Disopyramide In Serum Research Articles

High-Performance Liquid Chromatography with Chemiluminescence Detection of Disopyramide in Human Serum

High-Performance Liquid Chromatography with Chemiluminescence Detection of Disopyramide in Human Serum

Determination of free disopyramide in blood serum in situ using a disopyramide-sensitive membrane electrode

Free disopyramide levels in blood serum, the monitoring of which is especially effective for antiarrhythmic therapy, were determined in situ using a disopyramide-sensitive membrane electrode. Sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate was incorporated as the ion-exchanger and 2-fluoro-2′-nitrodiphenyl ether as the solvent mediator in a poly(vinyl chloride) membrane matrix to form the electrode. The lower limit of the detection for free disopyramide in serum was 0.8 μM. The free disopyramide concentrations measured by the ion-selective electrode agreed well with those determined by an established fluorescence polarization immunoassay that requires an additional ultrafiltration procedure to remove disopyramide bound to serum protein.

Altered Alpha-1-acid Glycoprotein Concentration and Free Fraction of Disopyramide in Patients with Heart Disease.

Alpha-1-acid glycoprotein (AAG) concentration and protein binding of disopyramide (DSP) in serum were measured in patients with heart disease. An increase in AAG (121±45mg/dl, mean±SD) was fbund in padents with heart failure as compared with healthy controls (73±14) and with cardiac patients without heart failure (78±12). The free fraction of DSP (0.35±0.12) was decreased in patients with heart failure as compared with control (0.56±0.11) and with patients without heart failure (0.47±0.15). The values of the heart failure patients returned to the level of cardiac patients with out heart failure (89±23 mg/dl and 0.48±0.07) with recovery from the decompensated stage. These findings suggest that the free concentration of DSP should be monitored frequently in cardiac patients, especially in patients with congestive heart failure.

ジソピラミドの経口投与後の臨床薬物動態と治療効果

The clinical pharmacokinetics of disopyramide (DP) were studied after single oral adminis tration of 200, 300 or 350 mg to healthy subjects and patients suffering from arrhythmia. The mean peak concentration of DP in serum (Cmax) was 3.98μg/ml, observed at a mean of 1.65h (tmax) after oral administration of 300 mg in the healthy subjects, and was 2.96μg/ml at 2.65h in the patients. The elimination rate constant (kel) and oral clearance (Cl/F) in the patients were significantly lower than those in the healthy subjects (0.144h-1 vs. 0.099h-1 for kel (p<0.05) and 9.11l/h vs. 6.14l/h for Cl/ F (p<0.05), respectively). Oral clearance was significantly correlated with creatinine clearance in the patients.DP treatment was effective in three of four patients suffering from premature ventricular contractions and in all four patients suffering from premature atrial contractions, in whom the effective level of DP was 1.4μg/ml. DP treatment was also effective in four of nine patients suffering from atrial fibrillation, in whom the effective level of DP was more than 1.9μg/ml. However, the minimum effective level of DP varied widely among the patients, thus necessitating monitoring of the serum DP concentration for effective treatment of arrhythmia.

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 μm 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.

Quantitative and qualitative binding characteristics of disopyramide in serum from patients with decreased renal and hepatic function.

Protein binding of disopyramide, binding capacities, affinity constants and serum concentrations of alpha 1-acid glycoprotein (AAG) were studied in five groups of patients. A: young healthy volunteers (n = 8); B: elderly patients with minor symptoms of ischaemic heart disease (n = 9); C: patients with cirrhosis of the liver and normal values of coagulation factors (II, VII and X), albumin and immunoglobulin G (n = 8); D: patients with cirrhosis and at least two abnormal of the previously mentioned values (n = 9) and E: eleven patients with severely impaired renal function. Subfractions of AAG (Fr1, Fr2 and Fr3) were determined by affinoimmunoelectrophoresis. AAG concentration was significantly (P less than 0.005) elevated in group E patients and decreased (P less than 0.025) in group D patients. Fr2 is probably associated with the high affinity, first binding site of disopyramide to AAG. Earlier observations of a reduced qualitative binding of disopyramide in patients with cirrhosis can be explained by a significant decrease in Fr2 (P less than 0.001) in group D patients. The protein binding of disopyramide in patients with uraemia was significantly increased due to a significant (P less than 0.005) increase in AAG concentration in spite of a smaller (P less than 0.025) affinity constant. Suggestions for therapeutic drug monitoring based on total serum concentrations are given.

Homogeneous substrate-labeled fluorescent immunoassay for disopyramide in human serum: semi- and fully automated procedures.

In this immunoassay for disopyramide in serum, to form the label, disopyramide is covalently attached to a fluorogenic enzyme substrate, 7-beta-galactosylcoumarin-3-carboxylic acid, which is nonfluorescent under the conditions of the assay. Hydrolysis, catalyzed by beta-galactosidase, yields a fluorescent product. As a result of competitive protein binding reactions between drug and label for limited antibody binding sites, this fluorescence is proportional to disopyramide concentration. The assay is sensitive to less than 0.5 mg of disopyramide per liter. Results obtained with either the semi-automated procedure (Ames TDA) or the fully automated (Optimate) procedure correlated well with those obtained by liquid chromatography (r = 0.98 and 0.99). For commercial controls containing various concentrations of the drug, the respective coefficients of correlation were 1.00 and 0.99 for the TDA and Optimate procedures. Within-run CVs for the two procedures were less than or equal to 5.1%, overall CVs less than or equal to 6.5%.

Protein Binding of Disopyramide and Elevated Alpha-1-Acid Glycoprotein Concentrations in Serum Obtained from Dialysis Patients and Renal Transplant Recipients

A rapid ultrafiltration technique was used to measure the free (unbound) fraction of disopyramide in serum obtained from 14 normal volunteers, 6 chronic hemodialysis patients, and 10 renal transplant recipients. The disopyramide-free fraction varied more than tenfold at a corresponding total (free plus bound) serum disopyramide concentration of 3 micrograms/ml and was related to the concentration of an acute-phase protein, alpha-1-acid glycoprotein (AAG), in patient serum. Moreover, disopyramide-free fraction values were nearly twofold lower than normal in serum specimens obtained from those renal patients and transplant recipients with corresponding AAG serum concentrations greater than 100 mg/100 ml. AAG concentrations varied tenfold in patient serum and were on average nearly three times higher than AAG concentrations in normal volunteer serum. These findings suggested that the free fraction of disopyramide and possibly other drugs which bind extensively to AAG may be lower, and the interpatient variability in drug binding may be much more pronounced in serum obtained from hemodialysis patients and transplant recipients than previously recognized.

Enzyme immunoassay of disopyramide in serum.

Disopyramide, an antiarrhythmic drug, was quantitated in serum by a commercially supplied enzyme immunoassay procedure. Replicate analyses of serum controls resulted in a within-assay coefficient of variation of less than or equal to 5% and a between-assay coefficient of variation of less than or equal to 7%. Regression analysis of 105 serum samples analyzed by this technique (y) and by gas chromatography (x) gave the equation y = 0.99x + 0.04 (r = 0.97). Clinical evaluation of the results indicates the enzyme immunoassay technique to be highly specific and sensitive for disopyramide. The selectivity of the assay vs other drugs has been determined.

Gas-chromatographic determination of disopyramide in serum, with use of a nitrogen-selective detector.

In this procedure for disopyramide in serum, the drug is extracted into n-heptane/isobutanol (96/4 by vol), then back-extracted into 1 mol/L H2SO4. The acidic solution is made basic with sodium hydroxide, extracted with diethyl ether, and the extract evaporated. The residue is redissolved in ethanol and analyzed by gas-chromatography, with use of a nitrogen-selective detector. p-Chlorodisopyramide is used as internal standard. Concentration and instrument response for serum extracts are linearly related from 1 to 5 mg/L, the slope being 0.61, the y-intercept -0.10, the standard error of estimate 0.01, and the correlation coefficient 0.99. Within-run precision was 6 and 4% for 3 and 5 mg/L concentrations, respectively, with a between-run precision of 7% at the 3 mg/L concentration. Diazepam interferes, but procainamide, chlordiazepoxide, quinidine, lidocaine, propranolol, sulfanilamide, and many other basic drugs do not.

Quantitative high-performance liquid-chromatographic method for determining disopyramide (Norpace) in serum.

We report a high-performance liquid-chromatographic method for measuring disopyramide (Norpace, Searle) in serum. The drug is extracted from 0.5 ml of serum into chloroform containing the internal standard p-chlorodisopyramide, separated on a reversed-phase octadecylsilyl column at room temperature, and detected at 254 nm. The method is sensitive to 0.2 mg of disopyramide per liter, with a linear response to at least 10 mg/liter. Within-day precision (CV) for frozen serum pools is 8.3 (n = 21) and (n = 22) at mean concentrations of 2.6 and 5.9 mg/liter, respectively. Day-to-day precision (CV) is 9.4 (n = 80) and 9.3 (n = 29) at mean concentrations of 2.8 and 6.7 mg/liter, respectively. Recoveries for disopyramide in serum averaged 98% over the linear range when compared against an aqueous standard taken through the entire analytical procedure. The method is relatively specific, as evidenced by interference studies with over 85 drugs.

Simple gas-liquid chromatographic method for the measurement of disopyramide in blood-plasma or serum and in urine

A simple method has been developed for the measurement of disopyramide in blood-plasma or serum at the concentrations attained during therapy. A relatively small (200 μl) sample volume is made basic and extracted with 50 μl of chloroform containing an internal standard, and the extract is analysed directly by gas-liquid chromatography with flame-ionization detection. The instrument calibration is linear and passes through the origin of the graph. Neither solvent transfer nor evaporation steps are used in the extraction procedure, which takes less than 3 min to complete, and urine specimens may be analysed by an analogous technique. No interference from either endogenous sample constituents or other drugs has been observed, although a simple back-extraction procedure is described which eliminates potential interference from a small number of basic and neutral drugs.

Gas—liquid chromatographic method for the routine estimation of disopyramide in plasma or serum

A rapid, sensitive and specific gas—liquid chromatographic method is presented for the routine monitoring of plasma concentrations of the anti-arrhythmic compound, dispyramide. The procedure involves extraction of the drug from alkaline plasma into ether, purification of the extract and gas chromatographic analysis using OV-101 liquid phase and flame ionization detection. The results demonstrate the accuracy and reproducibility of the method. Contrary to a previous report, it has been shown that delay in separating plasma from erythrocytes does not affect the disopyramide level in plasma.