KW-4679-induced inhibition of tachykininergic contraction in the guinea-pig bronchi by prejunctional inhibition of peripheral sensory nerves

A multicenter, double-blind, randomized, noninferiority comparison of 14 days' treatment with oral olopatadine 10 mg or cetirizine 10 mg in Chinese adults with cutaneous pruritus

OBJECTIVES

To assess whether olopatadine hydrochloride (OH) was noninferior to cetirizine in the treatment of cutaneous pruritus (CP).

PATIENTS AND METHODS

Patients with CP presenting at seven centers in China were randomly allocated to double-blind treatment with 5 mg of OH orally twice a day or cetirizine 10 mg orally once a day for 2 weeks. Patients were followed up on days 7 and 14. Noninferiority was predefined as a 20% maximum difference in the reduction of symptom score reducing indices (SSRI). Both intention-to-treat (ITT) and per-protocol populations were analyzed.

RESULTS

174 patients (86 receiving OH and 88 cetirizine) were included in the ITT population. In the ITT population, the mean reduction in SSRI was 0.640 ± 0.274 in the OH group and 0.603 ± 0.289 in the cetirizine group. The one-sided 97.5% CI (-0.047) met the criteria for noninferiority. Noninferiority was also demonstrated for SSRI in the per-protocol population, with reductions of 0.640 ± 0.271 with OH and 0.596 ± 0.287 with cetirizine (97.5% CI -0.043).The total effectiveness rate (TER) was similar in the OH (90.0%) and cetirizine (80.0%) groups. The corresponding one-sided 97.5% CI (-1.0%) also demonstrated noninferiority. The incidence of adverse events was 47.1% in the OH group and 41.4% in the cetirizine group (p = 0.453).

CONCLUSION

The efficacy of OH was noninferior to that of cetirizine in controlling itching indicating that it can be considered as a clinically relevant alternative therapy to cetirizine for the management of CP in adult Chinese patients.

Olopatadine attenuates the enhancement of capsaicin-evoked substance P release by bradykinin from cultured dorsal root ganglion neurons

Olopatadine, a second-generation antihistamine, has recently been suggested to have an inhibitory effect on the tachykinin release from guinea-pig tracheobronchial smooth muscle preparation. In the present study, using a highly sensitive radioimmunoassay for substance P, we observed that olopatadine attenuated the enhancement of capsaicin-induced substance P release by bradykinin with an IC(50) value of 12.5 microM, without any inhibitory effect on the substance P release induced by capsaicin, potassium or bradykinin from cultured dorsal root ganglion neurons. These data suggest that olopatadine may therefore be involved in the bradykinin-induced sensitization of the transient receptor potential vanilloid 1 in cultured dorsal root ganglion neurons.

The various effects of four H1-antagonists on serum substance P levels in patients with atopic dermatitis

Antiallergic drugs have various actions against allergy-associated cells and molecules as well as antihistamic properties. We studied the effects of antiallergics on the serum levels of substance P. Patients with atopic dermatitis were treated with one of four oral H1-antagonists for 14 days, and the serum level of substance P was measured before and after treatment in parallel with several atopic severity markers. Olopatadine significantly decreased the substance P level. This is in accordance with its known downmodulatory effect on tachykinin release. In contrast, cetiridine and fexofenadine unexpectedly increased the substance P level. In patients administered cetiridine, the blood severity markers for atopic dermatitis, including lactate dehydrogenase, eosinophil number, and the soluble forms of IL-2R, E-selectin, VCAM-1 and ICAM-1 were reduced after the treatment. Therefore, the elevation of SP was unrelated to the deterioration of atopic dermatitis but rather associated with improvement. Our study suggests that antiallergics can be divided into substance P-increasing and -decreasing types and raises the possibility that the increment of substance P by the former type is caused by the competitive occupation of substance P receptors.

Effects of olopatadine hydrochloride, an antihistamine drug, on skin inflammation induced by repeated topical application of oxazolone in mice

BACKGROUND

Olopatadine hydrochloride (olopatadine) is one of the second-generation antihistamines, which is prescribed for allergic disorders such as rhinitis, urticaria and eczema dermatitis.

OBJECTIVES

To investigate the possible anti-inflammatory effect of olopatadine on the chronic contact hypersensitivity response to repeated topical application of oxazolone in mice.

METHODS

The preventive and therapeutic effects of oral olopatadine were quantified by measurements of ear swelling, cytokine protein and mRNA expression in the ear lesion, and were compared with those of topical betamethasone 17-valerate (betamethasone).

RESULTS

The ear receiving repeated applications of oxazolone exhibited erythema, oedema and abrasion. Both preventive and therapeutic administration of olopatadine (10 mg kg(-1) day(-1)) significantly inhibited the ear swelling and the increased production of interleukin (IL)-4, IL-1beta, granulocyte-macrophage colony-stimulating factor (GM-CSF) and nerve growth factor. In the histopathological analysis, olopatadine ameliorated epidermal hyperplasia and infiltration of inflammatory cells. Consistent with these results, olopatadine significantly reduced the increased expression of interferon-gamma and IL-4 mRNA. Although betamethasone (0.012 mg ear(-1) day(-1)) showed similar activities to olopatadine against these responses, it caused atrophy of the ear skin.

CONCLUSIONS

These results indicate that olopatadine is an antihistamine agent having inhibitory activities against chronic inflammatory dermatitis, possibly resulting from its diminishing effect on elevated cytokines.

[Recent development of new drugs for the treatment of allergic diseases]

Due to the prevalence of allergic diseases such as bronchial asthma, allergic rhinoconjunctivitis and dermallergosis, efforts at the discovery of novel and effective medications for prevention and treatment of these conditions have been reinforced. Recently, it has been recognized that these allergic diseases are a chronic inflammatory disorder of the lower and upper airways and skin. In this article, we reviewed the recent development of the following new antiallergic therapies: anti-Th2 cytokine antibodies, decoy receptors, receptor antibodies, anti-IgE antibodies, anti-cell adhesion molecules antibodies, antisense oligonucleotides, keratinocyte modulators, inhibitors of phosphodiesterase 4, tachykinin receptor antagonists, and anti-histaminic drugs. Most of these new agents are aimed to inhibit various components of allergic inflammation. The future use of allergic disease therapies hold great promise and excitement.

Pharmacological, pharmacokinetic and clinical properties of olopatadine hydrochloride, a new antiallergic drug

Olopatadine hydrochloride (olopatadine, 11-[(Z)-3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b,e]oxepin-2-acetic acid monohydrochloride) is a novel antiallergic/histamine H1-receptor antagonistic drug that was synthesized and evaluated in our laboratories. Oral administration of olopatadine at doses of 0.03 mg/kg or higher inhibited the symptoms of experimental allergic skin responses, rhinoconjunctivitis and bronchial asthma in sensitized guinea pigs and rats. Olopatadine 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 inhibited the tachykininergic contraction in the guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Olopatadine exerted no significant effects on action potential duration in isolated guinea pig ventricular myocytes, myocardium and human ether-a-go-go-related gene channel. Olopatadine was highly and rapidly absorbed in healthy human volunteers. The urinary excretion of olopatadine accounted for not less than 58% and the contribution of metabolism was considerably low in the clearance of olopatadine in humans. Olopatadine is one of the few renal clearance drugs in antiallergic drugs. Olopatadine was shown to be useful for the treatment of allergic rhinitis and chronic urticaria in double-blind clinical trials. Olopatadine was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, pruritus cutaneous, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000. Ophthalmic solution of olopatadine was also approved in the United States for the treatment of seasonal allergic conjunctivitis in December, 1996 (Appendix: also in the European Union, it was approved in February 2002).

Effects of olopatadine hydrochloride on the cutaneous vascular hyperpermeability and the scratching behavior induced by poly-L-arginine in rats

Intradermal injections of poly-L-arginine induce cutaneous vascular hyperpermeability and scratching behavior in rats. Recently, we elucidated that the plasma extravasation involved both histamine and substance P, while the scratching behavior involved substance P, but not histamine. This study examined the effects of olopatadine hydrochloride (olopatadine), an antiallergic drug with histamine H1-antagonistic action, on the poly-L-arginine-induced responses. Olopatadine (1 mg/kg, p.o.) significantly inhibited both the plasma extravasation and the scratching behavior, suggesting that its inhibitory effects are mediated by the suppression of neuropeptidergic action as well as histaminic action. Olopatadine seems to be a novel-type drug for the treatment of dermatitis.

[Pharmacological, pharmacokinetic and clinical properties of olopatadine hydrochloride' (olopatadine), an antiallergic drug]

Olopatadine 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 inhibited the tachykininergic contraction in the guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Oral administration of olopatadine inhibited passive cutaneous anaphylaxis in rats, experimental allergic rhinitis and bronchial asthmatic responses in actively sensitized guinea pigs. Olopatadine exerted no significant effects on action potential duration in isolated guinea pig myocardium and ventricular myocytes. Olopatadine was highly and rapidly absorbed in healthy volunteers. The urinary excretion of olopatadine accounted for not less than 58% and the contribution of metabolism was low in the elimination of olopatadine. Olopatadine was shown to be useful for the treatment of allergic rhinitis and chronic urticaria in double-blind clinical trials. Olopatadine was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, pruritus cutaneous, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000.

Inhibitory effect of olopatadine hydrochloride on the sneezing response induced by intranasal capsaicin challenge in guinea pigs

To investigate the possible inhibitory effect of olopatadine hydrochloride (olopatadine), an antiallergic drug, on the tachykinin-mediated nasal responses, we examined the effect of olopatadine on the sneezing and the nasal rubbing responses induced by intranasal capsaicin challenge in guinea pigs. Olopatadine (10 mg/kg, p.o.) inhibited the sneezing response by 57% without affecting the nasal rubbing one. The antihistamines chlorpheniramine and clemastine did not affect the responses. Morphine caused the inhibition of both responses, which was antagonized by naloxone. These results suggest that olopatadine inhibits the sneezing response by the inhibition of the tachykinin release and not by its antihistaminic action.

[Effect of olopatadine hydrochloride, a novel antiallergic agent, on the QT interval in dogs]

Olopatadine hydrochloride (olopatadine), a novel antiallergic agent, is effective in the treatment of allergic rhinitis, chronic urticaria, eczema and dermatitis. It has been reported that terfenadine and astemizole cause side effects on the circulatory system such as QT prolongation followed by serious ventricular arrhythmias (torsades de pointes). To investigate the possibility of QT prolongation, we used both conscious normal dogs and hypokalemia-anesthetized dogs under two conditions: 1) olopatadine used alone and 2) olopatadine used in combination with itraconazole, the CYP3A4-inhibiting antifungal agent, in the present investigation. The group treated with terfenadine alone (30 mg/kg, p.o.) and the group treated with a combination of terfenadine (10 mg/kg, p.o.) and itraconazole (100 mg/kg, p.o.) had a significantly prolonged QT interval. On the other hand, the group treated with olopatadine alone (30 mg/kg, p.o.) and the group treated with a combination of olopatadine (30 mg/kg, p.o.) and itraconazole (100 mg/kg, p.o.) did not show any significant changes in QT interval. Moreover, olopatadine (1 and 5 mg/kg, i.v.) did not influence the QT interval in hypokalemia-anesthetized dogs. These results suggest that there is very little possibility of QT prolongation as a result of clinically used olopatadine.

Unique binding pocket for KW-4679 in the histamine H1 receptor

The histamine H1 receptor has an aspartate (Asp) residue in transmembrane helix 3 (TM3), which is well-conserved among biogenic amine receptors. The Asp residue is one of the most crucial amino acids for ligand binding. The tested histamine H1 receptor antagonists with tri- and tetracyclic structures were not selective for histamine H1 receptors and showed affinity for several other biogenic amine receptors. In contrast, KW-4679 ((Z)-11-[3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b, e]oxepin-2-acetic acid hydrochloride), a tricyclic compound, was a selective histamine H1 receptor antagonist. [3H]KW-4679 had high affinity (Kd value of 2.5 +/- 0.12 nM) for wild-type human histamine H1 receptors. In the [3H]KW-4679 binding assay, replacement of Asp107 by alanine by site-directed mutagenesis greatly reduced the affinities (280-2100-fold) of tri- and tetracyclic compounds, whereas this mutation led to a comparatively small reduction (14-fold) in KW-4679 affinity. These results demonstrate that the tested tri- and tetracyclic histamine H1 receptor antagonists which have a tight interaction with the Asp residue are not selective for the histamine H1 receptor. Furthermore, the high selectivity of KW-4679 might be explained by a unique binding pocket, which consists of the Asp residue and other acceptor sites, in the histamine H1 receptor.

Inhibitory effect of KW-4679, an anti-allergic drug, on tachykinin-mediated airway response induced by electrical vagal stimulation in guinea pigs

We examined the effect of KW-4679 ((Z)-11-[(3-dimethylamino) propylidene]-6,11-dihydro-dibenz[b,e]oxepin-2-acetic acid monohydrochloride), an anti-allergic drug, on the tachykinin-mediated airway response in guinea pigs. Electrical stimulation of the vagus nerve in atropine-treated and propranolol-treated guinea pigs caused a 38.1% decrease in dynamic compliance (Cdyn), which was suppressed by the combination of the tachykinin NK1-receptor antagonist (+/-)-CP-96345 and NK2-receptor antagonist SR 48968. KW-4679 at a dose of 3 mg/kg significantly reduced the decrease in Cdyn (P < 0.05). On the other hand, KW-4679 did not inhibit substance P or neurokinin A-induced decrease in Cdyn. These results suggest that KW-4679 may inhibit the tachykininergic airway response by prejunctional inhibition of peripheral sensory nerves.