Effects Of Oral Theophylline Research Articles

Effects of oral theophylline on sick sinus syndrome

Objectives. We sought to determine the effect of theophylline on cardiac pauses in sick sinus syndrome.Background. Sick sinus syndrome, a relatively benign condition, is usually treated with pacemaker implantation without any proved effectiveness. Thus, an appropriate pharmacologic therapy would be useful.Methods. Theophylline (200 to 400 mg/day for 1 month) was initially administered orally to 17 patients with sick sinus syndrome, which is manifested by sinus pauses of > 2.5 s. Eleven of the 17 patients subsequently received theophylline for an additional 8 to 37 months. Twenty-four-hour Holter recordings were obtained before treatment, at the end of 1 month of treatment and then at 6-month intervals.Results. Theophylline decreased the frequency of sinus pauses from 256 ± 230 to 23 ± 62 pauses per 24 h and decreased the duration of the longest pauses from 4.7 ± 1.8 to 2.2 ± 0.97 s after 1 month of treatment Subjective symptoms associated with cardiac pauses disappeared in 16 of 17 patients. Ventricular premature beats increased in frequency but did not last longer than two beats. Three patients experienced adverse effects. Nine of the 11 patients receiving long-term treatment had a good outcome, but 2 patients required a pacemaker because of the resppearance of long sinus pauses.Conclusions. The results suggest that oral theophylline may be beneficial for the treatment of patients with sick sinus syndrome.

Effect of theophylline and dipyridamole on the respiratory response to isocapnic hypoxia in normal human subjects

1. Twelve healthy young men took part in this investigation of the effect of oral theophylline and dipyridamole (two drugs known to affect the pharmacological effects of the purine nucleoside adenosine) on the respiratory response to isocapnic hypoxia. 2. The subjects underwent hypoxic rebreathing manoeuvres after 3-day pretreatments with each of the drugs for 12 h and were at least 2 h postprandial. For each in-Minute ventilation, the maximum rate of isometric inspiratory pressure development at the mouth and the ratio of inspiratory duration to total breath duration were analysed breath-by-breath and regressions of these variables upon the haemoglobin oxygen saturation were performed. 3. The slopes and intercepts of the lines describing the relationships of minute ventilation and the maximum rate of isometric inspiratory pressure development at the mouth with haemoglobin oxygen saturation were unaffected by the study drugs, and no differences in the pattern of breathing were observed. 4. We conclude that oral administration of these drugs does not result in alteration of the response of the respiratory system to progressive isocapnic hypoxia. 5. This suggests that either adenosine has no physiological role in hypoxic respiratory control as measured, or that it has opposing peripheral chemoreceptor and central respiratory centre effects which could not be distinguished by the techniques used.

Pharmacokinetics and cardio‐respiratory effects of oral theophylline in exercised horses

The pharmacokinetics of theophylline at rest and the effects on cardio-respiratory and blood lactate responses to exercise were investigated after repeated oral administrations in six healthy Standardbred horses. A dose of 5 mg/kg body weight was administered every 12 h. The binding of theophylline to plasma protein was also determined. There was good agreement between predicted and observed plasma concentrations of theophylline at steady state. The mean half-life of elimination was shown to be 17.0 +/- 2.5 h, the mean half life of absorption was 1.6 +/- 1.8 h, the apparent volume of distribution was 852 +/- 99.0 ml/kg and total plasma clearance 0.61 +/- 0.08 ml/kg/min. Theophylline showed very low plasma protein binding (12%). The heart rate and blood lactate levels, during and after exercise, were significantly increased during theophylline-treatment. There was an increase of the arterial oxygen tension after exercise and the arterial carbon dioxide values before and after exercise were significantly lower than the premedication values. No severe adverse effects of the drug were noted. The recommended oral dose is therefore 5 mg/kg every 12 h but due to inter-individual variation, an adjustment of the dose may be necessary. The changes in the studied exercise parameters indicate that the performance capacity may be impaired by theophylline in the healthy horse.

The effects of theophylline and salbutamol on right and left ventricular function in chronic bronchitis and emphysema

We have compared the effects of oral theophylline and salbutamol on right and left ventricular function in twelve patients with chronic bronchitis and emphysema. Right and left ventricular ejection fraction (RVEF and LVEF) were measured using multiple gated radionuclide ventriculography. Theophylline 600 mg and salbutamol 4 mg both produced increases in RVEF and LVEF. There were no significant changes in blood gases after either drug. The clinical significance of the effects of oral bronchodilators on cardiac function in patients with chronic bronchitis and emphysema has yet to be determined.

142. The effects of oral theophylline and terbutaline on skin tests and histamine release

142. The effects of oral theophylline and terbutaline on skin tests and histamine release