Evaluation of the Incstar Cyclo-Trac sp kit for the determination of cyclosporine in blood.

We measured cyclosporine in whole blood samples from renal and heart transplant patients by high performance liquid chromatography and by two radioimmunoassays with use of specified monoclonal antibodies. In particular, we evaluated the analytical performance of a new specific radioimmunoassay with an iodinated tracer. The reproducibility of the method is satisfactory (within-run CV 7.1 to 9.5% and between-run CV 7.2 to 10.3%). The limit of detection is 10.3 micrograms/L and the analytical recovery between 99 and 114%. The results obtained with samples from both renal heart transplant patients agree well with those obtained by HPLC and by a specific RIA that uses a tritiated tracer.

Haemodynamic effects of coffee and purified caffeine in normal volunteers: a placebo-controlled clinical study.

In order to evaluate the effects of 'espresso' Italian coffee on resting flow, blood pressure, and peripheral resistance, 15 non-coffee drinking healthy volunteers received 2 cups of regular coffee, 200 mg purified caffeine or placebo in a latin square double-blind crossover protocol. Before and 30, 60, 90 and 120 min after ingestion, segmental resting flow and BP were measured and peripheral resistance was calculated. An echocardiogram was also performed before and 60 and 120 min after caffeine intake. Both regular coffee and caffeine produced a significant decrease in resting flow and a significant increase in resistance; both systolic and diastolic BP also increased, although not significantly. No variation was observed in heart rate and in cardiac contractility. Placebo (highly decaffeinated coffee for regular coffee and china bitter extract for caffeine) did not produce any haemodynamic effect. In five other healthy volunteers used to drinking more than 5 cups of coffee a day, coffee administration had no effect. These data demonstrate that the caffeine contained in espresso Italian coffee is a vasoconstrictor agent whose effects however are completely blunted in usual coffee drinkers as a consequence of adaptation.

Effects of caffeine on glucose tolerance: a placebo-controlled study.

OBJECTIVE: The investigation was performed to study the effects of 200 mg oral caffeine on glucose tolerance. DESIGN: Single-blind Latin square with active treatment (caffeine) and placebo. SETTING: The University of Padova, Department of Internal Medicine. SUBJECTS: 30 nonsmoking healthy subjects aged 26-32 years who abstained not only from coffee but also from tea, chocolate and cola for 4 weeks and who had given their informed consent. INTERVENTIONS: A 75 g oral glucose tolerance test (OGTT) was performed after giving caffeine or placebo (highly decaffeinated coffee). RESULTS: The glycaemic curve was normal in all subjects and was similar in the two groups until the second hour; in subjects taking caffeine a shift towards the right was detected at the 2nd, 3rd and 4th hours in comparison to those taking the placebo. Blood insulin levels were comparable after caffeine and after placebo along the entire OGTT. CONCLUSIONS: The data suggest that caffeine intake induces a rise in blood glucose levels that is insulin independent.

Performance of a fluorescence polarization immunoassay system evaluated by therapeutic monitoring of four drugs.

Fluorescence polarization immunoassays (FPIA) for amikacin, gentamicin, quinidine, and theophylline (supplied by Roche Diagnostic Systems, made using a Cobas Fara centrifugal analyzer) were evaluated and compared with widely used monitoring analysis methods. For each drug, the between-assay imprecision was ascertained by calibration on the day of assay and by a stored calibration curve made at the beginning of the study. The precision of the amikacin and theophylline assays was acceptable [total coefficient of variation (CV) less than 7.5%] at all concentrations tested for each calibration mode. Imprecision of quinidine and gentamicin assays was significant at low concentrations (1.9 mg/L): total CV = 9.0% for quinidine assessed with stored calibration curve and total CV greater than 8.5% for gentamicin measured with the two calibration modes. The calibration curves for all four assays had a good stability (greater than 30 days). Linear regression analysis demonstrated close agreement between the FPIA (y) and the following comparative techniques (x): Abbott TDx assay for amikacin and gentamicin (r = 0.988, r = 0.974, respectively); Stratus fluorometric enzyme immunoassay for quinidine (r = 0.979); and EMIT Syva assay for theophylline (r = 0.993). It is concluded that fluorescence polarization immunoassay is a rapid and reliable method for the therapeutic monitoring of the four drugs tested. Moreover, the use of reagents on an instrument that can be implemented for a wide range of chemistries has significant advantages and cost benefits over dedicated instruments.

Fluorescence polarization immunoassay for cyclosporine A determination in whole blood.

A fluorescence polarization immunoassay (FPIA) for cyclosporine A (CsA) determination in blood was evaluated. The method demonstrated a good reproducibility both in within-run and between-run assays. The linearity range was 35-990 micrograms/L. Comparison of measurements in patients' whole blood with radioimmunoassay results showed higher estimates by the FPIA despite the good correlation coefficient. Finally, a poor agreement was observed between the evaluated method and the high-performance liquid chromatographic technique for CsA determination.

[Hemodynamic effects of "expresso" Italian coffee and pure caffeine on healthy volunteers]. / Effetti emodinamici del caffè espresso all'italiana e della caffeina pura in volontari sani.

In 15 healthy non-coffee-drinker subjects and in 5 usual coffee-drinkers, the effects were studied of 2 cups of "espresso" italian coffee and of 200 mg purified caffeine on blood pressure, heart rate, forearm rest flow and peripheral resistance. In the 15 non-coffee-drinkers, left ventricular ejection fraction, fractional shortening, cardiac output and end-systolic stress were also evaluated by a 2D-guided M-mode echocardiogram before and 60 and 120 min after oral administration of 200 mg purified caffeine. In the non-coffee-drinker volunteers, diastolic and systolic blood pressure and peripheral resistance increased both after "espresso" coffee and after caffeine. In the usual drinkers no hemodynamic effect was seen. No variation of cardiac contractility was observed. We conclude that caffeine contained in the "espresso" coffee obtained with the high-pressure italian procedure is a strong vasoconstrictor agent, while it has no action on cardiac contractility.

High-performance liquid chromatography for cyclosporin measurement: comparison with radioimmunoassay.

The large inter-patient variability in cyclosporin pharmacokinetics coupled with the agent's narrow therapeutic index with adverse effects resulting from supratherapeutic levels, necessitates individualization of drug dosage and therapeutic monitoring of cyclosporin blood levels. The performance of a liquid chromatographic method for the measurement of cyclosporin was evaluated and the results obtained by this method and by a specific radioimmunoassay were correlated. The method described is sensitive, selective, reproducible and easier to perform than other chromatographic methods. It is suitable for the daily measurement of cyclosporin in batches of up to 40 samples and the results correlate well with another chromatographic method and with the specific radioimmunoassay.

Haemodynamic effects of coffee and caffeine in normal volunteers: a placebo-controlled clinical study.

The acute haemodynamic effects of Italian coffee and 200 mg purified caffeine were investigated in 15 healthy non-coffee-drinkers compared to individuals who consumed placebo (highly decaffeinated coffee for regular coffee, and china bitter extract for caffeine). Before coffee and caffeine consumption and 30, 60, 90 and 120 min afterwards, rest flow and blood pressure were measured, and peripheral resistance in the arm was calculated; an echocardiogram was also performed before and 60 and 120 min after caffeine consumption. Both coffee and caffeine significantly decreased rest flow, and increased peripheral resistance. Systolic blood pressure increased by 10% and diastolic pressure increased by 5% for at least 2 h. No variation in heart rate or cardiac contractility was found. No effects were observed after placebo treatment. It is concluded that Italian coffee and caffeine increase blood pressure via vasoconstriction.