The effect of montelukast (10mg daily) and loratadine (10mg daily) on wheal, flare and itching reactions in skin prick tests

MRGPRX2 Is the Codeine Receptor of Human Skin Mast Cells: Desensitization through β-Arrestin and Lack of Correlation with the FcεRI Pathway

Codeine stimulates skin mast cells and is therefore used in skin tests and as an inducer of experimental itch. MRGPRX2 responds to various drugs, including opioids, to elicit pseudoallergic reactions, but whether it represents the main opiate receptor of skin mast cells remains unknown. By combining a number of approaches, including the silencing of MRGPRX2, we now report that MRGPRX2 is indeed the dominant codeine receptor of dermal mast cells. Activation by codeine displayed profound subject variability and correlated with secretion elicited by compound 48/80 or substance P but not by FcεRI aggregation. Degranulation by codeine was attenuated by stem cell factor, whereas the opposite was found for FcεRI. Compound 48/80 or codeine alone was able to achieve maximum MRGPRX2 activation. MRGPRX2 was rapidly internalized on codeine binding in a β-arrestin-1‒dependent manner. Codeine-triggered β-arrestin activation was also established by the Tango assay. Prestimulation with MRGPRX2 agonists (but not C3a or FcεRI aggregation) resulted in refractoriness to further stimulation by the same or another MRGPRX2 ligand (cross desensitization). This was duplicated in a cell line (RBL-MRGPRX2). Collectively, codeine degranulates skin mast cells through MRGPRX2, at which it acts as a balanced ligand. It has yet to be determined whether codeine-induced refractoriness could be exploited to desensitize MRGPRX2 to prevent severe pseudoallergic reactions.

The Involvement of the RhoA/ROCK Signaling Pathway in Hypersensitivity Reactions Induced by Paclitaxel Injection

A high incidence of hypersensitivity reactions (HSRs) largely limits the use of paclitaxel injection. Currently, these reactions are considered to be mediated by histamine release and complement activation. However, the evidence is insufficient and the molecular mechanism involved in paclitaxel injection-induced HSRs is still incompletely understood. In this study, a mice model mimicking vascular hyperpermeability was applied. The vascular leakage induced merely by excipients (polyoxyl 35 castor oil) was equivalent to the reactions evoked by paclitaxel injection under the same conditions. Treatment with paclitaxel injection could cause rapid histamine release. The vascular exudation was dramatically inhibited by pretreatment with a histamine antagonist. No significant change in paclitaxel injection-induced HSRs was observed in complement-deficient and complement-depleted mice. The RhoA/ROCK signaling pathway was activated by paclitaxel injection. Moreover, the ROCK inhibitor showed a protective effect on vascular leakage in the ears and on inflammation in the lungs. In conclusion, this study provided a suitable mice model for investigating the HSRs characterized by vascular hyperpermeability and confirmed the main sensitization of excipients in paclitaxel injection. Histamine release and RhoA/ROCK pathway activation, rather than complement activation, played an important role in paclitaxel injection-induced HSRs. Furthermore, the ROCK inhibitor may provide a potential preventive approach for paclitaxel injection side effects.

Australian and New Zealand Anaesthetic Allergy Group Perioperative Anaphylaxis Investigation Guidelines

These guidelines are a consensus document developed by a working party of the Australian and New Zealand Anaesthetic Allergy Group (ANZAAG) to provide an approach to the investigation of perioperative anaphylaxis. They focus primarily on the use of skin testing as it is the investigation with the greatest clinical utility for the identification of the likely causative agent and potentially safer alternatives. The practicalities and process of skin testing, its limitations, and the place of other tests are discussed. These guidelines also address the roles of graded challenge and in vitro testing. The implications of anaphylaxis associated with neuromuscular blocking agents, beta-lactam antibiotics, local anaesthetic agents and chlorhexidine are discussed. Evidence for the recommendations is derived from literature searches using the words skin test, allergy, anaphylaxis, anaesthesia, and each of the individual agents listed in these guidelines. The individual articles were then reviewed for suitability for inclusion in these guidelines. Where evidence was not strong, as is the situation for many perioperative agents, expert consensus from the ANZAAG working party was used. These guidelines are intended for use by specialists involved in the investigation of perioperative allergy. They have been approved following peer review by members of ANZAAG and are available on the ANZAAG website: http://www.anzaag.com/anaphylaxis-management/testing-guidelines.pdf .

Factors associated with negative histamine control for penicillin allergy skin testing in the inpatient setting

BACKGROUND

Identification of factors adversely affecting the utility of allergy skin testing is important in optimizing patient care. Inpatient penicillin skin test data from 1997 through 2007 demonstrate that up to 20% of attempted penicillin skin tests are indeterminate owing to a negative histamine test response, despite exclusion of H1 antagonists. Critical illness, vasopressors, steroid use, and psychotropic medications have been postulated to influence outcomes, but large studies are lacking.

OBJECTIVE

To identify factors associated with a negative histamine test response for the inpatient setting.

METHODS

Fifty-two cases were identified with a negative histamine response after penicillin skin testing in the absence of antihistamine therapy for 72 hours before testing. One hundred twenty-five controls with a normal histamine response were randomly selected from same population. Independent variables assessed included stay in the intensive care unit (ICU), skin color, diabetes, age, use of vasopressors, H2 blocker, steroids, other immunosuppressive drugs, thyroid replacement, proton pump inhibitors, diuretics, 5 categories of psychotropic medications, and amiodarone.

RESULTS

Mean age was 68 years for cases vs 60 years for controls (P = .002). Bivariate analysis showed ICU stay was more frequent in cases than in controls (73.1% vs 33.6%, P < .001). Regression analysis yielded odds ratios (ORs) of 8.18 (95% confidence interval 3.22-20.76) for ICU status, 3.76 (1.30-10.92) for systemic corticosteroids, and 4.90 (1.17-20.62) for H2 blockers as associated with lack of histamine response. For every additional year in age, there was increase in the OR of 1.04 (1.01-1.07).

CONCLUSION

Regression analysis supports ICU stay during skin testing as associated with a high OR for a negative histamine response independent of age. Systemic corticosteroids, H2 blockers, and older age are associated with a significant OR for a negative histamine response. This is one of largest studies on factors associated with a negative histamine response for the inpatient setting and has significant implications for clinical practice.

The effect of montelukast on wheal reactions in skin prick tests: a double-blind-placebo-controlled randomized trial

OBJECTIVE

It is well-known that number of drugs may interfere with wheal reactions in skin prick test. However, the effect of long-term use of montelukast, a cystenil leukotriene receptor antagonist, on skin prick test hasn't been full elucidated. The aim of present study was to demonstrate the effect of montelukast on skin prick tests (SPT).

METHODS

This is a single-center, randomized, double-blinded, placebo-controlled study including two treatment periods with a wash-out interval. The subjects received montelukast (5 mg per day), fexofenadine HCl (60 mg per day) and placebo (lactose) with a double-blinded manner during 7- and 21-days treatment periods with a 14 days wash-out period. Dermatophagoides farinae (D. farinae) was used as the skin test material, while histamine as positive control and normal saline as negative control. Overall, 7 skin prick tests were performed at following time points: before treatment periods, on the last days of both treatment periods, 24 h after completion of treatment periods, and on the last day of 14-days interval.

RESULTS

Sixty house dust mite (HDM) allergic children (23 girls and 37 boys) with allergic rhinitis and/or asthma completed the study. Mean age was 8.3 ± 2.0 years. In the fexofenadine group, a significant suppression was observed in post-treatment values when compared to baseline values in SPT with D. farinae (p = 0.019). In the montelukast group, no significant suppression was observed in SPT with D. farinae at all time points when compared to baseline.

CONCLUSIONS

Our results showed that montelukast had no effect on measurements of SPT. Thus, we concluded that there is no need to discontinue the treatment in order to perform SPT in patients receiving montelukast, even in those on montelukast treatment for at least 21 days.

Montelukast in pediatric asthma management

Leukotriene modifiers (receptor antagonist and biosynthesis inhibitor) represent the first mediator specific therapeutic option for asthma. Montelukast, a leukotriene receptor antagonist is the only such agent approved for use in pediatric patients. Montelukast modifies action of leukotrienes, which are the most potent bronchoconstrictors, by blocking Cysteinyl leukotriene receptors. Systemic drug like mountelukast can reach lower airways and improves the peripheral functions which play a crucial role in the evolution of asthma. Review of existing literature showed that montelukast compared to placebo has proven clinical efficacy in better control of day time asthma symptoms, percentage of symptom free days, need for rescue drugs and improvement in FEV 1. Studies also demonstrated improvement in airway inflammation as indicated by reduction in fractional exhaled nitric oxide, a marker of inflammation. Studies comparing low dose inhaled corticosteroids (ICS) with montelukast are limited in children and conclude that it is not superior to ICS. For moderate to severe persistent asthma, montelukast has been compared with long acting beta agonists (LABA) as an add-on therapy to ICS, montelukast was less efficacious and less cost-effective. It has beneficial effects in exercise induced asthma and aspirin-sensitive asthma. Montelukast has onset of action within one hour. Patient satisfaction and compliance was better with montelukast than inhaled anti-inflammatory agents due to oral, once a day administration. The recommended doses of montelukast in asthma are- children 1-5 years: 4 mg chewable tablet, children 6-14 years: 5mg chewable tablet,

ADULTS

10mg tablet; administered once daily. The drug is well tolerated. Based on the presently available data montelukast may be an alternative treatment for mild persistent asthma as monotherapy where ICS cannot be administered. It is also an alternative to LABA as an add-on therapy to ICS for moderate to severe persistent asthma. The other indications for use of montelukast include: allergic rhinitis, exercise induced bronchoconstriction and aspirin-induced asthma.