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1.
Anesth Prog ; 65(3): 192-196, 2018.
Article in English | MEDLINE | ID: mdl-30235429

ABSTRACT

Stabilization of circulatory dynamics is a critical issue in the anesthetic management of patients with hypertrophic cardiomyopathy (HCM). In this report, we managed general anesthesia for a 74-year-old male patient with nonobstructive HCM who developed circulatory instability intraoperatively. Severe bradycardia measuring 35 beats/min and hypotension measuring 78 mm Hg systolic were observed during surgery. Using stroke volume variation and stroke volume from the FloTrac as indices, successful circulatory management was performed with dopamine. The hypotension and bradycardia were thought to be the result of methyldigoxin and possibly associated with our perioperative management. Cardiology consult should have been obtained. We demonstrated that the FloTrac can be beneficial in diagnosing and managing cardiovascular instability and administration of dopamine in the anesthetic management of nonobstructive HCM patients.


Subject(s)
Anesthesia, General/adverse effects , Bradycardia/chemically induced , Cardiomyopathy, Hypertrophic/drug therapy , Cardiotonic Agents/adverse effects , Heart Rate/drug effects , Medigoxin/adverse effects , Oral Surgical Procedures/adverse effects , Aged , Bradycardia/diagnosis , Bradycardia/drug therapy , Bradycardia/physiopathology , Cardiomyopathy, Hypertrophic/diagnosis , Cardiomyopathy, Hypertrophic/physiopathology , Cardiotonic Agents/administration & dosage , Dopamine/administration & dosage , Electrocardiography , Humans , Male , Medigoxin/administration & dosage , Monitoring, Intraoperative/methods , Risk Factors , Treatment Outcome
2.
J Vet Intern Med ; 30(2): 553-9, 2016.
Article in English | MEDLINE | ID: mdl-26936799

ABSTRACT

BACKGROUND: Dilated cardiomyopathy (DCM) is a common cause of morbidity and mortality in the Irish Wolfhound (IW). However, the benefit of medical treatment in IW dogs with preclinical DCM, atrial fibrillation (AF), or both has not been demonstrated. OBJECTIVES: Compare the time to develop congestive heart failure (CHF) or sudden death in IW dogs with preclinical DCM, AF, or both receiving monotherapy with pimobendan, methyldigoxin, or benazepril hydrochloride. ANIMALS: Seventy-five client-owned IW dogs. METHODS: Irish Wolfhound dogs were prospectively randomized to receive pimobendan (Vetmedin®), benazepril HCl (Fortekor®), or methyldigoxin (Lanitop®) monotherapy in a 1:1:1 ratio in a blinded clinical trial. The prospectively defined composite primary endpoint was onset of CHF or sudden death. To assure stringent evaluation of treatment effect, data from dogs complying with the study protocol were analyzed. RESULTS: Sixty-six IW fulfilling the study protocol included 39 males, 27 females; median (interquartile range) age, 4.0 years (3.0-5.0 years) and weight, 70.0 kg (63.0-75.0 kg). Primary endpoint was reached in 5 of 23 (21.7%) IW receiving pimobendan, 11 of 22 (50.0%) receiving benazepril HCl, and 9 of 21 (42.9%) receiving methyldigoxin. Median time to primary endpoint was significantly longer for pimobendan (1,991 days; 65.4 months) compared to methyldigoxin (1,263 days; 41.5 months; P = .031) or benazepril HCl-(997 days; 32.8 months; P = .008) treated dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: In IW dogs with preclinical DCM, AF or both, pimobendan monotherapy significantly prolonged time to onset of CHF or sudden death than did monotherapy with benazepril HCl or methyldigoxin.


Subject(s)
Atrial Fibrillation/veterinary , Benzazepines/therapeutic use , Cardiomyopathies/veterinary , Dog Diseases/drug therapy , Medigoxin/therapeutic use , Pyridazines/therapeutic use , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Animals , Atrial Fibrillation/complications , Atrial Fibrillation/drug therapy , Cardiomyopathies/complications , Cardiomyopathies/drug therapy , Cardiotonic Agents/therapeutic use , Dogs , Female , Male
3.
Forensic Sci Int ; 241: e23-7, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24889325

ABSTRACT

A massive lethal overdose with beta-metildigoxin in a 36-week-old infant is presented. Determination of beta-metildigoxin and its metabolites digoxin, digoxigenin and digoxigenin-monodigitoxosid is achieved by a liquid chromatographic mass spectrometric (LC-MS/MS) method. Measured concentrations for beta-metildigoxin and digoxin in peripheral blood were 40.2 ng/ml and 25.6 ng/ml, respectively. Tissue distribution showed highest concentrations in kidney tissue and gastric content. The metabolite digoxigenin-monodigitoxosid could be detected in heart blood, duodenal content, gastric content and fat tissue while the metabolite digoxigenin could only be detected in gastric content since the drug was given by a stomach tube.


Subject(s)
Cardiotonic Agents/pharmacokinetics , Cardiotonic Agents/poisoning , Medication Errors , Medigoxin/pharmacokinetics , Medigoxin/poisoning , Cardiotonic Agents/administration & dosage , Chromatography, Liquid , Digoxigenin/analogs & derivatives , Digoxigenin/pharmacokinetics , Digoxin/pharmacokinetics , Drug Overdose , Forensic Toxicology , Humans , Hypertension, Pulmonary/therapy , Infant , Male , Medigoxin/administration & dosage , Tandem Mass Spectrometry , Tissue Distribution
4.
Am J Crit Care ; 19(4): 391-87, 2010 Jul.
Article in English | MEDLINE | ID: mdl-19875723

ABSTRACT

A woman ingested 10 mg of methyldigoxin in a suicide attempt and presented 19 hours after ingestion with clinical signs of glycoside intoxication. Her serum level of digoxin was 7.4 ng/mL, and antidotal therapy with Fab antibody fragments was started. The manufacturer's recommended dosing scheme was modified, with 80 mg Fab administered intravenously within 15 minutes followed by a continuous infusion at 30 mg/h. Total serum concentration of digoxin increased markedly within minutes after Fab therapy was started, while the level of free digoxin immediately decreased into the nontoxic range without recrudescent toxic effects of digoxin. The cumulative amounts of free and bound digoxin that were excreted in urine within 30 hours after ingestion were 900 microg and 1600 microg, respectively. Half-life of bound digoxin in urine was 9.9 hours; mean rate of clearance of bound digoxin in the urine was 7.0 mL/min. On the basis of these kinetic data, a smaller initial bolus dose of Fab followed by a continuous infusion may be a more tailored, cost-effective, and relatively safe therapy for patients who have overdosed on cardiac glycosides.


Subject(s)
Anti-Arrhythmia Agents/poisoning , Digoxin/blood , Immunoglobulin Fab Fragments/therapeutic use , Medigoxin/poisoning , Suicide, Attempted , Adult , Anti-Arrhythmia Agents/blood , Female , Half-Life , Humans , Immunoglobulin Fab Fragments/administration & dosage , Medigoxin/blood
5.
Regul Pept ; 156(1-3): 83-9, 2009 Aug 07.
Article in English | MEDLINE | ID: mdl-19465062

ABSTRACT

Pentadecapeptide BPC 157 (GEPPPGKPADDAGLV, MW 1419) reversed congestive heart failure and various arrhythmias, influenced the NO-system and showed no proarrhythmic effect. In therapy analogy, we challenged rats with digitalis, to show attenuation by BPC 157 and the relation between the NO-system and digitalis toxicity. (i). BPC 157 prophylactic effect. Development of cumulative intravenous digitalis toxicity, BPC 157 (50 microg, 10 microg, 10 ng/kg applied intravenously immediately before a methyldigoxin increment regimen (2.0/1.5/1.5/1.0 mg/kg at 15 min-intervals, total dose 6.0 mg/kg/45 min)) reduced the number of ventricular premature beats, prolonged the time before onset of ventricular tachycardia, reduced ventricular tachycardia and AV-block duration (microg-regimes) or reduced mainly the AV-block duration (ng-regimen). (ii). BPC 157 therapy. Advanced methyldigoxin toxicity (6.0 mg/kg i.v. bolus). BPC 157 applied at the 20th second of the grade 3 AV-block shortened AV-blocks, mitigated a further digitalis toxicity course. Ventricular tachycardias were either avoided (50 microg), or markedly reduced (10 microg, 10 ng). Fatal outcome was either avoided (50 microg), reduced (10 microg), or only delayed (10 ng) (iii) BPC 157, L-NAME, l-arginine, L-NAME+l-arginine application. L-NAME-application (5 mg/kg i.p.) aggravated methyldigoxin-arrhythmias. l-arginine (200 mg/kg i.p.) alone had no effect but blunted L-NAME-exaggeration (L-NAME+l-arginine). In this respect, BPC 157 (50 microg/kg i.p.) was prophylactically and therapeutically more effective: the antagonism of L-NAME with BPC 157 produced an effect similar to BPC 157 alone. In conclusion, digitalis-induced arrhythmias in rats could be prevented and counteracted by pentadecapeptide BPC 157, mainly through an interaction with the NO-system.


Subject(s)
Anti-Arrhythmia Agents/pharmacology , Arrhythmias, Cardiac/chemically induced , Heart Rate/drug effects , Medigoxin/pharmacology , Nitric Oxide/metabolism , Peptide Fragments/pharmacology , Proteins/pharmacology , Animals , Anti-Ulcer Agents/pharmacology , Arginine/pharmacology , Arrhythmias, Cardiac/drug therapy , Arrhythmias, Cardiac/prevention & control , Male , NG-Nitroarginine Methyl Ester/pharmacology , Rats , Rats, Wistar
6.
Pharmacol Rep ; 59(1): 107-11, 2007.
Article in English | MEDLINE | ID: mdl-17377214

ABSTRACT

Digoxin, a drug of narrow therapeutic index, is a substrate for common transmembrane transporter, P-glycoprotein, encoded by ABCB1 ( MDR1 ) gene. It has been suggested that ABCB1 polymorphism, as well as co-administration of P-glycoprotein inhibitors, may influence digoxin bioavailability. The aim of the present study was to evaluate the effects of ABCB1 gene polymorphism and P-gp inhibitor co-administration on steady-state digoxin serum concentration in congestive heart failure patients. Digoxin concentrations as well as 3435C > T and 2677G > A,T ABCB1 single nucleotide polymorphisms, were determined in 77 patients administered digoxin (0.25 mg daily) and methyldigoxin (0.50 mg daily), some of them co-medicated with known P-glycoprotein (Pgp) inhibitors. Significant differences were noted in digoxin serum concentrations (C(min,ss)) between patients co-administered and not co-administered P-gp inhibitors: 0.868 +/- 0.348 and 0.524 +/- 0.281 for digoxin (p < 0.002), as well as 1.280 +/- 0.524 and 0.908 +/- 0.358 for methyldigoxin (p < 0.02), respectively. No influence of ABCB1 2677G > A,T and C3435C > T polymorphisms on digoxin concentration was noted. Although some of the previous studies have shown that digoxin pharmacokinetics might be affected by ABCB1 genetic polymorphism, those modest changes are probably clinically irrelevant, and digoxin dose adjustment should include P-gp inhibitor co-administration rather than ABCB1 genotyping.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , Cardiotonic Agents/blood , Digoxin/blood , Heart Failure/drug therapy , Polymorphism, Single Nucleotide , ATP Binding Cassette Transporter, Subfamily B , Adult , Aged , Aged, 80 and over , Cardiotonic Agents/administration & dosage , Cardiotonic Agents/therapeutic use , DNA/analysis , Digoxin/administration & dosage , Digoxin/therapeutic use , Drug Therapy, Combination , Female , Heart Failure/blood , Heart Failure/genetics , Humans , Male , Medigoxin/administration & dosage , Medigoxin/pharmacokinetics , Medigoxin/therapeutic use , Middle Aged
7.
Physiol Res ; 55(3): 325-338, 2006.
Article in English | MEDLINE | ID: mdl-16083303

ABSTRACT

The effect of drugs from the class of cardiac (methyldigoxin, verapamil, propranolol), antiepileptic (carbamazepine), sedative (diazepam) and antihistaminic (promethazine) drugs on Na,K-ATPase activity of plasma membranes was studied in rat brain synaptosomes. Methyldigoxin in a concentration of 0.1 mmol/l inhibits enzyme activity by 80 %. Verapamil, propranolol and promethazine in concentrations of 20, 20 and 2 mmol/l respectively, entirely inhibit the ATPase activity. Carbamazepine and diazepam in concentrations of 0.02-60 mmol/l have no effect on the activity of this enzyme. According to the drug concentrations that inhibit 50 % of enzyme activity (IC(50)), the potency can be listed in the following order: methyldigoxin promethazine verapamil ? propranolol. From the inhibition of commercially available purified Na,K-ATPase isolated from porcine cerebral cortex in the presence of chosen drugs, as well as from kinetic studies on synaptosomal plasma membranes, it may be concluded that the drugs inhibit enzyme activity, partly by acting directly on the enzyme proteins. Propranolol, verapamil and promethazine inhibitions acted in an uncompetitive manner. The results suggest that these three drugs may contribute to neurological dysfunctions and indicate the necessity to take into consideration the side effects of the investigated drugs during the treatment of various pathological conditions.


Subject(s)
Brain/enzymology , Enzyme Inhibitors/pharmacology , Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors , Adenosine Triphosphate/metabolism , Animals , Brain/drug effects , Cell Membrane/drug effects , Cell Membrane/enzymology , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemistry , Kinetics , Male , Medigoxin/pharmacology , Promethazine/pharmacology , Propranolol/pharmacology , Rats , Rats, Wistar , Sodium-Potassium-Exchanging ATPase/chemistry , Sodium-Potassium-Exchanging ATPase/metabolism , Swine , Synaptosomes/drug effects , Synaptosomes/enzymology , Verapamil/pharmacology
9.
J Pharm Sci ; 94(6): 1196-203, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15858844

ABSTRACT

Recently, we found that potent P-glycoprotein (P-gp) inhibitors, such as verapamil and cyclosporin A, markedly modulated the pharmacokinetics of digoxin in rats, whereas they did not affect beta-methyldigoxin pharmacokinetics significantly. Digoxin is also a substrate of rat organic anion transporting polypeptide 2 (Oatp2). Here, we compared the magnitude of Oatp2-mediated drug interaction of digoxin and beta-methyldigoxin using amiodarone as an Oatp2 inhibitor in rats. Amiodarone (20 mg/kg) given intravenously significantly increased plasma levels and decreased biliary excretion, liver distribution, and intestinal distribution of digoxin administered intravenously at a dose of 10 mug/kg. Amiodarone also significantly decreased biliary excretion and liver distribution of beta-methyldigoxin, but the change in plasma levels of beta-methyldigoxin was quite small. These findings may give a clue in selecting these cardiac glycosides in clinical pharmacotherapy for patients receiving multiple drugs towards escape from Oatp2-mediated drug interactions.


Subject(s)
Digoxin/pharmacokinetics , Medigoxin/pharmacokinetics , Organic Cation Transport Proteins/physiology , ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology , Amiodarone/pharmacology , Animals , Drug Interactions , Male , Organic Anion Transporters , Rats , Rats, Wistar
10.
Arch Med Sadowej Kryminol ; 53(1): 19-31, 2003.
Article in Polish | MEDLINE | ID: mdl-14669547

ABSTRACT

This paper presents a case of suicidal poisoning of a woman with digoxin administered by injection. The autopsy of the subject was performed in the Institute of Forensic Medicine CMUJ. Body fluids (blood, urine, perylimph) and tissues (kidney, liver, brain) were collected for toxicological investigation. Digoxin determination was carried out by means of high performance liquid chromatography with mass spectrometry (HPLC/MS) which revealed digoxin in extremely high concentrations in specimens examined. The method is especially useful for analysis of cardiac glycosides in fatal poisonings for medicolegal purposes.


Subject(s)
Cardiotonic Agents/poisoning , Chromatography, High Pressure Liquid , Digoxin/poisoning , Expert Testimony/standards , Mass Spectrometry , Suicide , Adult , Autopsy , Calibration , Cardiotonic Agents/analysis , Chromatography, High Pressure Liquid/methods , Digoxin/analysis , Female , Forensic Medicine/methods , Humans , Mass Spectrometry/methods , Medigoxin/poisoning , Suicide/psychology , Time Factors
11.
Ther Drug Monit ; 25(4): 452-6, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12883228

ABSTRACT

The authors compared serum beta-methyldigoxin (MDx) levels in digitalized patients by enzyme immunoassay (EIA) using anti-MDx 3'-hemisuccinate BSA antiserum (antiserum-I) with commercial antidigoxin antiserum (antiserum-II). The usefulness of a phenyl boric acid (PBA) column for pretreatment of the serum samples was also investigated. The assay using antiserum-I demonstrated good accuracy and precision in the concentration range of 0.5 to 5 ng/mL. When the specificities of antiserum-I and antiserum-II were assessed by cross-reactivity studies with various related compounds, antiserum-I was much more specific for MDx antiserum-II. Using a phenyl boric acid (PBA) column, MDx, and digoxigenin, which exhibits a negligible cross-reactivity, were separated from serum, including MDx and its metabolites. The recovery tests of MDx using antiserum-I with a PBA column in human serum were satisfactory and no interference of metabolites of MDx was observed. Mean MDx concentrations in serum samples (n = 30) from digitalized patients by EIA using antiserum-I with PBA column, antiserum-I, and antiserum-II were 1.06, 1.30, and 1.74 ng/mL, respectively. These results indicate that our EIA system using antiserum-I with a PBA column for pretreatment of serum samples is useful to more precisely measure the unchanged type of MDx in patients.


Subject(s)
Cardiotonic Agents/blood , Digoxin/analogs & derivatives , Immunoenzyme Techniques/methods , Medigoxin/blood , Antibody Specificity , Borates , Cardiotonic Agents/immunology , Cross Reactions , Humans , Immune Sera , Indicators and Reagents , Medigoxin/immunology , Serum Albumin, Bovine
12.
J Pharm Sci ; 92(7): 1455-63, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12820149

ABSTRACT

Digoxin and beta-methyldigoxin were evaluated pharmacokinetically in terms of P-glycoprotein (P-gp)-mediated drug interactions in rats. Evaluation was made by measuring the effects of a potent P-gp inhibitor (verapamil, cyclosporin A) on in vitro efflux transport of these compounds across the everted small intestine, on in situ absorption from the small intestine, and on in vivo total plasma clearance (CL(total)) as well as biliary and urinary excretions after intravenous administration. Both the intestinal efflux transport and absorption of beta-methyldigoxin were approximately 1.5-fold greater than those of digoxin, probably due to its higher lipophilicity. Addition of verapamil (300 microM) significantly decreased the intestinal efflux transport and increased the intestinal absorption of digoxin. In contrast, the influence of verapamil on beta-methyldigoxin was small. Intravenous cyclosporin A (30 mg/kg) significantly decreased in vivo CL(total) and biliary excretion of digoxin, but affected little on beta-methyldigoxin clearances. These results suggest that P-gp-mediated drug interactions can easily occur in digoxin, but hardly in beta-methyldigoxin. These findings may give a clue in selecting these digitalis compounds in clinical use, towards escape from P-gp-mediated drug interactions or reduction of interindividual variations.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology , Digoxin/pharmacokinetics , Medigoxin/pharmacokinetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , Animals , Cyclosporine/pharmacology , Digoxin/blood , Drug Interactions/physiology , In Vitro Techniques , Intestinal Absorption/drug effects , Intestinal Absorption/physiology , Male , Medigoxin/blood , Rats , Rats, Wistar , Verapamil/pharmacology
13.
Biol Pharm Bull ; 26(2): 247-51, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12576688

ABSTRACT

We previously showed that enzyme immunoassay (EIA) of beta-methyldigoxin (MDx3) using anti-MDx3 3'-hemisuccinate-bovine serum albumin antiserum (Antiserum-I) was superior to that using commercial anti-digoxin antiserum (Antiserum-II) in terms of specificity and that pretreatment of human serum with phenyl boric acid (PBA) column was effective. In the present study, we examined the precision of EIA using Antiserum-I and the recovery of MDx3 after PBA column treatment in rat serum, and also investigated pharmacokinetic changes of MDx3 in rats. The intra- and inter-assay variations and recovery tests using Antiserum-I were good. The PBA column was effective in selectively separating MDx3 from rat serum containing MDx3 and its metabolites. The recovery tests using Antiserum-I with PBA column showed about 110% and the interference of metabolites of MDx3 was negligible. Serum concentration-time courses of MDx3 by EIA using Antiserum-I with PBA column and Antiserum-I were lower than that using Antiserum-II. The distribution volume at steady state and total body clearance values of MDx3 in these conditions were significantly higher than those using Antiserum-II. The usefulness of PBA column was ascertained, while effects of PBA column on these parameters were not significant. In addition, rapid absorption of MDx3 was observed by EIA using Antiserum-I with PBA column. These results suggest that EIA using Antiserum-I with PBA column for the pretreatment of serum samples should be a more useful and valuable system in therapeutic drug monitoring and pharmacokinetic studies of the unchanged type of MDx3 than Antiserum-II.


Subject(s)
Immune Sera/analysis , Immunoenzyme Techniques/methods , Medigoxin/pharmacokinetics , Animals , Male , Medigoxin/administration & dosage , Rats , Rats, Wistar
14.
Biol Pharm Bull ; 25(10): 1251-7, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12392073

ABSTRACT

We investigated the specificity of obtained antisera to beta-methyldigoxin by the enzyme immunoassay. Three types of hapten-bovine serum albumin (BSA) conjugates were synthesized to obtain high specific antisera to beta-methyldigoxin. The haptens were linked to the carrier protein through hemisuccinate at C-3' and C-3'' positions in the digitoxose chain and at C-12 position in the aglycone. Anti-beta-methyldigoxin 3'-hemisuccinate-BSA antiserum showed a low detection limit (0.2 ng/ml) and possessed high specificity for beta-methyldigoxin, exhibiting low cross-reactions with digoxigenin bisdigitoxoside (8.3%), dihydrodigoxin (4.8%), digitoxin (1.5%), and digoxigenin monodigitoxoside (0.95%), except for cross-reaction with digoxin (43%). Compared with commercial antidigoxin antiserum, clinically used to monitor beta-methyldigoxin concentration in human serum, cross-reaction data of anti-beta-methyldigoxin 3'-hemisuccinate-BSA antiserum showed higher specificity for beta-methyldigoxin. The intra-assay and inter-assay variations using this antiserum were less than 6.9% and 8.1%, respectively. The recovery tests were good, within the range of 96.2-104.3%. Phenyl boric acid (PBA) column treatment was effective to rapidly and selectively separate beta-methyldigoxin from the mixture of beta-methyldigoxin and its metabolites in human serum. The recovery tests of beta-methyldigoxin with PBA column in human serum were about 110% and interference of metabolites of beta-methyldigoxin was negligible. These results suggest that anti-beta-methyldigoxin 3'-hemisuccinate-BSA antiserum and PBA column treatment are useful to more precisely monitor the unchanged type of beta-methyldigoxin concentration in human serum.


Subject(s)
Immunoenzyme Techniques/methods , Medigoxin/blood , Animals , Humans , Immune Sera/analysis , Male , Medigoxin/analysis , Rabbits , Serum Albumin, Bovine/analysis
15.
Przegl Lek ; 58(1): 54-7, 2001.
Article in Polish | MEDLINE | ID: mdl-11450159

ABSTRACT

Three cases of patients with symptoms of digitalis overdosage were presented. The principal manifestations included complex supraventricular dysrhythmias and atrio-ventricular conduction disturbances. In the discussion a special attention was paid to digitalis dosage. Multiple factors influencing plasma concentration of digitalis including pharmacokinetics, bioavailability and drug interactions with glycosides were described. Short review of toxic manifestations of digitalis was made and the treatment of digitalis intoxication was outlined.


Subject(s)
Arrhythmias, Cardiac/chemically induced , Atrioventricular Node/drug effects , Digitalis Glycosides/poisoning , Digitalis/poisoning , Plants, Medicinal , Plants, Toxic , Aged , Aged, 80 and over , Captopril/pharmacology , Digitalis Glycosides/administration & dosage , Digitalis Glycosides/pharmacokinetics , Drug Interactions , Drug Overdose , Drug Therapy, Combination , Female , Heart Conduction System/drug effects , Humans , Male , Medigoxin/pharmacology , Middle Aged , Pentoxifylline/pharmacology , Tachycardia, Supraventricular/chemically induced
16.
Naunyn Schmiedebergs Arch Pharmacol ; 363(3): 337-43, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11284449

ABSTRACT

Digoxin is a drug with a narrow therapeutic index, which is substrate of the ATP-dependent efflux pump P-glycoprotein. Increased or decreased digoxin plasma concentrations occur in humans due to inhibition or induction of this drug transporter in organs with excretory function such as small intestine, liver and kidneys. Whereas particle size, dissolution rate and lipophilic properties have been identified as determinants for absorption of digitalis glycosides, little is known about P-glycoprotein transport characteristics of digitalis glycosides such as digitoxin, alpha-methyldigoxin, beta-acetyldigoxin and ouabain. Using polarized P-glycoprotein-expressing cell lines we therefore studied whether these compounds are substrates of P-glycoprotein. Polarized transport of digitalis glycosides was assessed in P-glycoprotein-expressing Caco-2 and L-MDR1 cells (LLC-PK1 cells stably transfected with the human MDR1 P-glycoprotein). Inhibition of P-glycoprotein-mediated transport of these compounds in Caco-2 cells was determined using the cyclosporine analogue PSC-833 (valspodar) as inhibitor of P-glycoprotein. No polarized transport was observed for ouabain. However, basal-to-apical transport of digitoxin, alpha-methyldigoxin and beta-acetyldigoxin was greater than apical-to-basal transport in Caco-2 and L-MDR1 cells. In Caco-2 cells net transport rates of these compounds were similar to those of digoxin (digoxin: 16.0+/-4.4%, digitoxin: 15.0+/-3.3%, beta-acetyldigoxin: 16.2+/-1.6%, alpha-methyldigoxin: 13.5+/-4.8%). Furthermore, polarized transport of these compounds could be completely inhibited by 1 microM PSC-833. In summary, these data provide evidence that not only digoxin, but also digitoxin, alpha-methyldigoxin and beta-acetyldigoxin are substrates of P-glycoprotein.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Acetyldigoxins/pharmacokinetics , Cardiotonic Agents/pharmacokinetics , Digitoxin/pharmacokinetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , Biological Transport , Caco-2 Cells/drug effects , Caco-2 Cells/metabolism , Cyclosporins/pharmacology , Humans , Medigoxin/pharmacokinetics
17.
Acta Cient Venez ; 50(1): 48-58, 1999.
Article in Spanish | MEDLINE | ID: mdl-10513038

ABSTRACT

The inotropic and chronotropic effects of Amiloride (AMI) and Dichloro-benzamil Amiloride (DBC-AMI) were studied on the guinea pig isolated atria, also, the interaction between these drugs and Beta-methyl-Digoxin (BM-DIGO), epinephrine and low extracellular potassium (1 mM). AMI (10(-3) M) has a negative chronotropic and positive inotropic effects, not dependent on the autonomic system. DCB-AMI has a bimodal effect on the contractile force: increases it at low concentrations but causes a decrease at concentrations higher than 10(-6) M. The effect of AMI on the sinus frequency is unchanged by BM-DIGO. AMI (10(-3) M) decreases the inotropic effect of BM-DIGO and increases the toxic concentration of this drug on isolated tissues. The dose-response curve to epinephrine was not changed by AMI. Similar results were obtained using DCB-AMI (2 x 10(-7) M). The positive inotropic effect obtained by low extracellular potassium (1 mM) was not altered by AMI. The activity of the Mg(++)-dependent, Na+/K+ ATPase measured in the microsomal fraction obtained from guinea pig heart was diminished (10%) by AMI (10(-3) M). The drug did not affect the inhibition of the enzyme induced by ouabain. In conclusion, our experiments show multiple effects of AMI and DCB-AMI on the guinea pig heart. The inhibition of the Na+/Ca++ exchange explains them only partially. A slow channel blocking effect appears fundamental to interpret our results.


Subject(s)
Amiloride/analogs & derivatives , Amiloride/pharmacology , Diuretics/pharmacology , Heart Atria/drug effects , Animals , Cardiotonic Agents/pharmacology , Drug Interactions , Female , Guinea Pigs , Heart Rate/drug effects , Male , Medigoxin/pharmacology , Myocardial Contraction/drug effects
18.
Acta cient. venez ; 50(1): 48-58, 1999. graf, tab
Article in Spanish | LILACS | ID: lil-240254

ABSTRACT

Se estudiaron los efectos cronotrópico e inotrópico de la Amilorida (AMI) y la dicloro-benzamil-Amilorida (DCB-AMI) sobre las aurículas aislada del acure, así como la interacción de estas drogas con la beta-metil-digoxina (BM_DIGO), la epinefrina y la disminución del potasio extracelular (de 4 a 1 mM). La AMI (1 mM) causa un efecto inotrópico positivo y cronotrópico negativo, independientes del sistema autonómico. La DCB-AMI causa um efecto bimodal sobre la fuerza de contracción: la aumenta a bajas dosis pero la disminuye a concentraciones mayores de 10(-6) M. También disminuye levemente la frecuencia sinusal. El efecto de la AMI sobre el automatismo sinusal no es alterado por la BM-DIGO. En cambio, la AMI ((10(-3 M) disminuye el efecto inotrópico positivo de la BM-DIGO e incrementa la dosis tóxica en preparaciones aisladas. La curva dosis-respuesta a la epinefrina no varía en presencia de AMI. Resultados similares se obtuvieron con DCB-AMI (2 x 10(-7 M). El incremento de contractilidad que se observa al disminuir la concentración extracelular de potasio a 1 mM no se altera en presencia de AMI. La actividad de la Na+/K+ ATPasa dependiente de Mg++ de la fracción microsomal obtenida del corazón del acure disminuye en 10 por ciento aproximadamente en presencia de AMI (1nM). Por otra parte, el efecto inhibitorio sobre la enzima obtenido con ouabaína no varía con esta droga. En conclusión, nuestros resultados sugieren múltiples efectos de la AMI y DCB-AMI sobre el corazón del acure. La inhibición del intercambiador Na+/Ca++ explica solo parte de ellos; el bloqueo de los canales lentos parece fundamental para explicar nuestras observaciones.


Subject(s)
Animals , Female , Guinea Pigs , Cardiotonic Agents/pharmacology , Diuretics/pharmacology , Amiloride/analogs & derivatives , Amiloride/pharmacology , Heart Atria/drug effects , Heart Rate/drug effects , Medigoxin/pharmacology , Drug Interactions , Myocardial Contraction/drug effects
19.
Masui ; 46(4): 521-4, 1997 Apr.
Article in Japanese | MEDLINE | ID: mdl-9128025

ABSTRACT

We reported a 79 year old man with preoperative bradycardia due to relative overdose of digitalis prior to undergoing subtotal gastrectomy. The patient had received metildigoxin 0.2 mg.day-1 for atrial fibrillation preoperatively and severe bradycardia of 35-41 bpm was found on the preoperative ECG examination. Serum digoxin level was detected to be 1.91 ng.ml-1 on the day before surgery. We thought this serum level must be toxic for him, even though it was within normal limits for the majority. As we thought that his bradycardia had been caused by relative overdose of digitalis, he was withheld to receive metildigoxin on the day before surgery and thereafter. Heart rate on arrival at the operating theater was around 40-45 bpm, and therefore the patient was placed on a temporary pacemaker catheter before the anesthetic induction to prevent aggravating bradycardia during anesthesia and surgery. Heart rate during procedure was 50-70 bpm and hemodynamics was stable. Intravenous digoxin was restarted on the 2nd postoperative day because of decrease in serum digoxin level to 0.84 ng.ml-1 and it was converted to metildigoxin 0.1 mg.day-1 when he was permitted to take pills per os. Our experience demonstrates that perioperative therapeutic drug monitoring is clinically important for anesthesiologists to make proper pharmacological management of surgical patients who have received digitalis.


Subject(s)
Anti-Arrhythmia Agents/adverse effects , Atrial Fibrillation/drug therapy , Bradycardia/prevention & control , Drug Monitoring , Intraoperative Complications/prevention & control , Medigoxin/adverse effects , Aged , Anesthesia, General , Anti-Arrhythmia Agents/pharmacokinetics , Atrial Fibrillation/complications , Bradycardia/chemically induced , Drug Overdose , Gastrectomy , Hemodynamics , Humans , Male , Medigoxin/pharmacokinetics , Pacemaker, Artificial , Stomach Neoplasms/complications , Stomach Neoplasms/surgery
20.
Pol Merkur Lekarski ; 2(8): 116-9, 1997 Feb.
Article in Polish | MEDLINE | ID: mdl-9538655

ABSTRACT

Digoxin in salvia and blood serum of 24 patients obtained Bemecor was determined by the method of FPIA (IMx-ABBOT). Mixed saliva was collected by three different types of Salivette (Sarstedt) given in order: normal Salivette with cotton wool swab, Slivette with polyester wool and Salivette with citric acid as a stimulator. It was found, that the correletio between the digoxin concentrations in saliva and serum and saliva/serum rations depended on the type of Salivette. The highest correlation was obtained with the Salivette with polyester wool (r = 0.892), but low concentrations of this drug in serum were good reflected in all samples of saliva, independent on kind of Salivette.


Subject(s)
Digoxin/analysis , Saliva/chemistry , Specimen Handling/methods , Digoxin/blood , Female , Humans , Male , Medigoxin/administration & dosage , Medigoxin/metabolism
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