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E Escudero

Publications and source records attributed to E Escudero.

52 records · Page 3Linked to original sources
PubMed1995

Pharmacokinetics of amoxicillin/clavulanic acid combination after intravenous and oral administration in goats.

The intravenous and oral pharmacokinetics of an amoxicillin and clavulanic acid combination (20 mg/kg of sodium amoxicillin and 5 mg/kg of potassium clavulanate) were studied in six goats. After intravenous administration the pharmacokinetics of both drugs could be described by an open two-compartment model. Amoxicillin had a greater distribution volume (0.19 +/- 0.01 l/kg) than clavulanic acid (0.15 +/- 0.01 l/kg), whereas the distribution and elimination constants were higher for the latter, which was eliminated more quickly than amoxicillin. After oral administration of both drugs their pharmacokinetic behaviour was best described by an open one-compartment model with first-order absorption. Elimination half-lives were twice as long after oral (2.15 +/- 0.20 h and 1.94 +/- 0.16 h for amoxicillin and clavulanic acid respectively) than after intravenous administration (1.20 +/- 0.16 h and 0.86 +/- 0.09, respectively). An apparent 'flip-flop' situation was evident in this study. Bioavailability was 27% for amoxicillin and 50% for clavulanic acid.

Absorption↗
PubMed1995

Comparative pharmacokinetics of amoxicillin/clavulanic acid combination after intravenous administration to sheep and goats.

The pharmacokinetic behaviour of an amoxicillin/clavulanic acid combination was studied after intravenous administration of single doses (20 mg/kg per kg body weight) to five sheep and six goats. The objective was to determine whether there are differences between sheep and goats in the disposition of amoxicillin and clavulanic acid. The plasma concentration-time data were analysed by compartmental pharmacokinetic and non-compartmental methods. The disposition curves for both drugs were best described by a biexponential equation (two-compartment open model) in sheep and goats. The elimination half-lives of amoxicillin were 1.43 +/- 0.16 h in sheep and 1.13 +/- 0.19 h in goats, and of clavulanic acid were 1.16 +/- 0.01 h and 0.85 +/- 0.09 h in sheep and goats respectively. The apparent volumes of distribution of amoxicillin and clavulanic acid were similar in the two species. Body clearances of amoxicillin were 0.09 +/- 0.01 L/h kg in sheep and 0.11 +/- 0.01 L/h kg in goats, and of clavulanic acid were 0.07 +/- 0.01 L/h kg and 0.12 +/- 0.01 L/h kg in sheep and goats respectively. The half-lives and body clearances of amoxicillin and clavulanic acid differed significantly between sheep and goats. It was concluded that the disposition of amoxicillin and clavulanic acid administered intravenously as an amoxicillin/clavulanic acid combination to sheep and goats differed between the two ruminant species. Even though the differences in disposition kinetics of both drugs were statistically significant, the same intravenous dosing rate of this antimicrobial combination can generally be used in sheep and goats.

Amoxicillin↗
PubMed1995

[Acyclovir nephrotoxicity].

We are presenting the case of a seventy-six year old male infected with Herpes zoster of the trigeminal nerve. He had no previous nephropathology, but developed acute renal failure following the administration of an intravenous bolus of Acyclovir. The existing literature was reviewed. Possible pathogenic mechanisms are discussed, and precautions against nephrotoxicity are emphasized.

Acute Kidney Injury↗
PubMed1994

Pharmacokinetics of oxytetracycline in goats: modifications induced by a long-acting formulation.

The pharmacokinetics of oxytetracycline were studied in goats, after the intravenous and intramuscular injection of a conventional and long-acting formulation. The antibiotic was distributed according to an open two-compartment model. The apparent volume of distribution (Vz) and the central compartment volume (Vc) were 1.443 litres/kg and 0.453 litre/kg, respectively, and the total body clearance was 0.156 litre/kg/hour. The mean half-lives (T1/2 lambda z) of the conventional formulation after intravenous and intramuscular administration were six hours 28 minutes and 10 hours 38 minutes, respectively, whereas the long-acting formulation had half-lives of six hours 36 seconds and 29 hours, respectively, after intravenous and intramuscular injection. From the results of these single administrations two intramuscular dosage regimens can be proposed that achieve minimum concentrations of over 0.5 mg/litre (the minimum inhibitory concentration for most susceptible pathogens): with the conventional formulation by administering an initial dose of 10 mg/kg and a maintenance dose of 8.5 mg/kg every 24 hours, and with the long-acting formulation by administering an initial dose of 20 mg/kg and a maintenance dose of 14 mg/kg every 48 hours.

Animals↗
PubMed1986

Heparin and the solubilization of asymmetric acetylcholinesterase.

Heparin solubilizes asymmetric acetylcholinesterase, from chick skeletal muscle and retina, as a 24 S complex which is quantitatively converted to conventional asymmetric molecular forms of the enzyme (A12 and A8, either class I or class II) upon exposure to high salt. The simultaneous presence of salt and heparin in the homogenization medium selectively prevents, however, the release of class II A-forms in both muscle and retina. Heparin may generally act by displacing native proteoglycans involved in the attachment of the enzyme tail to the extracellular matrix, or its neural equivalent, being in turn removed by salt to yield typical asymmetric enzyme forms. Heparin would also appear to displace some other molecules specifically involved in the EDTA-sensitive attachment of class II tailed forms, this effect being antagonized by salt.

Acetylcholinesterase↗
PubMed1981

Solubilization of collagen-tailed acetylcholinesterase from chick retina: effect of different extraction procedures.

We have extracted acetylcholinesterase from young chick retinas by homogenization in different solutions combining high salt concentration, ionic and nonionic detergents, and EDTA, looking for an optimum procedure for the solubilization of collagen-tailed, asymmetric structural forms of the enzyme. High salt and EDTA seem to be the only necessary requirements for the solubilization of acetylcholinesterase as the A12 form (20S), and the presence of detergent in the homogenization medium does not significantly improve the yield of tailed enzyme. Extraction in the absence of detergent has the potential advantage of a threefold enrichment of tailed enzyme, because only about one-third of the total retinal acetylcholinesterase activity is solubilized. Divalent cations, especially Ca2+, seem to be involved in the attachment of the tailed enzyme to the retinal membranes, at the tail level. High salt-EDTA-extracted 20S acetylcholinesterase (without detergent) aggregates in the presence of exogenous Ca2+ and becomes "insoluble." However, the aggregated 20S acetylcholinesterase can be completely recovered and brought back into solution by further addition of EDTA. Besides, the aggregation can be prevented by the inclusion of Triton X-100 in the homogenization buffer or by adding the detergent concurrently with Ca2+. It is postulated that the acetylcholinesterase collagenous tail is coated by acidic lipid molecules hydrophobically bound to the tail protein so that Ca2+ ionic bridges would actually link these lipid molecules (and consequently the tail) to the membrane matrix. Removal of the lipid coat (e.g., by Triton X-100) produces tailed acetylcholinesterase molecules that no longer aggregate in the presence of Ca2+ and are fully accessible to collagenase digestion.

Acetylcholinesterase↗
PubMed1981

Myocardial flow distribution. II : Empty beating heart, ventricular fibrillation and cardiac arrest.

Myocardial oxygen consumption (MVO2) and coronary blood flow (CBF) distribution were studied in 21 isolated, metabolically supported dog hearts. Measurements of MVO2 and CBF distribution were carried out in three different experimental conditions : empty beating heart (EBH), ventricular fibrillation (VF) and high potassium-induced cardiac arrest (CA). MVO2 was approximately the same in EBH and VF (4.09 +/- 0.77 and 4.28 +/- 0.68 ml O2 min-1 100 g-1 respectively), and significantly lower in the group with CA (2.40 +/- 0.18 ml O2 min-1 100 g-1, P less than 0.05). Total CBF showed no significant differences among the three groups (84 +/- 7 ml/min in EBH; 78 +/- 7 ml/min in VF and 83 +/- 7 ml/min in CA). Subendocardial CBF per unit of tissue mass was significantly lower in hearts with VF (0.43 +/- 0.01 ml/min-1 g-1, P less than 0.05) when tested against the other two groups of experiments (0.69 +/- 0.03 ml min-1 g-1 in EBH and 0.65 +/- +/- 0.04 ml min-1 g-1 in CA). This was also reflected in the endo/epi ratio, that was significantly lower in VF (1.41 +/- 0.07, P less than 0.05) with respect to the other two groups (2 +/- 0.09 in EBH and 2.21 +/- 0.07 in CA). From data presented here we can conclude that cardioplegia, even in absence of hypothermia, is a method that will assure myocardial protection providing : (1) a lower subendocardial MVO2; (2) a higher subendocardial CBF, which helps for a prompt recovery during reperfusion.

Animals↗
PubMed1980

Solubilization of 20S acetylcholinesterase from the chick central nervous system.

The ionic detergent sodium cholate, in the presence of 1 M NaCl, solubilizes a 20S acetylcholinesterase from chick retina and other brain tissues previously extracted with a buffered solution containing 1% Triton X-100 and 1 M NaCl. This 20S acetylcholinesterase appears to be a tailed form of the enzyme which, upon collagenase digestion, is converted to a 22S (mainly) form. This finding suggests that the vertebrate central nervous system does contain asymmetric, collagen-tailed forms of acetylcholinesterase, as is the case in skeletal muscle and cholinergic ganglia.

Acetylcholinesterase↗
PubMed1979

Comparative metabolism of histamine in two Amphibia anura.

The metabolism of histamine has been compared in Rana ridibunda and Discoglossus pictus, both Amphibia anura. An intralymphatic injection of 14C-histamine (5 microCi) was administered to the animals and the total radioactivity excreted in the urine was measured 24, 48, and 72 hours later. The metabolites excreted in the urine at 24 hours were analyzed by thin-layer chromatography and subsequent autoradiography. In both species approximately 60--70% of the injected dose was found in the urine by 72 hours. In Rana ridibunda two histamine metabolites were found: imidazoleacetic and methylimidazoleacetic acid. The present results suggest that the catabolism of histamine differs in the two species.

Amphibians↗
PubMedDate not supplied

Crystal structure and molecular conformation of the cyclic hexapeptide cyclo-(Gly-Aib-Gly)2.

We have synthesized and crystallized the cyclic peptide (Gly-Aib-Gly)2. Its structure has been determined by conventional X-ray diffraction methods. In the crystal it adopts a conformation with one beta-turn (type I) and its mirror image at the other side of the ring. All conformational angles are similar to those reported for these amino acids residues. In particular the Aib residue has a conformation intermediate between alpha- and 3(10)-helical conformations. The ring is an adequate model for the beta-turn conformation. A molecule of formic acid is found in the crystal which shows a very short hydrogen bond with one of the glycine carbonyl groups.

Crystallography, X-Ray↗
PubMedDate not supplied

Pharmacokinetics of amoxicillin/clavulanic acid combination after intravenous and intramuscular administration to pigeons.

The pharmacokinetics of amoxicillin/clavulanic acid (4:1) combination were studied after intravenous and intramuscular administration of single doses (25 mg kg(-1) bodyweight) to 50 pigeons. The plasma concentrations-time data were analysed by compartmental pharmacokinetics and non-compartmental methods. The disposition curves for both drugs after intravenous administration were best described by a two-compartment open model. The apparent volumes of distribution of amoxicillin and clavulanic acid were 1.77 litres kg(-1) and 1.30 litres kg(-1) respectively. The body clearances of amoxicillin and clavulanic acid were not significantly different. The elimination half-lives of amoxicillin after intravenous and intramuscular administration were 1.22 (0.09) hour and 1.52 (0.09) hour respectively, and those of clavulanic acid were 1.15 (0.08) hour and 1.49 (0.08) hour. After intramuscular administration both drugs had a significantly longer half-life (P<0.05) than that after the intravenous treatment. The bioavailability after the intramuscular injection was high and similar for both drugs (75.98 per cent for amoxicillin and 74.61 per cent for clavulanic acid). The mean peak plasma concentration of clavulanic acid (0.29 hour) was reached earlier than amoxicillin (0.38 hour) and peak concentrations were proportional to the dose of both products administered (5.81 mg litre(-1) of amoxicillin and 1.89 mg litre(-1) of clavulanic acid). From a single administration it is proposed that an intramuscular dosage regimen of 105 mg kg(-1) of the combination (84 mg kg(-1) of amoxicillin and 21 mg kg(-1) of clavulanic acid) every 12 hours will achieve minimum concentrations > or =0.5 mg litre(-1) (minimum inhibitory concentration of most susceptible pathogens).

Amoxicillin↗
PubMedDate not supplied

The pharmacokinetics of moxidectin after oral and subcutaneous administration to sheep.

The pharmacokinetic parameters of moxidectin were determined in ten sheep following a single subcutaneous or oral drench at a dose of 0.2 mg.kg-1. The plasma kinetics were best fitted by a two-compartment model. Moxidectin was detected in the plasma at the first sampling time (1 h) and thereafter for at least 60 d. The AUC were similar after both treatments indicating the same bioavailability for the two routes of administration. The oral route was characterized by a higher Cmax value (28.07 ng.mL-1 than after subcutaneous injection (8.29 ng.mL-1 and by significantly faster absorption as indicated by Tmax of 0.22 d and 0.88 d for oral and subcutaneous administrations, respectively. The most striking result of this experiment was the longer mean residence time reported for the subcutaneous route, i.e. 16.80 d as compared to 12.55 d for the oral drench. This differences is in agreement with previous studies demonstrating the longer anthelmintic efficacy of the subcutaneous route in comparison with oral administration.

Administration, Oral↗