Study of the peak splitting in an alternative method for the radiochemical purity measurement of 99mTechnetium-sestamibi.

One of the alternative methods for the measurement of radiochemical purity (RCP) of Technetium-sestamibi uses Whatman 3MM paper as the stationary phase and ethyl acetate as the mobile phase. However, alternative method shows peak splitting and shouldering of the radiopharmaceutical. This could be because of higher levels of analyte. We aimed to assess the effect of sample dilution (1 : 1) on this method and to compare these RCP values with the reference method. The diluted samples showed a unique peak in the radiopharmaceutical zone, but the RCP values were significantly different (P<0.05) and correlated poorly with the reference method.

Influence of body mass index and type of low-level exercise on the side effect profile of regadenoson.

PURPOSE: Regadenoson, an A2A adenosine receptor pharmacologic stress agent for radionuclide myocardial perfusion imaging (MPI), is administered as a single, fixed dose. We studied the side effect profile of regadenoson combined with two types of low-level exercise, according to body mass index (BMI). METHODS: Three hundred and fifty-six patients (46.1% men, mean age 67.7±10.7 years, range 31-90 years) underwent regadenoson stress testing combined with low-level exercise. Subjects were classified according to BMI as normal, overweight, or obese, and the type of low-level exercise performed as walking on the treadmill (TE group, n=190) or forcefully swinging legs while sitting (SS group, n=166). Patients' demographics, medical history, clinical symptoms during stress, changes in ECG, oxygen saturation (SatO2), systolic blood pressure (SBP), and heart rate (HR) were evaluated. RESULTS: Groups were comparable (p=ns) with regard to cardiovascular risks factors. The incidence of side effects was similar across BMI (p=ns), although the TE patients showed improved profiles over those with SS exercise, with a significantly lower incidence of flushing, dizziness and nausea/gastrointestinal discomfort (12.9% vs. 28.4%; 19.9% vs. 33.4%; 11.4% vs. 19.2%, respectively; all p<0.05). Regarding the hemodynamic response, we did not observe significant changes in SBP and HR after regadenoson administration across BMI categories. Comparing the TE and SS groups, no significant changes were observed in SBP, but there was a higher increase in HR in the TE group (p<0.05). CONCLUSIONS: Regadenoson in combination with low-level exercise is safe and well tolerated over a wide range of BMI, with TE exercise showing a better side effect profile than SS.

Comparative study of the safety of regadenoson between patients with mild/moderate chronic obstructive pulmonary disease and asthma.

PURPOSE: To compare the safety of regadenoson, a selective agonist of A2A adenosine receptors, combined with low-level exercise, between subjects with mild/moderate chronic obstructive pulmonary disease (COPD) and asthma referred for myocardial perfusion imaging (MPI). METHODS: We studied 116 patients, of whom 67 had COPD and 49 asthma (62 % men, mean age 68.3 ± 11.3 years, range 31 - 87 years). Patient demographics, past medical history, medications, clinical symptoms during stress and changes in blood pressure (BP) and heart rate (HR) were evaluated. RESULTS: Both groups were comparable with regard to hypertension, dyslipidaemia, diabetes and medications with the exception of a higher rate of use of anticholinergics in patients with COPD and of antileukotrienes in asthmatics (58.2 % vs. 28.6 % and 1.5 % vs. 14.3 %, respectively; all p < 0.01). There was a higher incidence of dyspnoea in COPD patients and of headache and feeling hot in asthmatic patients (40.3 % vs. 22.4 %, 6 % vs. 18.4 % and 10.4 % vs. 26.5 %, respectively; all p < 0.05). Although there was no difference in the incidence of other adverse events, we observed a higher frequency in asthmatics of flushing, dry mouth, sweating and fatigue (1.5 % vs. 6.1 %, 14.9 % vs. 24.5 %, 0 % vs. 4.1 % and 37.3 % vs. 49 %, respectively). Adverse events were self-limiting, except in three patients who suffered persistent dyspnoea (2 of 67 COPD patients; 1 of 49 asthma patients) requiring theophylline administration. We observed no significant changes in BP among either group, but there was a tendency towards a higher increase in systolic BP in COPD patients following regadenoson administration (148.3 ± 27.6 vs. 154.6 ± 31.0 mmHg, p = 0.056). CONCLUSION: This study showed a good safety profile in our series of COPD and asthma patients undergoing MPI. Regadenoson was well tolerated by all patients, with dyspnoea, headache and feeling hot showing differences between groups.

A new method for the radiochemical purity measurement of ¹¹¹In-pentetreotide.

OBJECTIVES AND METHODS: The recommended method for the measurement of radiochemical purity (RCP) of ¹¹¹In-labelled pentetreotide is thin-layer chromatography with a silica gel as the stationary phase and a 0.1 N sodium citrate solution (pH 5) as the mobile phase. According to the supplier's instructions, the mobile phase must be prepared before the test is carried out, and the recommended stationary phase is off-market. We propose a new method for RCP measurement in which the mobile phase is acid citrate dextrose, solution A, which does not need to be prepared beforehand, and thin-layer chromatography is performed with a silica gel-impregnated glass fibre sheet as the stationary phase. We used both methods to measure the percentages of radiopharmaceutical and impurities. RESULTS: The range of RCP values obtained was 98.0-99.9% (mean=99.3%) by the standard method and 98.1-99.9% (mean=99.2%) by the new method. We observed no differences between the RCP values of both methods (P=0.070). CONCLUSION: The proposed method is suitable for RCP testing because it yields results that are in good agreement with those of the standard method and because it is easier to perform as the mobile-phase solution need not be prepared in advance.