Aspirin Medication in Dogs

Aspirin (acetylsalicylic acid; ASA) is widely used in both human and veterinary medicine. Therapeutic plasma salicylate concentrations (PSCs) can be reached using enteric-coated ASA tablets, but a delay in the initial rise and large fluctuations in the PSCs have been reported. From experiments described previously, the authors concluded that the large type enteric-coated ASA tablets were not suitable for use in beagle dogs.

In the first experiment described here, these large type tablets were administered to large mongrel dogs. Although the mean PSC reached therapeutic levels after 44 h, in individual dogs subtherapeutic concentrations were frequently recorded. In the second experiment microgranulated type enteric-coated ASA tablets were given to beagle dogs in a crossover design study. PSCs in all dogs exceeded minimal therapeutic levels 6 h after tablet administration. Stable therapeutic PSCs were found in both groups on different feeding regimens. In the third experiment the two types of enteric-coated ASA tablets were administered to fasting beagles. Comparable therapeutic PSCs were reached with both formulations.

From the present studies it can be concluded that the large type enteric-coated ASA tablet is not suitable for use in large mongrel dogs. Secondly, it can be concluded that the microgranulated type enteric-coated ASA tablet is suitable for the use in beagle dogs. In the third experiment it was proven that fasting eliminated the differences in mean PSC curves between the two types of ASA medication.

On the basis of canine gastric physiology the authors expect similar types of large enteric-coated tablets of other drugs to generate comparably poor plasma concentrations. The gastric evacuation of tablets is primarily related to the tablet dimensions and digestibility, and not to the drug contained by these tablets.

Myocardial perfusion reserve compared with peripheral perfusion reserve: a [13N]ammonia PET study

INTRODUCTION

[13N]ammonia PET allows quantification of myocardial perfusion. The similarity between peripheral flow and myocardial perfusion is unclear. We compared perfusion flow in the myocardium with the upper limb during rest and adenosine stress [13N]ammonia PET to establish whether peripheral perfusion reserve (PPR) correlates with MPR.

METHODS

[13N]ammonia myocardial perfusion PET-scans of 58 patients were evaluated (27 men, 31 women, age 64 ± 13 years) and were divided in four subgroups: patients with coronary artery disease (CAD, n = 15), cardiac syndrome X (SX, n = 14), idiopathic dilating cardiomyopathy (DCM, n = 16), and normal controls (NC, n = 13). Peripheral limb perfusion was measured in the muscular tissue of the proximal upper limb and quantified through a 2-tissue-compartment model and the PPR was calculated (stress/rest ratio). MPR was also calculated by a 2-tissue-compartment model. The PPR results were compared with the MPR findings.

RESULTS

Mean myocardial perfusion increased significantly in all groups as evidenced by the MPR (CAD 1.99 ± 0.47; SX 1.39 ± 0.31; DCM 1.72 ± 0.69; NC 2.91 ± 0.78). Mean peripheral perfusion also increased but not significantly and accompanied with great variations within and between groups (mean PPR: CAD 1.30 ± 0.79; SX 1.36 ± 0.71; DCM 1.60 ± 1.22; NC 1.27 ± 0.63). The mean difference between PPR and MPR for all subpopulations varied widely. No significant correlations in flow reserve were found between peripheral and myocardial microcirculatory beds in any of the groups (Total group: r = -0.07, SEE = 0.70, CAD: r = 0.14, SEE = 0.48, SX: r = 0.17, SEE = 0.30, DCM: r = -0.11, SEE = 0.71, NC: r = -0.19, SEE = 0.80).

CONCLUSION

No correlations between myocardial and peripheral perfusion (reserve) were found in different patient populations in the same PET session. This suggests a functional difference between peripheral and myocardial flow in the response to intravenously administered adenosine stress.

[Analgesics; the use of aspirin in dogs; effects of tablet type and food intake on plasma salicylate level]

Administration of acetylsalicylic acid (aspirin) in the dog may cause gastric mucosal damage. Enteric-coated tablets protect the canine stomach during oral aspirin medication. A therapeutic plasma salicylate concentration can be attained using enteric-coated aspirin tablets at a dosage of 25 mg/kg TID. In a series 4 of experiments using adult beagle and large mixed breed dogs and two types enteric-coated tablets, the influence of food intake on the plasma salicylate concentration was studied. Tablets were administered with 8h intervals and food intake was either once daily or three time daily with 8h intervals. Plasma salicylate concentrations were also studied during fasting. It is concluded that, when using enteric-coated tablets, the plasma salicylate concentration in the dog after oral medication is strongly influenced by the aspirin dosage, the tablet type and the feeding pattern. Large enteric-coated tablets may accumulate in the stomach over several days and are not suitable for use in the dog. The gastric accumulation is caused by the enteric-coating of the large tablets and not by the aspirin medication.

Multiple wavelength illumination in flow cytometry using a single arc lamp and a dispersing element

The principle of a multiple wavelength illumination method for flow cytometers, based upon a combination of a helium-neon laser and an arc lamp as illumination sources is described. By using a prism, the light from the arc lamp is dispersed and the different colors are imaged at different places on the sample stream. The small angle light scattering from the helium-neon laser light is measured as a relevant parameter and serves as a trigger signal for subsequent measurements of fluorescence or scattering of light from the arc lamp. Two experimental systems are described utilizing this principle: a system where the emission is detected orthogonally with respect to the direction of the illumination beams, and an epi-illumination system. With the orthogonal set-up multiple wave-length right angle scattering measurements are possible. This is illustrated by showing that the orthogonal scattering from erythrocytes is strongly dependent on the illumination wavelength. It is further shown that the apparatus is suitable for the measurement of intracellular pH using the pH dependence of the excitation spectrum of fluorescein. The epi-illumination system allows excitation of two (or more) fluorescent dyes with different excitation spectra. In this case the emission spectra of the fluorescent dyes may overlap substantially. This is shown by simultaneous measurement of DNA and protein of Chinese hamster lung cells using mitramycin and tetramethyl rhodamin isothiocyanate (TRITC).