Archive for the ‘COLD’ Category


The present results in humans are in agreement with results obtained in conscious dogs, where neither acute nor chronic (six days) hypoxia affected theophylline disposition. However, these results differ from those obtained in a rabbit study, where it was shown that short term hypoxia (mean Pa02 of 55 mmHg) significantly decreased theophylline clearance. This discrepancy may be due to species differences or to protocol differences (in the rabbits, hypoxia was acute and of short duration and in addition, the rabbits had slight respiratory alkalosis). The discrepancy may also have been caused by other factors related to the patients chronic respiratory disease, which may have influenced theophylline disposition. It is unlikely, however, that our results were biased by the experimental protocol (eg, blood sampling for only six hours), as the estimated theophylline kinetic parameters are in total agreement with those reported in the literature. (more…)

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  • Theophylline Disposition in Patients with COLD with and without Hypoxemia: DiscussionThere was no relationship between the slight changes in theophylline clearance and the variations in Pa02. However, when the patients were divided into two groups according to their PaC02 values, with 45 mm Hg as the cutoff, it was apparent that subjects with normal PaC02 values (lower than 45 mm Hg), had significantly higher values of theophylline clearance than patients with PaC02 values above 45 (Fig 2). Moreover, when considering the ten patients before and after therapy, the changes in theophylline clearance were inversely correlated (r= —0.5264; p<0.02) with the values of PaC02 (Fig 3). so (more…)

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  • Pharmacokinetic parameters were calculated using conventional model independent methods by means of a nonlinear regression curve-fitting program. In order to calculate the apparent volume of distribution (Vd) and the apparent systemic clearance (C1T), we subtracted the area under theophylline plasma concentrations curve function of time (AUC) corresponding to the decline of theophylline plasma concentration at time 0 (calculated as from the total value of theophylline AUC (AUQmJ. Theophylline renal clearance (Cl*) was calculated by dividing the amount recovered in urine for six hours by the AUC©*. Theophylline metabolic clearance (C1M) was estimated from the equation CIT-C1R. this (more…)

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  • Theophylline Disposition in Patients with COLD with and without Hypoxemia: ProtocolDrug therapy had been used in these patients prior to the study. This included oral theophylline (eight patients), salbutamol (two patients), amoxacillin (two patients), almitrine (two patients), cysteine derivatives (five patients) and furosemide, K+ supplements, oxitropium and occasionally nitrates (one patient). Only four patients received theophylline between the two experiments. In all cases, theophylline was interrupted 24 hours prior the experiment. Prior and during the study, the patients drank the same amount of coffee (one to two cups per day) and none of them ate chocolate. Eight of the subjects were occasional wine drinkers (one to three cups per day). website (more…)

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  • The present study further investigated the effect of arterial blood gases on theophylline disposition. The experimental protocol differed from that of the earlier studies in two critical areas: first, the disposition of theophylline was assessed in the same patients with hypoxia and later on oxygen therapy, and second, theophylline and its three major metabolites were assayed in urine so as to document how hypoxia influenced theophylline biotransformation. (more…)

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  • Theophylline Disposition in Patients with COLD with and without Hypoxemia

    Oct 27, 2014 Author: Walter Mcneil | Filed under: COLD

    Theophylline Disposition in Patients with COLD with and without HypoxemiaTheophylline systemic clearance is decreased in a variety of disease states, eg, severe airway obstruction, COLD in the elderly, pneumonia, cor pulmonale, congestive heart failure, acute pulmonary edema, and hepatic failure. Theophylline hepatic extraction ratio, expressed as the ratio of the rate of extraction (arterial less venous concentrations) to the rate of presentation (arterial concentration), is low and its plasma protein binding is only 50 percent. Thus, one may speculate that a decrease in theophylline clearance should be related to a reduction in its rate of biotransformation. In all the above diseases states except hepatic failure, the mechanism explaining this decrease remains obscure. (more…)

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