Simultaneous determination of disopyramide and its mono-N-dealkyl metabolite in plasma and urine by high-performance liquid chromatography

A rapid and sensitive liquid chromatography/tandem mass spectrometry assay for simultaneous quantitation of disopyramide and its major metabolite, mono-isopropyl-disopyramide, in rat plasma and its application to a pharmacokinetic study

Disopyramide as an antiarrhythmic agent has been used for treating ventricular tachycardia and metabolized into its major metabolite, mono-isopropyl-disopyramide, by CYP3A4. We developed a novel, selective, highly sensitive, accurate, rapid method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of disopyramide and mono-isopropyl-disopyramide in rat plasma. This study is the first report for the assay validation using LC-MS/MS in biological fluids after simple protein-precipitation method. The most sensitive signals by multiple reaction monitoring (MRM) showed at m/z 340.2 → 239.2 and 298.2 → 239.2 with same fragment ion for disopyramide and mono-isopropyl-disopyramide, respectively. The lower limit of quantification (LLOQ) was determined at 2 ng/mL for both analytes and the linear concentration ranges were found to be 2-2000 ng/mL for disopyramide and 2-1000 ng/mL for mono-isopropyl-disopyramide. Finally, this assay was successfully applied to pharmacokinetic analysis of disopyramide and mono-isopropyl-disopyramide after oral and intravenous administration of disopyramide.

Electrochemical behavior of disopyramide and its adsorptive stripping determination in pharmaceutical dosage forms and biological fluids

Electrochemical behavior of disopyramide (DPA) and optimum conditions to its quantitative determination were investigated using voltammetric methods. Some electrochemical parameters such as diffusion coefficient, surface coverage of adsorbed molecules, electron transfer coefficient, standard rate constant and number of electrons were calculated using the results of cyclic and square-wave voltammetry. All studies were based on the quasi-reversible and adsorption-controlled electrochemical reduction signal of DPA at about –1.60 V vs Ag|AgCl at pH 10.0 in Britton–Robinson buffer. This adsorptive character of molecule was used to develop fully validated, new, rapid, selective and simple square-wave cathodic adsorptive stripping voltammetric (SWCAdSV) method to the direct determination of DPA in pharmaceutical dosage forms and biological samples without time-consuming steps prior to drug assay. Peak current of electrochemical reduction of DPA was found to change linearly with the concentration in the range from 7.15 × 10–8 mol l–1 (0.024 mg l–1) to 1.43 × 10–6 mol l–1 (0.49 mg l–1). Limit of detection (LOD) and limit of quantification (LOQ) were found to be 5.65 × 10–8 mol l–1 (0.019 mg l–1) and 1.88 × 10–7 mol l–1 (0.064 mg l–1), respectively. The method was successfully applied to assay the drug in tablets, human serum and human urine with good recoveries at about 100%.

Automated determination of disopyramide and N-monodealkyldisopyramide in plasma by reversed-phase liquid chromatography with a column switching system

A rapid and simple column liquid chromatographic method involving a column switching system for the determination of disopyramide and its N-monodealkyl metabolite (NMD) in plasma is described. The deproteinized plasma is applied to an automated system. Purification and concentration were performed using a precolumn connected to a six-position valve; analytical separation was done on-line using a cyano reversed-phase column with a mobile phase consisting of 10 mmol/l trimethylamine (pH 2.5, adjusted with phosphoric acid)-acetonitrile-tetrahydrofuran (78:20:2, v/v/v). Absorbance was measured at 265 nm, with a minimum detectable amount of disopyramide and NMD of 0.1 micrograms/ml. The method can be applied to drug monitoring and pharmacokinetic studies.

Simplified, rapid and inexpensive extraction procedure for a high-performance liquid chromatographic method for determination of disopyramide and its main metabolite mono-N-dealkylated disopyramide in serum

A simplified, rapid and inexpensive extraction procedure for the determination of the antiarrhythmic drug disopyramide and its main metabolite mono-N-desalkylated disopyramide in serum by high-performance liquid chromatography has been developed. The analysis uses ultraviolet detection at 254 nm, and a 5 micron reversed-phase column with a mobile phase of water-triethylamine-acetonitrile-PIC-B8 reagent. Serum extraction is performed with dichloromethane and 1 M sodium hydroxide. p-Chlorodisopyramide is used as internal standard. Recovery rates were 94.5% (S.D. 5.7%) for disopyramide, 96.8% (S.D. 2.2%) for mono-N-desalkylated disopyramide and 97.9% (S.D. 2.8%) for the internal standard.

A HPLC method for the simultaneous determination of disopyramide, lidocaine and their monodealkylated metabolites

This paper describes a simple high-performance liquid chromatographic method for the determination of disopyramide and lidocaine simultaneously with their dealkylated metabolites. After basic tert-butyl methyl ether extraction and back-extraction with phosphoric acid, the drugs and their metabolites were injected into a Supelcosil CN column and the absorbance of the eluate was measured at 215 nm. The sensitivity was 0.3 mumol/l and the obtained precision, selectivity and stability during storage were adequate for the performed clinical studies in patients therapeutically treated with disopyramide and/or lidocaine. Some results from the clinical studies are briefly presented.

Drug level monitoring: cardiovascular drugs

Methods for the determination of cardiovascular drugs in blood and plasma are critically reviewed with emphasis on gas and liquid chromatographic techniques. The importance of the various procedures is discussed, in particular sample work-up where the conditions for isolation and derivatization of the compounds are decisive for the accuracy and precision of the methods. Compared with other assay techniques chromatographic methods are generally to be preferred owing to their better selectivity. In the review the following groups are discussed: digitalis glycosides, antiarrhythmic agents, beta-adrenoceptor antagonists, vasodilating agents, antihypertensive compounds, and diuretics.

Simultaneous quantitation of disopyramide and its mono-dealkylated metabolite in human plasma by fused-silica capillary gas chromatography using nitrogen-phosphorus specific detection

A nitrogen-specific detector gas-liquid chromatographic assay method is reported which provides improved selectivity and sensitivity for disopyramide and its mono-N-dealkylated metabolite using a crosslinked fused-silica capillary column. The quantitation of disopyramide and mono-N-dealkylated disopyramide was accomplished by injecting trifluoroacetic anhydride-treated samples containing derivatized internal standard p- chlorodisopyramide , into a gas chromatograph equipped with a nitrogen--phosphorus detector and an automatic liquid sampler. A 25 m X 0.31 mm crosslinked, 5% phenylmethyl silicone-coated fused-silica column was utilized and samples were injected using the splitless injection mode. Linearity was observed in the range 0.05-5.00 micrograms/ml for disopyramide and 0.02-3.00 micrograms/ml for the mono-N-dealkylated metabolite. The coefficient of variation was found to be within 10% for both compounds in the concentration range studied.

Derivatization reactions in the gas—liquid chromatographic analysis of drugs in biological fluids

Alkylation, acylation, silylation and other derivatization reactions applied to the gas chromatographic analysis of drugs in biological matrices are reviewed. Reaction conditions are discussed in relation to reaction mechanisms. Detector-oriented labelling of drugs, and derivatization with chiral reagents for the separation of enantiomers are surveyed. Data on the sample clean-up, derivatization and GLC analysis of more than 300 drugs and related compounds are listed.