Therapeutic points of intervention and clinical implications: role of desloratadine

Safety evaluation of desloratadine in allergic rhinitis

INTRODUCTION

Desloratadine is a biologically active metabolite of second-generation antihistamine loratadine. It is also indicated for the treatment of allergic diseases, including allergic rhinitis.

AREAS COVERED

A Medline search was conducted to identify preclinical and clinical studies of desloratadine. This was supplemented with additional articles obtained from online sources. The focus of this review is on the safety profile of desloratadine.

EXPERT OPINION

The review of these data indicates that the safety profile of desloratadine is similar to other second-generation antihistamines. Desloratadine is highly selective for histamine H₁-receptors, does not cross the blood-brain barrier (BBB), and has minimal adverse events (very low sedation rate), with a better safety and tolerability than first-generation antihistamines. Desloratadine is safe and well tolerated without having central nervous system (CNS) or cardiovascular effects and with low drug interaction.

The effect of regular versus on-demand desloratadine treatment in children with allergic rhinitis

OBJECTIVE

Desloratadine is a potent antihistamine. Whether regular or on-demand use of desloratadine influences its therapeutic efficacy in allergic rhinitis is unknown. The aim of the study was to compare the clinical efficacy and the anti-inflammatory activity of regularly administered desloratadine to its on-demand use in children with allergic rhinitis due to pollen allergy.

METHODS

Thirty-seven patients with allergic rhinitis with or without mild intermittent asthma were enrolled in a prospective parallel group study. Patients were treated with desloratadine regularly or on-demand during pollen season. Rescue medications and symptom scores were recorded on a diary card. Nasal flow rate and inflammatory markers were recorded, and methacholine (Mch) challenge test was administered before and within the pollen season.

RESULTS

Though symptoms were lower in the evening than in the morning (p<0.001), there was no difference between the two groups. There was no difference between the groups with respect to medication score except that the salbutamol use was lower in the regular treatment group during the fourth week (p=0.032) in the pollen season. Nasal flow rate and inflammatory markers failed to show any difference between the groups. A significant reduction in PC20 values (provocative concentration of Mch causing a 20% fall in FEV(1)) was observed in regular (p=0.016) and on-demand (p=0.005) treatment groups compared to the pre-season measurements. The number of children with a PC20 below 8 mg/ml increased significantly in the on-demand group.

CONCLUSION

Our study demonstrates that on-demand use of desloratadine during the pollen season is clinically as effective as regular treatment. However, regular treatment may provide better control of lower airway symptoms and airway reactivity.

Combining desloratadine and pseudoephedrine in the treatment of seasonal allergic rhinitis

Nonsedating antihistamines are a first-line therapy in the management of allergic rhinitis. They relieve the majority of the histamine-mediated symptoms of the condition, including rhinorrhea, sneezing, and pruritus. The nonsedating antihistamine desloratadine is effective in alleviating the symptoms of both seasonal and perennial allergic rhinitis. It may also have some decongestant properties, and thus help to alleviate nasal congestion. Administering desloratadine in combination with the decongestant pseudoephedrine may offer allergic rhinitis patients with moderate-to-severe nasal congestion the benefits of desloratadine's effectiveness for alleviating histamine-mediated symptoms plus pseudoephedrine's relief from nasal congestion. This drug profile reviews a combination therapy containing desloratadine and pseudoephedrine, approved in the USA for the relief of the symptoms of seasonal allergic rhinitis, including nasal congestion.

Effect of desloratadine on epithelial cell granulocyte-macrophage colony-stimulating factor secretion and eosinophil survival

BACKGROUND

Second-generation antihistamines are H(1) receptor antagonists and may have additional anti-inflammatory effects.

OBJECTIVE

The aims of the study were to evaluate the effect of desloratadine (DL) on cytokine secretion by epithelial cells from both nasal mucosa (NM) and polyps (NP), and on eosinophil survival primed by epithelial cell secretions.

METHODS

Epithelial cells were cultured and stimulated with fetal bovine serum (FBS), IL-1beta or TNF-alpha with and without DL for 24 h. Culture supernatant cytokines concentration were measured by ELISA. Peripheral blood eosinophils were incubated with human epithelial cell conditioned media (HECM) and DL. Eosinophil survival was assessed by Trypan blue dye exclusion. Results are expressed as mean+/-SEM of cytokine concentration (pg/mL) or eosinophil survival index (%).

RESULTS

FBS increased granulocyte-macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), IL-6, IL-8, and TGF-beta(1) secretion in epithelial cell cultures from both NM and NP. Only GM-CSF secretion was significantly (P<0.05) inhibited by a dose-response of DL compared with positive controls, in both NM (10(-5) m: 125+/-36 pg/mL, 10(-6) m: 95+/-22 pg/mL vs. control: 256+/-91 pg/mL, n=6) and NP (10(-5) m: 80+/-29 pg/mL, 10(-6) m: 109+/-45 pg/mL vs. control: 333+/-212 pg/mL, n=6). DL also showed an inhibitory effect on HECM-induced eosinophil survival from both NM and NP. At 72 h, DL significantly (P<0.01) inhibited eosinophil survival induced by HECM from NM (10(-5) m: 19.9+/-5.5%, n=9; 10(-6) m: 28.7+/-7.7%, n=9) and NP (10(-5) m: 6.2+/-2.8%, n=11) compared with HECM alone (NM: 42.1+/-7.3%; NP: 45.3+/-8.1%).

CONCLUSION

The inhibitory effects of DL on epithelial cell GM-CSF secretion and on eosinophil survival induced by epithelial cell secretions, suggest that this H(1) antagonist may regulate eosinophil inflammation in upper airways.

A Review of the Evidence from Comparative Studies of Levocetirizine and Desloratadine for the Symptoms of Allergic Rhinitis

BACKGROUND

Levocetirizine and desloratadine are newer antihistamines indicated for the treatment of allergic rhinitis and chronic idiopathic urticaria.

OBJECTIVE

This article discusses the pharmacokinetics and pharmacodynamics of levocetirizine and desloratadine and reviews studies that have directly compared the effects of these 2 drugs in allergic rhinitis and urticaria.

METHODS

Relevant articles were identified through a search of MEDLINE from 1999 through 2004 using the main search terms levocetirizine and desloratadine.

RESULTS

Levocetirizine is absorbed rapidly and reaches a steady-state plasma concentration more quickly than does desloratadine. It is also metabolized to a lesser extent than desloratadine, has a lower V(d), and has higher specificity for histamine(1) receptors. Eight well-controlled trials were identified that directly compared the effects of levocetirizine and desloratadine in the skin and nose of healthy individuals and patients with allergic rhinitis. Drug activity was measured in terms of wheal, flare, and itch reactions; nasal symptoms or symptom scores; increases in concentrations of inflammatory markers; or facial thermography. In most of these trials, levocetirizine had a faster onset and greater consistency of effect than desloratadine. The differences in the pharmacokinetic and pharmacodynamic profiles of the 2 drugs may partially explain these clinical findings.

CONCLUSIONS

Levocetirizine may be preferred to desloratadine as a treatment option for allergic rhinitis because of its faster onset of action and greater consistency of effect. Although comparative studies in chronic idiopathic urticaria are not available, data from histamine-induced wheal and flare studies in healthy volunteers suggest that levocetirizine may be more effective in preventing itching than desloratadine.

Desloratadine partially inhibits the augmented bacterial responses in the sinuses of allergic and infected mice

BACKGROUND

Allergic rhinitis (AR) is considered a major predisposing factor for the development of acute bacterial rhinosinusitis. How AR augments a bacterial infection is unknown.

OBJECTIVE

Our purpose in this study was to test whether an H1 receptor antagonist, desloratadine, could reduce the augmented effect of an ongoing allergic reaction on acute bacterial rhinosinusitis.

METHODS

Three groups of infected and ovalbumin (OVA)-sensitized mice were studied: (1) infected and allergic mice treated with desloratadine, (2) infected and allergic mice treated with placebo, and (3) infected mice. A fourth group of uninfected, non-sensitized mice served as a control for the cellular changes. BALB/c mice were sensitized by two intraperitoneal injections of OVA given 8 days apart. One day after the second injection, the mice were nasally exposed daily to 6% OVA (the groups treated with desloratadine or placebo) or phosphate-buffered saline (PBS) (the infection-only group) for 5 days. After the second OVA exposure, the mice were intranasally inoculated with Streptococcus pneumoniae. Desloratadine or placebo was given daily throughout the OVA exposure period. Nasal allergic symptoms were observed by counting of nasal rubbing and sneezing for 10 min after OVA or PBS nasal challenge. On day 5 post-infection, nasal lavage culture was done, and the inflammatory cells in the sinuses were evaluated by flow cytometry.

RESULTS

Mice that were made allergic, infected, and treated with placebo showed more organisms and phagocytes than did only infect mice. They also manifested allergic nasal symptoms and eosinophil influx into the sinuses. Desloratadine treatment during allergen exposure reduced allergic symptoms and reduced sinonasal infection (P<0.05). There tended to be less myeloid cell and neutrophil influx (P=0.09 both), but not eosinophil influx (P=0.85) compared with that in the placebo-treated group.

CONCLUSION

Desloratadine treatment during nasal challenge inhibited allergic symptoms and reduced sinonasal infection, suggesting that histamine via an H1 receptor plays a role in the augmented infection in mice with an ongoing allergic reaction.

Desloratadine prevents compound 48/80-induced mast cell degranulation: visualization using a vital fluorescent dye technique

BACKGROUND

Desloratadine is a selective H1-antihistamine used in the treatment of allergic rhinitis and chronic idiopathic urticaria. Desloratadine inhibits the release of allergic inflammatory mediators in vitro. We studied the impact of desloratadine on mast cell degranulation due to activation and re-activation by the secretagogue, compound 48/80.

METHODS

Rat peritoneal eluate containing 5-6% mast cells were activated by a low concentration of compound 48/80 in a medium containing the vital fluorescent dye, Sulforhodamine-B (SFRM-B, 200 microg/ml), which is engulfed by activated mast cells. The fluorescent image of activated mast cells was captured digitally and the total fluorescent area was analyzed when desloratadine was applied before or after compound 48/80.

RESULTS

Mast cells were not activated by desloratadine (10(-4) M), SFRM-B (200 microg/ml), or diluent alone. A low concentration of compound 48/80 (0.125 microg/ml) induced fluorescence, while mast cells lost fluorescent images due to further degranulation on re-exposure to compound 48/80. Desloratadine (10(-8)-10(-4) M), inhibited compound 48/80-induced mast cell degranulation in a concentration-dependent manner. Desloratadine also reduced the loss of fluorescent images due to re-exposure to compound 48/80.

CONCLUSIONS

Desloratadine may have a mast cell stabilizing effect at low concentrations in response to repeated mast cell activation in vitro.

Desloratadine: an update of its efficacy in the management of allergic disorders

Desloratadine (Clarinex, Neoclarityn, Aerius, Azomyr, Opulis, Allex), the principal metabolite of loratadine, is itself an orally active, nonsedating, peripheral histamine H(1)-receptor antagonist. It is indicated in the US and Europe for the treatment of seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR) and chronic idiopathic urticaria (CIU). It has a rapid onset of effect, efficacy throughout a 24-hour dosage interval, and sustained efficacy in these allergic conditions, as demonstrated in placebo-controlled trials of up to 6 weeks' duration in adult and adolescent patients. At present, there are no published direct comparisons of desloratadine and other H(1)-antihistamines; however, the principal, potential clinical advantages of desloratadine over late-generation H(1)-antihistamines are the drug's decongestant activity, which has been corroborated in several studies of patients with allergic rhinitis, and its anti-inflammatory effects. Indeed, the decongestant activity of desloratadine did not differ from that of pseudoephedrine in a trial in patients with SAR, and in patients with SAR and coexisting asthma, desloratadine reduced asthma symptoms and beta(2)-agonist use, and improved forced expiratory flow in 1 second. However, these issues warrant further study. Desloratadine is generally well tolerated. The overall incidence of adverse events in adults, adolescents and children was not significantly different to that with placebo, and similar proportions of desloratadine or placebo recipients reported events such as pharyngitis, dry mouth, myalgia, somnolence, dysmenorrhoea or fatigue. Desloratadine does not cause sedation or prolong the corrected QT (QTc) interval, can be administered without regard to concurrent intake of food and grapefruit juice, and appears to have negligible potential for drug interactions mediated by several metabolic systems.

CONCLUSION

Although comparative studies with second-generation and other recently developed H(1)-antihistamines are needed to define the drug's clinical profile more clearly, desloratadine can be expected to claim a prominent place in the management of allergic disorders in general, and in the amelioration of specific symptoms of allergy (e.g. nasal congestion) in patients with such disorders.

Advances in allergy management

Our understanding of the pathophysiology of allergy has moved to the molecular level, while study of epidemiology and genetics has revealed risks of developing allergies based on environmental and genetic profiles, and pharmacoeconomic data have enabled accurate measurement of the immense burden of allergic disease. These advances in allergy research have affected its management, particularly the search for new antiallergy therapies. New therapies should intervene in the systemic allergy inflammatory cascade and provide clinical efficacy that extends to multiple allergic disease states. In addition, these new therapies should present no additional safety issues, offer improvements over existing therapies, and have an impact on disease-impaired quality of life. In vitro studies show that desloratadine, a new, once-daily, nonsedating, selective histamine H1-receptor antagonist, blocks the systemic allergy cascade at multiple points. Desloratadine 5 mg once daily relieves the symptoms of chronic idiopathic urticaria and of both seasonal (SAR) and perennial allergic rhinitis. In patients with concomitant asthma and SAR, asthma symptoms are relieved and beta2-agonist medication use is decreased by desloratadine. Unlike many other second-generation histamine H1-receptor antagonists, desloratadine provides the added benefit of efficacy against nasal obstruction in SAR. Desloratadine improves quality of life by decreasing the impact of allergic symptoms on sleep and on daily activities.

Impact and modulation of nasal obstruction

Nasal obstruction, the leading symptom of allergic rhinitis, results from the combined activity of early- and late-phase allergic reactions. Desloratadine inhibits both early- and late-phase inflammatory mediators in vitro. Thus, double-blind, placebo-controlled, randomized, crossover trials were conducted to assess the efficacy of desloratadine against nasal obstruction, measured objectively and subjectively, during controlled exposure of patients with seasonal allergic rhinitis to allergen. Positive results were obtained in three single-dose studies; desloratadine 5 mg resulted in a greater improvement from baseline than did placebo in the total symptom score and the nasal obstruction symptom score (P </= 0.02). Desloratadine was more effective than placebo in a multiple-dose study; desloratadine 5 mg was given once daily for 7 days, and a 6-h allergen challenge was administered at the end of treatment compared with placebo. Desloratadine treatment was associated with less deterioration from baseline in the mean nasal airflow (P < 0.05) and in the mean severity score for the symptom of nasal obstruction (P < 0.03). Desloratadine significantly reduces the severity of nasal obstruction in patients with seasonal allergic rhinitis.