Highly specific and sensitive liquid chromatography-tandem mass spectrometry method for the determination of 3-desmethylthiocolchicine in human plasma as analyte for the assessment of bioequivalence after oral administration of thiocolchicoside

RP-LC gradient elution method for simultaneous determination of thiocolchicoside, aceclofenac and related impurities in tablet formulation

Objective:

The aim of the present study is to develop a simple and precise HPLC method for simultaneous determination of thiocolchicoside, aceclofenac and related impurities in a tablet formulation and validate as per ICH guidelines. The aim of study extends to perform forced degradation study to trace the degradation pathways of potential degradant impurities.

Materials and Methods:

The separation was achieved on a 4.6 mm × 100 mm, 3 μm C₁₈ column at 40°C with the mobile phase containing 0.1 M ammonium acetate buffer and methanol in a gradient mode at a flow rate of 1.0 mL min⁻¹. The UV detection was carried out at 257 nm.

Results:

Acelofenac, thiocolchicoside and their related compounds were well separated from each other with good resolution and symmetry factor without interference of excipients. The method for assay was linear in the range of 10-200 μg mL⁻¹ for aceclofenac and 0.4 to 8 μg mL⁻¹ for thiocolchicoside.

Conclusion:

The method was validated according to ICH guidelines and the acceptance criteria for accuracy, precision, linearity, specificity, robustness, ruggedness and system suitability were met in all cases. The method was highly specific, as two related compounds of thiocolchicoside and nine related compounds of aceclofenac were well separated from each other. Stress study ensured the specificity of the method as the unknown degradation products formed during stress studies did not interfere with the determination of thiocolchicoside and aceclofenac, thus proving the stability indicating capacity of the method.

Stability Studies of Thiocolchicoside in Bulk and Capsules Using RP-HPTLC/Densitometry

A new stability-indicating reversed-phase high-performance thin-layer chromatographic (RP-HPTLC) method for densitometric analysis of thiocolchicoside was developed and validated. The chromatograms were developed using aluminum plates pre-coated with silica gel 60 RP-18 F254S as a stationary phase and methanol : water (70 : 30 v/v) as a mobile phase. The compact band for thiocolchicoside was observed at R f value of 0.60 ± 0.02 at an absorption wavelength of 377 nm. The linear regression data for the calibration plots (r (2) = 0.9984) was found with respect to peak area in the concentration range of 100-600 ng per band. The limit of detection (LOD) and limit of quantification (LOQ) were 9.77 ng and 29.63 ng, respectively. The drug was exposed to acidic and alkaline hydrolysis, oxidation, photo degradation, and dry heat conditions. The peaks of degradation products were well-resolved from the peak of the standard drug with significantly different R f values. Statistical analysis proved that the established RP-HPTLC method is reproducible, selective, and accurate for the determination of thiocolchicoside in its formulations. The method can effectively separate the drug from its degradation products, and it can be considered as stability-indicating assay.

Development and validation of UV-Visible spectrophotometric baseline manipulation methodology for simultaneous analysis of drotraverine and etoricoxib in pharmaceutical dosage forms

Introduction:

A simple, economical, precise, and accurate new UV spectrophotometric baseline manipulation methodology for simultaneous determination of drotaverine (DRT) and etoricoxib (ETR) in a combined tablet dosage form has been developed.

Materials and Methods:

The method is based on baseline manipulation (difference) spectroscopy where the amplitudes at 274 and 351 nm were selected to determine ETR and DRT, respectively, in combined formulation and methanol was used as solvent. Both the drugs obey Beer's law in the concentration ranges of 4–20 μg/mL for DRT and 4.5–22.5 μg/mL for ETR.

Results:

The results of analysis have been validated statistically and recovery studies confirmed the accuracy and reproducibility of the proposed method which were carried out by following the ICH guidelines.

Conclusion:

It has been concluded that a new simple and accurate UV spectrophotometric baseline manipulation method was developed for simultaneous do not declare DRT and ETR in a combined tablet dosage form has been developed.

Development and validation of a HPTLC method for simultaneous estimation of lornoxicam and thiocolchicoside in combined dosage form

Aim:

To develop a simple, precise, rapid and accurate HPTLC method for the simultaneous estimation of Lornoxicam (LOR) and Thiocolchicoside (THIO) in bulk and pharmaceutical dosage forms.

Materials and Methods:

The separation of the active compounds from pharmaceutical dosage form was carried out using methanol:chloroform:water (9.6:0.2:0.2 v/v/v) as the mobile phase and no immiscibility issues were found. The densitometric scanning was carried out at 377 nm. The method was validated for linearity, accuracy, precision, LOD (Limit of Detection), LOQ (Limit of Quantification), robustness and specificity.

Results:

The R_f values (±SD) were found to be 0.84 ± 0.05 for LOR and 0.58 ± 0.05 for THIO. Linearity was obtained in the range of 60–360 ng/band for LOR and 30–180 ng/band for THIO with correlation coefficients r² = 0.998 and 0.999, respectively. The percentage recovery for both the analytes was in the range of 98.7–101.2 %.

Conclusion:

The proposed method was optimized and validated as per the ICH guidelines.

Rapid and sensitive liquid chromatography–tandem mass spectrometry method for the quantitation of colchicine in human plasma

A rapid and sensitive method to determine colchicine in human plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Colchicine and the internal standard (I.S.), tegafur, were extracted from the matrix with n-hexane:dichloromethane:isopropanol (300:150:15, v/v/v) and separated by reversed-phase high-performance liquid chromatography (HPLC) using formic acid:10 mM ammonium acetate:methanol (1:49:75, v/v/v) as the mobile phase in a run time of 2.5 min. Detection was carried out by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring (MRM) mode. The assay was linear in the concentration range 0.050-10 ng/ml with intra- and inter-day precision (as relative standard deviation (R.S.D.)) of <2 and <7%, respectively. The method was applied to a pharmacokinetic study of colchicine in healthy volunteers given an oral dose of 2.0 mg.

New metabolic and pharmacokinetic characteristics of thiocolchicoside and its active metabolite in healthy humans

Thiocolchicoside (TCC) has been prescribed for several years as a muscle relaxant drug, but its pharmacokinetic (PK) profile and metabolism still remain largely unknown. Therefore, we re-investigated its metabolism and PK, and we assessed the muscle relaxant properties of its metabolites. After oral administration of 8 mg (a therapeutic dose) of 14C-labelled TCC to healthy volunteers, we found no detectable TCC in plasma, urine or faeces. On the other hand, the aglycone derivative obtained after de-glycosylation of TCC (M2) was observed and, in addition, we identified, as the major circulating metabolic entity, 3-O-glucuronidated aglycone (M1) obtained after glucuro-conjugation of M2. One hour after oral administration, M1 plus M2 accounted for more than 75% of the circulating total radioactivity. The pharmacological activity of these metabolites was assessed using a rat model, the muscle relaxant activity of M1 was similar to that of TCC whereas M2 was devoid of any activity. Subsequently, to investigate the PK profile of TCC in human PK studies, we developed and validated a specific bioanalytical method that combines liquid chromatography and ultraviolet detection to assay both active entities. After oral administration, TCC was not quantifiable with an lower limit of quantification set at 1 ng/mL, whereas its active metabolite M1 was detected. M1 appeared rapidly in plasma (tmax=1 h) and was eliminated with an apparent terminal half-life of 7.3 h. In contrast, after intramuscular administration both active entities (TCC and M1) were present; TCC was rapidly absorbed (tmax=0.4 h) and eliminated with an apparent terminal half-life of 1.5 h. M1 concentration peaked at 5 h and this metabolite was eliminated with an apparent terminal half-life of 8.6 h. As TCC and M1 present an equipotent pharmacological activity, the relative oral pharmacological bioavailability of TCC vs. intramuscular administration was calculated and represented 25%. Therefore, to correctly investigate the PK and bioequivalence of TCC, the biological samples obtained must be assayed with a bioanalytical method able to specifically analyse TCC and its active metabolite M1.

Determination of thiocolchicoside in its binary mixtures (thiocolchicoside-glafenine and thiocolchicoside-floctafenine) by TLC-densitometry

The proposed method is based on TLC separation of thiocolchicoside from its binary mixtures (thiocolchicoside-glafenine and thiocolchicoside-floctafenine) followed by densitometric measurement at 375 nm. Separation was carried out on silica gel plates GF(254) using ethyl acetate:methanol:acetic acid (84:13:3%, v/v/v). Various conditions affecting separation and measurement were studied and optimized. Calibration was performed using third-order polynomial equation. It was found superior to first-order with respect to quantification range (0.25-25 microg per spot), correlation coefficient and standard error of estimation. The proposed method was successfully applied for the determination of thiocolchicoside in its synthetic binary mixtures and commercial tablets. Results were compared with those obtained by reference methods and non-significant difference was obtained regarding accuracy and precision. Assay precision using two-way ANOVA was performed on results of inter- and intra-day applications of the method.