Additive role of tiotropium in severe asthmatics and Arg16Gly in ADRB2 as a potential marker to predict response
ALLERGY
Authors: Park, H. -W.; Yang, M. -S.; Park, C. -S.; Kim, T. -B.; Moon, H. -B.; Min, K. -U.; Kim, Y. -Y.; Cho, S. -H.
Abstract
Recent findings have raised new interests about the use of anticholinergics, especially tiotropium, for the treatment of asthma. This study was performed to determine whether an additional improvement in lung function is obtained when tiotropium is administrated in addition to conventional therapies in severe asthmatics, and to identify factors capable of predicting the response to tiotropium, using a pharmacogenetic approach. A total of 138 severe asthmatics on conventional medications and with decreased lung function were randomly recruited. Tiotropium 18 mu g was added once a day and lung functions were measured every 4 weeks. Responders were defined as those with an improvement of >= 15% (or 200 ml) in the forced expiratory volume in 1 s (FEV1) that was maintained for at least 8 successive weeks. Eleven single nucleotide polymorphisms (SNPs) in CHRM1-3 (coding muscarinic receptors one to three) which were identified by re-sequencing, and Arg16Gly and Gln27Glu in ADRB2 (coding beta(2) adrenoreceptor) were scored in 80 of the 138 asthmatics. Forty-six of the 138 asthmatics (33.3%) responded to tiotropium treatment. Logistic regression analyses (controlled for age, gender, and smoking status) showed that Arg16Gly in ADRB2 [P = 0.003, OR (95% CI) = 0.21 (0.07-0.59) in a minor allele-dominant model] was significantly associated with response to tiotropium. As many as 30% of severe asthmatics on conventional medications with reduced lung function were found to respond to adjuvant tiotropium. The presence of Arg16Gly in ADRB2 may predict response to tiotropium.
The Cholinergic System: An Emerging Drug Target for Schizophrenia
CURRENT PHARMACEUTICAL DESIGN
Authors: Gibbons, Andrew; Dean, Brian
Abstract
Background: Cognitive deficits are amongst the most socially debilitating and least effectively treated symptoms of schizophrenia. The cholinergic system is a promising target for the design of novel drugs that can more effectively treat these symptoms. Methods: We review the literature supporting the dysfunction of the cholinergic system in schizophrenia, discuss the preclinical and clinical data showing that modulating the cholinergic system could improve the symptoms of schizophrenia and review the main pharmacological strategies being investigated to treat cholinergic dysfunction in schizophrenia. Results: Post-mortem and neuroimaging studies suggest there are widespread reductions in cholinergic receptor signalling in the cortex as well as subcortical regions, such as the hippocampus and striatum, in individuals with schizophrenia. Potential cholinergic drug targets are being pursued to increase receptor function. These include inhibiting the activity of the enzyme acetylcholinesterase to increase synaptic acetylcholine levels, and increasing the nicotinic receptor and muscarinic receptor activity with agonists or positive allosteric modulators. Conclusion: Amongst the most promising drug targets for treating schizophrenia are the alpha(7)-nicotinic receptor and the CHRM1 and CHRM4 muscarinic receptors. The recent development of allosteric modulators that selectively target these receptors offers the potential to more effectively treat the symptoms of schizophrenia.