Determination of tadalafil in small volumes of plasma by high-performance liquid chromatography with UV detection

Development of a Rapid LC-MS/MS Method for Simultaneous Quantification of Donepezil and Tadalafil in Rat Plasma: Its Application in a Pharmacokinetic Interaction Study after Oral Administration in Rats

This study aimed to establish a simple and sensitive analytical method to simultaneously quantify donepezil (DPZ) and tadalafil (TAD) in rat plasma using lansoprazole (LPZ) as an internal standard (IS) by using liquid chromatography tandem mass spectrometry. The fragmentation pattern of DPZ, TAD, and IS was elucidated using multiple reaction monitoring in electrospray ionization positive ion mode for the quantification of precursor to production at m/z 380.1 → 91.2 for DPZ, m/z 390.2 → 268.1 for TAD, and m/z 370.3 → 252.0 for LPZ. The extracted DPZ and TAD from plasma using acetonitrile-induced protein precipitation was separated using Kinetex C18 (100 × 2.1 mm, 2.6 µm) column with a gradient mobile phase system consisting of 2 mM ammonium acetate and 0.1% formic acid in acetonitrile at a flow rate of 0.25 mL/min for 4 min. The selectivity, lower limit of quantification, linearity, precision, accuracy, stability, recovery, and matrix effect of this developed method was validated according to the guidelines of the U.S. Food and Drug Administration and the Ministry of Food and Drug Safety of Korea. The established method achieved acceptance criteria in all validation parameters, ensuring reliability, reproducibility, and accuracy, and was successfully implemented in a pharmacokinetic study on the co-administration of DPZ and TAD orally in rats.

Cytochrome P450 3A4-mediated pharmacokinetic interaction study between tadalafil and canagliflozin using high-performance thin-layer chromatography

Diabetes is a known risk factor for sexual dysfunction in men; diabetic men have an increased risk of erectile dysfunction compared to non-diabetic men. Canagliflozin is one of the common antidiabetic drugs that is readily used in the treatment of type-2 diabetes. Concomitantly phosphodiesterase 5 inhibitors, such as tadalafil, can be given to the patient to alleviate erectile dysfunction. Canagliflozin is reported to be one of the cytochrome P450 3A4 enzyme inhibitors, that might seriously influence blood concentration levels of tadalafil but there is no study till now, discussing this interaction. Therefore, a fast, simple, and sensitive high-performance thin-layer chromatographic method was developed, validated, and applied for the simultaneous determination of tadalafil and canagliflozin in spiked and real human plasma. The limit of detection for tadalafil was 0.14 ng/band and for canagliflozin was 0.16 ng/band. The limit of quantitation value for tadalafil was 0.43 ng/band and for canagliflozin was 0.47 ng/band. Tadalafil and canagliflozin were determined simultaneously in real human plasma using the described procedure and the method was applied for in vivo pharmacokinetic drug interaction study between the studied drugs, which proved significant interaction between them when administered simultaneously.

M. Ali H. Fabric phase sorptive extraction coupled with UPLC-ESI-MS/MS method for fast and sensitive quantitation of tadalafil in a bioequivalence study

The current study coupled fabric phase sorptive extraction (FPSE) with ultraperformance liquid chromatography method with electrospray ionization and tandem mass detection (UPLC-ESI-MS/MS) for fast and sensitive determination of tadalafil (TAD) in a bioequivalence study. Fabric phase sorptive extraction allowed direct extraction of TAD from the sample matrix with improved selectivity, repeatability, and recoveries. A sol–gel Carbowax 20 M (CX-20 M) coated FPSE membrane revealed the best extraction efficiency for TAD because of its strong affinity for analytes via intermolecular interactions, high mass transfer rate to FPSE membrane, and high permeability. An automated multiple reaction monitoring (MRM) optimizer was employed for the best selection of the precursor and product ions, ion breakdown profile, the fine adjustment of the fragmentor voltages for each precursor ions, and the collision energies for the product ions. The chromatographic separation was conducted using a mobile phase A: 5.0 mM ammonium acetate with 0.1 % formic acid in water and mobile phase B: formic acid (0.1%) in acetonitrile in ratio (55:45, v/v) through isocratic elution mode on an Agilent EclipsePlus C18 (50 × 2.1 mm, 1.8 μm) column and the flow rate was adjusted at 0.4 mL min⁻¹. The total run time per sample was 1.0 min. The method was validated by FDA standards for bioanalytical method validation over a concentration range of 0.1–100 ng mL⁻¹ with a correlation coefficient of 0.9993 and the lower limit of quantitation (LLOQ) was 0.1 ng mL⁻¹ in rat plasma. Intra- and inter-assay precision (%RSD) were lower than 4.1% and accuracy (%RE) was within 2.4%. The developed FPSE-UPLC-ESI-MS/MS method was effectively used in a randomized, two-way, single-dose, crossover study to compare the bioequivalence of two TAD formulations from different companies in male rats and verified to be bioequivalent.

A concise review of bioanalytical methods of small molecule immuno-oncology drugs in cancer therapy

Immuno-oncology (IO) is an emerging option to treat cancer malignancies. In the last two years, IO has accounted for more than 90% of the new active drugs in various therapeutic indications of oncology drug development. Bioanalytical methods used for the quantitation of various IO small molecule drugs have been summarized in this review. The most commonly used are HPLC and LC-MS/MS methods. Determination of IO drugs from biological matrices involves drug extraction from the biological matrix, which is mostly achieved by simple protein precipitation, liquid-liquid extraction and solid-phase extraction. Subsequently, quantitation is usually achieved by LC-MS/MS, but HPLC-UV has also been employed. The bioanalytical methods reported for each drug are briefly discussed and tabulated for easy access. Our review indicates that LC-MS/MS is a versatile and reliable tool for the sensitive, rapid and robust quantitation of IO drugs.

Determination of Phosphodiesterase Inhibitors Tadalafil, Roflumilast and Roflumilast N-Oxide Using LC-MS in Guinea Pig Plasma

Phosphodiesterases are known as a super-family of 11 isoenzymes, which can exert various functions based on their organ distribution. In this work, a rapid and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry method was developed for quantification of tadalafil (phosphodiesterase five inhibitor), roflumilast (RF) (phosphodiesterase four inhibitor) and its active metabolite, RF N-oxide in guinea pig plasma. Chromatographic separation was carried out on UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) at a flow rate 0.5 mL/min, using 0.2% formic acid in acetonitrile and 0.2% formic acid in water as mobile phases within 4 min. Detection was performed using a triple quadrupole mass spectrometer employing electrospray ionization operated in positive mode using multiple reaction monitoring mode. The method utilized deuterium labeled internal standards, and was validated according to European Medicines Agency guidelines. It showed excellent linearity in the range of 0.5-500.0 ng/mL for all analytes with coefficient of determination >0.99. The intra- and inter-day precisions (relative standard deviation %) were within 6.7%, and the recoveries were greater than 73.4%. Using this method, plasma samples from experiments of phosphodiesterase four, and five inhibitors in a model of ovalbumin-induced allergic inflammation in guinea pigs were analyzed.

Quantitation of tadalafil in human plasma using a sensitive and rapid LC-MS/MS method for a bioequivalence study

A highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of tadalafil (TAD) in human plasma. TAD and its deuterated internal standard (IS), tadalafil-d3, were extracted from 200 µL plasma using Phenomenex Strata-X-C 33 µ extraction cartridges. Chromatographic analysis was carried out on Synergi™ Hydro-RP C18 (100 mm × 4.6 mm, 4 µm) column with a mobile phase consisting of methanol and 10 mM ammonium formate, pH 4.0 (90:10, v/v), delivered at a flow rate of 0.9 mL/min. Quantitation of the protonated analyte was done on a triple quadrupole mass spectrometer using multiple reaction monitoring via electrospray ionization. The precursor to product ions transitions monitored for TAD and TAD-d3 were m/z 390.3 → 268.2 and m/z 393.1 → 271.2, respectively. The calibration curve was linear over the concentration range of 0.50-500 ng/mL with correlation coefficient, r2 ≥ 0.9994. Acceptable intra-batch and inter-batch precision (≤ 3.7%) and accuracy (97.8% to 104.1%) were obtained at five concentration levels. The recovery of TAD from spiked plasma was highly precise and quantitative (98.95% to 100.61%). Further, the effect of endogenous matrix components was minimal. TAD was found to be stable under different storage conditions in human plasma and also in whole blood samples. The validated method was successfully used to determine TAD plasma concentration in a bioequivalence study with 20 mg TAD tablets in 24 healthy volunteers. Method performance was evaluated by reanalyzing 115 study samples.

Selective and rapid determination of tadalafil and finasteride using solid phase extraction by high performance liquid chromatography and tandem mass spectrometry

Highly selective and fast liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for simultaneous determination of tadalafil (TDL) and finasteride (FNS) in human plasma. The method was successfully applied for analysis of TDL and FNS samples in clinical study. The method was validated as per USFDA (United States Food and Drug Administration), EMA (European Medicines Agency), and ANVISA (Agência Nacional de Vigilância Sanitária-Brazil) bio analytical method validation guidelines. Glyburide (GLB) was used as common internal standard (ISTD) for both analytes. The selected multiple reaction monitoring (MRM) transitions for mass spectrometric analysis were m/z 390.2/268.2, m/z 373.3/305.4 and m/z 494.2/369.1 for TDL, FNS and ISTD respectively. The extraction of analytes and ISTD was accomplished by a simple solid phase extraction (SPE) procedure. Rapid analysis time was achieved on Zorbax Eclipse C18 column (50 × 4.6 mm, 5 μm). The calibration ranges for TDL and FNS were 5-800 ng/ml and 0.2-30 ng/ml respectively. The results of precision and accuracy, linearity, recovery and matrix effect of the method are acceptable. The accuracy was in the range of 92.9%-106.4% and method precision was also good; %CV was less than 8.1%.

Influence of the PDE5 inhibitor tadalafil on redox status and antioxidant defense system in C2C12 skeletal muscle cells

Phosphodiesterase type 5 inhibitors (PDE5Is), widely known for their beneficial effects onto male erectile dysfunction, seem to exert favorable effects onto metabolism as well. Tadalafil exposure increases oxidative metabolism of C2C12 skeletal muscle cells. A rise in fatty acid (FA) metabolism, requiring more oxygen, could induce a larger reactive oxygen species (ROS) release as a byproduct thus leading to a redox imbalance. The aim of this study was to determine how PDE5I tadalafil influences redox status in skeletal muscle cells to match the increasing oxidative metabolism. To this purpose, differentiated C2C12 skeletal muscle cells were treated with tadalafil and analyzed for total antioxidant capacity (TAC) and glutathione levels as marker of redox status; enzyme activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) engaged in antioxidant defense; and lipid peroxidation (TBARS) and protein carbonyls (PrCar) as markers of oxidative damage. Tadalafil increased total intracellular glutathione (tGSH), CAT, SOD, and GPx enzymatic activities while no changes were found in TAC. A perturbation of redox status, as showed by the decrease in the ratio between reduced/oxidized glutathione (GSH/GSSG), was observed. Nevertheless, it did not cause any change in TBARS and PrCar levels probably due to the enhancement in the antioxidant enzymatic network. Taken together, these data indicate that tadalafil, besides improving oxidative metabolism, may be beneficial to skeletal muscle cells by enhancing the enzymatic antioxidant system capacity.

Validated UPLC-MS/MS method for the determination of tadalafil in human plasma and its application to a pharmacokinetic study

A simple, rapid, and reliable UPLC-MS/MS method was developed and validated for the determination of tadalafil in human plasma. The plasma samples were deproteinized with acetonitrile. Chromatographic separation was performed on a Shiseido C18 (100 × 2.1 mm, 2.7 µm) column with isocratic elution using 2.0 mM ammonium acetate and acetonitrile (55:45, v/v) with 0.1% formic acid at a flow rate of 0.7 mL/min. The total run time was 1 min per sample. The quantitative analysis was performed using multiple reaction monitoring at transition of m/z 390.4 → 268.3 for tadalafil and m/z 475.3 → 283.3 for sildenafil as an internal standard. The method was fully validated over a concentration range of 5–1,000 ng/mL with a lower quantification limit of 5 ng/mL. Intra- and inter-day precision (relative standard deviation, %RSD) were within 8.4% and accuracy (relative error, %RE) was lower than -3.2%. The developed and validated method was successfully applied to a pharmacokinetic study of tadalafil (20 mg) in Korean healthy male subjects (n = 12).

Insulin-like effect of the phosphodiesterase type 5 inhibitor tadalafil onto male human skeletal muscle cells

BACKGROUND

Phosphodiesterase type 5 inhibitors (PDE5i), widely used to treat male erectile dysfunction, seem to counteract insulin resistance (IR) in animals and humans. IR, primarily manifest in peripheral tissues and particularly in skeletal muscle, is due to impaired insulin signal transduction. Investigators have been focusing onto intracellular defects responsible for IR to identify suitable pharmacological tools targeted toward the specific defects. Albeit some effects of PDE5i have been reported onto animal muscular tissues or cells, whether and how they might affect metabolic processes directly in human skeletal muscle still remains unclear.

AIM

We aimed to investigate in human fetal skeletal muscle cells (Hfsmc) the effect of tadalafil, one of PDE5i, onto some intracellular factors involved in response to insulin, such as ras-raf mitogen activated protein kinase (MAPK), phosphatidylinositol 3-kinase/protein kinase B (PKB/Akt), glycogen synthase kinase 3β (GSK-3β), and the transcriptional factor c-Myc; proliferation rate; lactate (lact) and free fatty acid (ffa) release; activity of citrate synthase (CS) and succinate dehydrogenase (SDH), both enzymes of Kreb's cycle; PDE5 gene expression.

MATERIALS AND METHODS

Western blot analysis, enzyme-linked immunosorbent assay, enzymatic assays, cell count, MTT assay and Real Time PCR were performed in Hfsmc with and without tadalafil.

RESULTS

In Hfsmc tadalafil affected the insulin-related intracellular cascade, by increasing MAPK, PKB/Akt, GSK-3β phosphorylation and c-Myc expression. ffa release and CS activity also significantly increased, with no changes in SDH activity and lact release.

CONCLUSIONS

Tadalafil, like insulin, targeted part of the machinery dedicated to energy management and metabolic control in human skeletal muscle cells.

A simple and sensitive HPLC fluorescence method for determination of tadalafil in mouse plasma

A simple and sensitive high-performance liquid chromatographic (HPLC) method utilizing fluorescence detection was developed for the determination of the phosphodiesterase type 5 inhibitor tadalafil in mouse plasma. This method utilizes a simple sample preparation (protein precipitation) with high recovery of tadalafil (∼98%), which eliminates the need for an internal standard. For constituent separation, the method utilized a monolithic C(18) column and a flow rate of 1.0mL/min with a mobile phase gradient consisting of aqueous trifluoroacetic acid (0.1% TFA in deionized water pH 2.2, v/v) and acetonitrile. The method calibration was linear for tadalafil in mouse plasma from 100 to 2000ng/mL (r>0.999) with a detection limit of approximately 40ng/mL. Component fluorescence detection was achieved using an excitation wavelength of 275nm with monitoring of the emission wavelength at 335nm. The intra-day and inter-day precision (relative standard deviation, RSD) values for tadalafil in mouse plasma were less than 14%, and the accuracy (percent error) was within -14% of the nominal concentration. The method was utilized on mouse plasma samples from research evaluating the potential cardioprotective effects of tadalafil on mouse heart tissue exposed to doxorubicin, a chemotherapeutic drug with reported cardiotoxic effects.

Development and validation of a high-performance liquid chromatographic method using fluorescence detection for the determination of vardenafil in small volumes of rat plasma and bile

A new, simple and sensitive high-performance liquid chromatography (HPLC) method with fluorescence detection was developed and validated for the determination of vardenafil in small volumes of rat plasma and bile. The absorbance and fluorescence characteristics of vardenafil were studied and factors that affect the HPLC resolution and fluorescence intensity were examined and optimized. Vardenafil and the internal standard cisapride were extracted using acetonitrile. The separation was achieved on a C18 column at 35 degrees C using acetonitrile-50 mM ammonium acetate aqueous solution (pH 6.8) (40:60) as mobile phase. At a flow rate of 1 ml/min, the total run time was 18 min. Fluorescence was measured with excitation and emission set at 280 and 470 nm, respectively. The calibration curves were linear from 10 to 1000 ng/ml and 0.2-100 microg/ml for plasma and bile samples, respectively. The intra- and inter-day imprecision did not exceed 10.8%, and the accuracy was within 9.6% deviation of the nominal concentration. The method was used successfully to investigate the disposition and biliary excretion of vardenafil in rats.

Validated liquid chromatographic–ultraviolet method for the quantitation of tadalafil in human plasma using liquid–liquid extraction

A highly selective, sensitive and rapid HPLC method has been developed and validated to quantify tadalafil in human plasma. The tadalafil and internal standard (loratadine, I.S.) were extracted by liquid-liquid extraction technique followed by an aqueous back-extraction allowing injection of an aqueous solvent in the HPLC system. The chromatographic separation was performed on a reverse phase BDS Hypersil C-18 column (250 mm x 4.6 mm, 5 microm, Thermo Separation Co., USA) with a mobile phase of acetonitrile and aqueous solution containing 0.012 M triethylamine+0.020 M orthophosphoric acid (50/50, v/v). The analytes were detected at 225 nm. The assay exhibited a linear range of 5-600 ng/mL for tadalafil in human plasma. The lower limit of quantitation (LLOQ) was 5 ng/mL. The within- and between batch precision (expressed as coefficient of variation, C.V.) did not exceed 10.3% and the accuracy was within -7.6% deviation of the nominal concentration. The recovery of tadalafil from plasma was greater than 66.1%. Stability of tadalafil in plasma was excellent with no evidence of degradation during sample processing (auto-sampler) and 30 days storage in a freezer. This validated method is applied for the clinical study of the tadalafil in human volunteers.