Biomedical subjects

A Olcay

Publications and source records attributed to A Olcay.

6 recordsLinked to original sources

PubMed2004

New support for clarifying the relation between ST segment resolution and microvascular function: degree of ST segment resolution correlates with the pressure derived collateral flow index.

OBJECTIVE: To investigate the relation between the degree of ST segment resolution (STR) after thrombolysis and the pressure derived collateral flow index (CFIp), determined using an intracoronary pressure measurement technique in patients with recent myocardial infarction. METHODS: 33 patients were studied. TIMI grade III flow was achieved in the infarct related artery by thrombolysis. A surface ECG was obtained on admission and 90 minutes later. The sum of ST segment elevations was measured by summing all leads with ST elevation on the baseline ECG and on the 90 minute ECG (after thrombolysis) and calculating the percentage recovery. The study population was divided into two groups, with good STR (> or = 50%; group 1) or poor STR (< 50%; group 2). After angiography, a fibreoptic pressure monitoring guidewire was advanced to the stenosis to be dilated. The CFIp was determined as the ratio [coronary wedge pressure - central venous pressure]/[mean aortic pressure - central venous pressure]. RESULTS: The mean STR on the surface ECG was 54.6% and mean (SD) CFIp was 0.25 (0.12) (range 0.10-0.41). There was an inverse correlation between the individually calculated percentage of STR and CFIp (r = -0.64, p < 0.01). The mean CFIp was lower in patients with a good STR than in those with a poor STR (0.18 (0.07) v 0.27 (0.10), p < 0.02). CONCLUSIONS: Although TIMI grade III flow was achieved after thrombolysis, a worse STR on the surface ECG was associated with higher CFIp measured in the infarct related artery. CFIp appears to reflect the degree of microvascular obstruction by quantifying impedance of the microvasculature.

Blood Pressure↗

PubMed1977

Serum glycoside concentrations after single or repeated intravenous doses of beta-methyl-digoxin and digoxin.

The aim of the present investigation was to estimate the ratio of the intravenous doses of beta-methyl-digoxin and digoxin required to produce identical serum glycoside concentrations in man. 20 patients on intravenous maintenance therapy were changed from beta-methyl-digoxin to the identical dose of digoxin or vice versa. Each drug was given for 7 days. Serum concentrations 13% higher were found during administraton of beta-methyl-digoxin. Assuming a half life of 60 h after withdrawal, the dose of digoxin producing the same minimum serum concentration was estimated to be 1.16 times higher than that of beta-methyl-digoxin. 18 healthy volunteers received 0.4 mg beta-methyl- digoxin, and 23 the same dose of digoxin, as an intravenous infusion over 2 h. The serum concentrations and urinary glycoside excretion were measured over a period of 32 hrs. During the first hour after the infusion the serum concentration of digoxin declined more rapidly than that of beeta-methyl-digoxin. Thereafter, the ratio of the serum concentrtions did not change appreciably up to the end of the investigation. The area under the serum concentration/time curve was about 13% greater for beta-methyl-digoxin than for digoxin; this difference was not significant. The average renal clearance was 96 +- 9 ml for beta-methyl-digoxin, 151 +- 13 ml for digoxin. Since the total body clearance of digoxin is only about 1.16 times higher than that of beta-methyl-digoxin, the lower renal clearance of beta-methyl-digoxin must partly be compensated by higher extrarenal clearance. From the ratios of the areas under the serum concentration/time curves after single doses of beta-methyl-digoxin and digoxin, and the minimum serum concentrations during maintenance therapy, it was concluded that the dose of digoxin to produce the same average serum concentrations would be about 1.15 times higher than that of beta-methyl-dogoxin. In comparison wtih the large variations in individual dosage of digoxin and beta-methyl-digoxin, this difference is too small to be of practical importance.

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PubMed1976

Absorption of beta-methyl-digoxin determined after a single dose and under steady state conditions.

Single doses of beta-methyl-digoxin 0.4 mg were given to groups of 17-18 healthy volunteers as an intravenous infusion lasting 2 hours, or orally as Lanitop Liquidum or Lanitop tablets. The serum glycoside concentration and urinary glycoside excretion were measured over 8 and 32 h. The absolute bioavailability from the oral preparations in comparison with the infusion was lower for the first 8 h than for the entire 32 h of the investigation; the relative bioavailability from tablets was the same as from the solution for both periods. For both periods the area under the serum concentration/time curve and the urinary glycoside excretion were significantly lower after administration of the tablets than after intravenous infusion. Taking the average of both parameters, the absolute bioavailability of beta-methyl-digoxin was about 80% from the solution and about 70% from the tablets. In 18 patients undergoing intravenous or oral therapy with beta-methyl-digoxin steady state glycoside concentration were compared in a cross-over study of intravenous maintenance therapy with Lanitop ampoules or oral treatment with Lanitop tablets. For a standard daily dose of 0.2 mg beta-methyl-digoxin the serum concentrations were 1.35 +/- 0.10 ng/ml during both intravenous and oral administration. The intra-individual variation in glycoside concentration after changing from intravenous to oral maintenance therapy, or vice versa, was about the same as during continued intravenous or oral administration. It is concluded that the rate of rise of serum concentration after a single dose may be a useful indicator of the rate of absorption, but that the area under the serum concentration/time curve and the urinary glycoside excretion up to 32 h are unsuitable for determining equivalent doses of different formulations or routes of administration of digitalis glycosides.

Administration, Oral↗

PubMed1975

[Gycoside serum concentrations under maintenance therapy with Lanicor, Card-Lamuran, MF708d, and Lanitop (author's transl)].

The biological availability of digitoxin from Lanicor was compared with that from two different galenical preparations of Card-Lamuran (Card-Lamuran and MF708d both containing equal amounts of active ingredients: 0,125 mg digitoxin and 10 mg raubasine). The patients who were kept on their individually adjusted oral digitoxin maintenance dosage received the three preparations in a randomised order. Additionally, the equivalent dosages of Lanicor and Lanitop were determined from the data on their biological availability. In 24 patients with heart failure (mean age 70.5 years), radioimmunoassay of the glycoside concentration in the serum was performed. The patients were cardially well compensated with Lanicor and it could be assumed that there would be no change in the daily maintenance dosage for the entire period of the study (42 days). Our results show that digitoxin had the same bio-availability from Lanicor and the two different galenical preparations of Card-Lamuran and MF708d. Patients can therefore safely be switched from one of these preparations to the other. On average, doses of Lanicor 1.55 times higher than those of Lanitop must be given to obtain the same serum glycoside concentrations. The variation of this factor was no greater than the variation in serum concentrations of digitoxin during continued maintenance therapy with Lanicor. The mean serum concentrations of digitoxin under maintenance therapy in our geriatric patients (mean value 2.1 mg/ml) were higher than the digitoxin concentrations published in the literature for younger patients (average 1.4 ng/ml). The calculated daily maintenance doses providing a digitoxin concentration of 1.4 mg/ml were ca. 0.3 mg Lanicor and ca. 0.2 mg Lanitop. This is somewhat less than generally assumed. This agrees with the clinical experience that the glycoside maintenance dosage in elderly patients is generally less than in middle-aged patients.

Age Factors↗

PubMedDate not supplied

Ischemia-reperfusion-induced delay in intestinal transit. Role of endothelins.

BACKGROUND/AIMS: To evaluate the involvement of ET-1 in ischemia-reperfusion (I/R) injury. METHODS: Superior artery occlusion was performed in Wistar albino rats for 30 min followed by 2-hour (early reperfusion; ER) or 24-hour (late reperfusion; LR) reperfusion periods. RESULTS: Intestinal transit was found to be reduced in the ER and LR groups (19.0 +/- 2.5%; p < 0.001 and 72.7 +/- 6.0%; p < 0.05, respectively) compared to the control group (85. 8 +/- 2.5%), while treatment with the ET receptor antagonist bosentan (BOS; 10 mg/kg i.v.) abolished this delay in LR. Myeloperoxidase activity showed a significant increase in ER (7.07 +/- 85.70 U/g; p < 0.001) compared to control (281.16 +/- 43.23 U/g), but BOS had no effect on this increase. The protein oxidation level was found to be higher in LR (5.92 +/- 0.77 nmol/mg protein; p < 0. 05) compared to the control (3.77 +/- 0.45 nmol/mg protein), and was reversed by BOS treatment. CONCLUSION: The results of the present study imply that I/R delays intestinal transit involving an endothelin-dependent mechanism.

Animals↗

PubMedDate not supplied

Pharmacokinetics of metildigoxin and digoxin in geriatric patients with normal and elevated serum creatinine levels.

The pharmacokinetics of digoxin and metildigoxin were investigated in geriatric patients on maintenance treatment. Minimum serum glycoside concentrations were determined on 3 consecutive days, and the elimination rate over a withdrawal period of 4 to 6 days was studied. In patients with serum creatinine levels of less than or equal to 1.3 mg/dl, the oral standard dose D1) of digoxin necessary for a minimum serum concentration of 1.0ng/ml was 1.4 times higher than that of metildigoxin. There was no significant difference in the elimination rate of both glycosides. The pharmacokinetics of metildigoxin were further investigated in patients with elevated serum creatinine levels. The standard dose was best correlated with the creatinine clearance, calculated from the serum creatinine, age, weight and sex of the patients. The apparent volume of distribution of metildigoxin decreased with the drug's total body clearance.

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