Nocturnal asthma and the use of theophylline

The nocturnal worsening of asthma is a common event in asthma patients. Some studies have shown the prevalence of nocturnal asthma to be as high as 75% of patients. It is important to understand this phenomenon as nocturnal asthma is associated with decreased daytime cognitive function and increased morbidity and mortality. The exact mechanism for decrements in overnight lung function is not known. However, there are many different processes associated with nocturnal asthma. Day-to-night change in both circulating bronchodilating and bronchoconstricting mediators occur which favour airway narrowing and increased bronchial hyperresponsiveness at night. The beta2 adrenergic receptors decrease in both number and function at night which is associated with a genetic polymorphism, a glycine 16 substitution. Neuroinfluences such as increased nocturnal cholinergic tone also contribute to nocturnal asthma, and a hallmark of nocturnal asthma is increased airway inflammation during sleep. Long-acting theophylline preparations have long been associated with improvement in overnight lung function. Some of these agents can be used in a chronotherapeutic modality, that is, higher blood levels at night when the disease is worse and lower blood levels during the day when lung function is routinely better. Theophylline works as both a bronchodilator and an anti-inflammatory agent to improve nocturnal asthma.