Bronchodilators and corticosteroids in the treatment of asthma

Synthesis and bronchodilator activity of new quinazolin derivative

Taking lead from a naturally occurring quinazolin vasicine, a number of compounds were developed and evaluated for bronchodilator and anti-allergic activities. One of these compounds was 2,4-diethoxy-6,7,8,9,10,12-hexahydroazepino[2,1-b]quinazolin-12-one, hereinafter named 95-4, exhibited marked bronchodilator activity evaluated on contracted trachea or constricted tracheo-bronchial tree. On intestinal smooth muscle too it showed relaxant effect. Tracheal relaxant effect was not found to be mediated through beta-adrenoceptors. Cumulative dose-response study with acetylcholine and histamine indicated for its non-specific direct effect on smooth muscles. 95-4 was found to be more potent than theophylline and less to that of salbutamol on dose basis. Tested by a number of experimental models, it was found devoid of anti-allergic activity. It was also found to be free from any adverse effect. 95-4 due to its marked bronchial muscle relaxant effect can find use in conditions associated with spasm of bronchial muscles.

Corticosteroids: the mainstay in asthma therapy

Inflammation is now marked as a central feature of asthma pathophysiology and aims of current asthma management are not only to treat acute symptoms of wheezing, breathlessness, chest tightness, cough but also to suppress the underlying inflammatory component. Despite the availability of a number of drugs, corticosteroids remain the mainstay in the management of all types of asthma as these are the most potent and effective antiinflammatory agents available so far. Corticosteroids suppress virtually every step in inflammation. However therapeutic doses of oral glucocorticoids are associated with a range of adverse reactions. To overcome these side effects, inhalations have been developed to deliver glucocorticoids directly to the lungs and in the process a number of aerosol preparations have become available, which have advantage of significantly lower toxicity due to low systemic absorption from the respiratory tract and rapid inactivation. Despite considerable efforts by pharmaceutical industry, it has been difficult to develop novel therapeutic agents for asthma management, which could surpass inhaled corticosteroids. Currently the data favours using inhaled corticosteroids as monotherapy in the majority of patients in all kinds of asthma. If combination therapy is recommended to achieve additional control in severe asthma cases, other drugs such as beta-agonists, antileukotrienes, theophylline, etc. are considered as adjunct therapies to corticosteroids. This review discusses the importance of corticosteroids as first line therapy for asthma treatment with the availability of inhaled corticosteroids for chronic treatment and oral formulations for treating acute exacerbations of moderate to severe asthma.

Novel phthalimide derivatives, designed as leukotriene D(4) receptor antagonists

A series of phthalimide acid derivatives was synthesized and evaluated as leukotriene D(4) receptor antagonists. The tetrazolephthalimide LASSBio 552 (7) was shown to be able to inhibit the contractile activity induced by 100 nM of LTD(4) in guinea-pig tracheal strips with an IC(50) = 31.2 microM. In addition, LASSBio 552 (7) has been showed to present a better efficacy than zafirlukast (1) used as standard.

Synthesis and bronchodilatory activity of some nitrogen bridgehead compounds

A series of tricyclic nitrogen bridgehead compounds 7-22 have been synthesised and evaluated for their in vitro bronchodilatory activity using isolated guinea pig tracheal chain, precontracted with acetylcholine. The relaxant effect of 2,3,4,5-tetrahydroazepino[2,1-b]-8,9-dimethoxyquinazolin-11(1H)-one (7) (DPJ-386) was greater than that of theophylline, aminophylline and quinazoline derivative 3, which lacks methoxy groups at positions 8 and 9. Various nitrogen containing functionalities such as benzylamino, acetamido, benzamido and phthalimido were also introduced at 9 position of 3. This resulted in loss of relaxation activity in precontracted guinea pig tracheal chain. These results show that the better relaxation property possessed by compound 7 hydrochloride is due to methoxy groups at 8 and 9 positions.