Potential genetic influences on the response to asthma treatment

Drug-Drug Interactions in Vestibular Diseases, Clinical Problems, and Medico-Legal Implications

Peripheral vestibular disease can be treated with several approaches (e.g., maneuvers, surgery, or medical approach). Comorbidity is common in elderly patients, so polytherapy is used, but it can generate the development of drug-drug interactions (DDIs) that play a role in both adverse drug reactions and reduced adherence. For this reason, they need a complex kind of approach, considering all their individual characteristics. Physicians must be able to prescribe and deprescribe drugs based on a solid knowledge of pharmacokinetics, pharmacodynamics, and clinical indications. Moreover, full information is required to reach a real therapeutic alliance, to improve the safety of care and reduce possible malpractice claims related to drug-drug interactions. In this review, using PubMed, Embase, and Cochrane library, we searched articles published until 30 August 2021, and described both pharmacokinetic and pharmacodynamic DDIs in patients with vestibular disorders, focusing the interest on their clinical implications and on risk management strategies.

Pharmacogenomic Response of Inhaled Corticosteroids for the Treatment of Asthma: Considerations for Therapy

There is a large interindividual variability in response to ICSs in asthma. About 70% of the variance in ICS response is likely due at least partially to genetically determined characteristics of target genes. In this article, we examine the effects on the ICS response of gene variations in the corticosteroid pathway, and in the pharmacokinetics of corticosteroids, and also those outside the corticosteroid pathway, which have the potential to influence corticosteroid activity. Although the available evidence indicates that responses to ICSs in asthma are influenced by different genetic variants, there are still deep uncertainties as to whether a real association between these genetic variants and corticosteroid response could also possibly exist because there are difficulties in reproducing pharmacogenetic findings. This explains at least partly the insufficient use of pharmacogenomic data when treating asthmatic patients, which creates a real limitation to the proper use of ICSs in an era of precision medicine that links the right patient to the right treatment. Knowing and dealing with the genetic factors that influence the therapeutic ICS response is a fundamental condition for prescribing the right dose of ICS to the right patient at the right time.

CHRM2 but not CHRM1 or CHRM3 polymorphisms are associated with asthma susceptibility in Mexican patients

Asthma is a complex disease for which genetic predisposition has been widely documented. Considerable evidence supports the hypothesis that polymorphisms in the muscarinic-cholinergic (CHRM) genes could be involved in asthma pathogenesis, bronchial hyperresponsiveness, and mucus secretion. To determine whether single nucleotide polymorphisms (SNPs) or haplotypes in CHRM1, CHRM2, or CHRM3 are associated with asthma in Mexican pediatric population. We performed a case-control study including 398 pediatric cases with asthma and 450 healthy controls. We analyzed 19 SNPs distributed among these three genes. Two of the seven SNPs located in CHRM2, the 3' untranslated region rs8191992 and rs6962027, differed significantly in allele frequencies between patients with asthma and healthy controls [odds ratio (OR) 1.42, 95 % confidence interval (95 % CI) 1.14-1.77, P = 0.001, and OR 1.50, 95 % CI 1.21-1.87, P = 0.0002, respectively]. Statistical significance remained after multiple comparison corrections (P = 0.003 and P = 0.005, respectively). The haplotypes AA and TT, containing both major and minor alleles from rs8191992 and rs6962027, also differed between cases and controls. The haplotype AA occurred at a lower frequency in cases (OR 0.67, 95 % CI 0.53-0.85, P = 0.001) whereas the haplotype TT was overrepresented in cases compared to controls (28 vs 21 %, respectively; OR 1.46, 95 % CI 1.15-1.85, P = 0.002). No association was observed between CHRM1 or CHRM3 SNPs or haplotypes and asthma. CHRM2 polymorphisms are implicated in the genetic etiology of asthma.

Pharmacogenomics of beta2-agonist: key focus on signaling pathways

Asthma is one of the most common respiratory diseases, where inhalation and exhalation are obstructed due to narrowing of the airways by broncho-constriction or by inflammation. Among all the available anti-asthma therapies, beta2-agonists are the most effective bronchodilators available, and give rapid relief of asthma symptoms. Evidence suggests that the degree of beta2-agonist response varies greatly between patients and genetic factors have a major role in it. Despite several studies on the beta2-agonist pharmacogenetics, significant gaps in knowledge still remain and need to be resolved before the pharmacotyping of beta2-agonist responsiveness comes to clinical practice. As we know, beta2-agonists show their influence by targeting beta2-adrenergic receptors, leading to the activation of beta2-adrenergic receptors and its downstream cascade. Signaling through beta2-adrenergic receptors mediates numerous airway functions by regulating broncho-constriction and dilation pathways. Therefore, it is an important prerequisite to understand these pathways, which will assist in defining the variability in therapeutic responses for beta2-agonists. Owing to the complexity of the action of a beta2-agonist and its therapeutic response, a broader genomics approach will help in optimizing therapy for the individual patient. This might be achieved by considering and focusing on receptor/s at which the drug binds directly, signal transduction cascades or downstream proteins and proteins involved in the relaxation and constriction of the airway smooth muscle. Considering that a drug response may involve a large number of proteins, it seems unlikely that a single polymorphism or haplotype in a single gene would explain a high degree of drug response variability in a consistent fashion. Thus, it shows that a polygenic approach will be more appropriate. In order to follow this, the mode of action of the beta2-agonist and its downstream signaling cascade should essentially be assessed to resolve the beta2-agonist enigma.

Safety of inhaled corticosteroids: room for improvement

Inhaled corticosteroids (ICS) are the standard of care in asthma and are widely used in the treatment of patients with chronic obstructive pulmonary disease. High-dose regimens and long-term use of ICS in predisposed individuals may be associated with a variety of side effects, similar to those observed with systemic corticosteroid therapy. Side effects associated with long-term ICS use include reduction in growth velocity, cataracts, glaucoma, osteoporosis, and fractures. Fear of unwanted complications may be of concern in all patients using ICS, particularly in age- and gender-specific populations that are more prone to develop side effects or to reduce treatment adherence because of physical, behavioral, or psychological problems. In addition to concerns about ICS safety, dosing regimens that are difficult to follow may further reduce a patient's ability to comply with treatment. Ciclesonide, a new-generation ICS with unique pharmacokinetic properties, was developed to provide effective anti-inflammatory control for asthma with once-daily administration to improve patient adherence and a high safety profile to reduce the occurrence of local and systemic side effects.

Genetic diversity and new therapeutic concepts

The differences in medicinal drug responses among individuals had been known for quite some time. Some patients exhibit a life-threatening adverse reaction while others fail to show an expected therapeutic effect. Intermediate responses between the above two extreme cases are also known. In fact, it has been recently reported that approximately 100,000 deaths and more than 2 million hospitalizations annually in the United States are due to properly prescribed medications. This interindividual variability could be due in part to genetically determined characteristics of target genes or drug metabolizing enzymes. This has now been substantiated by a variety of studies. We know that "one size fits all" is not correct. Therefore, the application of pharmacogenetic concepts to clinical practice is an excellent goal in the postgenomic era. The successful completion of the human genome project provided necessary molecular tools, such as high-throughput SNP genotyping, HapMap, and microarray, that can be applied to develop proper therapeutic options for individuals. Recently, there have been considerable scientific, corporate, and policy interest in pharmacotherapy. However, identification of causal variations in a target gene is only a starting point, and the progress in this rapidly developing field is slower than expected. One major drawback could be due to the multigene determinant of drug response that requires a genome-wide screening. Additionally, application of pharmacogenetic knowledge into clinical practice requires a high level of accuracy, precision (risk/benefit ratio), and strict regulations. This is because the pharmacogenetic approach raises several ethical, moral, and legal questions. It is also necessary that both health professionals and the general public must be urgently educated. Despite these limitations, translation of pharmacogenomic data into clinical practice would certainly provide better opportunities to increase the safety and efficacy of medicine in the future.