An automated streamlined method for the therapeutic drug monitoring of digoxin based on the online-solid-phase extraction liquid chromatography tandem high-resolution mass spectrometry

RATIONALE

Digoxin is widely used in the clinical treatment of cardiovascular diseases. However, due to its extremely narrow therapeutic window, therapeutic drug monitoring (TDM) is vitally important. In consideration of the time-consuming and labor-intensive nature of the traditional techniques, an automated and efficient method was required for the clinical individualized TDM of digoxin.

METHODS

An online solid-phase extraction liquid chromatography tandem high-resolution mass spectrometry (online-SPE-LC-HRMS) method was developed and applied for the determination of digoxin in plasma. The online SPE-LC steps included pretreatment and separation of plasma samples that were carried out using a Waters Oasis HLB cartridge and XBridge Shield RP18 column, respectively. A high-resolution Q Orbitrap mass spectrometer with targeted-selected ion monitoring in negative scan mode was applied to monitor formate-adduct ions [M + HCOO]^- m/z 825.42781 for digoxin.

RESULTS

Linearity was shown over the range 0.1-10 ng mL^-1 for digoxin with correlation coefficients of R²  > 0.999. The lower limit of quantitation (LLOQ) for digoxin was 0.1 ng mL^-1 . Extraction recoveries ranged from 82.61% to 94.28% for digoxin. The intra- and inter-day precision values were < 5.53% with accuracy ranging from 84.97% to 96.75%. The total running time was 10 min for each sample.

CONCLUSION

The established method displayed satisfactory recoveries, accuracy, precision, and stability, and successfully applied on the TDM of digoxin. This automated streamlined method provides a powerful tool to guide the individualized administration of digoxin, which is significant for the practice of precision medicine.

Antiarrhythmic Properties of Elsholtzia ciliata Essential Oil on Electrical Activity of the Isolated Rabbit Heart and Preferential Inhibition of Sodium Conductance

Elsholtzia ciliata essential oil (E. ciliata) has been developed in Lithuania and internationally patented as exerting antiarrhythmic properties. Here we demonstrate the pharmacological effects of this herbal preparation on cardiac electrical activity. We used cardiac surface ECG and a combination of microelectrode and optical mapping techniques to track the action potentials (APs) in the Langendorff-perfused rabbit heart model during atrial/endo-/epi-cardial pacing. Activation time, conduction velocity and AP duration (APD) maps were constructed. E. ciliata increased the QRS duration and shortened QT interval of ECG at concentrations of 0.01-0.1 μL/mL, whereas 0.3 μL/mL (0.03%) concentration resulted in marked strengthening of changes. In addition, the E. ciliata in a concentration dependent manner reduced the AP upstroke dV/dtmax and AP amplitude as well as APD. A marked attenuation of the AP dV/dtmax and a slowing spread of electrical signals suggest the impaired functioning of Na+channels, and the effect was usedependent. Importantly, all these changes were at least partially reversible. Our results indicate that E. ciliata modulates cardiac electrical activity preferentially inhibiting Na+ conductance, which may contribute to its effects as a natural antiarrhythmic medicine.

Arnebiae Radix prevents atrial fibrillation in rats by ameliorating atrial remodeling and cardiac function

ETHNOPHARMACOLOGICAL RELEVANCE

Arnebiae Radix, a common herbal medicine in China, is often utilized to treat blood-heat syndrome and has been reported to exert an effect on the heart.

AIM OF THE STUDY

The combination of acetylcholine (Ach) and CaCl₂ has been widely used to induce atrial fibrillation (AF) in animals. However, whether Arnebiae Radix displays any preventive action on Ach-CaCl₂ induced AF in rats remains uncertain. In our study, we attempted to investigate the protective effects of Arnebiae Radix on Ach-CaCl₂ induced AF compared to amiodarone, which was employed as the positive control.

MATERIALS AND METHODS

To establish the AF model, SD rats were treated with a mixture of 0.1 mL/100 g Ach-CaCl₂ (60 μg/mL Ach and 10 mg/mL CaCl₂) by tail vein injection for 7 days. Rats were also given a gavage of Arnebiae Radix (0.18 g/mL) one week before or concurrently with the establishment of the AF model. At the end of the experimental period, the induction, duration and timing of AF were monitored using electrocardiogram recordings. Left atrial tissues were stained to observe the level of fibrosis. Electrophysiological measurements were used to examine atrial size and function.

RESULTS

In Ach-CaCl₂-induced AF rats, Arnebiae Radix decreased AF induction, duration and susceptibility to AF. In addition, Arnebiae Radix significantly reduced atrial fibrosis and inhibited atrial enlargement induced by Ach-CaCl₂. Moreover, there was an apparent improvement in cardiac function in the Arnebiae Radix-treated group.

CONCLUSIONS

Our findings indicate that Arnebiae Radix treatment can attenuate Ach-CaCl₂-induced atrial injury and serve as an effective therapeutic strategy for the treatment of AF in the future.

An impact of the ring substitution in nicorandil on its adsorption on silver nanoparticles. Surface-enhanced Raman spectroscopy studies

The substituent effect on structure and surface activity of biologically active nicorandil was investigated by means of surface-enhanced Raman spectroscopy (SERS). Vibrational characterization was a basis for investigation of the adsorption profile of nicorandil and 1-methylnicorandil on silver nanoparticles. An assignment of SERS bands was performed by the comparison of the Raman spectra of both compounds in the solid state and in solutions, complemented by DFT calculations. Even though the nitro group was found to be the most attractive to the silver surface, the strong impact of the methyl substituent changed this preferable adsorption mechanism in 1-methylnicorandil. Protonation of the nitrogen atom in the pyridinium ring was also found to have an impact on absorption mechanism.

Protective effects of saffron (Crocus sativus) against lethal ventricular arrhythmias induced by heart reperfusion in rat: a potential anti-arrhythmic agent

CONTEXT

Saffron (Crocus sativus L.) has been used as a cuisine spice in eastern and western societies for thousands of years. In traditional medicine, saffron is recommended for the treatment of various kinds of disorders including heart palpitations.

OBJECTIVE

We investigated the hypothesis of the protective effect of saffron on lethal cardiac arrhythmias induced by heart ischemia-reperfusion in rat.

MATERIALS AND METHODS

Animals were divided into a control (CTL) group that received tap water, Saf50, Saf100 and Saf200 groups that were orally treated with aqueous extracts of saffron, at dosages of 50, 100 and 200 mg/kg/day, respectively, and amiodarone (Amio) group that orally received 30 mg/kg/day for seven days. On day 8, heart ischemia-reperfusion was induced by ligation and releasing of the left anterior descending coronary artery.

RESULTS

During reperfusion, the numbers and durations of ventricular fibrillation (VF) decreased in all groups compared to the CTL group (p < 0.05). Ventricular tachycardia (VT)/VF numbers (3.2 ± 1.2), durations (4.9 ± 2.6) and also arrhythmia severity (1.9 ± 0.35) were decreased significantly in the Saf100 group versus CTL group values (18.4 ± 11.6, 52 ± 31 and 3.3 ± 0.3, respectively). The PR and QTcn intervals of ECG were significantly longer in the Saf200 group (p < 0.001 versus CTL). The other doses of saffron only significantly prolonged the QTcn interval.

CONCLUSION

The results suggest that pretreatment with saffron, especially at the dosage of 100 mg/kg/day, attenuates the susceptibility and incidence of fatal ventricular arrhythmia during the reperfusion period in the rat. This protective effect is apparently mediated through reduction of electrical conductivity and prolonging the action potential duration.

Effect of daurisoline on HERG channel electrophysiological function and protein expression

Daurisoline (1) is a bis-benzylisoquinoline alkaloid isolated from the rhizomes of Menispermum dauricum. The antiarrhythmic effect of 1 has been demonstrated in different experimental animals. In previous studies, daurisoline (1) prolonged action potential duration (APD) in a normal use-dependent manner. However, the electrophysiological mechanisms for 1-induced prolongation of APD have not been documented. In the present study, the direct effect of 1 was investigated on the hERG current and the expression of mRNA and protein in human embryonic kidney 293 (HEK293) cells stably expressing the hERG channel. It was shown that 1 inhibits hERG current in a concentration- and voltage-dependent manner. In the presence of 10 μM 1, steady-state inactivation of V(1/2) was shifted negatively by 15.9 mV, and 1 accelerated the onset of inactivation. Blockade of hERG channels was dependent on channel opening. The expression and function of hERG were unchanged by 1 at 1 and 10 μM, while hERG expression and the hERG current were decreased significantly by 1 at 30 μM. These results indicate that 1, at concentrations below 30 μM, exerts a blocking effect on hERG, but does not affect the expression and function of the hERG channel. This may explain the relatively lower risk of long QT syndrome after long-term usage.

[Antiarrhythmic effect of ethyl acetate extract from Chrysanthemum Morifolium Ramat on rats]

OBJECTIVE

To investigate the effect of ethyl acetate extract from Chrysanthemum Morifolium Ramat (CME) on experimental arrhythmia induced by ischemia/reperfusion or aconitine in rats and to explore its underlying mechanisms.

METHODS

Arrhythmia model in intact rat was induced by aconitine (30 microg/kg body weight, i.v.). In isolated Langendorff perfused rat hearts, regional ischemia and reperfusion was induced by ligation and release of left anterior descending artery. The ventricular fibrillation threshold (VFT), effective refractory period (ERP), and diastolic excitation threshold (DET) in the isolated heart were measured. The action potentials of papillary muscle in rat right ventricle were recorded by conventional glass microelectrode technique.

RESULTS

Compared with control group CME significantly decreased the number and duration of ventricular tachycardia (VT); delayed the occurrence of ventricular premature beats (VPB) and VT induced by aconitine. Arrhythmia score of the CME group was lower than that in aconitine-treated group. CME markedly prolonged the ERP and increased the VFT in the isolated perfused rat hearts during ischemia and reperfusion. CME prolonged action potential duration at 50% and 90% repolarization of the right ventricular papillary muscles and decreased the maximal rate of rise of the action potential upstroke, but did not affect the resting potential, amplitude of action potential.

CONCLUSION

CME can reduce myocardial vulnerability and exerts its antiarrhythmic effects induced by aconitine or ischemia/reperfusion, which may be related to its prolongation of action potential duration and effective refractory period that enhance the electrophysiological stability of myocardiaium.

[HPLC fingerprint of the antiarrhythmic fraction of Valeriana officinalis]

OBJECTIVE

To establish HPLC fingerprints of the Antiarrhythmic fraction of Valeriana officinalis.

METHODS

Agilent C18 (250 mm x 4.6 mm, 5 microm) column was used and the acetonitrile-water was chosen as the mobile phase in a gradient mode. The column temperature was 380 degrees C and the detection wavelength was 218 nm. The detection time was 70 min, and the flow rate was 1.0 mL/ min.

RESULTS

Fifteen characteristic peaks were indicated in HPLC fingerprints. The relative retention time and the ranges of relative areas of the common peaks were also determined.

CONCLUSION

This method is simple and accurate with a good reproducibility and provides a reference standard for the quality control of Valeriana officinalis.

[Cardioprotective and antiarrhythmic properties of preparations from Leuzea carthamoides, Aralia mandshurica, and Eleutherococcus senticosus]

It is established that pretreatment with Leuzea carthamoides extract (LCE) (1 ml/kg per os during 8 days) prevents the development of stress-induced (6-hr painful-emotional stress) damage of the rat heart. A chronic administration of LCE (1 ml/kg per os during 8 days) increased the cardiac tolerance to the cardiotoxic action of D, L-isoproterenol and the arrhythmogenic action of epinephrine. Pretreatment with naloxone (2 mg/kg) completely eliminated the cardioprotective effect LCE and attenuated but not abolished the antiarrhythmic effect of the phytoadaptogen. A chronic administration of LCE elevated the level of beta-endorphin levels in the rat blood plasma. It is suggested that the cardioprotective effect of LCE is related to an increase in the level of opioid peptides, which produce stimulation of the opioid receptors. It is also established that preliminary chronic administration of Aralia mandshurica extract (AME) increases the cardiac resistance to the arrhythmogenic action of a 45-min coronary artery occlusion, but has no effect on the necrosis/risk area ratio. A pretreatment with Eleutherococcus senticosus extract (ESE) (1 ml/kg per os during 8 days) prevented the stress-induced damages of the rat heart. A chronic administration of ESE increased the cardiac tolerance to the cardiotoxic action of D, L-isoproterenol and the arrhythmogenic action of epinephrine. The pretreatment with naloxone (2 mg/kg) completely eliminated both the cardioprotective action and the antiarrhythmic effect of the phytoadaptogen. A chronic administration of ESE increased the beta-endorphin level in the rat blood plasma. It is suggested that the cardioprotective and antiarrhythmic effects of ESE is also related to an increase in the endogenous opioid peptide levels. A chronic administration of ESE had no effect on the arrhythmogenic effect of a 45-min coronary artery occlusion and did not change the necrosis/risk area ratio in rats.

[Effects of CASI on myocardial ischemia-reperfusion arrhythmia in rats]

OBJECTIVE

To observe the protective effect of compound acanthopanax senticosus injection (CASI) on myocardial ischemia-reperfusion arrhythmia in rats.

METHOD

The myocardial ischemia-reperfusion model was induced by 30 min coronary occulusion and 60 min reperfusion in openchest anesthetized rats. The changes of arrhythmia with electrocardiogram lead II, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), the contents of malondialdehyde (MDA) and Ca2+ in myocardium were determined.

RESULT

In rats treated by CASI (in a dosage of 25, 50 and 100 mg x kg(-1) femoral vein infusion at 30 min after coronary occulusion), the incidence of myocardial ischemia-reperfusion ventricular arrhythmias, for instance the ventricular tachycardia (VT) and ventricular fibrillation (Vf), was effectively prevented, the appearing time of arrhythmia was delayed and the duration of arrhythmia was shortened, while the elevated ST segment lowered as well. At the same time, the contents of myocardial Ca2+ and MDA were decreased significantly as well as the activities of myocardial SOD and GSH-Px increased markedly.

CONCLUSION

CASI is of protective effect on myocardial ischemia-reperfusion arrhythmia, which may be related to scavenging the oxygen free radicals and Ca2+ overload formed during reperfusion.

CE coupling with end-column electrochemiluminescence detection for chiral separation of disopyramide

CE with electrochemiluminescence (ECL) detection technique was successfully applied for the chiral separation of a kind of class IA antiarrhythmic racemic drug. To the best of our knowledge, this is the first report of ECL detection used in chiral CE. To get better detection sensitivity and good enantioresolution at the same time, the conditions of capillary inlet and outlet buffer were systematically optimized. Unlike the traditional chiral separation method, the buffers we used in the capillary inlet and outlet differed from each other in terms of buffer pH, ionic strength, type of BGE as well as buffer composition. Under the optimum conditions, baseline enantioseparation and highly sensitive detection of the enantiomers were achieved. Wide linear relationship of each enantiomer was achieved in the range of 5 x 10(-7) to 2 x 10(-5) mol/L with relative coefficients of 0.996 and 0.997, respectively. The detection limits were estimated to be 8 x 10(-8) and 1.0 x 10(-7) mol/L (S/N = 3) for the enantiomers, respectively. In addition, a successful application of this new method to the chiral separation of the racemic drug in spiked plasma samples confirmed the validity and applicability of the chiral CE-ECL method.

[Study on effect of Tiaomaiyin injection on experimental arrhythmia]

OBJECTIVE

To study the effect of Tiaomaiyin injection on the experimental arrhythmia for analyzing its underlying mechanism in the treatment of cardiovascular disease.

METHOD

Experimental animals anesthetized with 20% urethane (6 mL x kg(-1)) were evenly randomized into control group, positive control group, low-dose and high-dose Tiaomaiyin group. The rate of ventricular fibrillation (VF) chloroform-induced in mice, and the epoch of ventricular extrasystole (VE), ventricular tachycardia (VT),VF and cardiac arrest (CA), actonitine-induced in rats (1.0 microg x mL(-1) x min(-1)), and vabain-induced in guinea pigs (10 microg x mL(-1) x min(-1)), were detected respectively. The result loas converted into cumulative dosage of actonitine or vabain. In ischemia-reperfusion model in rats, the duration of arrhythmia and activity of superoxide dismutase (SOD) and malondialdehyde (MDA) were detected.

RESULT

After venous injection of Tiaomaiyin, VF in mice was lower significantly (P < 0.01), VE, VT, VF in rats and VF in guinea pigs were lowered considerably (P <0.05). The duration of arrhythmia in ischemia-reperfusion model was reduced considerably (P < 0.05), and the activity of myocardial SOD was raised significantly (P <0.01).

CONCLUSION

Tiaomaiyin shows the reduction of experimental arrhythmia and protect effect to ischemia-reperfusion injury of the heart, which indicates that the effect mechanism may have the relationship with inhabition of lipid peroxidation and damnification of the free radical.

[Comparing the actions of the three flavone ingredients in choerospondias axillaris on arrhythmias induced by aconitine]

OBJECTIVE

To compare the actions of the three flavone ingredients in choerospondias axillaris on arrhythmias Induced by aconitine.

METHOD

Langendorff perfuse was applied in the experiment, the antiarrhythmic action was to study by using aconitine on the the isolated heart; The antiarrhythmic action of the three flavone ingredients in choerospondias axillaris was to study by using i.v. aconitine in rat to induce arrhythmias.

RESULT

Compared with the NS group, sample 1 and sample 2 both significantly prolonged the beginning time of VF of isolated heart and increased the dosage of aconitine, sample 3 reduced the beginning time of VF of isolated heart and decreased the dosage of aconitine, sample 1 and sample 2 both greatly prolonged the beginning time of VE, VT, VF, HA; sample 3 greatly reduced the beginning time of VT,VF. The actions of the three samples were in a concentration-dependent way.

CONCLUSION

Sample 1 and sample 2 both resisted the occurrence of arrhythmias induced by aconitine, sample 3 markedly promoted the occurrence of arrhythmias induced by aconitine.

[Effect of puerarin on L-type calcium channel in isolated rat ventricular myocytes]

OBJECTIVE

To observe the effect of Puerarin on L-type calcium channel in isolated rat ventricular myocytes.

METHOD

The cardiac ventricular myocytes were isolated enzymatically by Langendorff perfusion techniques at constant flow rate. Whole-cell recording of patch-clamp techniques was used to observe the current of L-type calcium channel.

RESULT

Puerarin 2.4 mmol x L(-1) could inhibit the current of L-type calcium channel of rat ventricular myocytes and this inhibition was time-dependent. Purerarin elevated the current-voltage (I-V) curve of calcium current.

CONCLUSION

Puerarin can inhibit L-type calcium current of rat ventricular myocytes. Which implies that puerarin takes part in anti-myocardial ischemia and anti-arrhythmics partly due to the inhibition of L-type calcium channel.

Enantiomeric Separation of Basic Drugs with Partially Filled Serum Albumin as Chiral Selector in Capillary Electrophoresis

A reliable method is presented for the chiral separation of three basic drugs (mexiletine, chlorpheniramine and propranolol) with serum albumins (human and porcine, HSA and PSA) as chiral selectors by capillary electrophoresis in combination with the partial filling technique. Based on the systematic optimization of operation variables, the chiral separation of mexiletine, chlorpheniramine and propranolol was achieved in the pH 7.4 phosphate buffer by using HSA, PSA and PSA as selectors, respectively. The chiral recognition ability of HSA and PSA was compared. HSA and PSA show a different chiral recognition ability for each of the three drugs. In addition, the association constants between enantiomeric drugs and proteins were determined to be 2.00 and 3.80 x 10(2) M(-1) for mexiletine and HSA, 0.59 and 1.12 x 10(3) M(-1) for chlorpheniramine and PSA, and 0.87 and 1.42 x 10(3) M(-1) for propranolol and PSA. The method for the chiral separation and determination of association constants possesses the advantages of simple performance, effective avoiding of the interference of the UV detection from protein, and lowering of the reagent consumption.

[Effect of tetradrine on electrophysilogic changes caused by rising of left ventricular preload in guinea pigs]

OBJECTIVE

To investigate the changes of guinea pig heart electrophysiological properties caused by increasing left ventricular preload, and to assess the effects of tetradrine on these changes.

METHOD

Working model preparation of guinea pig hearts in vitro was used, and the preload of left ventricle was increased by adjusting the prefusion pressure of left atria. The changes of heart electrophysiologic parameters including monophasic action potential duration (MAPD90), monophasic action potential amplitude (MAPA), effective refractory period (ERP) and ventricular fibrillation threshold (VFT) were observed before and after altering the preload of left ventricle, and compared in the absence and presence of tetradrine, streptomycin or verapamil.

RESULT

The rising of left ventricular preload led to shortening of MAPD90, ERP, and to descent of MAPA, VFT (all P<0.01). Both Tetradrine and streptomycin inhibited these changes of heart electrophysiologic parameters caused by elevation of left ventricular afterload (all P<0.01). In contrast, verapamil had no effects on the preload-related electrophysiological changes (all P>0.05).

CONCLUSION

Electrophysiologic changes caused by increasing left ventricular preload may be inhibited by tetrandrine, through inhibition of stretch-activated ion channels.

Pharmacokinetic-pharmacodynamic modeling of daurisoline and dauricine in beagle dogs

AIM

To study the combined pharmacokinetic-pharmacodynamic (PK-PD) model of daurisoline and dauricine, and compare their effects on cardiac electrophsiology, blood pressure, and hemodynamics in beagle dogs.

METHODS

The plasma drug concentration was determined by the reversed-phase HPLC method and the effects on cardiac and hemodynamics were recorded by polygraph. The pharmacokinetic and PK-PD model parameters were calculated.

RESULTS

The pharmacokinetics were best fitted to a two-compartment open model, and the relationship between effect and effect compartment concentration of both drugs could be represented by the sigmoid-E(max) model. There were no significant differences in main pharmacokinetics and PK-PD parameters between the two drugs.

CONCLUSION

No statistically different kinetic disposition characteristics and potencies of inhibitory effects on myocardial function of daurisoline and dauricine were found in beagle dogs.

Stereoselective chromatography of cardiovascular drugs: an update

This review reports the latest achievements in chromatographic enantioseparations of various classes of cardiovascular drugs and selected applications of these methods in pharmaceutical and clinical analysis. The use of these drugs as test compounds for new chiral stationary phases and different parameters of chromatographic processes is also presented.

Cardiovascular pharmacological effects of bisbenzylisoquinoline alkaloid derivatives

Tetrandrine, dauricine, daurisoline and neferine are bisbenzylisoquinoline alkaloid derivatives isolated from Chinese traditional medicine and herbs. The cardiovascular pharmacological effects and the mechanism of actions of these compounds were reviewed. Tetrandrine isolated from Stephania tetrandra S Moore possesses antihypertensive and antiarrhythmic effects. The antihypertensive effects of tetrandrine have been demonstrated in experimental hypertensive animals and in hypertensive patients. Recent studies showed that in addition to its calcium antagonistic effect, tetrandrine interacted with M receptors. Modulation by M receptor is one of the pharmacological mechanisms of cardiovascular effects of tetrandrine. Dauricine and daurisoloine were isolated from Menispermum dauricum DC. The antiarrhythmic effects of dauricine have been verified in different experimental arrhythmic models and in cardiac arrhythmic patients. Dauricine blocked the cardiac transmembrane Na+,K+ and Ca2+ ion currents. Differing from quinidine and sotalol, which exhibited reverse use-dependent effect, dauricine prolonged APD in a normal use-dependent manner in experimental studies. The antiarrhythmic effect of daurisoline and neferine which is an alkaloid isolated from Nelumbo nucifera Gaertn, and their mechanisms of actions have also been studied. The antiarrhythmic effect of daurisoline is more potent than that of dauricine.

Molecular cloning and functional expression of a gene encoding an antiarrhythmia peptide derived from the scorpion toxin

From a cDNA library of Chinese scorpion Buthus martensii Karsch, full-length cDNAs of 351 nucleotides encoding precursors (named BmKIM) that contain signal peptides of 21 amino acid residues, a mature toxin of 61 residues with four disulfide bridges, and an extra Gly-Lys-Lys tail, were isolated. The genomic sequence of BmKIM was cloned and sequenced; it consisted of two exons disrupted by an intron of 1622 bp, the largest known in scorpion toxin genomes, inserted in the region encoding the signal peptide. The cDNA was expressed in Escherichia coli. The recombinant BmKIM was toxic to both mammal and insects. This is the first report that a toxin with such high sequence homology with an insect-specific depressant toxin group exhibits toxicity to mammals. Using whole cell patch-clamp recording, it was discovered that the recombinant BmKIM inhibited the sodium current in rat dorsal root ganglion neurons and ventricular myocytes and protected against aconitine- induced cardiac arrhythmia.

[Sequential isolation of superoxide dismutase and ajmaline from a tissue culture of Rauwolfia serpentina Benth]

Two biologically active compounds, the enzyme superoxide dismutase (EC 1.15.1.1) and the antiarrhythmic indole alkaloid ajmaline, were isolated from a callus culture of Rauwolfia serpentina Benth. Sequential isolation of biologically active compounds by metal-chelate affinity chromatography followed by azoadsorbent affinity chromatography allowed us to obtain highly purified products. The yields of superoxide dismutase and ajmaline were 180 mg/kg biomass and 16.5 g/kg dry weight, respectively.

Application of sulfobutylether-beta-cyclodextrin with specific degrees of substitution for the enantioseparation of pharmaceutical mixtures by capillary electrophoresis

In this research the separation of the enantiomers of the basic drug bidisomide (SC-40230) from five closely related known process impurities was investigated using several neutral and anionic sulfobutylether beta-cyclodextrins (SBE-beta-CDs) as isomer selectors. Several novel sulfobutylether derivative mixtures and purified charge types having a specific degree of substitution were used to study the effect of selector charge on the efficiency and selectivity of both chiral and achiral separations. The effects of run buffer pH, selector type, and selector concentration on the chiral separation of bidisomide and the achiral separation of the related process impurities was also investigated. The related process impurity, SC-47500, displayed significant peak tailing with SBE-beta-CD mixtures which contained mono- to deca-substituted cyclodextrins. This problem was explored using isolated SBE-beta-CD charge types having degrees of substitution from one to seven. Peak tailing increased as the charge on the selector increased, suggesting that the distortion was due to electrodispersion and the large countercurrent mobility of the negatively charged complexes. Pure charge types having a lower degree of substitution provided adequate chiral and achiral selectivity, while eliminating the severe peak distortion caused by electrodispersion. The complete analysis of the bidisomide enantiomers and the related impurities was achieved with a pH 2.5 running buffer containing 5-10 mM of the isolated sulfobutylether charge types SBE[2]ds(1)sr-beta-CD or SBE[3]ds(1)sr-beta-CD. These conditions gave baseline resolution of bidisomide enantiomers and all five impurities, thus allowing both chiral and achiral purity to be determined in a single run.

Separation and quantitation of azimilide and its putative metabolites by capillary electrophoresis

Reliable methods based on capillary electrophoresis (CE) have been developed for the separation and quantitation of azimilide, an antiarrhythmic drug under development at Procter & Gamble Pharmaceuticals (P&GP). Both capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) were employed in the separation of azimilide from its impurities, degradants and/or metabolites. Separation of azimilide from NE-11178, F-410, F-1054 and F-1292 was obtained by MECC at pH 9 with 50 mM sodium dodecyl sulfate (SDS). The separation of azimilide and NE-10171, a key metabolite of azimilide, was difficult because their structures differ by only a single methyl group. The best separation was achieved under acidic pH conditions with cetyltriethyl ammonium chloride (CTAC) additive in the buffer. All of the CE separations were completed within a substantially shorter time and with better resolution than the corresponding high-performance liquid chromatography (HPLC) separations. Quantitation was done with azimilide and NE-10171. Calibration curves ranging from 10 to 1000 microg/ml were obtained with R2 greater than 0.997 for both azimilide and NE-10171. The back-calculated concentrations of the calibration standards and the recoveries of the quality control (QC) samples were within the acceptance range currently used for HPLC methods. These results demonstrated the viability of CE as an alternative technique for drug metabolism studies in support of pharmaceutical development.

[The detection and quantitative determination of lidocaine and novocainamide in biological fluids]

Offers methods for isolation of lidocaine and novocainamide present together in the urine, blood plasma, and saliva. Demonstrates the possibility of identifying these substances in biological fluids by thin-layer and gas liquid chromatography. Proposes methods for measuring lidocaine and novocainamide in biological objects by UV spectrometry (combined polynomial) and gas liquid chromatography. Demonstrates the reliability of the results.

[The differential diagnosis of fatal outcomes in patient treatment with lidocaine]

A method for isolation, identification, and measurement of lidocaine is proposed for investigations of biological specimens. The presence of lidocaine is confirmed by common alkaloid reactions, chromatography in a thin layer of adsorbent, and color test. Lidocaine concentration is measured by extraction photoelectrocolorimetry. A formula is proposed, permitting a tentative assessment of the injected lidocaine dose. The threshold identification value is 0.2 mg%, threshold detection value 0.5 mg%.

Chromatographic (TLC) analysis of diltiazem in pharmaceutical form in presence of other antiarrhythmics

Diltiazem was identified by TLC method on silica gel by ascending technique, in presence of five another antiarrhythmic drugs (disopyramide, flecainide, lidocaine, lorcainide, procainamide). Suitable conditions for separation of diltiazem were established using ethanol-benzene-dioxane-ammonia (2:20:16:3) as the mobile phase. When using acidified iodoplatinate solution or Dragendorff reagent as indicators, the amount of diltiazem as small as 100 ng can be identified. The TLC method is simple and sensitive and it was used to identify diltiazem in tablets.

Isolation and characterization of sulphoxidation metabolites of moricizine in rat and human biological fluids

The sulphoxidation metabolites of moricizine, moricizine sulphoxide (M-sulphoxide) and moricizine sulphone (M-sulphone) were isolated and identified in the rat bile and urine and in human plasma and urine following administration of moricizine hydrochloride. The sulphoxide and sulphone were synthesized chemically by peroxidation of moricizine hydrochloride with hydrogen peroxide at 25 degree C and 60 degree C, respectively, and were characterized by melting point determination (MP), infrared spectroscopy (IR), mass spectroscopy (MS), thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). In the rats (n=7), which were kept in metabolic cages and given intravenous moricizine (0.72 mg), the mean +/- SD percentages recovered in the urine as moricizine, M-sulphoxide and M-sulphone were 0.11 +/- 0.09%, 0.74 +/- 0.45% and 5.16 +/- 4.24%, respectively. The corresponding recoveries in the bile were 0.13 +/- 0.04% as moricizine, 3.39 +/- 1.62% as M-sulphoxide and 2.16 +/- 1.07% as M-sulphone. After an oral dose of moricizine HCl (300 mg) the plasma concentrations of moricizine, M-sulphoxide and M-sulphone at 4 h in two healthy subjects were 0.43, 0.11 and 0.10 microg/ml and 0.32, 0.17 and 0.27 microg/ml, respectively for Subject 1 and Subject 2. The percentages of dose recovered in the urine as moricizine, M-sulphoxide and M-sulphone were 0.14 and 0.02%, 0.27 and 0.36%, and 0.30 and 0.24%, respectively for Subject 1 and Subject 2. It is suggested that an investigation of the disposition of moricizine and its sulphoxidation metabolites in patients will be valuable for elucidating the prolonged effects in the treatment of ventricular arrhythmias.

[Effects of isorhynchophylline on physiological characteristics of isolated guinea pig atrium]

Isorhynchophylline (Iso) inhibits the automaticity and contractile force of isolated guinea pig atrium in a concentration-dependent manner, 30 mumol/L markedly depresses adrenaline-induced automaticity, 10 mumol/L prolongs functional refractory period and decreases excitability. Furthermore, 10 mumol/L of Iso reduces the effect of ouabain on contractile force in left atrium and 0.3 mmol/L markedly inhibits the response to paired stimulation.

[Experimental study on cellular electrophysiology of Viscum coloratum flavonoid in treating tachyarrhythmias]

Viscum Coloratum Flavonoid (VCF) is one of the dihydro-flavonoids isolated and purified from the stem and leaf of Viscum Coloratum. It was proved both experimentally and clinically to have the effects of anti-tachyarrhythmias. The mechanism of this effect, however, was unclear. In this study, the effects of the drug on the fast response action potentials (FAP) in canine Purkinje fibers and guinea pig ventricular myocardial cells were investigated by glass-microelectrode technique. The results indicated that 0.1 mg/ml VCF accelerated the repolarizations of 2nd and 3rd phase of FAP, shortened action potential duration (APD), and slightly shortened effective refractory period (ERP) (canine) or unchanged (guinea pig). delta ERP/delta APD ratio was increased, therefore, ERP was relatively prolonged. All effects appeared after using the drug for 2 minutes, reached stable status after 10 minutes, and disappeared after washing off the drug for 15 minutes. It was suggested that VCF was the drug which exerted effects rapidly, maintained effects shortly, and had effects reversibly. The cellular electrophysiologic mechanisms of VCF on anti-tachyarrhythmias should be attributed to prolong the ERP relatively and abolish the reentry. This drug is particularly applicable to the tachyarrhythmias due to reentry.

[Alkaloids of plumula Nelumbinis]

Six alkaloids were isolated from the green seed embryo of Nelumbo nucifera growing in Ruichang, Jiangxi province. On the basis of physiochemical properties and spectroscopic methods (UV, IR, NMR, MS) they were identified as: lotusine, nuciferine, pronuciferine, liensinine, isoliensinine and neferine.

Reversed-phase LC resolutions of chiral antiarrhythmic agents via derivatization with homochiral isothiocyanates

The search for new antiarrhythmic agents has been intense, because the established drugs for the treatment of cardiac arrhythmias are neither uniformly effective nor well-tolerated. Among the recently introduced new antiarrhythmic agents are tocainide (TOC), mexiletine (MEX), flecainide (FLE), and propafenone (PRO). Each of these drugs is a chiral amine used clinically as the racemic mixture. We have examined the high-performance liquid chromatographic chiral resolution of the above four drugs via derivatization with homochiral derivatizing agents (HDAs). The amino functionality of the drugs was reacted with four homochiral isothiocyanates, 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (TAGIT), (R)-alpha-methylbenzyl isothiocyanate (RAMBI), (S)-1-(1-naphthyl)ethyl isothiocyanate (SNEIT), and (R)-1-(2-naphthyl)ethyl isothiocyanate (RBEIT). Complete separation of the two peaks (resolution factor R = 1.5) was achieved with all four HDAs for TOC, with TAGIT, RBEIT, and RAMBI for MEX, with TAGIT and SNEIT for PRO, and only with TAGIT for FLE. SNEIT was used to develop analytical procedures for the determination of the enantiomeric composition of TOC in human urine and blood serum. The four HDAs offer several advantages over many other HDAs and should be useful in studies of enantioselective drug action and disposition.

Appearance of a cardiodepressant factor in the medium incubating in situ the posterior pituitary lobe of the rat. II. Differentiation from other active compounds

In the previous article the occurrence of cardiodepressant activity in the fluid incubating in situ the posterior pituitary lobe of the rat was described (Acta Physiol. Pol., 1984, 35, 460-468). In the present study the cardiodepressant fraction of the medium incubating in situ the posterior pituitary lobe was subjected to further purification by means of thin-layer chromatography on Silica gel G. Three fractions were isolated, one of which caused a 69% decrease of beating rate of an isolated auricles of the right atrium in the two-day-old rats. In this fraction the presence of neither lipids nor compounds containing phosphate residue was detected. On the basis of the site of elution of the cardiodepressant fraction from the column filled with Sephadex G-15, it was demonstrated that the molecular weight of the cardiodepressant factor was less than 1500 and more than 832. The obtained results show that the cardiodepressant activity is associated with a low-molecule compound, probably with peptide structure, which is released into the fluid incubating in situ the posterior pituitary lobe.

Simultaneous liquid-chromatographic determination of five antiarrhythmic drugs and their major active metabolites in serum

We report an isocratic "high-performance" liquid chromatographic method for the simultaneous measurement of tocainide, lidocaine, procainamide, quinidine, disopyramide, and their major active metabolites in serum. The drugs are extracted from 200 microL of serum at pH 9.5 with 1.5 mL of 1,2-dichloromethane, concentrated by evaporation, and separated on a CN-bonded-phase column at 40 degrees C (flow rate 2 mL/min) with a pH 7.1 mobile phase of acetonitrile/methanol/phosphate buffer (60/7/33, by vol); the phosphate buffer contains 10 mmol of KH2PO4 and 0.5 mmol of triethylamine per liter. The antiarrhythmic drugs elute in the K' (capacity factor) range of 1.43 (lidocaine) to 5.7 (disopyramide). Results vary linearly with drug concentration to at least 30 mg/L; the detection limit is 0.1-0.2 mg/L. Within-run precision (CV) ranges from 0.9% to 5.0% and day-to-day precision from 2.1% to 6.2%, depending on the specific drug and its concentration in serum. Extraction efficiencies vary from 76% to 85% and analytical recoveries from 98.5% to 103%. At toxic serum concentrations, several basic drugs may interfere with the assay of some antiarrhythmics, but only hydroxyzine, verapamil, and certain local anesthetics interfere at therapeutic concentrations.

[Determination of the concentration of a new antiarrhythmic, flecainide, in plasma using high pressure liquid chromatography (HPLC): sample preparation with extraction columns]

A method is described for the rapid determination of flecainid (Tambocor) in human plasma. Flecainid is removed from alkalized plasma by binding to a C-18 extraction column. After washing the column with methanol/water (1 + 1, by vol.) and acetonitrile/water (45 + 55, by vol.), the drug is extracted with methanol and determined by HPLC. Sample preparation takes about 15 minutes. With this method, flecainid can be determined directly in the concentration range 100-2000 micrograms/l, with an accuracy of 5-10% depending on the concentration. The results agree well with those obtained by the longer established but lengthy liquid extraction method.

Comparative biochemistry and pharmacology of salivary gland secretions. III. Chromatographic isolation of a myocardial depressor protein (MDP) from the venom of Crotalus atrox

A protein has been isolated from the venom of the western diamondback rattlesnake (Crotalus atrox) which induces acute myocardial depression when administered to experimental animals. Purification was achieved by gel filtration on Sephadex G-100, DEAE- and CM-cellulose ion-exchange chromatography, ultra-filtration, and adsorption chromatography on hydroxyapatite. Amino acid analysis of the highly purified protein indicated N-terminal isoleucine and C-terminal tyrosine residues, and the absence of free sulfhydryl groups. Rabbits were immunized against the myocardial depressor protein (MDP) and a highly specific antiserum prepared which made it possible to study other snake venoms for the presence or absence of MDP. All of the North American Crotalid species of snakes contain MDP in varying degrees of concentration, but none of the Asiatic snake venoms tested reacted with the antiserum to the myocardial depressor protein. Intravenous administration of MDP to experimental animals (dogs, cats) produces an immediate and profound decrease in the cardiac output, the left ventricular systolic and mean pressures, the velocity of shortening of the contractile element, the systemic arterial pressure and an elevation in the left ventricular end-diastolic and pulmonary wedge pressures. These hemodynamic changes indicate that MDP administration induces an acute myocardial failure which is does dependent. The potential use of this protein for the reproducible causation of left ventricular failure, obviating the need for the more commonly used surgical ligation of the coronary arteries, warrants a full investigation into its structure, active site and its mechanism of action on the myocardial cell.