An improved high-throughput liquid chromatographic/tandem mass spectrometric method for terbinafine quantification in human plasma, using automated liquid–liquid extraction based on 96-well format plates

Rapid back flushed direct sample injection bio-analytical HPLC-UV method for therapeutic drug monitoring of terbinafine

A rapid back flushed (BF) direct sample injection (DSI) high-performance liquid chromatography (HPLC) with UV detection (BF-DSI-HPLC-UV) has been developed to determine terbinafine (TERB) in human serum. For online solid phase extraction step, an isocratic mobile phase of phosphate buffer saline (pH 7.4) at 1 mL/min and a short protein-coated ODS column (PC-ODS-column) were used for the purification and enrichment of TERB. Two different chromatographic modes of PC-ODS-column were simultaneously operated. Macromolecular proteins were extracted by size-exclusion liquid chromatography, while TERB trapping and enrichment were achieved through reversed-phase liquid chromatography. The clear fraction containing TERB was transferred from the PC-ODS-column by BF mode onto the quantification step through a high pressure switching valve. An analytical mobile phase consisting of 80% methanol and 1% triethylamine in distilled deionized water (pH) 6 at 1 mL/min was used for the final separation on an ODS analytical column. TERB was quantified and detected by UV-detector at 224 nm. The proposed method showed high correlation coefficient (>0.999) over the concentrations range 4-1600 ng/mL with recoveries ranging from 98.48 to 93.86%. Measurement of TERB concentration in serum after administration of a single dose of 250 mg oral tablet was used to evaluate the applicability of the BF-DSI-HPLC-UV for pharmacokinetic study.

Simple and Fast Determination of Terbinafine in Human Urine by Dilute and Shoot HPLC-DAD Using a Core-Shell Column

BACKGROUND

Terbinafine is an allylamine antifungal that is effective against many fungi, dermatophytes and moulds. Analytical methods are required for the determination of terbinafine in biological fluids to perform therapeutic drug monitoring and pharmacokinetic studies.

OBJECTIVE

The aim of this study was to develop and validate a novel and fast method combining dilute and shoot approach and high-performance liquid chromatography coupled with photodiode array detection for the determination of terbinafine in human urine.

METHODS

Chromatographic parameters including mobile phase composition, pH, flow rate and injection volume were assessed and optimized. The separation of terbinafine and naproxen (internal standard) was achieved within 3 min using a C18 core-shell column (Raptor ARC-18, 100 x 4.6 mm, 2.7 μm) under isocratic conditions. Samples were eluted from the column at the flow rate of 1.4 mL/min using a mobile phase containing 0.2% triethylamine in water (pH 3.4 with formic acid): acetonitrile (45:55, v/v).

RESULTS

The presented technique was linear in the range of 25-2000 ng/mL. Intra- and inter-day reproducibility at four quality control levels (25, 200, 750 and 1500 ng/mL) were less than 7%, with relative errors ranging from -5.40% to 5.91%. The limit of detection was 12.60 ng/mL. The developed method has three main advantages compared to existing methods: simplicity and greenness of sample preparation, use of core-shell column and short analysis time.

CONCLUSION

The results of this study indicate that the combination of dilute and shoot approach and core-shell column can be regarded as an advantageous application for the fast determination of terbinafine in the urine.

Determination of terbinafine in human plasma using UPLC-MS/MS: Application to a bioequivalence study in healthy subjects

A high-throughput and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the determination of terbinafine in human plasma. The method employed liquid-liquid extraction of terbinafine and terbinafine-d7 (used as internal standard) from 100 μL human plasma with ethyl acetate-n-hexane (80:20, v/v) solvent mixture. Chromatography was performed on a BEH C₁₈ (50 × 2.1 mm, 1.7 μm) column using acetonitrile-8.0 mm ammonium formate, pH 3.5 (85:15, v/v) under isocratic elution. For quantitative analysis, MS/MS ion transitions were monitored at m/z 292.2/141.1 and m/z 299.1/148.2 for terbinafine and terbinafine-d7, respectively, using electrospray ionization in the positive mode. The method was validated according to regulatory guidance for selectivity, sensitivity, linearity, recovery, matrix effect, stability, dilution reliability and ruggedness with acceptable accuracy and precision. The method shows good linearity over the tested concentration range from 1.00 to 2000 ng/mL (r²  ≥ 0.9984). The intra-batch and inter-batch precision (CV) was 1.8-3.2 and 2.1-4.5%, respectively. The method was successfully applied to a bioequivalence study with 250 mg terbinafine in 32 healthy subjects. The major advantage of this method includes higher sensitivity, small plasma volume for processing and a short analysis time.

Advances in antifungal drug measurement by liquid chromatography-mass spectrometry

Fungal infections, especially invasive types, have become a serious healthcare problem as the immunocompromised population increases. There are five main classes of antifungal drugs: polyenes, flucytosine, allylamines, azoles, and echinocandins. Therapeutic drug monitoring (TDM) is justified for flucytosine and triazoles due to their large inter- and intra-individual pharmacokinetic variability and their high tendency for drug-drug interactions. Available methods for measuring these drugs include bioassay, liquid chromatography and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The LC-MS/MS approach is preferred due to its superior analytic sensitivity and specificity. In this review, we highlight TDM methods by LC-MS/MS for these antifungal drugs searchable in PubMed by December 1, 2018. LC-MS/MS methods that were developed for other purposes such as pharmacokinetics or toxicokinetics were also included. We have critically analyzed these methods with an emphasis on sensitivity, specificity, simplicity, throughput and robustness.

Quantitative Investigation of Terbinafine Hydrochloride Absorption into a Living Skin Equivalent Model by MALDI-MSI

The combination of microspotting of analytical and internal standards, matrix sublimation, and recently developed software for quantitative mass spectrometry imaging has been used to develop a high-resolution method for the determination of terbinafine hydrochloride in the epidermal region of a full thickness living skin equivalent model. A quantitative assessment of the effect of the addition of the penetration enhancer (dimethyl isosorbide (DMI)) to the delivery vehicle has also been performed, and data have been compared to those obtained from LC-MS/MS measurements of homogenates of isolated epidermal tissue. At 10% DMI, the levels of signal detected for the drug in the epidermis were 0.20 ± 0.072 mg/g tissue for QMSI and 0.28 ± 0.040 mg/g tissue for LC-MS/MS at 50% DMI 0.69 ± 0.23 mg/g tissue for QMSI and 0.66 ± 0.057 mg/g tissue for LC-MS/MS. Comparison of means and standard deviations indicates no significant difference between the values obtained by the two methods.

Analytical methods for determination of terbinafine hydrochloride in pharmaceuticals and biological materials

Terbinafine is a new powerful antifungal agent indicated for both oral and topical treatment of mycosessince. It is highly effective in the treatment of determatomycoses. The chemical and pharmaceutical analysis of the drug requires effective analytical methods for quality control and pharmacodynamic and pharmacokinetic studies. Ever since it was introduced as an effective antifungal agent, many methods have been developed and validated for its assay in pharmaceuticals and biological materials. This article reviews the various methods reported during the last 25 years.

Thin-film octadecyl-silica glass coating for automated 96-blade solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry for analysis of benzodiazepines

A thin-film octadecyl (C18)-silica glass coating was developed as the extraction phase for an automated 96-blade solid-phase microextraction (SPME) system coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Various factors (e.g., sol-gel composition and aging time, coating preparation speed, coating thickness, and drying conditions) affecting the quality of C18-silica glass thin-film coating were studied and optimized. The results showed that the stability and durability of the coating are functions of the coating thickness and drying conditions. Coating thickness is controlled by sol-gel composition, aging time and the withdrawal speed in the dipping method. Automated sample preparation was achieved using a robotic autosampler that enabled simultaneous preparation of 96 samples in a 96-well plate format. Under the optimum SPME conditions the proposed system requires a total of 140 min for preparation of all 96 samples (i.e., 30 min preconditioning, 40 min equilibrium extraction, 40 min desorption and 30 min carry over step). The performance of the C18-silica glass 96-blade SPME system was evaluated for high-throughput analysis of benzodiazepines from phosphate-buffered saline solution (PBS) and human plasma, and the reusability, repeatability, and validity of the system were evaluated. When analysing spiked PBS and human plasma, the inter-blade reproducibility for four benzodiazepines was obtained in the ranges of 4-8% and 9-11% RSD (relative standard deviation), respectively, and intra-blade reproducibility were in the ranges of 3-9% and 8-13% RSD, respectively. The limits of detection and quantitation for plasma analysis were in the ranges of 0.4-0.7 ng/mL and 1.5-2.5 ng/mL for all four analytes.