Anti-inflammatory properties of antihistamines: an update

Use of H-1 Antihistamine in Dermatology: More than Itch and Urticaria Control: A Systematic Review

H-1 antihistamines are commonly used in dermatological practice for itch and urticaria control. The widespread expression of H-1 receptor on different cells in the skin and various biologic functions of H-1 antihistamines indicate the possible treatment potentials of H-1 antihistamines in dermatology. A literature search was performed on PubMed and Embase, targeting articles reporting use of antihistamine for purposes other than itch and urticaria control in dermatological practice. Several off-label usages of antihistamines were identified, including alopecia, acne, Darier disease, eosinophilic dermatoses, paraneoplastic dermatoses, psoriasis, lichen nitidus, radiation dermatitis, skin dysesthesia, and cutaneous malignancies. Additional benefits were observed when H-1 antihistamines were used either alone or in combination with other therapeutic modalities. Although various novel uses of H-1 antihistamines have been uncovered, the evidence level of most included studies is weak. Further randomized control trials are warranted to better evaluate the efficacy and dosage of H-1 antihistamine for dermatological disorders.

Modulation of Allergic Inflammation in the Nasal Mucosa of Allergic Rhinitis Sufferers With Topical Pharmaceutical Agents

Allergic rhinitis (AR) is a chronic upper respiratory disease estimated to affect between 10 and 40% of the worldwide population. The mechanisms underlying AR are highly complex and involve multiple immune cells, mediators, and cytokines. As such, the development of a single drug to treat allergic inflammation and/or symptoms is confounded by the complexity of the disease pathophysiology. Complete avoidance of allergens that trigger AR symptoms is not possible and without a cure, the available therapeutic options are typically focused on achieving symptomatic relief. Topical therapies offer many advantages over oral therapies, such as delivering greater concentrations of drugs to the receptor sites at the source of the allergic inflammation and the reduced risk of systemic side effects. This review describes the complex pathophysiology of AR and identifies the mechanism(s) of action of topical treatments including antihistamines, steroids, anticholinergics, decongestants and chromones in relation to AR pathophysiology. Following the literature review a discussion on the future therapeutic strategies for AR treatment is provided.

Update on rupatadine in the management of allergic disorders

In a review of rupatadine published in 2008, the primary focus was on its role as an antihistamine, with a thorough evaluation of its pharmacology and interaction with histamine H1 -receptors. At the time, however, evidence was already emerging of a broader mechanism of action for rupatadine involving other mediators implicated in the inflammatory cascade. Over the past few years, the role of platelet-activating factor (PAF) as a potent mediator involved in the hypersensitivity-type allergic reaction has gained greater recognition. Rupatadine has dual affinity for histamine H1 -receptors and PAF receptors. In view of the Allergic Rhinitis and its Impact on Asthma group's call for oral antihistamines to exhibit additive anti-allergic/anti-inflammatory properties, further exploration of rupatadine's anti-PAF effects was a logical step forward. New studies have demonstrated that rupatadine inhibits PAF effects in nasal airways and produces a greater reduction in nasal symptoms than levocetirizine. A meta-analysis involving more than 2500 patients has consolidated the clinical evidence for rupatadine in allergic rhinoconjunctivitis in adults and children (level of evidence Ia, recommendation A). Other recent advances include observational studies of rupatadine in everyday clinical practice situations and approval of a new formulation (1 mg/ml oral solution) for use in children. In this reappraisal, we revisit some key properties and pivotal clinical studies of rupatadine and examine new clinical data in more detail including studies that measured health-related quality of life and studies that investigated the efficacy and safety of rupatadine in other indications such as acquired cold urticaria, mosquito bite allergy and mastocytosis.

Nasal nitric oxide and nasal eosinophils decrease with levocetirizine in subjects with perennial allergic rhinitis

BACKGROUND

Allergic rhinitis is commonly treated with antihistamines. Monitoring improvement of airway inflammation noninvasively using nasal nitric oxide (nNO) would be clinically useful. To determine the anti-inflammatory effect of oral levocetirizine dihydrochloride (LC), we measured nNO and nasal eosinophils (nEos) in perennial allergic rhinitis (PAR) subjects.

METHODS

A randomized double-blind placebo-controlled crossover design was used. Inclusion criteria consisted of subjects having a PAR history, exam and diary scores consistent with active symptoms, and positive skin testing. Subjects taking allergy medications 1 month before the study were not enrolled. After consenting, 31 subjects (24 female subjects; mean age, 29 years) were randomized to either oral LC (5 mg) or matching placebo for 2 weeks. After 2 week washout, subjects started the other 2-week treatment. At each visit, nNO was measured by aspiration at each nare using a nasal kit from NIOX (Aerocrine, Sweden) in parts per billion; nEos was collected from nasal smears and measured by microscopy using the scoring system (0-4+) and symptoms were self-reported using the allergic Rhinitis Quality of Life Questionnaire (RQLQ). Daily allergy symptom scores (total symptom score [TSS] 4) were collected at each visit.

RESULTS

During LC, mean baseline nNO was 807 ± 317 parts per billion (ppb; left) and 831 ± 332 ppb (right) and decreased significantly to 688 ± 266 ppb and 702 ± 286 ppb, respectively (p < 0.05). No significance was found during placebo treatment (778 ± 270 ppb, 808 ± 299 ppb to 802 ± 271 ppb, 813 ± 273 ppb). The mean nNO change was also significant compared with placebo (-125 ppb versus +14 ppb; p < 0.05). There was a significant decrease in nEos with LC compared with placebo (3.1-2.5 versus 2.9-2.6; p < 0.05). RQLQ scores were significantly improved with LC only. In TSS-4 scoring, a trend toward improvement during LC and significant worsening during placebo was found. Baseline nNO predicted changes in nasal eosinophils (nEos) and RQLQ.

CONCLUSION

We showed that oral LC therapy decreased objective markers of rhinitis inflammation, nNO and nEos, in patients with PAR. Improvement in symptom scoring was also found with LC treatment.

No cardiac effects of therapeutic and supratherapeutic doses of rupatadine: results from a 'thorough QT/QTc study' performed according to ICH guidelines

AIMS

To evaluate the effects of therapeutic and supratherapeutic doses of rupatadine on cardiac repolarization in line with a 'thorough QT/QTc study' protocol performed according to International Conference on Harmonization guidelines.

METHODS

This was a randomized (gender-balanced), parallel-group study involving 160 healthy volunteers. Rupatadine, 10 and 100 mg day(-1), and placebo were administered single-blind for 5 days, whilst moxifloxacin 400 mg day(-1) was given on days 1 and 5 in open-label fashion. ECGs were recorded over a 23-h period by continuous Holter monitoring at baseline and on treatment days 1 and 5. Three 10-s ECG samples were downloaded at regular intervals and were analysed independently. The primary analysis of QTc was based on individually corrected QT (QTcI). Treatment effects on QTcI were assessed using the largest time-matched mean difference between the drug and placebo (baseline-subtracted) for the QTcI interval. A negative 'thorough QT/QTc study' is one where the main variable is around < or =5 ms, with a one-sided 95% confidence interval that excludes an effect >10 ms.

RESULTS

The validity of the trial was confirmed by the fact that the moxifloxacin-positive control group produced the expected change in QTcI duration (around 5 ms). The ECG data for rupatadine at both 10 and 100 mg showed no signal effects on the ECG, after neither single nor repeated administration. Furthermore, no pharmacokinetic/pharmacodynamic relationship, gender effects or clinically relevant changes in ECG waveform outliers were observed. No deaths or serious or unexpected adverse events were reported.

CONCLUSIONS

This 'thorough QT/QTc study' confirmed previous experience with rupatadine and demonstrated that it had no proarrhythmic potential and raised no concerns regarding its cardiac safety.

Levocetirizine modulates lymphocyte activation in patients with allergic rhinitis

Levocetirizine, a second generation non-sedating antihistamine that blocks the H(1) histamine receptor, may exhibit immunoregulatory properties that augment its primary pharmacological mechanism. To investigate this possibility, 13 Kuwaiti seasonal allergic rhinitis (SAR) patients were treated with levocetirizine for four weeks in comparison with a 7-member placebo-treated control group, followed by clinical evaluation and flow cytometric analysis of peripheral venous blood for inflammatory cell and lymphocyte subpopulation profiles. Relative to the controls, levocetirizine-treated patients exhibited an expected reduction in early phase allergic symptoms, including sneezing (P<0.001), nasal itching (P<0.01), nasal congestion, and running nose (P<0.001); reduced percentages of eosinophils (P<0.05); and three subpopulations of activated T lymphocytes: CD4+CD29+, CD4+CD212+, and CD4+CD54+ (P<0.05). Levocetirizine treatment also correlated with a significant increase in the percentage of CD4+CD25+ T cells (P<0.001). The ability of levocetirizine to reduce percentage representation of cell phenotypes known to contribute to inflammatory tissue damage (eosinophils, CD4+CD29+, CD4+CD212+, and CD4+CD54+) and expand percentages of CD4+CD25+, which may include protective immunoregulatory (Treg) cells, indicates that the drug has pharmacological potential beyond the immediate effects of H(1) histamine-receptor inhibition. Although the present data does not define a therapeutic mechanism, the results reported here establish important trends that may be used to guide future mechanistic examination of immunoregulatory capacity of H(1) inhibitors.

An approach to the patient with urticaria

Patients with urticaria make up a large proportion of the referrals to allergy clinics. There are many causes of urticaria and it is the clinical history which is most important when attempting to identify potential causes; however, urticaria is very often idiopathic. In a small minority of patients urticaria may be a symptom of a serious underlying medical illness or the allergic symptoms may progress to cause systemic reactions, and it is important to identify these patients and to remember that severe urticaria is a distressing and disabling condition. This review will discuss classification, investigation and treatment of urticaria and will consider some of the more unusual types of urticaria that may be encountered in the out-patient clinic.

Rupatadine in allergic rhinitis and chronic urticaria

Histamine is the primary mediator involved the pathophysiology of allergic rhinitis and chronic urticaria, and this explains the prominent role that histamine H(1)-receptor antagonists have in the treatment of these disorders. However, histamine is clearly not the only mediator involved in the inflammatory cascade. There is an emerging view that drugs which can inhibit a broader range of inflammatory processes may prove to be more effective in providing symptomatic relief in both allergic rhinitis and chronic urticaria. This is an important consideration of the Allergic Rhinitis and its Impact on Asthma (ARIA) initiative which provides a scientific basis for defining what are the desirable properties of an 'ideal' antihistamine. In this review of rupatadine, a newer dual inhibitor of histamine H(1)- and PAF-receptors, we evaluate the evidence for a mechanism of action which includes anti-inflammatory effects in addition to a powerful inhibition of H(1)- and PAF-receptors. We assess this in relation to the clinical efficacy (particularly the speed of onset of action) and safety of rupatadine, and importantly its longer term utility in everyday life. In clinical trials, rupatadine has been shown to be an effective and well-tolerated treatment for allergic rhinitis and chronic idiopathic urticaria (CIU). It has a fast onset of action, producing rapid symptomatic relief, and it also has an extended duration of clinical activity which allows once-daily administration. In comparative clinical trials rupatadine was shown to be at least as effective as drugs such as loratadine, cetirizine, desloratadine and ebastine in reducing allergic symptoms in adult/adolescent patients with seasonal, perennial or persistent allergic rhinitis. Importantly, rupatadine demonstrated no adverse cardiovascular effects in preclinical or extensive clinical testing, nor negative significant effects on cognition or psychomotor performance (including a practical driving study). It improved the overall well-being of patients with allergic rhinitis or CIU based on findings from quality of life questionnaires and patient global rating scores in clinical trials. Thus, rupatadine is a recently introduced dual inhibitor of histamine H(1)- and PAF-receptors, which has been shown to be an effective and generally well-tolerated treatment for allergic rhinitis and chronic urticaria. It possesses a broader profile of anti-inflammatory properties inhibiting both inflammatory cells and a range of mediators involved in the early- and late-phase inflammatory response, but the clinical relevance of these effects remain to be clarified.

Effects of cyproheptadine and cetirizine on eosinophilic airway inflammation in cats with experimentally induced asthma

OBJECTIVE

To determine whether oral administration of cyproheptadine or cetirizine blocks the action of serotonin and histamine, respectively, and results in diminished eosinophilic airway inflammation in cats with experimentally induced asthma.

ANIMALS

9 cats in which asthma was experimentally induced through exposure to Bermuda grass allergen (BGA) during a 3-month period.

PROCEDURES

Cats were randomized to receive monotherapy with each of 3 treatments for 1 week: placebo (flour in a gelatin capsule, PO, q 12 h), cyproheptadine (8 mg, PO, q 12 h), or cetirizine (5 mg, PO, q 12 h). A 1-week washout period was allowed to elapse between treatments. Prior to and following each 1-week treatment period, blood and bronchoalveolar lavage fluid (BALF) samples were collected. The percentage of eosinophils in BALF was evaluated to determine treatment efficacy. Serum and BALF BGA-specific immunoglobulin contents and plasma and BALF histamine concentrations were determined via ELISAs. Plasma and BALF serotonin concentrations were measured by use of a fluorometric method.

RESULTS

The mean +/- SD percentage of eosinophils in BALF did not differ significantly among treatment groups (placebo, 40 +/- 22%; cyproheptadine, 27 +/- 16%; and cetirizine, 31 +/- 20%). Among the treatment groups, BGA-specific immunoglobulin content and histamine and serotonin concentrations were not significantly different.

CONCLUSIONS AND CLINICAL RELEVANCE

In cats with experimentally induced asthma, cyproheptadine and cetirizine were not effective in decreasing airway eosinophilic inflammation or in altering several other measured immunologic variables. Neither cyproheptadine nor cetirizine can be advocated as monotherapy for cats with allergen-induced asthma.