Methylxanthine therapy and reversible airway obstruction

Methylxanthines in asthma

Methylxanthines represent a unique class of drugs for the treatment of asthma. The methylxanthine theophylline has demonstrated efficacy in attenuating the three cardinal features of asthma - reversible airflow obstruction, airway hyperresponsiveness, and airway inflammation. At doses achieving relatively high serum levels in which toxic side effects are sometimes observed, direct bronchodilatory effects of theophylline are recognized. At lower serum concentrations, theophylline is a weak bronchodilator but retains its capacity as an immunomodulator, anti-inflammatory, and bronchoprotective drug. Intense investigation into the molecular mechanisms of action of theophylline has identified several different points of action. Phosphodiesterase inhibition and adenosine receptor antagonism have both been implicated in promoting airway smooth muscle relaxation and bronchodilation. Similar mechanisms of action may explain the inhibitory effects of theophylline on immune cells. At lower concentrations that fail to inhibit phosphodiesterase, effects on histone deacetylase activity are believed to contribute to the immunomodulatory actions of theophylline. Since anti-inflammatory and immunomodulatory effects of methylxanthines are realized at lower serum concentrations than are required for bronchodilation, theophylline's predominant role in asthma treatment is as a controller medication for chronic, persistent disease.

Use of Propentofylline in Feline Bronchial Disease: Prospective, Randomized, Positive-Controlled Study

Propentofylline is a methylxanthine derivative with bronchodilating actions similar to those of theophylline. Nineteen cats with bronchial disease were enrolled in this study. All cats received a low dose of prednisolone; 10 of the cats additionally received propentofylline. Propentofylline-treated cats significantly improved in their auscultation scores, respiratory pattern scores, and radiological bronchial markings score over the observation period, and they coughed less and slept less at the end of the study. No significant changes were noted in the control group. This study provides evidence that a combination therapy with prednisolone and propentofylline in cats with bronchial disease might be superior over monotherapy with prednisolone.

Drug therapy approaches in the treatment of acute severe asthma in hospitalised children

Acute severe paediatric asthma remains a serious and debilitating disease throughout the world. The incidence and mortality from asthma continue to increase. Early, effective and aggressive outpatient therapy is essential in reducing symptoms and preventing life-threatening progression. When complications occur or when the disease progresses to incipient respiratory failure, these children need to be managed in a continuous care facility where aggressive and potentially dangerous interventions can be safely instituted to reverse persistent bronchospasm. The primary drugs for acute severe asthma include oxygen, corticosteroids, salbutamol (albuterol) and anticholinergics. Second-line drugs include heliox, magnesium sulfate, ketamine and inhalational anaesthetics. Future therapies may include furosemide, leukotriene modifiers, antihistamines and phosphodiesterase inhibitors. This review attempts to explore the multitude of medications available with emphasis on pharmacology and pathophysiology.

Effect of theophylline on urinary excretion of 3-methylhistidine in patients with lung disease

Theophylline, which is commonly used for the treatment of lung disease, has been reported to stimulate lipolysis, glycogenolysis, and gluconeogenesis. This study was initiated to investigate whether theophylline therapy also induces catabolic changes in protein metabolism and thus provides additional substrates for energy metabolism. Urinary excretion of 3-methylhistidine (3-MH) as an index of myofibrillar protein catabolism was measured at the end of a 7-day treatment period with theophylline and a 5-day basal untreated control period in eight patients with stable chronic obstructive pulmonary disease (COPD), eight patients with stable asthma, and eight normal healthy volunteers. Basal urinary 3-MH excretion and 3-MH/creatinine ratios, and nutritional indices assessed were not different in the three groups. Under similar drug (except theophylline), dietary, and activity regimens, comparison of the two experimental periods showed that theophylline increased mean urinary 3-MH excretion and 3-MH/creatinine ratios in all three groups of subjects. These changes were significant in the COPD and asthmatic patients (mean 3-MH +/- SD, mumol/d: basal, 176 +/- 46 v 206 +/- 46; and basal, 190 +/- 27 v 216 +/- 45, respectively, P less than .05) and persisted when 3-MH values were normalized to creatinine excretion (15% to 38%, P less than .005). In contrast, the mean increment was marginal in the group of normal volunteers and this discrepancy of effect between groups may be attributed to dietary noncompliance. Furthermore, the response of the COPD group was significantly greater than the asthmatic and control groups (1.8x and 11.3x, respectively, P less than .05). In conclusion, these results suggest that theophylline may enhance myofibrillar protein degradation.(ABSTRACT TRUNCATED AT 250 WORDS)