Mast cell stabilization and anti-histamine effects of olopatadine ophthalmic solution: a review of pre-clinical and clinical research

BACKGROUND: Histamine receptor activation and degranulation of mast cells are the mechanisms by which the ocular itching, hyperemia, chemosis, eyelid swelling, and tearing of seasonal allergic conjunctivitis are induced. Some of the topical solutions available as anti-allergy therapies are intended to interfere with these mechanisms, and the body of research regarding the capabilities of these therapeutic molecules continues to expand. OBJECTIVE: To review the currently available literature regarding one topical ophthalmic anti-allergy agent, olopatadine (Patanol), and its anti-histaminic and mast cell stabilizing actions, both in pre-clinical and clinical settings. DESIGN AND METHODS: Relevant research of laboratory, animal model, and clinical trial studies performed using olopatadine was reviewed. MEDLINE literature searches were conducted and supplemented by additional reports which furthered relevant discussion or were necessary to verify the information resulting from original searches. RESULTS: Olopatadine demonstrates unique properties both pre-clinically and clinically which differentiate it from other therapeutic molecules in its class of dual action mast cell stabilizer/anti-histamine. Its non-perturbation of cell membranes, human conjunctival mast cell stabilization in vivo and in vitro, and superior efficacy as compared to other topical anti-allergic medications including mast cell stabilizers, anti-histamines, and dual action agents, all contribute to olopatadine's profile. CONCLUSIONS: Peer-reviewed literature suggests that olopatadine is clinically superior to the other anti-allergic molecules because of its strong anti-histaminic qualities and its unique ocular mast cell stabilizing properties.     

Olopatadine: a drug for allergic conjunctivitis targeting the mast cell

Importance of the field: Ocular allergic diseases are characterized by specific activation of conjunctival mast cells with subsequent release of preformed and newly formed mediators. Mast cells are thus the first therapeutic target of ocular anti-allergic treatments.

Areas covered in this review: In this review, a Medline literature search was conducted on conjunctival mast cells, their role in ocular allergy and mast cell stabilization by ocular anti-allergic compounds.

What the reader will gain: Olopatadine hydrochloride, a mast cell stabilizer and histamine receptor antagonist, has been shown to inhibit mast cell activation in an in vitro model of human mast cell culture, reducing histamine and TNF-α release and upregulating proinflammatory mediators in conjunctival epithelial cells. In the in vivo conjunctival allergen challenge (CAC) model in allergic subjects, combined with objective evaluations of tear mediators and cytology, olopatadine reduced histamine tear levels and all aspects of allergic inflammation, confirming the positive clinical effects observed in active allergic patients.

Take home message: Mast cells play a central role in the pathogenesis of ocular allergy. The CAC model is ideal for assessing the mast cell stabilizing effects of anti-allergic compounds. This review of clinical studies demonstrates the superiority of olopatadine compared with other topical allergic drugs.     

Evaluation of the effects of olopatadine ophthalmic solution, 0.2% on the ocular surface of patients with allergic conjunctivitis and dry eye*

ABSTRACT

Purpose: Olopatadine hydrochloride 0.2% (Pataday^?, Alcon, Fort Worth, USA) is a topical ocular anti-allergic agent that has shown high rates of efficacy in treating ocular itching, the primary symptom of allergic conjunctivitis, and allows for once-daily dosing. Since some patients suffer from signs or symptoms of dry eye in addition to ocular allergy, this study was designed to evaluate the safety of olopatadine 0.2% in a population of patients with both allergic conjunctivitis and dry eye.

Methods: This was a single-center, 3-visit, double-masked, randomized study. Fifty-two patients diagnosed with ocular allergy and mild-to-moderate dry eye were evaluated. After a run-in period, patients were randomized to receive either olopatadine hydrochloride 0.2% or a tear saline, and self-dosed once-daily for 1 week. Outcome measures included tear film break-up time, corneal and conjunctival staining, tear volume and flow as measured by fluorophotometry, Schirmer's test, injection, and symptom evaluations.

Results: No significant differences between the treatment groups were observed (?p > 0.05). No serious adverse events occurred during the trial. Variability in the presentation of dry eye can hinder the observation of treatment effects. Although the study design facilitated the comparison of olopatadine 0.2% against an agent that was certain to not exacerbate dry eye, future comparison of olopatadine 0.2% against other agents in its drug class would provide useful information about relative drug tolerabilities.

Conclusion: As there were no significant changes in the signs and symptoms of dry eye, olopatadine hydrochloride 0.2% is safe to use in ocular allergy patients with mild-to-moderate dry eye.     

Efficacy and comfort of olopatadine 0.2% versus epinastine 0.05% ophthalmic solution for treating itching and redness induced by conjunctival allergen challenge

ABSTRACT

Background: Olopatadine 0.2% (Pataday, Alcon Laboratories Inc., Fort Worth, Texas, USA) and epinastine 0.05% (Elestat, Inspire Pharmaceuticals, Inc., Durham, NC, USA) are topical ocular anti-allergic agents. Both are H₁ antihistamine/mast cell stabilizers indicated for the treatment of ocular itching associated with allergic conjunctivitis.

Objective: To compare the efficacy and comfort of olopatadine 0.2% with epinastine 0.05%, in the prevention of ocular itching associated with allergic conjunctivitis following conjunctival allergen challenge (CAC).

Research design and methods: This was a 7 week, four visit, double-masked, randomized, placebo-controlled CAC study. Visit 1 screened subjects for positive ocular allergic responses and Visit 2 confirmed those responses. At Visit 3, 92 subjects were randomized into one of four treatment groups to receive one drop of study medication in each eye: (1) olopatadine 0.2%/placebo, (2) epinastine 0.05%/placebo, (3) olopatadine 0.2%/epinastine 0.05%, (4) placebo/placebo. Subjects were challenged 12?h after drop instillation to evaluate duration of action. At Visit 4, subjects were challenged 5?min after drop instillation to evaluate onset of action. Drop comfort was assessed at Visit 4.

Main outcome measures; results: This article focuses on the results of the onset-of-action challenge (Visit 4). At Visit 4, ocular itching was assessed at 3, 5, and 7?min and redness was assessed at 7, 15, and 20?min post-challenge. Drop comfort was assessed upon instillation, at 30?s, and at 1, 2, and 5?min post-instillation. Olopatadine 0.2%-treated eyes exhibited significantly lower mean ocular itching scores versus epinastine 0.05%-treated eyes at 5 (?p = 0.024) and 7?min (?p = 0.003) post-challenge. Olopatadine 0.2%-treated eyes exhibited significantly lower mean redness scores versus epinastine 0.05%-treated eyes at all time points post-challenge (ciliary: p ≤ 0.013, conjunctival: p ≤ 0.015, episcleral: p ≤ 0.006). Olopatadine 0.2% was rated as significantly more comfortable than epinastine 0.05% at 1?min post-drop instillation (?p = 0.003). All adverse events were non-serious and unrelated to study medication. Although the CAC model reproduces allergic responses that are not environmentally-induced, patients experience varying severities of responses as are seen in real-world situations.

Conclusion: Olopatadine 0.2% was superior to epinastine 0.05% in preventing ocular itching and redness at onset when induced by the CAC model.     

Mechanisms of antihistamines and mast cell stabilizers in ocular allergic inflammation

Mast cells play a central role in allergic reactions and inflammation. Successful anti-allergic therapies have typically targeted mast cell mediators, particularly histamine. Antihistaminic compounds interact with the various histamine receptors found on many cells, whereas other compounds such as disodium cromoglycate, are referred to as mast cell stabilizers, as they inhibit degranulation. Some of the most successful compounds developed recently are dual-action, in that they have both anti-histaminic and mast cell stabilizing activities. Recent trends in pharmaceutical intervention, however, have been focused on the secondary effects of mast cell mediators on epithelial cell adhesion molecule expression and mediator release in the process of allergic inflammation. Since, the ocular mucosa is highly exposed to environmental allergens it is commonly involved in allergic reactions and, as such, has been a useful and accessible model in which to test new therapies in vivo. These ocular allergen provocation studies permit analysis of ocular surface cells and evaluation of tear film mediators. Furthermore, techniques to purify conjunctival mast cells have facilitated the study of the effects of mast cell stabilizing compounds on other mast cell mediators, such as cytokines, and the direct effects of mast cell mediators on epithelial cells in vitro. This review will discuss current understanding of how anti-histamines and mast cell stabilizers work, particularly in the context of molecular mechanisms of ocular allergic inflammation.     

A review of olopatadine for the treatment of ocular allergy

Ocular allergy affects > 20% of the general population and many therapeutic preparations are available to individuals experiencing the most common forms – seasonal and perennial allergic conjunctivitis. 0.1% Olopatadine topical ophthalmic solution is currently approved for the treatment of allergic signs and symptoms in patients ≥ 3 years of age. Olopatadine is available in Europe as Opatanol^® and in > 30 other countries as Patanol^®. It inhibits mast cell degranulation and antagonises histamine receptors to manage the itching, redness, chemosis, tearing and lid swelling of the ocular allergic reaction, and its mast cell stabilising ability has been demonstrated both in vitro (using human conjunctival mast cells) and in vivo (human clinical experience). This article reviews both the laboratory and clinical information available on olopatadine, prefaced by a discussion of the current understanding of the ocular allergic reaction and followed by the future implications for this compound. Both laboratory and clinical studies have established the efficacy, safety and comfort of olopatadine in several study design models and comparisons to other antiallergy medications. The application of olopatadine, specifically in the management of lid swelling, an allergic sign recalcitrant to therapy and nasal allergic symptoms has also been established. In the future, a new formulation containing 0.2% olopatadine exhibits a duration of action up to 24 h, supporting once-daily dosing.     

Comparative efficacy of olopatadine 0.1% ophthalmic solution versus levocabastine 0.05% ophthalmic suspension using the conjunctival allergen challenge model

SUMMARY

Objective: To compare the efficacy of olopatadine and levocabastine in reducing ocular allergic itching and vascular hyperemia (redness) induced by conjunctival allergen challenge.

Research design and methods: The study was a randomized, double-masked, contralateral study using the conjunctival allergen challenge (CAC) model. At Visit 1, subjects with a positive allergen skin test and a history of allergic conjunctivitis were administered increasing concentrations of allergen until at least a moderate grade 2 ocular itching and conjunctival redness response was obtained in both eyes. Allergic signs were graded on standardized 0–4 scales. Subjects who reacted positively were re-challenged at Visit 2 with the pre-determined concentration of allergen. Subjects who again responded with at least a grade 2 bilateral ocular itching and conjunctival redness score at Visit 2 were eligible for drug evaluation. At Visit 3, subjects received olopatadine in one eye and levocabastine in the contralateral eye according to a computer-generated randomization scheme generated prior to commencement of the study. Ocular discomfort was then graded in both eyes. Subjects were bilaterally challenged with the predetermined concentration of allergen 27?min after topical drug administration, such that the first post-challenge assessment was made 30?min post-drug instillation. Allergic signs and symptoms were evaluated at 3?min, 10?min, and 20?min post-challenge and safety and efficacy analyses were performed.

Results: Sixty-eight subjects received study drug and were included in the safety and efficacy analyses. Ocular itching scores for olopatadine were significantly lower than levocabastine at 3?min and 10?min post-challenge (?p < 0.001). Ocular redness scores for olopatadine were significantly lower than levocabastine at all time points post-challenge (?p < 0.0001). Of all subjects, 4.41% reported ocular discomfort in the olopatadine eye and 26.5% in the levocabastine treated eye.

Conclusion: Olopatadine treated eyes had significantly less itching and redness than levocabastine treated eyes after conjunctival allergen challenge. Olopatadine was also associated with less discomfort upon instillation than levocabastine.     

Efficacy and comfort of olopatadine versus ketotifen ophthalmic solutions: a double-masked,environmental study of patient preference

SUMMARY

Background: Ocular allergies cause itching, redness, chemosis, tearing, and swelling of the eyelids in sensitized individuals. The options available for treatment of ocular allergy include olopatadine 0.1% (Opatanol; Patanol [US]*) and ketotifen 0.025% (Zaditen; Zaditor [US]?). Patient preference for an eye drop can often be a primary factor in determining the level of compliance and satisfaction with any given therapy.

Objective: This study sought patient perspective on eye drop efficacy in controlling signs and symptoms of allergic conjunctivitis and eye drop comfort. Also evaluated were the factors considered by patients when making decisions of preference.

Methods: One hundred patients with previous history and current symptoms of seasonal or perennial allergic conjunctivitis were enrolled at two centers (Athens, Greece, N = 50; Padova, Italy, N = 50) for this two visit, double-masked study. Qualified patients received two masked bottles of medication (one olopatadine, one ketotifen) and were asked to use both medications as needed over the course of four weeks, but not to exceed usage of two drops of medication per eye per day. At the second visit, patients answered five questions comparing the two masked medications in terms of preference, drop comfort, and efficacy in treatment of signs and symptoms. Patients also defined the factors upon which they based these decisions.

Results: A significantly greater percentage of patients (81%) selected olopatadine when asked which medication they preferred; which they found more comfortable; which they found more efficacious in reducing symptoms of allergy; and which they would select if visiting the doctor's office (P < 0.0001). Seventy-six percent (76%) of patients considered both efficacy and comfort when making their preference decisions (P < 0.0001). No adverse events were volunteered or elicited.

Conclusion: In this study, patients preferred to use the anti-allergy eye drop olopatadine over ketotifen after using both drops and evaluating relative efficacy and comfort during the course of four weeks. A significantly greater percentage of the patients preferred to use olopatadine during the study period, found it more efficacious and comfortable, and would select olopatadine if visiting their doctor's office during allergy season.     

Differential regulation of IL-4 expression and degranulation by anti-allergic olopatadine in rat basophilic leukemia (RBL-2H3) cells

Olopatadine hydrochloride (olopatadine) is an anti-allergic drug that functions as a histamine H(1) antagonist and inhibits both mast cell degranulation and the release of arachidonic acid metabolites in various types of cells. In this study, we examined the ability of olopatadine to inhibit the expression of cytokine genes in vitro via high-affinity receptors for immunoglobulin E in mast cells, using a rat basophilic leukemia (RBL-2H3) cell line and an in vivo mouse model. Levels of gene expression in RBL-2H3 cells were determined by semi-quantitative RT-PCR, and serum interleukin-4 (IL-4) level in mice was quantified by ELISA. Olopatadine inhibited significantly the induction of IL-4 expression by mast cells both in vivo and in vitro. Olopatadine inhibited Ca(2+) influx through receptor-operated channels (ROC) without affecting Ca(2+) release from intracellular stores. Comparative analysis of olopatadine with other anti-allergic drugs and the ROC blocker SKF-96365 demonstrated that the potency of inhibition of Ca(2+) influx correlated with the degree of suppression of degranulation and arachidonic acid release. Inhibition of Ca(2+) influx decreased phosphorylation of p38 mitogen-activated protein kinase and c-Jun NH(2)-terminal kinase, which participate in regulation of cytokine (e.g. IL-4) gene expression. However, the rank order of inhibition of Ca(2+) influx did not correspond to reduction of IL-4 expression, suggesting that an unknown mechanism(s) of action, in addition to inhibition of Ca(2+) influx, is involved in the expression of cytokines in mast cells.     

Assessing treatment satisfaction in patients treated with pramlintide as an adjunct to insulin therapy

ABSTRACT

Objective: This study was designed to assess treatment satisfaction in patients using pramlintide who had not previously achieved glycemic targets with insulin therapy alone. Assessment included the association between treatment satisfaction and clinical outcomes (changes in post-prandial glucose [PPG], glycosylated hemoglobin [HbA_1c], weight, and insulin requirements).

Research design and methods: In this open-label study 240 participants with type 1 diabetes and 160 participants with type 2 diabetes added pramlintide to their established insulin regimen. Mealtime insulin doses were subsequently adjusted to optimize glycemic control.

Main outcome measures: Seven-point glucose profiles, weight, and insulin requirements were obtained at baseline and months 1, 3, and 6; HbA_1c levels were obtained at baseline and months 3 and 6. Participants completed a treatment satisfaction questionnaire (TSQ) at months 1, 3, and 6.

Results: Participants rated the study treatment regimen including pramlintide significantly (?p < 0.001) superior to their pre-study regimens in terms of ‘glucose control’, ‘eating-weight control’, and ‘general benefits’ at all three TSQ administrations. Regression analysis of treatment satisfaction at 6 months revealed several independent predictors (?p < 0.05). Participants who were able to reach the maximum dosage of pramlintide per protocol, and those who experienced more reduction in PPG and insulin requirements during the study, reported higher satisfaction with glucose control and general benefits; those who lost more weight reported higher treatment satisfaction on all three TSQ measurements.

Conclusions: Greater satisfaction with the study regimen was reported on all treatment satisfaction factors at all three TSQ administrations, with all advantages representing large treatment effects. Treatment satisfaction was higher for patients who experienced better clinical outcomes (decreases in weight, insulin dose requirements, and PPG levels). Study limitations include the fact this was an open-label study.     

A review of olopatadine for the treatment of ocular allergy

Ocular allergy affects > 20% of the general population and many therapeutic preparations are available to individuals experiencing the most common forms--seasonal and perennial allergic conjunctivitis. 0.1% Olopatadine topical ophthalmic solution is currently approved for the treatment of allergic signs and symptoms in patients > or = 3 years of age. Olopatadine is available in Europe as Opatanol) and in > 30 other countries as Patanol. It inhibits mast cell degranulation and antagonises histamine receptors to manage the itching, redness, chemosis, tearing and lid swelling of the ocular allergic reaction, and its mast cell stabilising ability has been demonstrated both in vitro (using human conjunctival mast cells) and in vivo (human clinical experience). This article reviews both the laboratory and clinical information available on olopatadine, prefaced by a discussion of the current understanding of the ocular allergic reaction and followed by the future implications for this compound. Both laboratory and clinical studies have established the efficacy, safety and comfort of olopatadine in several study design models and comparisons to other antiallergy medications. The application of olopatadine, specifically in the management of lid swelling, an allergic sign recalcitrant to therapy and nasal allergic symptoms has also been established. In the future, a new formulation containing 0.2% olopatadine exhibits a duration of action up to 24 h, supporting once-daily dosing.     

Emodin, a naturally occurring anthraquinone derivative, suppresses IgE-mediated anaphylactic reaction and mast cell activation

The high-affinity receptor for IgE (Fc?RI)-mediated activation of mast cells plays an important role in allergic diseases such as asthma, allergic rhinitis and atopic dermatitis. Emodin, a naturally occurring anthraquinone derivative in oriental herbal medicines, has several beneficial pharmacologic effects, such as anti-cancer and anti-diabetic activities. However, the anti-allergic effect of emodin has not yet been investigated. To assess the anti-allergic activity of emodin, in vivo passive anaphylaxis animal model and in vitro mouse bone marrow-derived mast cells were used to investigate the mechanism of its action on mast cells. Our results showed that emodin inhibited degranulation, generation of eicosanoids (prostaglandin D₂ and leukotriene C₄), and secretion of cytokines (TNF-α and IL-6) in a dose-dependent manner in IgE/Ag-stimulated mast cells. Biochemical analysis of the Fc?RI-mediated signaling pathways demonstrated that emodin inhibited the phosphorylation of Syk and multiple downstream signaling processes including mobilization of intracellular Ca²⁺ and activation of the mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and NF-κB pathways. When administered orally, emodin attenuated the mast cell-dependent passive anaphylactic reaction in IgE-sensitized mice. Thus, emodin inhibits mast cell activation and thereby the anaphylactic reaction through suppression of the receptor-proximal Syk-dependent signaling pathways. Therefore, emodin might provide a basis for development of a novel anti-allergic drug.     

Olopatadine hydrochloride ophthalmic solution for the treatment of allergic conjunctivitis

Introduction: Olopatadine hydrochloride is an antihistamine and mast cell stabilizer available as oral, intranasal and ocular preparations. Most of the practical applications of olopatadine therapy focus on the treatment of allergic rhinoconjunctivitis via intranasal and ocular routes.

Areas covered: This article was created from a comprehensive literature search with information taken from meta-analyses, systematic reviews, and clinical trials of children and adults. The articles that have been selected, evaluate the use of intranasal and ocular antihistamines and their role in allergic rhinoconjunctivitis.

Expert opinion: Olopatadine is significantly more effective than placebos in relieving the symptoms of allergic rhinoconjunctivitis. It can function both as a viable alternative or addition to first line therapies such as intranasal steroids and oral antihistamines.     

Analysis of patents on anti-allergic therapies issued in China from 1988 to 2008

Background: The prevalence of allergic diseases has increased dramatically in recent decades. Therefore, there is a pressing need for the development of effective anti-allergic services worldwide. However, little is known what anti-allergic products have been patented in China and what the potential drug candidates for patents are in China.

Objective: To analyze the patents of anti-allergic products for the last 20 years and help pharmaceutical companies and individuals to understand the potential candidates for anti-allergic patents in China.

Methods: Data were obtained from the People’s Republic of China Country Intellectual Property Rights Bureau website and United States Patent and Trademark Office website.

Results: A total of 789 anti-allergic patents have been granted in China during the past 20 years, which all focused on synthetic compounds, traditional Chinese medicines (TCM), combinations of synthetic compounds and TCM, biological products and medical apparatus. It appears that more and more effective therapeutic components of TCM rather than whole herbs have been patented in recent years and alteration of natural molecules to produce more therapeutically effective molecules has emerged as a novel trend for the modernization of TCM. The patents on synthetic anti-allergic compounds in China mainly focus on well-known targets, such as histamine receptor and leukotrienes, which consist of 93% of patents for validated targets.

Conclusion: The number of anti-allergic patents applied in China is far lower than that in the US. Therefore, there are great opportunities for obtaining anti-allergic patents, particularly patents on active ingredients from TCM in China.     

Efficacy and tolerability of newer antihistamines in the treatment of allergic conjunctivitis

Treatment for allergic conjunctivitis has markedly expanded in recent years, providing opportunities for more focused therapy, but often leaving both physicians and patients confused over the variety of options. As monotherapy, oral antihistamines are an excellent choice when attempting to control multiple early-phase, and some late-phase, allergic symptoms in the eyes, nose and pharynx. Unfortunately, despite their efficacy in relief of allergic symptoms, systemic antihistamines may result in unwanted adverse effects, such as drowsiness and dry mouth. Newer second-generation antihistamines (cetirizine, fexofenadine, loratadine and desloratadine) are preferred over older first-generation antihistamines in order to avoid the sedative and anticholinergic effects that are associated with first-generation agents. When the allergic symptom or complaint, such as ocular pruritus, is isolated, focused therapy with topical (ophthalmic) antihistamines is often efficacious and clearly superior to systemic antihistamines, either as monotherapy or in conjunction with an oral or intranasal agent.Topical antihistaminic agents not only provide faster and superior relief than systemic antihistamines, but they may also possess a longer duration of action than other classes including vasoconstrictors, pure mast cell stabilisers, NSAIDs and corticosteroids. Many antihistamines have anti-inflammatory properties as well. Some of this anti-inflammatory effect seen with 'pure' antihistamines (levocabastine and emedastine) may be directly attributed to the blocking of the histamine receptor that has been shown to downregulate intercellular adhesion molecule-1 expression and, in turn, limit chemotaxis of inflammatory cells. Some topical multiple-action histamine H(1)-receptor antagonists (olopatadine, ketotifen, azelastine and epinastine) have been shown to prevent activation of neutrophils, eosinophils and macrophages, or inhibit release of leukotrienes, platelet-activating factors and other inflammatory mediators. Topical vasoconstrictor agents provide rapid relief, especially for redness; however, the relief is often short-lived, and overuse of vasoconstrictors may lead to rebound hyperaemia and irritation. Another class of topical agents, mast cell stabilisers (sodium cromoglicate [cromolyn sodium], nedocromil and lodoxamide), may be considered; however, they generally have a much slower onset of action. The efficacy of mast cell stabilisers may be attributed to anti-inflammatory properties in addition to mast cell stabilisation. In the class of topical NSAIDs, ketorolac has been promoted for ocular itching but has been found to be inferior for relief of allergic conjunctivitis when compared with olopatadine and emedastine. Lastly, topical corticosteroids may be considered for severe seasonal ocular allergy symptoms, although long-term use should be avoided because of risks of ocular adverse effects, including glaucoma and cataract formation.     

Evolving paradigm in the management of allergic rhinitis-associated ocular symptoms: role of intranasal corticosteroids

ABSTRACT

Background: Along with nasal symptoms, ocular symptoms such as itching, tearing, and redness are common, bothersome components of the allergic rhinitis (AR) profile. Treatment of the patient with ocular allergy symptoms should take into account a variety of factors, including severity of symptoms, convenience/compliance issues, and patient preferences.

Objectives: To review from the primary care perspective the epidemiology, pathophysiology, and management of ocular symptoms associated with AR, and to evaluate the emerging role of intranasal corticosteroids (INSs).

Findings: A search of the PubMed database identified clinical trials that assessed efficacy of agents in reducing ocular allergy symptoms. Internet searches identified further information including data on over-the-counter agents for treatment of ocular symptoms. Searches were conducted using search terms such as pathophysiology, epidemiology, ocular allergy, quality of life, drug class, and drug names. Primary care physicians are often the first point of contact for patients with seasonal AR (SAR) or perennial AR (PAR) symptoms. Ocular allergy associated with SAR and PAR (seasonal and perennial allergic conjunctivitis, respectively) is characterized by both early- and late-phase reactions, with symptoms often persisting long after allergen exposure. Non-pharmacologic measures such as allergen avoidance, use of artificial tears, and cool compresses are pertinent for all ocular allergy sufferers, but may not afford adequate symptom control. Pharmacotherapy options have traditionally included topical ophthalmic products for cases of isolated ocular symptoms, and oral antihistamines for patients with both nasal and ocular symptoms. However, this paradigm is changing with new evidence regarding the efficacy of INSs in reducing ocular symptoms. A number of meta-analyses and individual studies, most of which studied ocular symptoms as secondary variables, have demonstrated the ocular effects of INSs versus topical and oral antihistamines. Additional prospective studies on this topic are encouraged to provide further evidence for these findings.

Conclusions: In light of their well-established efficacy in reducing nasal allergy symptoms, INSs offer a compre­hensive treatment option in patients with nasal and ocular symptoms. Oral antihistamines and/or topical eye drops may also be necessary depending on symptom control.     

牛樟芝水提取物抗过敏作用及其机制研究

目的 研究牛樟芝水提物的抗过敏作用并初步探讨其作用机制。方法 采用大鼠被动皮肤过敏模型、小鼠迟发型超敏模型、小鼠全身皮肤瘙痒模型、小鼠腹腔毛细血管通透性模型,观察牛樟芝水提物在体抗过敏作用。采用体外培养的RBL-2H3肥大细胞,观察牛樟芝水提物对细胞增殖及凋亡的影响,初步探讨其抗过敏反应的作用机制。结果 体内试验中,牛樟芝水提物显著降低大鼠被动皮肤过敏反应,明显降低小鼠耳肿胀度、胸腺指数及脾指数,提高右旋糖酐所致皮肤瘙痒阈值,减少小鼠瘙痒次数,抑制组胺所致血管通透性上升;体外试验中,其剂量相关性的抑制RBL-2H3细胞增殖,促进细胞凋亡。结论 牛樟芝水提取物有一定的抗过敏作用,其机制与促进RBL-2H3细胞凋亡有关。     

Contributions of basal and post-prandial hyperglycaemia to micro- and macrovascular complications in people with type 2 diabetes

ABSTRACT

Background: People with Type 2 diabetes mellitus are at high risk of cardiovascular disease and microvascular complications. A number of epidemiological studies have shown a strong relationship between the prevalence of vascular complications and raised levels of plasma glucose and glycated haemoglobin (HbA_1c). Accumulating evidence supports the superior independent prognostic importance of the post-challenge glucose level, measured either 1 or 2?h after a glucose load. Thus, data from studies conducted in Europe, the USA, and particularly the Pacific rim and South Asia suggest that 2-h glucose is a better predictor of cardiovascular and all-cause mortality than pre-breakfast glucose, both in people with diabetes and those with pre-diabetic impaired glucose tolerance (IGT). Pathophysiological studies suggest that post-prandial rises in hyperglycaemia can trigger endothelial damage through multiple mechanisms, including increased oxidative stress and the increased expression of atherogenic circulating adhesion molecules and inflammatory cytokines that induce and regulate cell recruitment, migration, growth, and proliferation. Optimal pharmacological control of meal-time glucose levels can help to lower the HbA_1c and thus may reduce the incidence of vascular complications in many people with diabetes. Moreover, emerging evidence suggests that reducing meal-time hyperglycaemia may delay the progression from pre-diabetic states toward overt diabetes.

Scope: This review (based on MEDLINE searches, 1980?2005) examines the evidence linking the microvascular and macrovascular complications of diabetes and glycaemic control, assesses the relative contributions of basal and meal-time concentrations, and considers the implications for optimal treatment for people with Type 2 diabetes or with prediabetic IGT.     

Effects of a new formulation of olopatadine ophthalmic solution on nasal symptoms relative to placebo in two studies involving subjects with allergic conjunctivitis or rhinoconjunctivitis

ABSTRACT

Background: A new formulation of olopatadine hydrochloride ophthalmic solution (olopatadine 0.2%) was evaluated in two separate, randomized, placebo-controlled, double-masked, hybrid environmental studies intended to determine efficacy and safety in subjects with histories of seasonal allergic conjunctivitis or rhinoconjunctivitis.

Design and methods: In these 10- and 12-week trials (conducted April–August 2003 and July–December 2001, respectively), subjects assessed their ocular signs and symptoms. Additionally, subjects in the 10-week trial evaluated the frequency of their nasal symptoms while subjects in the 12-week trial evaluated both the frequency and severity of their nasal symptoms. The two trials had a combined enrollment of 500 subjects (217 males, 283 females) including 44 children aged 10–17 years; the combined population was 81.4% Caucasian, 9.2% Black, 2% Hispanic, and 7.4% other. Daily throughout these studies, either ragweed (fall study) or grass (spring study) pollen counts were obtained from each investigative center. Slope analyses were conducted on the nasal symptom assessments by pollen count.

Results: The nasal results from the two clinical trials are presented herein. In the fall study, relative to placebo, olopatadine 0.2% significantly reduced the frequency of pollen effects on sneezing (p = 0.0355) and itchy nose (p = 0.0032), and reduced the severity of pollen effects on sneezing (p = 0.0451), itchy nose (p = 0.0178), and runny nose (p = 0.0327). In the spring study, olopatadine 0.2% significantly reduced the frequency of pollen effects on sneezing (p = 0.0017) and runny nose (p = 0.0031) relative to placebo. In the fall trial, 2 subjects discontinued due to treatment-related adverse events (tachycardia and dry eye), while in the spring study, no subject discontinued due to a treatment-related adverse event. No subject in either study suffered a treatment-related serious adverse event.

Conclusions: For the subjects enrolled in these studies, olopatadine 0.2% appeared to be safe, well-tolerated, and effective in significantly reducing the frequency and/or severity of some effects of pollen on nasal symptoms.