The effect of antihistamines on seizures induced by increasing-current electroshocks: ketotifen, but not olopatadine, promotes the seizures in infant rats.

Clinical reports have shown that some antihistamines, such as ketotifen, occasionally produced seizures, especially in pre-school age children or young patients with epilepsy. The purpose of this study was to investigate whether olopatadine, one of the most efficacious antihistamines, promotes seizures induced by electroshocks in young rats. We investigated the seizures induced by electroshock using increasing-current delivery in 3- or 4-week-old rats, and found that the threshold-current of tonic extensor seizures was elevated with age in weeks in the vehicle-treatment groups. While caffeine decreased the threshold-current in every age group of rats, pentylenetetrazole, a γ-aminobutyric acid (GABA)(A) receptor antagonist, significantly decreased them only in 4-week-old rats. On the other hand, ketotifen decreased them only in 3-weeks-old rats. In the 3-week-old rats, neither olopatadine nor fexofenadine had any effect on the threshold-currents of tonic extensor seizures. These results showed that histaminergic neuro-transmission in the brain plays a crucial role in inhibiting seizures in rats soon after weaning, but is no longer effective in rats as they approach sexual maturation. In addition, unlike ketotifen, olopatadine, as well as fexofenadine, do not promote the occurrence of seizures in infant rats.

Olopatadine hydrochloride improves dermatitis score and inhibits scratch behavior in NC/Nga mice.

BACKGROUND: Control of itch is an important issue in the treatment of atopic dermatitis (AD). Itch is mediated by a variety of pruritogens, including histamine, and promoted by neurite outgrowth in the epidermis of AD patients, probably due to the release of nerve growth factor. OBJECTIVES: We investigated the effects of orally administered olopatadine hydrochloride (olopatadine) on itching, itching mediators, and neuritogenic action in a mouse model. MATERIALS AND METHODS: NC/Nga mice were treated topically with Dermatophagoides farinae body (Dfb) extract twice weekly for 4 weeks to induce AD-like lesions. They were concomitantly given oral olopatadine, distilled deionized water, or topical tacrolimus during the last 2 weeks. RESULTS: Olopatadine significantly suppressed scratching, improved the dermatitis score, inhibited neurite outgrowth, and decreased the elevated inflammatory markers, growth factors and histamine content in the lesional skin, and serum concentration of Dfb-specific IgE. Notably, olopatadine treatment increased semaphorin 3A expression in the epidermis. CONCLUSIONS: Our study confirms the pleiotropic effects of olopatadine, i.e. inhibition of inflammation and neurite extension into the epidermis.

Efficacy of repeated pretreatment with olopatadine hydrochloride on rhinitis induced by intranasal instillation of toluene-2,4-diisocyanate in rats.

It is well known that starting treatment for cedar pollinosis therapy with second-generation antihistamines before the initial day of pollen scattering can relieve nasal symptom severity during the pollen season. Olopatadine hydrochloride (olopatadine) is an antiallergic agent with histamine H(1) receptor antagonistic action. We have evaluated the effects of repeated preadministration of olopatadine on the toluene-2,4-diisocyanate-induced rhinitis in rats. A single administration of olopatadine suppressed sneezing and the increases in histamine, nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) production in nasal lavage fluid. When olopatadine was administered repeatedly once a day for 7 days before provocation, its inhibitory effects were enhanced compared to the effect of a single administration. Although the repeated administration of fexofenadine enhanced the inhibitory effects on sneezing, it did not inhibit the increases in NGF and VEGF production. These results show that the suppression of the increase in NGF and VEGF might partially be involved in the improvement of nasal allergy signs by the treatment with olopatadine. It is expected that the early treatment with olopatadine may achieve stable therapeutic effects.

Effect of olopatadine hydrochloride, an anti-histamine drug, on rhinitis induced by intranasal instillation of toluene-2,4-diisocyanate in rats.

The main symptoms of allergic rhinitis (AR) are sneezing, rhinorrhea and nasal obstruction. In patients with AR, levels of nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) increase. Olopatadine hydrochloride (olopatadine) is an anti-allergic agent with histamine H1 receptor antagonistic action. To investigate whether olopatadine has an effect on inflammatory reactions, toluene-2,4-diisocyanate (TDI)-sensitized rats were used as an animal model of nasal allergy. Nasal allergy signs (sneezing, rhinorrhea and inflammation) were induced after TDI challenge. Amounts of NGF and VEGF in the nasal lavage fluid increased. Olopatadine reduced nasal allergy signs and inhibited increases in NGF and VEGF. These findings suggest that the increases in NGF and VEGF production are involved in the mechanism responsible for nasal allergy signs in TDI-challenged rats. Other histamine H1 receptor antagonists did not inhibit and instillation of histamine did not increase TDI-induced NGF and VEGF production. Therefore, olopatadine appears to exert additional biological effects other than its blockade of the histamine H(1) receptor. These results suggest that suppression of neurogenic inflammatory reactions might be partially involved in the improvement of allergy signs after treatment with olopatadine.

Olopatadine ameliorates rat experimental cutaneous inflammation by improving skin barrier function.

Olopatadine hydrochloride (olopatadine) is an antiallergic agent with histamine H(1) receptor antagonistic action. We investigated the possible efficacies of olopatadine on the chronic inflammatory dermatitis and the impaired skin barrier functions induced by repeated application of oxazolone in rats. Oxazolone-sensitized rats were challenged with oxazolone applied to the ear every 3 days. Olopatadine was orally administered once daily (1 and 3 mg/kg/day). The effects of the drug were quantified by measurements of ear thickness, levels of cytokines in the lesioned ear and the number of scratching episodes. As parameters of skin barrier function, transepidermal water loss (TEWL) and hyaluronic acid (HA) levels in the lesioned ear were measured. The effect of olopatadine on the production of HA by cultured dermal fibroblasts was also measured. Repeated topical application of oxazolone to rat ears induced local inflammation that was exemplified by swelling. In inflamed ears, the amount of IFN gamma increased at both the protein and mRNA level, but IL-4 levels changed minimally. Olopatadine significantly decreased ear swelling and the number of scratching episodes. The drug also significantly inhibited the increase of IFN gamma and nerve growth factor production in inflamed ears. Olopatadine significantly inhibited the increase in TEWL and the decrease in HA in lesioned ears. Furthermore, the drug stimulated the production of HA by cultured dermal fibroblasts. These results suggest that olopatadine suppressed inflammation and scratching not only by inhibiting cytokine production, but also by repairing skin barrier function.

Histamine H1 receptor antagonist blocks histamine-induced proinflammatory cytokine production through inhibition of Ca2+-dependent protein kinase C, Raf/MEK/ERK and IKK/I kappa B/NF-kappa B signal cascades.

Histamine H1 receptor (H1R), a therapeutic target for alleviation of acute allergic reaction, may be also involved in mediating inflammatory responses via effects on cytokine production. However, the mechanisms whereby histamine induces cytokine production are poorly defined. In this study, we comprehensively investigated the signaling pathway involved in cytokine expression caused by histamine, using native human epidermal keratinocytes. We confirmed the expression of functional H1R by reverse transcription-polymerase chain reaction (RT-PCR), Western blotting and histamine-induced Ca(2+) elevation. Histamine induced concentration- and time-dependent production of granulocyte-macrophage-colony stimulating factor (GM-CSF), interleukin (IL)-8 and IL-6, which was completely blocked by olopatadine, an H1 antagonist. Histamine activated the phosphorylation of protein kinase C (PKC), c-Raf, mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK), extracellular signal-regulated kinase (ERK), I kappa B kinase (IKK), inhibitory kappa B (I kappa B)-alpha and nuclear factor-KB (NF-kappa B) p65, which was inhibited by Ro-31-8220, a PKC inhibitor. Also, Ro-31-8220 significantly suppressed the expression of these cytokines. BAPTA-AM, an intracellular Ca(2+) chelator, also reduced PKC phosphorylation and cytokine expression. PD98059, a MEK inhibitor, and BAY 11-8702, an I kappa B-alpha inhibitor, reduced ERK and NF-kappa B cascade activation, respectively, with little effect on PKC phosphorylation. PD98059 preferentially inhibited GM-CSF production whereas BAY 11-8702 prevented IL-8 and IL-6 production. Furthermore, in addition to the above cytokines, histamine stimulated the biosynthesis and/or release of numerous keratinocyte-derived mediators, which are probably regulated by the ERK or NF-kappa B cascades. Our study suggests that histamine activates Ca(2+)-dependent PKC isoforms that play crucial roles in the activation of Raf/MEK/ERK and IKK/I kappa B/NF-kappa B cascades, leading to up-regulation of cytokine expression. Thus, the anti-inflammatory benefit of H1 antagonists may be in part due to prevention of cytokine production.

The effects of olopatadine hydrochloride on the number of scratching induced by repeated application of oxazolone in mice.

It is suggested that atopic dermatitis is a skin disease associated with itching as subjective symptoms, and histamine H(1) receptor antagonists are used in order to prevent the itching, and the deterioration for scratch by itching. Histamine H(1) receptor selective anti-histamine olopatadine hydrochloride (olopatadine; Allelock shows consistent efficacy and safety in the treatment of allergic disorders. We investigated the possible efficacy of olopatadine on the number of scratching induced by repeated application of oxazolone in BALB/c mice. The repeated treatment of olopatadine significantly inhibited the ear swelling and the increased number of scratching. It significantly inhibited the increased production of interleukin (IL)-4, IL-1beta and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the lesioned ear. Moreover, it significantly inhibited the increased production of nerve growth factor (NGF) and substance P. On the other hand, loratadine, bepotastine and chlorpheniramine did not inhibit the ear swelling and the increased number of scratching. These results indicate that olopatadine inhibited not only the increased production of cytokines but also NGF and substance P unlike other histamine H(1) receptor antagonists. It was suggested that olopatadine suppressed the increased number of scratching by the anti-inflammatory effects. Therefore, olopatadine appears to exert additional biological effects besides its blockade of a histamine H(1) receptor.

Olopatadine hydrochloride suppresses hot flashes induced by topical treatment with tacrolimus ointment in rats.

Tacrolimus ointment is prescribed for patients with atopic dermatitis, although it is known to cause transient burning sensations and hot flashes in the applied skin. The aim of this study was to evaluate the effects of olopatadine hydrochloride (olopatadine), an antiallergic agent with a histamine H1 receptor (H1R) antagonistic activity, on the incidence of hot flashes induced by topical treatment with tacrolimus ointment in rats. Consequently, the skin temperature was increased by the topical application of tacrolimus ointment in rats, and the rise in skin temperature was inhibited by pretreatment with olopatadine in a dose-dependent manner. Inhibitory effect of olopatadine on tacrolimus-induced skin temperature elevation was significantly more potent than that of cetirizine hydrochloride, other antiallergic agent with H1R antagonistic activity, at doses in which both agents exhibit comparable H1R antagonistic activity in rats. These results suggest that H1R antagonistic activity-independent mechanism contribute to the inhibitory effect of olopatadine on tacrolimus-induced skin temperature elevation. Olopatadine also significantly inhibited increases in vascular permeability and nerve growth factor production in the skin induced by topical tacrolimus treatment. Thus, the onset of hot flashes in rats is quantitatively determined by measuring the skin temperature and olopatadine attenuates hot flashes induced by topical tacrolimus ointment in rats, suggesting that the combination application with olopatadine and tacrolimus ointment is useful for improving medication adherence with tacrolimus ointment treatment in patients with atopic dermatitis.

Pharmacological studies of diacerein in animal models of inflammation, arthritis and bone resorption.

Diacerein has proved to be effective in the treatment of osteoarthritis. We investigated the effects of diacerein in animal models of carrageenin-, zymosan-, or dextran-induced paw edema and adjuvant-induced arthritis and in ovariectomized rats. In acute inflammatory models, unlike classical nonsteroidal anti-inflammatory drugs such as naproxen and ibuprofen, diacerein inhibited the rat paw edema induced by various agents. In the adjuvant-induced arthritic rats, diacerein at 100 mg/kg/day significantly suppressed the paw edema and the increase in serum mucoprotein. Addition of 3 mg/kg/day naproxen to each diacerein (3, 10, 30 mg/kg/day) dose resulted in significantly greater anti-inflammatory activity than with naproxen alone. In the ovariectomized rats, diacerein (10, 100 mg/kg/day) also significantly prevented bone loss and reduced the serum alkaline phosphatase and decreased the excretion of urinary hydroxyproline. In addition, rhein (10, 30 microM) inhibited calcium release from mouse calvaria induced by interleukin-1 beta, prostaglandin E(2) and parathyroid hormone 1-34 human fragment. These findings indicate that diacerein is a novel anti-inflammatory drug with pharmacological properties different from those of classical nonsteroidal anti-inflammatory drugs and support the clinical investigation of the use of combination therapy with diacerein and nonsteroidal anti-inflammatory drugs in patients with not only osteoarthritis but also rheumatoid arthritis.

Olopatadine ophthalmic solution suppresses substance P release in the conjunctivitis models.

BACKGROUND: Olopatadine hydrochloride ophthalmic solutions are treated for allergic conjunctival diseases that are a selective histamine H1 receptor antagonist and an inhibitor of the release of mediators including histamine from the human mast cells. Substance P (SP) levels are increased in tears of patients with allergic conjunctivitis. However, little is known about the regulation of SP release by anti-allergic ophthalmic solutions. OBJECTIVE: We investigated that the effect of olopatadine hydrochloride ophthalmic solutions (olopatadine 0.1% and olopatadine 0.2%) on rat conjunctivitis models compared with other anti-allergic ophthalmic solutions. METHODS: Conjunctivitis was induced by subconjunctival injection of histamine or intravenous injection of ovalbumin in rats passively sensitized with anti-ovalbumin anti-serum. The releases of SP were determined in the conjunctiva and tears using rat antigen-induced conjunctivitis models. RESULTS: Olopatadine 0.1% and 0.2% significantly inhibited the increased conjunctival dye leaked in the histamine- or antigen-induced hyperpermeability. The inhibitory effects by olopatadine were more potent than by other tested anti-allergic ophthalmic solutions. Moreover, olopatadine significantly inhibited the release of SP from the conjunctiva. CONCLUSION: These results indicate that olopatadine ophthalmic solutions appear to exert additional SP release inhibition besides dual-action such as selective histamine H1 receptor antagonistic action and mast cell stabilization action.

Investigation of the antiallergic activity of olopatadine on rhinitis induced by intranasal instillation of antigen in sensitized rats using thermography.

BACKGROUND: The main symptoms of allergic rhinitis (AR) are sneezing, rhinorrhea and nasal obstruction. It was reported that the nasal skin temperature after intranasal administration of histamine or grass pollen rose. In patients with AR, the levels of nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) have increased in nasal fluids and mucosa. OBJECTIVE: The present study were to determine the temperature changes of the nose in rat allergic rhinitis model, and if olopatadine, an antiallergic agent with histamine H1 receptor antagonistic action, proved to be effective, were studied the productions of NGF and VEGF in nasal lavage fluids (NALF). In the present study, we used ovalbumin (OVA)-sensitized rats as an animal model of nasal allergy and examined the effects of olopatadine on the skin temperature of the nose area, and the productions of NGF and VEGF in NALF. METHODS: The temperature changes of the nose area were carried out with thermo tracer in rat passively sensitized with OVA antiserum. The numbers of sneezing episodes were counted and, NGF and VEGF levels in NALF were examined using the specific ELISA. RESULTS: In OVA-sensitized rats, the number of sneezing episodes increase and the nasal skin temperature rise were provoked after OVA challenge. The levels of NGF and VEGF in NALF also were increased. Olopatadine reduced the increased frequency of sneezing and the nasal skin temperature rise. It also inhibited the increased NGF and VEGF productions in NALF. CONCLUSION: The nasal skin temperature after OVA challenge rose even in OVA-sensitized rats. These results suggest that the suppression of the increased NGF and VEGF levels might partially be involved in the improvement of allergy-like behavior (sneezing and nasal skin temperature rise) by the treatment of olopatadine.

Role of fibroblast growth factor 8 (FGF8) in animal models of osteoarthritis.

INTRODUCTION: Fibroblast growth factor 8 (FGF8) is isolated as an androgen-induced growth factor, and has recently been shown to contribute to limb morphogenesis. The aim of the present study was to clarify the role of FGF8 in animal models of osteoarthritis (OA). METHODS: The expression of FGF8 in the partial meniscectomy model of OA in the rabbit knee was examined by immunohistochemistry. The effect of intraperitoneal administration of anti-FGF8 antibody was tested in a model of OA that employed injection of monoiodoacetic acid or FGF8 into the knee joint of rats. The effect of FGF8 was also tested using cultured chondrocytes. Rabbit articular chondrocytes were treated with FGF8 for 48 hours, and the production of matrix metalloproteinase and the degradation of sulfated glycosaminoglycan in the extracellular matrix (ECM) were measured. RESULTS: The expression of FGF8 in hyperplastic synovial cells and fibroblasts was induced in the meniscectomized OA model, whereas little or no expression was detected in normal synovium. Injection of FGF8 into rat knee joints induced the degradation of the ECM, which was suppressed by anti-FGF8 antibody. In the monoiodoacetic acid-induced arthritis model, anti-FGF8 antibody reduced ECM release into the synovial cavity. In cultured chondrocytes, FGF8 induced the release of matrix metalloproteinase 3 and prostaglandin E2, and caused degradation of the ECM. The combination of FGF8 and IL-1alpha accelerated the degradation of the ECM. Anti-FGF8 antibody suppressed the effects of FGF8 on the cells. CONCLUSION: FGF8 is produced by injured synovium and enhances the production of protease and prostaglandin E2 from inflamed synoviocytes. Degradation of the ECM is enhanced by FGF8. FGF8 may therefore participate in the degradation of cartilage and exacerbation of osteoarthritis.

Olopatadine suppresses the migration of THP-1 monocytes induced by S100A12 protein.

Olopatadine hydrochloride (olopatadine) is an antiallergic drug with histamine H(1) receptor antagonistic activity. Recently, olopatadine has been shown to bind to S100A12 which is a member of the S100 family of calcium-binding proteins, and exerts multiple proinflammatory activities including chemotaxis for monocytes and neutrophils. In this study, we examined the possibility that the interaction of olopatadine with S100A12 inhibits the proinflammatory effects of S100A12. Pretreatment of olopatadine with S100A12 reduced migration of THP-1, a monocyte cell line, induced by S100A12 alone, but did not affect recombinant human regulated upon activation, normal T cell expressed and secreted (RANTES)-induced migration. Amlexanox, which also binds to S100A12, inhibited the THP-1 migration induced by S100A12. However, ketotifen, another histamine H(1) receptor antagonist, had little effect on the activity of S100A12. These results suggest that olopatadine has a new mechanism of action, that is, suppression of the function of S100A12, in addition to histamine H(1) receptor antagonistic activity.

Effect of olopatadine and other histamine H1 receptor antagonists on the skin inflammation induced by repeated topical application of oxazolone in mice.

Histamine H1 receptor antagonists have long been prescribed for atopic dermatitis as an adjuvant therapy with topical therapy by local applied steroids. Olopatadine is one of the second-generation histamine H1 receptor antagonists that are treated for allergic disorders. We investigated that the effect of olopatadine on oxazolone-induced chronic contact hypersensitivity response in BALB/c mice compared with other histamine H1 receptor antagonists loratadine, cetirizine and fexofenadine. The chronic contact hypersensitivity induced by repeated application of oxazolone was treated with olopatadine and other histamine H1 receptor antagonists at the effective doses on histamine-induced paw edema in mice. The effects of these drugs in the oxazolone-induced model were quantified by measurements of ear swelling, and levels of cytokines in the lesioned ear. Olopatadine significantly inhibited the ear swelling and the increased production of IL-4, IL-1beta, IL-6, GM-CSF and NGF in the lesioned ear. On the other hand, the other histamine H1 receptor antagonists did not significantly suppress the increase in ear thickness. Moreover, they did not affect the production of cytokines in the lesioned ear. These results indicate that olopatadine appears to exert additional biological effects besides its blockade of the histamine H1 receptor.

Properties of olopatadine hydrochloride, a new antiallergic/antihistaminic drug.

Olopatadine hydrochloride (CAS 140462-76-6, KW-4679, AL-4943A; hereinafter referred to as olopatadine) is a novel antiallergic drug that is a selective histamine H1 receptor antagonist possessing inhibitory effects on the release of inflammatory lipid mediators such as leukotriene and thromboxane from human polymorphonuclear leukocytes and eosinophils. Olopatadine also inhibits the tachykininergic contractions in guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Oral administration of olopatadine at doses of 0.03 mg/kg or higher reduces the symptoms of experimental allergic cutaneous responses and rhinoconjunctivitis in sensitized animals. Preclinical and clinical evaluations have demonstrated that olopatadine is a safe drug. After oral administration to healthy volunteers, olopatadine was rapidly and extensively absorbed. Unlike most other antiallergic drugs which are eliminated via hepatic metabolism, olopatadine is mainly excreted into urine. Olopatadine did not affect cytochrome P450 activities in human liver microsomes and consequently drug-drug metabolic interactions are unlikely. In double-masked clinical trials, olopatadine was shown to be effective at alleviating symptoms of allergic diseases. The drug (Allelock) was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, cutaneous pruritus, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000. An ophthalmic solution of olopatadine is also useful for the treatment of allergic conjunctivitis: this formulation (Patanol) was approved in the USA and the European Union for the treatment of seasonal and perennial allergic conjunctivitis in 1996 and 2002, respectively.