Search

Copyright of Herz is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The value of early therapy with beta-blocking agents in acute myocardial infarction (AMI) undergoing reperfusion is not yet well established. Newer beta-blocking agents such as carvedilol offer potential advantages in the setting of ischemia and reperfusion injury. We randomized 100 patients with acute ST-elevation myocardial infarction (STEMI) to receive either 12.5 mg carvedilol or 50 mg metoprolol tartrate orally already before percutaneous coronary intervention (PCI) of the infarct-related artery, uptitrating to a daily target dose of 50 mg carvedilol or 150 mg metoprolol during the first week. Pts. were subjected to left ventricular (LV) angiography just before reperfusion and after 14 days to compare ejection fraction (EF) and regional wall motion abnormalities by quantitative LV analysis. Furthermore, kinetics of cardiac troponin T (cTnT), NT-proANP, NT-proBNP, endothelin, argenine vasopressin, epinephrine and norepinephrine were assessed during the first 12 hours and again at 2 weeks. In addition, reperfusion-induced rhythm abnormalities like VT, triplets, couplets, and bradycardic events were assessed continuously during the first 12 hours starting at reperfusion by Holter analysis. Both groups did not differ with respect to onset of pain, target vessel, extent of coronary heart disease, age, gender, rate of stenting or use of a GP IIb/IIIa inhibitor, pre- and postinterventional TIMI flow grade, time course of heart rate or blood pressure. There were neither significant differences in the cardiac and neurohumoral markers nor in the occurrence of arrhythmias between both treatment groups. Within 14 days, EF improved by 5.8±2.0% (mean±SEM) in the metoprolol group and by 5.2±2.1% in the carvedilol group (n.s.). Area of infarction was reduced by 6.1±2.9% in the metoprolol group and by 12.8±3.6% of total LV outline in the carvedilol group (n.s.). Maximum hypokinesia in the central infarcted region was diminished by 0.40±0.11 standard deviation (SD) in the metoprolol group and by 0.34±0.13 SD in the carvedilol group (n.s.). In the setting of direct PCI in acute STEMI, administration of carvedilol before reperfusion appears not to be superior to metoprolol with respect to myocardial injury and improvement of global and regional LV function. The study documents equivalent improvement of LV function and similar kinetics of cardiac and neurohumoral markers in pts. with acute STEMI undergoing direct PCI if the pts. were immediately treated with either carvedilol or metoprolol. Thus, superiority of carvedilol in experimental studies did not translate into a clinical benefit. [ABSTRACT FROM AUTHOR]

Copyright of Der Internist is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A 36 year old male was admitted to the intensive care unit with acute digitalis intoxication after ingestion of 350 digitoxin tablets (=35 mg digitoxin). He was treated with Fab fragments of a digitalis antiserum raised in sheep, the concentrations of digitoxin in serum, urine and dialysates being measured with two automated digitoxin immunoassays based on fluorescence labelling techniques. Whereas one assay reflected the total digitoxin concentrations, including that bound to the antidote, the other measured only the bioactive 'free' form of the drug. This article examines the use and limitations of both assay systems in assessing and monitoring cases of digitalis poisoning. [ABSTRACT FROM AUTHOR]

A massive digitoxin (DGTX) intoxication in a 36-year-old man (35 mg DGTX) was treated by prolonged and repeated i.v.-infusions of Fab fragments of anti-digitalis antibodies (FAB). Blood and urine samples were collected over a 98 h period for monitoring the efficacy and adequacy of FAB treatment. DGTX concentrations were determined after protein precipitation (release of FAB-bound and protein-bound DGTX) in unprocessed serum and urine samples, and after aliquots of these samples had been dialysed in vitro against DGTX-free buffer (elimination of DGTX not bound to FAB). The difference in DGTX concentration between the unprocessed and dialysed samples was the amount of DGTX bound to plasma proteins and the small fraction of unbound DGTX being relevant for the therapeutic and toxic effects of the drug. Before FAB therapy was started, the total serum DGTX concentration was 535 nmol/l. The first FAB infusion (320 mg) was started 11 h after drug ingestion. Since this amount of FAB was insufficient to bind all DGTX present in the serum, cardiac DGTX toxicity (total AV-block) persisted. During a second FAB infusion (400 mg) the patient reverted to regular AV-conduction. At this time most of the DGTX in serum was FAB-bound. Toxic symptoms (sinus arrest) reappeared twice and were accompanied by increasing amounts of non-antibody-bound DGTX in the serum. Additional application of FAB (2 x 80 mg) resulted in the immediate disappearance of arrhythmia. During FAB-treatment total DGTX serum concentrations and renal DGTX clearance rose, indicating redistribution of drug from tissue to serum and urinary elimination of FAB-bound DGTX, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) [ABSTRACT FROM AUTHOR]

The oxazaphosphorine antineoplastic ifosfamide (IF) is metabolized by two different initial pathways: ring oxidation (“activation”), forming 4-OH-IF (“activated IF”), and side-chain oxidation with liberation of chloroacetaldehyde (CAA), forming the inactive metabolites 3-dechloroethylifosfamide or 2-dechloroethylifosfamide (3-DCE-IF, 2-DCE-IF). 4-OH-IF and 4-OH-IF-derived acrolein are thought to be responsible for IF-induced urotoxicity (hemorrhagic cystitis), whereas CAA may be involved in IF-associated nephrotoxicity (renal tubular damage). The thiol compound 2-mercaptoethane sulfonate sodium (mesna) has proved to inactivate sufficiently the urotoxic metabolites of oxazaphosphorine cytostatics and is therefore routinely given to patients receiving IF chemotherapy. The cumulative urinary excretion of IF, 4-OH-IF, 3-DCE-IF, 2-DCE-IF, mesna, and its disulfide dimesna was studied in 11 patients with bronchogenic carcinoma receiving IF on a 5-day divided-dose schedule (1.5 g/m2 daily) with concomitant application of mesna (0.3 g/m2 at 0, 4, and 8 h after IF infusion). On day 1 the mean cumulative 24-h urinary recoveries (percentage of the IF dose) recorded for IF, 4-OH-IF, 3-DCE-IF, and 2-DCE-IF were 13.9%, 0.52%, 4.8%, and 1.5%, respectively. On day 5 the corresponding values were 12.2%, 0.74%, 9.9%, and 3.6%, respectively. This time-dependent increase in urinary excretion of IF metabolites, which is caused by rapid autoinduction of hepatic oxidative metabolism, may result in a higher probability for the development of urotoxic and nephrotoxic side effects during prolonged IF application. The mean 24-h urinary recoveries (percentage of the daily mesna dose) recorded for mesna/dimesna on day 1 (day 5) were 23.8%/45.2% (21.2%/39.8%), respectively. The mean molar excess of urinary reduced (“free”) mesna over 4-OH-IF ranged from 11 to 72 on day 1 and from 6 to 40 on day 5. This indicates that although urinary excretion of 4-OH-IF rises with repeated IF application, mesna in standard doses should sufficiently inactivate the urotoxic IF metabolites. [ABSTRACT FROM AUTHOR]

The initial metabolism of the oxazaphosphorine cytostatic ifosfamide (IF) consists of two different pathways: ring oxidation at carbon-4 forms the cytostatically active metabolite 4-hydroxyifosfamide (4-OH-IF, "activated ifosfamide"), whereas side-chain oxidation with liberation of the presumably neurotoxic compound chloroacetaldehyde (CAA) that may also be responsible for IF-associated nephrotoxicity results in the formation of the cytostatically inactive metabolites 2-dechloroethylifosfamide (2-DCE-IF) and 3-dechloroethylifosfamide (3-DCE-IF). The pharmacokinetics of IF and its metabolites were investigated in 11 patients with bronchogenic carcinoma receiving IF on a 5-day divided-dose schedule (1.5 g/m2 daily). Blood samples were drawn on days 1 and 5 for up to 24 h after the start of the IF infusion. IF, 2-DCE-IF, and 3-DCE-IF were simultaneously quantified by gas chromatography (GC) with an NIP flame-ionization detector (NPFID), CAA was determined by GC with an electron-capture detector (ECD), and the highly unstable compound 4-OH-IF was measured using a high-performance liquid chromatography (HPLC) assay with fluorometric detection of 7-OH-quinoline, which is formed by the condensation of 4-OH-IF-derived acrolein with m-aminophenol. As compared with the values obtained on day 1, on day 5 the terminal half-life and AUC values determined for IF were reduced by 30% (6.36 vs 4.06 h and 1781 vs 1204 nmol h ml-1, respectively), whereas the maximal concentration (Cmax) values were not affected significantly (199.1 vs 181.1 nmol ml-1). This known phenomenon is explained by autoinduction of hepatic IF metabolism and was paralleled by increased metabolite levels. The mean Cmax values determined for 4-OH-IF, CAA, 3-DCE-IF, and 2-DCE-IF (on day 1/on day 5) were 1.51/2.59, 2.69/4.85, 12.9/26.5, and 8.6/16.7 nmol ml-1, respectively. The corresponding AUC values were 11.3/16.5, 30.3/34.3, 146/354, and 111/209 nmol h ml-1, respectively. As calculated by intraindividual comparison, the mean Cmax (day 5): Cmax (day 1) ratios for 4-OH-IF, CAA, 3-DCE-IF, and 2-DCE-IF were 1.94*, 2.05*, 2.52*, and 2.33*, respectively; the corresponding AUC (day 5): AUC (day 1) ratios were 1.51*, 1.29, 2.34*, and 2.23*, respectively (* P < 0.05). These data reveal that during fractionated-dose IF therapy the cancerotoxic effect of the drug increases. If the assumed role of CAA in IF-associated neurotoxicity and nephrotoxicity is a dose-dependent phenomenon, the probability of developing these side effects would also increase during prolonged IF application. [ABSTRACT FROM AUTHOR]

The plasma concentrations and tissue distribution of thiopurines were studied in mice after oral administration of 50 mg/kg azathioprine (AZA) using HPLC analysis. Peak concentrations of AZA and three other thiopurine metabolites in plasma [thiouric acid (TUA) greater than 6-mercaptopurine (6-MP) greater than AZA greater than 8-hydroxy-AZA] were observed as early as 10 min after drug application, thus indicating fast absorption and extensive metabolism of AZA, and were followed by a rapid decline. The extraction of thiopurines from organs (intestinal mucosa, liver, kidney, testes, spleen, and bone marrow) and from red blood cells (RBCs) was preceded by an acid hydrolysis procedure resulting in the release of thiopurine bases from their corresponding ribonucleotides. 6-MP, 6-thioxanthene (6-TX), 6-thioguanine (6-TG), TUA, and 8-hydroxy-6-MP (8-OH-6-MP) were extracted from the organs, whereas only 6-MP and 8-OH-6-MP were found in the processed RBCs. Initially, high concentrations of TUA, the endpoint of metabolic AZA degradation, were detected in the intestinal mucosa and in the liver. This provides evidence for a first-pass metabolism of AZA in these two organs. The initial concentrations of 6-MP extracted from the organs were about 10-fold those found in plasma. This indicates rapid cellular uptake of 6-MP and an accumulation of 6-MP derivatives that can be explained by formation of the 6-MP ribonucleotide thioinosine monophosphate (TIMP). With the exception of plasma and RBCs, 6-TG, which may originate from intracellular 6-thioguanosine nucleotides (TGNs), was extracted from all organs examined in the study. From the sequence of appearance of 6-MP, 6-TX, and 6-TG extracted from spleen and bone marrow homogenates, it can be assumed that formation of TGN occurs via the nucleotide interconversion pathway TIMP----6-thioxanthosine monophosphate----6-thioguanosine monophosphate. The highest concentrations of 6-TG derivatives were found in the spleen and bone marrow. This correlates with the clinical and experimental observation that AZA cytotoxicity mainly affects bone-marrow stem cells and lymphocytes and supports the hypothesis (derived from in vitro experiments) that the incorporation of TGN into DNA is the cytotoxic mechanism of AZA and 6-MP. [ABSTRACT FROM AUTHOR]

A 61-year-old man developed a pyrescia accompanied by a massive intravascular hemolysis after abdominal surgery (Whipple's operation) of a pancreatic adenocarcinoma. Abdominal ultrasound and the abdominal CT-scan showed marked aerobilia and multiple liver abscesses. Laboratory tests demonstrated the presence of the Thomsen-Friedenreich cryptantigen (TCA) on the membranes of the patient's erythrocytes. The enzymatic cleavage of N-acetyl-neuraminic acid usually covering the TCA may lead to a life threatening intravascular hemolysis. Since Clostridial bacteriae typically synthesize neuraminidase, the presumptive diagnosis of Clostridial sepsis complicated by massive hemolysis was made. Immediate antibiotic therapy including penicillin G and metronidazole stopped hemolysis within a few hours and the patient servived. On the following day, microbiological examination identified Clostridium perfringens in the patient's blood cultures. Clostrial sepsis should be suspected in patients with underlying infections and/or malignant diseases, particularly of the gastrointestinal or genitourinary tract, who present with septic shock and acute intravascular hemolysis. Whereas microbiological specification of the organism is time consuming, the relatively simple agglutination test with anti-TCA peanut lectin can provide a rapid presumptive diagnosis. The immediate onset of an appropriate antimicrobial therapy is of central importance and might be life-saving. [ABSTRACT FROM AUTHOR]

The initial metabolism of ifosfamide (IF) consists of two different pathways: enzymatic hydroxylation at carbon-4 forms the cytostatically active metabolite 4-OH-IF ('activated ifosfamide') whereas side-chain oxidation results in the liberation of chloroacetaldehyde, a compound with possible neurotoxic properties. The pharmacokinetics of ifosfamide and its activated form were investigated in 12 cancer patients, who received both oral and i.v. treatment in a randomized sequence on days 1 and 3 at a dose of 1 g/m ( n=7) or 1.5 g/m ( n=5). In 3 patients the pharmacokinetics of chloroacetaldehyde were also investigated. After oral application, ifosfamide absorption proceeded rapidly, the oral bioavailability was 0.92. Independent of the route of ifosfamide application on day 1, the terminal half-life on day 3 (when the drug was given by the alternative route) was decreased in 6 out of the 12 patients, thus indicating self-induction of hepatic metabolism. 4-OH-IF was already present 20 min after ifosfamide administration. In the individual patient the concentrations of 4-OH-IF were always higher after oral than after i.v. IF application: the mean p.o.:i.v. ratios for c and the area under the concentration/time curve were 2.3 and 1.7 respectively ( P<0.05). In a first series of 3 patients the chloroacetaldehyde concentrations measured after oral ifosfamide application were about twice as high as those when the drug was given intravenously. These results indicate that (in comparison to the i.v. route) orally administered ifosfamide may be more cancerotoxic but also leads to higher levels of chloroacetaldehyde. This would explain the neurotoxic sideeffects previously seen after oral administration of comparatively low ifosfamide doses. [ABSTRACT FROM AUTHOR]