It has been reported that CYP1A2 genotype is involved in the rate-limiting step in the metabolism of many drugs such as caffeine in myocardial infarction [26], theophylline in asthma [27], and clozapine in schizophrenia [28], as well as in the bioactivation of procarcinogens [29]. This evidence concerns the gene CYP1A2 and asthma.