CHEMOTHERAPY FOR CHRONIC-BRONCHITIS CONTROVERSIES

Chronic bronchitis is a common inflammatory disease of the airways cha racterised by cough, sputum production and associated features such as dyspnoea and respiratory obstruction. It has a poor prognosis once fu lly developed and imposes a heavy financial burden on affected societi es. Chronic bronchitis is subject to periodic exacerbations in which t he role of bacterial infection and the rightful place of antibiotic th erapy is only slowly emerging, largely due to the non-homogeneity of t he populations under study. Haemophilus influenzae is implicated as th e pathogen in more than half of all bacterial exacerbations, Streptoco ccus pneumoniae and Moraxella catarrhalis accounting for a further thi rd. Viruses and mycoplasmas are also involved. Some 18-25% of patients receiving domiciliary therapy may fail to respond to initial treatmen t, callling into question the efficacy of antibiotics in acute exacerb ations. In part this may relate to sub-optimal respiratory pharmacokin etics as most antibiotics are quite effective against sensitive respir atory pathogens in vitro. However, bacterial resistance rates against traditional agents are rising rapidly in Europe and new agents are nee ded to counter this threat. Paradoxically few such agents have been sh own to improve on the results of amoxycillin and other standard drugs, probably because most trials include patients with exacerbations of o nly mild-to-moderate severity due to sensitive pathogens. Since recent large scale studies have demonstrated the efficacy of antibiotic ther apy compared with placebo in defined exacerbations, use of these defin itions has allowed mon realistic assessment of new agents which, in te rms of improved antibacterial potency and respiratory pharmacokinetics , should offer superior efficacy. Regression analysis of a large scale general practice survey in the UK has now shown the frequency of exac erbations and the presence of co-morbid conditions to correlate signif icantly with a poor therapeutic outcome and thus, by implication, with severity. Future trials of antibacterial chemotherapy for acute bacte rial exacerbations of chronic bronchitis should incorporate such crite ria so that real differences between existing and improved compounds c an be assessed.