P115 Reversed-phase high-performance liquid chromatography as rapid and simple method for quantifications of terbinafine drug in human serum from dermatophytosis cases
Authors: Thakur Sheetal , Shaw Dipika , Narang Tarun , Dogra Sunil , Kaur Harsimran , Ghosh Anup K , Rudramurthy Shivaprakash M. 
Published: September 2022

Abstract

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

Objectives
The alarming situation of treatment failure cases in dermatophytosis and resistance to the first-line drug (terbinafine) is a worrisome condition for the management of tinea cases. However, studies also reported non-responders to terbinafine treatment even when the isolates are susceptible to this drug in vitro. Thus, evaluating the pharmacokinetic profile of terbinafine might help better manage dermatophytosis. This study was conducted to standardize and validate a rapid and simple reversed-phase high-performance liquid chromatography (HPLC)-based protocol for terbinafine in serum/plasma of dermatophytosis cases.

Methods
HPLC analysis was standardized for terbinafine drug on an Agilent 1290 infinity system (Agilent Technologies InC., USA). Chromatographic parameters including mobile phase [acetonitrile (A), methanol (M), and water (W)], flow rate (0.7-1.5 ml/min), injection volume (20 μl), and various wavelengths ranging from 220 to 265 nm under isocratic conditions were assessed and optimized. The mobile phase consisted of a filtered and degassed mix of A: W and M: W with various ratios of 85:15, 60:40, 50:50, and M-100%, respectively. Quality control samples were prepared in drug-free serum by spiking with the terbinafine at 0.0312-100 μg/mL concentrations. An equal volume of serum and acetonitrile (A) were mixed. The mixture was vigorously vortexed for 30 s, followed by high-speed centrifugation at 13 000 rpm at 40°C for 10 min. The supernatant was transferred into the chromatographic vials and placed in the autosampler of HPLC for injection. The standardized method was tested in 6 dermatophytosis patients’ serum/plasma samples collected at 3-time points (first, second, and third week of start of antifungal).

Results
Linearity of calibration standard for terbinafine was optimized at 250C at a flow rate of 1.0 ml/min, injection volume 20 μl, 8 minutes run time with the standardized wavelength at 245 nm under isocratic conditions. The best suitable graph was determined by plotting the area under the curve (AUC) and peak height separately against the drug concentrations measured by reversed-phase- HPLC for terbinafine drugs (Fig. 1a and b). The standardized mobile phase consisted of filtered and degassed Methanol (100, v/v). The chromatographic separation was achieved on an Agilent C18 column, and 4.3 ± 1 time represents the peak for terbinafine drug. Based on the standardized protocol, six tinea cases were included for validation, and the therapeutic range achieved for terbinafine in clinical samples was 0.6 to 1.13 μg/ml.

Conclusions
The standardization of HPLC method was successfully applied to quantify terbinafine in spiked samples with terbinafine drug and showed no observable interferences at the standardized parameter. Further evaluation with larger number of samples is warranted.