Effects of fexofenadine on the early response to nasal allergen challenge

Pharmacotherapy of Itch-Antihistamines and Histamine Receptors as G Protein-Coupled Receptors

Itching can decrease quality of life and exacerbate skin symptoms due to scratching. Itching not only contributes to disease progression but also triggers complications such as skin infections and eye symptoms. Therefore, controlling itching is very important in therapeutic management. In addition to the well-known histamine, IL-31, IL-4 and IL-13 have recently been reported as factors that induce itching. Itching may also be caused by factors other than these histamines. However, we do not know the extent to which these factors are involved in each disease. In addition, the degree of involvement is likely to vary among individuals. To date, antihistamines have been widely used to treat itching and are often effective, suggesting that histamine is more or less involved in itchy diseases. This review discusses the ligand-receptor perspective and describes the dynamics of G protein-coupled receptors, their role as biased agonists, their role as inverse agonists, proactive antihistamine therapy, and drug selection with consideration of impaired performance and anti-PAF effects.

Nasal challenges in allergen immunotherapy trials

PURPOSE OF REVIEW

The nasal allergen challenge (NAC) model can be a valuable diagnostic tool for allergic rhinitis. Alongside its clinical use, NACs can be used as primary and secondary endpoints in studies evaluating allergen immunotherapy (AIT) products for allergic rhinitis treatment. This review will discuss the technical aspects of the NAC model and provide a summary of recent studies using NACs to assess existing and new AIT treatments.

RECENT FINDINGS

Over the last 2 years, both titrated and single-dose nasal challenge protocols have been used to evaluate immunotherapies targeting grass, birch, house dust mite, and cat allergens. Early efficacy and dose-finding trials showed improvements in allergic symptoms and nasal tolerance to allergens after AIT treatment with standardized extracts or modified forms of whole allergen. NACs were also used in two proof-of-concept studies to illustrate the efficacy of intralymphatic immunotherapy with two concomitant allergens and subcutaneous immunotherapy with Fel d 1-specific IgG-blocking antibodies.

SUMMARY

Along with existing therapies, nasal challenges are useful in evaluating AIT treatments in the very early stages of clinical development. However, because of the variety in challenge techniques and symptom assessments available, special attention must be placed in the protocol design in order to compare the study results with existing NAC publications.

Immunoassay-based measurement of clinical biomarkers for monitoring changes in nasal cavity

BACKGROUND

Many drugs for treatment of allergies, migraine headaches, inflammation, and other indications are administered into the nasal cavity providing access to the immune and central nervous systems. One of the concerns for using this route of administration is potential damage to the nasal epithelium and mucosal regions. We assembled a panel of clinical biomarkers that can be used to monitor changes in the nasal epithelium, mucosa, and olfactory regions in preparation for clinical trials involving drugs administered via intranasal route. These biomarkers included albumin, elastase, IL-6, IL-8, lactoferrin, myeloperoxidase and nerve growth factor.

METHODS

Immunoassays were developed and used to measure changes in these biomarkers in nasal lavage samples collected twice daily from 30 assumed-healthy volunteers over a 2-day period. Various statistical methods including analysis of variance (ANOVA), paired t-test and Pearson's product-moment correlation were used to evaluate the data.

RESULTS

Although the basal levels of these biomarkers were varied among subjects, the data show that the concentrations of albumin, elastase and IL-8 were significantly higher in samples collected in the morning compared to samples collected later during the day. Pre-washing nasal cavity prior to collecting nasal lavage samples did alter the measurement of elastase and albumin, but did not influence the levels of the other biomarkers.

CONCLUSIONS

These data show that this panel of biomarkers can be used to monitor changes in the nasal cavity including those affected by diurnal fluctuations. These results also provide useful baseline values and sources of variability for each biomarker that could be used to help design clinical trials.

Fexofenadine hydrochloride in the treatment of allergic disease: a review

Fexofenadine is a selective, non-sedating H1 receptor antagonist, marketed in the United States since 2000. The FDA approved an oral suspension in 2006, for the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria in children. The tablet, capsule, and oral suspension are bioequivalent. Although fexofenadine does not use P450 CYP 3A4 it does interact with a number of drugs at P-glycoprotein and organic anion transporter polypeptides. The risk of toxicity from other drugs may increase with the administration of fexofenadine. Orange and grapefruit juices reduce the bioavailability of fexofenadine. Fexofenadine has been shown to have an impact on inflammatory mediators, other than histamine, such as decreasing the production of LTC₄, LTD₄, LTE₄, PGE₂, and PGF_2α; inhibiting cyclo-oxygenase 2, thromboxane; limiting iNOS generation of NO; decreasing cytokine levels (ICAM-1, ELAM-1, VCAM-1, RANTES, I-TAC, MDC, TARC, MMP-2, MMP-9, tryptase); and diminishing eosinophil adherence, chemotaxis, and opsonization of particles. These effects may provide benefit to some of the inflammatory responses of an acute allergic reaction and provide a basis for future development of H1 antagonists with stronger anti-inflammatory effects. These studies also support the contention that fexofenadine is effective for the treatment of allergic rhinits and chronic idiopathic urticaria.

Clinical efficacy and pharmacokinetic profiles of intranasal and oral cetirizine in a repeated allergen challenge model of allergic rhinitis

BACKGROUND

Intranasal and oral antihistamines are effective in treating allergic rhinitis. Studies comparing these routes of administration of an antihistamine regarding efficacy and pharmacokinetic profile are lacking.

OBJECTIVE

To compare topical and oral routes of administration of cetirizine regarding efficacy, plasma exudation, and systemic drug levels in a repeated allergen challenge model of allergic rhinitis.

METHODS

Oral cetirizine dihydrochloride, 10 mg once daily, and topical cetirizine dinitrate in a dose corresponding to 4.4 mg of the dihydrochloride salt twice daily were given to grass pollen-sensitive individuals for 12 days in a double-blind, placebo-controlled, crossover design. Timothy grass pollen allergen challenges were given once daily for 7 days using a nasal spray device. Nasal symptoms and peak inspiratory flow were recorded in the morning, 10 minutes after allergen challenge, and in the evening. The pharmacokinetics of the treatments was monitored in 8 patients. The remaining 28 patients were challenged topically with histamine 12 and 24 hours after the final topical and oral cetirizine doses, respectively. Nasal lavage levels of alpha2-macroglobulin were determined to evaluate histamine-induced mucosal plasma exudation.

RESULTS

During the last 3 days of the repeated allergen challenge model, chronic symptoms were established. Both treatments reduced symptoms 10 minutes after allergen challenge (P < .001 vs placebo). Neither treatment reduced morning and evening symptoms or nasal peak inspiratory flow. Topical, but not oral, cetirizine reduced histamine-induced plasma exudation (P < .01 vs placebo) when systemic drug levels were similar in the 2 treatment regimens.

CONCLUSIONS

Topical and oral cetirizine reduced acute nasal symptoms produced by allergen challenges in patients with established chronic symptoms. There were also antihistaminic effects of topical cetirizine not related to systemic drug levels.

Effects of fexofenadine hydrochloride in a guinea pig model of antigen-induced rhinitis

Allergic rhinitis is an inflammatory disease of the nasal mucosa, induced by histamine, leukotrienes, and other substances released from mast cells. Fexofenadine hydrochloride, the active metabolite of terfenadine, is a novel, nonsedating antiallergic drug having H1 receptor antagonistic activity. Fexofenadine is effective for the treatment of allergic rhinitis. However, its mechanism of action in attenuating nasal congestion has not yet been elucidated. Therefore, we first examined the effects of fexofenadine on a guinea pig model of antigen-induced rhinitis. We also evaluated the effects of mepyramine, zafirlukast and ramatroban in this model; these drugs are an H1 receptor antagonist, a selective leukotriene antagonist and a selective thromboxane antagonist, respectively. Rhinitis was induced by ovalbumin (OVA) instillation into the nasal cavity of animals that had been sensitized by two earlier OVA injections (s.c. and i.p.). The nasal airway resistance was measured for 45 min after the challenge. Fexofenadine hydrochloride (20 mg/kg) and terfenadine (20 mg/kg) administered orally 70 min prior to the challenge significantly inhibited (fexofenadine, p < 0.001, terfenadine, p < 0.05) the increase in nasal airway resistance. Ramatroban (30 mg/kg) administered orally 60 min prior to the challenge also significantly inhibited (p < 0.05) the increase in nasal airway resistance. In contrast, mepyramine (3 mg/kg i.v.) and zafirlukast (3 mg/kg p.o.) failed to reduce the increase in nasal airway resistance. These results suggest that thromboxane may be involved in the increase in the nasal airway resistance in this model. Accordingly, fexofenadine may reduce the increase in nasal airway resistance by inhibiting the release of chemical mediators, including thromboxane, that are involved in the increase in nasal airway resistance in this model.

Roles of histamine and its receptors in allergic and inflammatory bowel diseases

Mast cell has a long history of being recognized as an important mediator-secreting cell in allergic diseases, and has been discovered to be involved in IBD in last two decades. Histamine is a major mediator in allergic diseases, and has multiple effects that are mediated by specific surface receptors on target cells. Four types of histamine receptors have now been recognized pharmacologically and the first three are located in the gut. The ability of histamine receptor antagonists to inhibit mast cell degranulation suggests that they might be developed as a group of mast cell stabilizers. Recently, a series of experiments with dispersed colon mast cells suggested that there should be at least two pathways in man for mast cells to amplify their own activation-degranulation signals in an autocrine or paracrine manner. In a word, histamine is an important mediator in allergic diseases and IBD, its antagonists may be developed as a group of mast cell stabilizers to treat these diseases.

Similar rapid onset of action and magnitude of effect of fexofenadine and cetirizine as assessed by inhibition of histamine-induced wheal-and-flare reaction

BACKGROUND

Histamine-induced wheal-and-flare studies are useful, objective tests for determining differences in the peripheral H1-receptor blockade activities of antihistamines.

OBJECTIVE

To evaluate the time of occurrence of 95% inhibition of histamine-induced wheal and flare after administration of fexofenadine hydrochloride, 180 mg, or cetirizine, 10 mg.

METHODS

Forty-two volunteers (aged 18-60 years) were included in a randomized, double-blind, crossover study. Skin prick tests were undertaken using histamine (100 mg/mL) before treatment and 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 hours after treatment. Wheal and flare areas were evaluated, and the time to occurrence of 95% inhibition and the frequency of subjects exhibiting 95% inhibition before median time to 95% inhibition were calculated.

RESULTS

Mean +/- SD time to 95% wheal inhibition was 2.46 +/- 0.71 hours with fexofenadine and 2.55 +/- 0.57 hours with cetirizine. The estimated mean difference between fexofenadine and cetirizine (-7 minutes in favor of fexofenadine; 2-sided 95% confidence interval, -21 to +7 minutes) was not statistically significant (P = .34). For wheal, 29% of subjects receiving fexofenadine and 24% receiving cetirizine achieved 95% inhibition before the median time of inhibition (2.5 hours). An exact permutation test yielded a P = .37. For flare, 26% of subjects receiving fexofenadine and 10% receiving cetirizine achieved 95% inhibition before the median time of inhibition (3 hours; P = .12 by exact permutation test).

CONCLUSIONS

Fexofenadine and cetirizine have comparable onset of action times and similar frequencies of inhibition, as evaluated by the occurrence of 95% inhibition of histamine-induced wheal and flare.

Levocetirizine better protects than desloratadine in a nasal provocation with allergen

BACKGROUND

Direct comparisons of antihistamines are rare but very much needed. Newly available antihistamine preparations, levocetirizine, the R-enantiomer of racemate cetirizine, and desloratadine, an active metabolite of loratadine, have been recently released for allergic rhinitis.

OBJECTIVE

We sought to compare levocetirizine and desloratadine in a nasal provocation test (NPT) with grass pollen.

METHODS

Twenty-four volunteers with grass pollen allergy and a history of rhinitis were enrolled in a double-blind, placebo-controlled, crossover study. Three NPTs were performed in a dose-escalating manner during the out-of-season period 4 hours after a single dose of levocetirizine (5 mg), desloratadine (5 mg), or placebo.

RESULTS

CONCLUSIONS

This study demonstrates a better overall protection of a single dose of levocetirizine compared with desloratadine in an NPT with grass pollen allergen. In contrast to late-phase inflammatory markers, which were unaffected, extravascular leakage of the early-phase marker albumin was significantly limited by levocetirizine.

Effect of the second-generation antihistamine, fexofenadine, on cough reflex sensitivity and pulmonary function

AIMS

Current guidelines recommend the use of first-generation antihistamines for the treatment of cough due to rhinitis/postnasal drip syndrome. The antitussive activity of the second-generation antihistamine, fexofenadine, has not been investigated. Therefore, we evaluated the effect of fexofenadine on capsaicin-induced cough in healthy volunteers and in subjects with acute viral upper respiratory tract infection (URI).

METHODS

Twelve healthy volunteers and 12 subjects with URI underwent pulmonary function testing and capsaicin cough challenge on two separate days, 2 h after ingesting 180 mg fexofenadine or matched placebo. Subjects inhaled single, vital-capacity breaths of capsaicin aerosol, administered in incremental doubling concentrations, until the concentration inducing five or more coughs (C5) was determined.

RESULTS

In both subject groups, C5 was not significantly different after fexofenadine compared to placebo. In subjects with URI, pulmonary function studies were also similar. In healthy volunteers, however, FEV1 and FEF(25-75), pulmonary function parameters reflecting the degree of airway dilatation, were significantly increased after fexofenadine. Mean (95% CI) values for FEV1(L) after fexofenadine and placebo were 3.16 (2.77, 3.55) and 3.08 (2.69, 3.47), respectively (P = 0.017). Mean values for FEF(25-75)(L/s) were 3.49 (3.10, 3.88) and 3.26 (2.79, 3.72), respectively (P = 0.029).

CONCLUSIONS

Fexofenadine demonstrated no antitussive activity against capsaicin-induced cough in healthy volunteers and subjects with URI. The ineffectiveness of fexofenadine in suppressing cough probably reflects the lack of anticholinergic activity and central nervous system penetrance that is characteristic of first-generation antihistamines. The mild bronchodilation induced by fexofenadine in healthy volunteers is of unclear clinical significance and requires further investigation.

Randomized, double-masked comparison of olopatadine ophthalmic solution, mometasone furoate monohydrate nasal spray, and fexofenadine hydrochloride tablets using the conjunctival and nasal allergen challenge models

BACKGROUND

It is presumed that exposure to allergens in the environment occurs through both the eyes and the nose. Allergic rhinoconjunctivitis is typically treated with a nasal spray or systemic antihistamine, neither of which may provide adequate relief of the ocular component of the disease.

OBJECTIVE

This study was designed to gain a better understanding of the physiologic interaction between the conjunctival and nasal mucosa and thus help establish a profile for the most effective ocular treatment in patients whose allergies have both an ocular and a nasal component.

METHODS

This was a single-center, randomized, double-masked clinical study using the conjunctival allergen challenge (CAC) and nasal allergen challenge (NAC) models. It compared the clinical signs and symptoms induced by CAC and NAC, the effects of drugs administered by 3 different routes, and the movement of fluorescein after instillation into the eye and nose (Jones test), and assessed levels of of inflammatory mediators in tears and nasal secretions. At visit l, subjects previously identified as CAC responders underwent NAC to determine the dose of allergen necessary to elicit a sufficient positive reaction. At visit 2, which took place 1 week later, subjects with a positive reaction at visit 1 were randomized to group A (CAC) or group B (NAC), and underwent challenge to confirm the allergen dose necessary to produce a positive reaction. Subjects who qualified were randomized to receive 1 of 3 treatments: olopatadine 0.1% ophthalmic solution, placebo nasal spray, and placebo tablets; mometasone furoate monohydrate 50-microg nasal spray, placebo topical solution, and placebo tablets; or fexofenadine hydrochloride 180-mg tablets, placebo topical solution, and placebo nasal spray. All study medications were administered according to their approved labeling: drops were administered twice daily in the eyes, and the nasal sprays and tablets were administered once daily. At visit 3, which took place 1 week after visit 2, subjects received study medication and 15 minutes later underwent CAC or NAC as before. The primary efficacy variables were ocular itching, ocular redness, and overall nasal symptoms (sneezing, rhino rrhea/postnasal drip, nasal pruritus, palatal pruritus, and nasal congestion) rated on standard scales. Peak nasal inspiratory flow (PNIF) was measured at each visit, and the Jones test was performed at visits 1 and 3. At baseline and after challenge at visits 2 and 3, tear and nasal lavage samples were collected from a subset of randomly selected subjects for analysis of eosinophil cationic protein and tryptase.

RESULTS

Seventy-three subjects (42 women, 31 men; mean age, 45.26 years [range, 21-73 years]) were screened, and all were randomized to treatment. Two subjects did not complete the study. CAC induced clinically significant (>1 unit difference) ocular and nasal signs and symptoms, whereas NAC induced clinically significant nasal signs and symptoms only. In group A, there was a greater reduction in ocular itching with olopatadine compared with mometasone and fexofenadine at 3 minutes (P = 0.003 and P = 0.008, respectively) and 5 minutes (P = 0.007 and P = 0.013) after challenge. Although the difference was not statistically significant, overall relief of conjunctival redness (average of 3 vessel beds) was greatest in the olopatadine group, followed by fexofenadine. In group B, prevention of total nasal symptoms was significantly greater with mometasone compared with fexofenadine at 20 minutes (P = 0.006) and 30 minutes (P = 0.014) after challenge. There were no statistically significant differences between treatment groups in nasal symptom scores at any time point after CAC. There were also no significant differences in PNIF between treatment groups. Fluorescein was present in nasal secretions within 5 minutes of being instilled into the eye; no fluorescein was detected in the eye after instillation into the nose.

CONCLUSIONS

In this study, exposure of the nasal mucosa to allergen resulted in allergic rhinitis, and exposure of the ocular the ocular surface to allergen resulted in conjunctivitis with a secondary effect in the nose. These results suggest movement of allergens, their mediators, and antiallergy drugs from the ocular surfaces into the nasal cavity, with no meaningful movement from the nasal cavity to the ocular surface. In this controlled model, both the systemic agent and the nasal spray failed to control ocular symptoms. The topical ophthalmic solution provided the most effective management of allergic ocular signs and symptoms, and the nasal spray was most effective for nasal symptoms. Combined use of a nasal spray and topical ophthalmic solution may provide maximal relief in patients whose allergies have both ocular and nasal components.