.14→271.10 for GL and m/z 285.08→193.10 for IS, respectively. The validated method was successfully applied to the pharmacokinetic and tissue distribution study of GL in rats after intravenous administration. Good linearity was found between 2.5-2000ng/mL (r>0.996) for plasma samples, and calibration curves were also linear for other tissue samples over a wide range. The results indicated that GL has linear pharmacokinetic properties after intravenous administration at three doses. GL could distribute to tissues quickly and the major distribution tissue of GL in rats was liver. This was the first report of pharmacokinetic and tissue distribution data for GL.