Sinomenine-induced histamine release-like anaphylactoid reactions are blocked by tranilast via inhibiting NF-κB signaling.

Zhengqing Fengtongning (ZQFTN), the pharmaceutical preparation of sinomenine (SIN) derived from the medicinal plant Sinmenium acutum, is well-known in China as an effective treatment for rheumatoid arthritis (RA). However, its histamine-release anaphylactoid reactions (HRARs) occur often in some patients. Therefore, it is desirable to establish effective clinical protocols to manage such HRARs. In the study, rat models with systemic HRARs and local HRARs of the skin were established. The level of vascular permeability and mast cell numbers was determined by quantitative analysis using Evans blue dye and histological assays. The levels of histamine, leukotriene B4 (LTB4) and IL-33 in plasma were detected by UHPLC-SPE-MS, ELISA and immunohistochemistry assays, respectively. The results demonstrated that SIN significantly induced both systemic and local HRARs in rats, showing significant decrease of body temperature, increases in vascular permeability in skin, injury of lung tissues and mast cell infiltration and IL-33 expression in skin and lung tissues. Mechanistic study showed that tranilast could prevent SIN-triggered HRARs via inhibition of H1 receptor gene expression and NF-κB signaling. Our findings provide evidence that mast cell membrane stabilizers and H1 receptor blockers effectively prevent SIN-induced HRARs, and cromolyn, cetirizine and tranilast can be used in the clinic for the management of HRARs induced by ZQFTN.

Efficacy of Tripterygium hypoglaucum Hutch in adults with chronic urticaria.

OBJECTIVES: The study objectives were to evaluate the efficacy and safety of Tripterygium hypoglaucum Hutch (THH) in adult with severe chronic urticaria (CU) by performing a randomized, double-blind, placebo-controlled clinical trial. METHODS: Seventy-eight (78) adult patients with severe CU, 21-58 years of age, responding poorly to antihistamines alone, were randomly divided into two groups: the therapeutic group with THH 3 tablets 3 times daily (n = 40) and the control group with placebo 3 tablets 3 times daily (n = 38). Meanwhile, all patients jointly received cetirizine hydrochloride (HCl) 10 mg once daily throughout the study period. The efficacy of THH was assessed by the scoring system of 4-point scale and the subject's global assessment of relief. RESULTS: Sixty-nine (69) of 78 patients (37 in the therapeutic group, 32 in the control group) completed the study. By the end of the fourth week, there was a 67% improvement of total effective rate (TER) with THH compared with a 28% improvement with placebo by per-protocol analysis (χ(2) = 10.68, p = 0.0011), while by intention-to-treat analysis, 63% and 24% improvements of TER were respectively observed in the therapeutic group and the control group (χ(2) = 11.36, p = 0.001). THH with cetirizine showed statistical superiority to placebo with cetirizine during each study week for changes in total severity scores (p ≤ 0.001). In weekly analyses, THH was also statistically superior to placebo in reducing the mean pruritus scores during each study week (p ≤ 0.005). CONCLUSIONS: This study shows that the therapeutic effect of THH with cetirizine is predominant over that of cetirizine alone in adult CU. THH with cetirizine may play an important role in the therapy of CU and be a useful treatment for CU.

Improved methodology for identifying the teratogenic potential in early drug development of hERG channel blocking drugs.

Drugs blocking the potassium current IKr of the heart (via hERG channel-inhibition) have the potential to cause hypoxia-related teratogenic effects. However, this activity may be missed in conventional teratology studies because repeat dosing may cause resorptions. The aim of the present study was to investigate an alternative protocol to reveal the teratogenic potential of IKr-blocking drugs. The IKr blocker astemizole, given as a single dose (80 mg/kg) on gestation day (GD) 13 to pregnant rats caused digital defects. In whole rat embryo culture (2h) on GD 13, astemizole caused a decrease in embryonic heart rate at 20 nM, and arrhythmias at 200-400 nM. Cetirizine, without IKr-blocking properties, did not affect the rat embryonic heart in vitro. The present study shows that single dose testing on sensitive days of development, together with whole embryo culture, can be a useful methodology to better characterize the teratogenic potential of IKr-blocking drugs.

A new variant of the basophil activation test for allergen-induced basophil CD63 upregulation. The effect of cetirizine.

OBJECTIVE: The aim of our study was to determine the diagnostic usefulness of a newly developed basophil activation test (BAT) in patients allergic to Dermatophagoides pteronyssinus and pollens. We also analyzed the influence of cetirizine on CD63 upregulation. This popular antihistamine strongly inhibits skin tests, but its impact on BAT sensitivity remains unknown and deserves at least preliminary determination. METHODS: The study sample comprised 22 patients allergic to house dust mite and pollens and 19 healthy controls. All participants underwent skin prick testing and the newly developed flow-cytometric basophil activation test. The protocol for allergen-induced basophil CD63 upregulation consisted of whole blood samples that were processed and stained with anti-CCR3/CD63 antibodies added to the buffer at the beginning of stimulation. Skin prick tests and BAT were performed twice--before and 2 hours after ingestion of 10 mg of cetirizine. RESULTS: The new BAT is characterized by its short processing time, easy basophil gating, and strong CD63 upregulation with very high sensitivity and excellent specificity. Our results suggest that allergen-induced CD63 upregulation by higher doses of allergens is not inhibited 2 hours after administration of cetirizine (unlike skin prick tests). CONCLUSION: The BAT is a very useful and precise method for the diagnosis of allergy to aeroallergens. It is not influenced by cetirizine.

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

OBJECTIVE: To determine whether oral administration of cyproheptadine or cetirizine blocks the action of serotonin and histamine, respectively, and results in diminished eosinophilic airway inflammation in cats with experimentally induced asthma. ANIMALS: 9 cats in which asthma was experimentally induced through exposure to Bermuda grass allergen (BGA) during a 3-month period. PROCEDURES: Cats were randomized to receive monotherapy with each of 3 treatments for 1 week: placebo (flour in a gelatin capsule, PO, q 12 h), cyproheptadine (8 mg, PO, q 12 h), or cetirizine (5 mg, PO, q 12 h). A 1-week washout period was allowed to elapse between treatments. Prior to and following each 1-week treatment period, blood and bronchoalveolar lavage fluid (BALF) samples were collected. The percentage of eosinophils in BALF was evaluated to determine treatment efficacy. Serum and BALF BGA-specific immunoglobulin contents and plasma and BALF histamine concentrations were determined via ELISAs. Plasma and BALF serotonin concentrations were measured by use of a fluorometric method. RESULTS: The mean +/- SD percentage of eosinophils in BALF did not differ significantly among treatment groups (placebo, 40 +/- 22%; cyproheptadine, 27 +/- 16%; and cetirizine, 31 +/- 20%). Among the treatment groups, BGA-specific immunoglobulin content and histamine and serotonin concentrations were not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: In cats with experimentally induced asthma, cyproheptadine and cetirizine were not effective in decreasing airway eosinophilic inflammation or in altering several other measured immunologic variables. Neither cyproheptadine nor cetirizine can be advocated as monotherapy for cats with allergen-induced asthma.

Hybrid approach for the design of highly affine and selective dopamine D(3) receptor ligands using privileged scaffolds of biogenic amine GPCR ligands.

A series of compounds containing privileged scaffolds of the known histamine H(1) receptor antagonists cetirizine, mianserin, ketotifen, loratadine, and bamipine were synthesized for further optimization as ligands for the related biogenic amine binding dopamine D(3) receptor. A pharmacological screening was carried out at dopamine D(2) and D(3) receptors. In the preliminary testing various ligands have shown moderate to high affinities for dopamine D(3)receptors, for example, N-(4-{4-[benzyl(phenyl)amino]piperidin-1-yl}butylnaphthalen-2-carboxamide (19a) (hD(3)K(i)=0.3 nM; hD(2)K(i)=703 nM), leading to a selectivity ratio of 2343.

Effects of histamine H(1) receptor antagonists on depressive-like behavior in diabetic mice.

We previously reported that streptozotocin-induced diabetic mice showed depressive-like behavior in the tail suspension test. It is well known that the central histaminergic system regulates many physiological functions including emotional behaviors. In this study, we examined the role of the central histaminergic system in the diabetes-induced depressive-like behavior in the mouse tail suspension test. The histamine contents in the hypothalamus were significantly higher in diabetic mice than in non-diabetic mice. The histamine H(1) receptor antagonist chlorpheniramine (1-10 mg/kg, s.c.) dose-dependently and significantly reduced the duration of immobility in both non-diabetic and diabetic mice. In contrast, the selective histamine H(1) receptor antagonists epinastine (0.03-0.3 microg/mouse, i.c.v.) and cetirizine (0.01-0.1 microg/mouse, i.c.v.) dose-dependently and significantly suppressed the duration of immobility in diabetic mice, but not in non-diabetic mice. Spontaneous locomotor activity was not affected by histamine H(1) receptor antagonists in either non-diabetic or diabetic mice. In addition, the number and affinity of histamine H(1) receptors in the frontal cortex were not affected by diabetes. In conclusion, we suggest that the altered neuronal system mediated by the activation of histamine H(1) receptors is involved, at least in part, in the depressive-like behavior seen in diabetic mice.

Cetirizine, an H1-receptor antagonist, suppresses the expression of macrophage migration inhibitory factor: its potential anti-inflammatory action.

BACKGROUND: H1-receptor antagonists are often effective in the treatment of allergic disorders such as atopic dermatitis. Cetirizine, a putative H1-receptor antagonist, has recently been shown to have anti-inflammatory properties through the inhibition of leucocyte recruitment and activation, and by the reduction of ICAM-1 expression on keratinocytes. OBJECTIVE: To further elucidate the anti-inflammatory properties of cetirizine, we first examined its effects on antigen-induced eosinophilia and neutrophila in vivo. We then examined the anti-inflammatory effects of cetirizine on a human keratinocyte A431cell line. METHODS: Mice were sensitized subcutaneously with ragweed pollen and were challenged intraperitoneally with the allergen. Cetirizine diluted in sterile water (0-20 mg/kg) or only sterile water was administered orally. Peritoneal cells were obtained at 8 and 24 h after challenge. The eosinophilia and neutrophilia induced by ragweed pollen extract were quantitated. Macrophage migration inhibitory factor (MIF), macrophage inflammatory protein 2 (MIP-2) and eotaxin contents of peritoneal fluid were also measured by mouse ELISA. The effects of cetirizine on MIF-induced IL-8 production in A431 cells were examined by ELISA. The effects of cetirizine on MIF expression and production in A431 cells were examined by human MIF ELISA and Northern blot analysis. RESULTS: Eosinophilia and neutrophilia induced by ragweed pollen extract were found to be significantly reduced in cetirizine-treated mice (20 mg/kg). MIF, a pleuripotent cytokine, was significantly decreased at 8 and 24 h in the peritoneal fluid by cetirizine treatment. MIP-2 and eotaxin were also decreased 8 and 24 h, respectively, after challenge in the peritoneal fluid with cetirizine treatment. MIF stimulates IL-8 production in A431 cells. We found that MIF production in A431 cells was inhibited by 10 microm cetirizine. Consistent with this, cetirizine significantly inhibited MIF-induced IL-8 production. CONCLUSION: These results suggest that cetirizine exerts its anti-inflammatory effects by inhibiting MIF as well as IL-8 production, such as those involved in inflammatory allergic skin disease, suggesting a broad spectrum of action beyond its mere H1-receptor-antagonistic function.

Mast cell stabilization, lipoxygenase inhibition, hyaluronidase inhibition, antihistaminic and antispasmodic activities of Aller-7, a novel botanical formulation for allergic rhinitis.

Allergic rhinitis, also known as hay fever, rose fever or summer catarrh, is a major challenge to health professionals. A large number of the world's population, including approximately 40 million Americans, suffers from allergic rhinitis. A novel, botanical formulation (Aller-7) has been developed for the treatment of allergic rhinitis using a combination of extracts from seven medicinal plants, including Phyllanthus emblica, Terminalia chebula, T. bellerica, Albizia lebbeck, Piper nigrum, Zingiber officinale and P. longum, which have a proven history of efficacy and health benefits. The clinical manifestations of allergy are due to a number of mediators that are released from mast cells. The effect of Aller-7 on rat mesenteric mast cell degranulation was studied by incubating different concentrations of Aller-7 and challenging them with a degranulating agent, compound 48/80. The inhibitory activity of Aller-7 was determined against lipoxygenase and hyaluronidase, the key enzymes involved in the initiation and maintenance of inflammatory responses. Furthermore, most of these manifestations are due to histamine, which causes vasodilatation, increasing capillary permeability and leading to bronchoconstriction. Hence, the antihistaminic activity of Aller-7 was determined is isolated guinea pig ileum substrate using cetirizine as a positive control. The antispasmodic effect of Aller-7 on contractions of guinea pig tracheal chain was determined using papaverine and cetirizine as controls. Aller-7 exhibited potent activity in all these in vitro models tested, thus demonstrating the novel anti-allergic potential of Aller-7.

Effects of cetirizine dihydrochloride on human lymphocytes in vitro: evaluation of chromosome aberrations and sister chromatid exchanges.

The ability of cetirizine dihydrochloride, an antihistaminic agent, to induce chromosome aberrations as well as sister chromatid exchanges (SCEs) was evaluated in human lymphocyte cultures treated in vitro. The following concentrations were tested: 25, 50, 75, 100 and 200 micrograms/ml. The results of our study revealed that cetirizine dihydrochloride is capable of inducing chromosome aberrations, at least at the higher concentrations studied, 100 and 200 micrograms/ml. The majority of aberrations was of chromatid type. Cetirizine is also a weak inducer of SCEs. Further studies are now warranted in order to define the in vivo cytogenetic activity of cetirizine in humans.

Cellular inflammatory responses during immediate, developing, and established late-phase allergic cutaneous reactions: effects of cetirizine.

BACKGROUND: In some previous studies, the antihistamine cetirizine has inhibited both developing (at 6 hours) and established (at 24 hours) gross late-phase skin reactions (LPR) to pollen antigens, possibly relevant to clinical drug effects. However, the effects of cetirizine at the histologic level require further definition. OBJECTIVE: To characterize cetirizine effects on gross and histologic inflammatory events from 20 minutes to 24 hours after intradermal antigen challenge in sensitive patients. METHODS: Gross and histologic responses to intradermal pollen antigen, codeine, histamine, and buffer diluent were assessed during randomized 7-day treatments with cetirizine and placebo. Accumulated neutrophils, eosinophils, activated (EG2+) eosinophils, and T lymphocytes were quantitated. The degrees of extracellular deposition of lactoferrin from neutrophils and eosinophilic cationic protein (ECP) from eosinophils were also assessed. RESULTS: During placebo treatment, wheal-and-flare responses were significantly greater to antigen at 20 minutes (p < 0.01) and induration at 6 hours (p < 0.01) at antigen challenge sites than at buffer diluent sites. During cetirizine treatment, these wheal-and-flare responses to antigen were inhibited significantly (p < 0.01) but gross LPRs were not affected. During placebo treatment, significantly more cells per high-power field were found in antigen sites than in buffer sites of neutrophils at 20 minutes (p < 0.01) and 24 hours; than in eosinophils at 20 minutes, 6 hours, and 24 hours (p < 0.01 for each); than in EG2+ cells at 20 minutes (p = 0.004), 6 hours (p = 0.001), and 24 hours (p = 0.02); and at T lymphocyte sites at 24 hours (p = 0.001). Extracellular deposition of lactoferrin and ECP was significantly greater at antigen sites than at buffer sites at 6 and 24 hours. Cetirizine treatment had no significant effect on these responses. CONCLUSION: Neutrophils, eosinophils, and T lymphocytes were persistently more common at antigen sites than at buffer sites through 24 hours. Many of these neutrophils and eosinophils were activated, releasing more lactoferrin and ECP into the extracellular dermis for at least 24 hours after antigen challenge. Cetirizine inhibited gross immediate responses to antigen, but not the gross LPR nor the cellular inflammatory responses seen in such LPR sites.

Cellular inflammatory responses and mediator release during early developing late-phase allergic cutaneous inflammatory responses: effects of cetirizine.

BACKGROUND: Events in developing cutaneous late-phase allergic reactions can be characterized by a combination of skin chamber and biopsy approaches. In some previous studies, cetirizine reportedly inhibited mediator release and/or inflammatory cell responses in late-phase reactions. OBJECTIVE: This study was carried out to determine the effects of cetirizine on early late-phase reactions by using skin chamber and skin biopsy specimens. METHODS: Skin chamber responses during a 6-hour challenge with pollen antigens were assessed in 15 sensitive subjects during randomized, crossover treatment with cetirizine (20 mg/day) or placebo for 7-day periods with measurements of humoral and cellular components. Biopsy specimens of the underlying dermis were obtained. RESULTS: During cetirizine treatment, there was significant (p < 0.01) inhibition of immediate wheal and flare reactions to pollen antigens (34, 46%), codeine (41, 65%), and histamine (38, 68%). However, gross late-phase reactions at 6 hours were unaffected. During both cetirizine and placebo treatment, there was significantly greater accumulation at antigen sites in: (1) skin chamber levels of histamine, total cells, lactoferrin, and eosinophil cationic protein; (2) eosinophils (total and activated) on appended cover glasses; (3) deposition of lactoferrin and eosinophil cationic protein in the underlying dermis. However, these responses were not significantly different during cetirizine treatment compared with placebo treatment periods. CONCLUSION: A persistent pattern of inflammatory cell accumulation with release of granule proteins during early late-phase reactions was unaffected by cetirizine treatment.

Estudo clínico comparativo entre cetirizina e placebo no tratamento de pacientes com rinite alérgica perene / Comparative clinical study between cetirizine and placebo in the treatment of patients with perennial allergic rhinitis

O estudo teve como objetivo avaliar a tolerabilidade, a eficácia clínica e a segurança do uso da cetirizina (CTZ) no tratamento da rinite alérgica perene. O estudo foi comparativo contra placebo (PLB), duplo-cego, randomizado, cruzado. Os pacientes receberam um período de 15 dias com CTZ (10 mg em dose única di ria), seguido de outro período de 15 dias com PLB, ou vice-versa de acordo com lista de aleatorizaçäo. Setenta e dois pacientes foram admitidos e 52 deles completaram os dois períodos de tratamento previstos. A CTZ mostrou superioridade nos seguintes sintomas de rinite alérgica: coriza, obstruçäo nasal, crises de espirro, prurido nasal e conjuntivite. O sintoma tosse näo foi modificado por qualquer dos tratamentos. Os sinais físicos de rinite alérgica, como coloraçäo da mucosa, hipertrofia de cornetos, secreçäo nasal e inflamaçäo faríngea, mantiveram-se inalterados com os dois tratamentos. O mesmo ocorreu com os sinais vitais: pressäo arterial, frequência cardíaca, frequência respiratória e peso. Durante o período de tratamento com a CTZ foram observados eventos adversos em sete pacientes (12,3 por cento) e no período PLB foram observados eventos adversos em oito pacientes (14 por cento). Os eventos adversos mais frequentes no período de tratamento com CTZ foram sonolência e aumento subjetivo de peso (nÝo confirmado ao exame físico); no período PLB foram tontura, aumento de apetite e cefaléia. Durante o período de tratamento com a CTZ nove pacientes interromperam o tratamento, sendo oito pacientes por abandono ou falta de colaboraçäo do paciente e um por evento adverso (urticária ao frio näo controlada). Durante o período PLB 11 pacientes interromperam o tratamento, sendo dez pacientes por abandono ou falta de colaboraçäo do paciente e um por evento adverso (tontura e calafrios). Concluímos que a CTZ se mostrou clinicamente superior ao PLB em efic cia, proporcionando alívio dos sintomas da rinite alérgica perene e sintomas conjuntivais. A incidência de eventos adversos com CTZ nÝo diferiu da observada com PLB. A cetirizina é um anti-histamínico eficaz e bem tolerado, com posologia cômoda em relaçäo aos anti-histamínicos clássicos, podendo ser utilizada para tratamento da rinite alérgica.

Effect of H1 and H2 antagonists on nasal symptoms and mediator release in atopic patients after nasal allergen challenge during the pollen season.

During the pollen season, quantitative determination of the chemical mediators and eosinophil count was performed in 16 patients with hay fever after nasal allergen challenge (NAC). The aim of this study was objectively to assess the effect of H1 and of a combination of H1 and H2 antagonists on nasal symptoms, mediator release, and eosinophil count during an allergic reaction. NAC was performed at baseline (V1), 2 weeks after treatment with cetirizine 10 mg/day (V2), and after a combined therapy with cetirizine 10 mg and cimetidine 800 mg a day during the following week (V3). Results showed a significant (p < 0.05 or p < 0.01) relief of nasal symptoms such as: itching, sneezing, rhinorrhea and congestion, and of objective parameter such as: reduction of the number of sneezes after NAC at V2 and V3. Neither H1 antagonist nor a combination of H1 and H2 antagonists showed any effect on eosinophilia and ECP concentration caused by natural allergen exposure, nor on histamine and tryptase release immediately after NAC. When a combination of H1 and H2 antagonists was administered significant reduction of the nasal airway resistance and increase of the nasal air flow were demonstrated.

The effects of a new generation of H1 antihistamines (cetirizine and loratadine) on histamine release and the bronchial response to histamine in atopic patients.

The effects of two selective H1 receptor blockers, cetirizine and loratadine, in comparison with placebo, on basophil histamine release and the bronchial response to histamine were assessed. The studies were performed in a group of 18 patients with pollinosis and 22 with atopic asthma. Both tests were performed before and after medication. Histamine release from isolated basophils was evaluated by Shore's method using anti-IgE and pollen antigen as stimulants. The bronchial provocation tests were performed by Ryan's method. The results were expressed as PC20FEV1. It was shown that both drugs significantly inhibited basophil histamine release induced by anti-igE or specific allergen. It was also found that these drugs effectively reduced the bronchial response to histamine challenge. These findings confirm the beneficial clinical effect of a new generation of selective H1 blockers in the treatment of IgE-mediated allergic diseases, and also the possible role of these drugs in the therapy of atopic asthma.

Insulin/hypoglycemia-induced adrenocorticotropin and beta-endorphin release: involvement of hypothalamic histaminergic neurons.

We have previously found that histamine (HA) is involved in the mediation of restraint- and ether stress-induced release of the POMC-derived peptides ACTH and beta-endorphin (beta-END). In the present study we investigated the possible involvement of hypothalamic histaminergic neurons in the mediation of insulin/hypoglycemia-induced release of ACTH and beta-END in conscious male rats. To do so, hypoglycemia stress was performed during 1) inhibition of HA synthesis, 2) activation of inhibitory presynaptic HA H3-auto-receptors, or 3) blockade of postsynaptic HA H1- or H2-receptors. Hypoglycemia (plasma glucose, 2.2 +/- 0.3 nmol) induced by insulin (3 IU/kg, ip) caused a 3- to 5-fold increase in the plasma concentrations of ACTH and beta-END. A negative exponential correlation was found between the plasma glucose concentration and the ACTH and beta-END levels. Pretreatment of the animals with the HA synthesis inhibitor alpha-fluoromethylhistidine (1.0 mumol) intracerebroventricularly (icv) in a lateral ventricle, inhibited the ACTH and beta-END responses to insulin/hypoglycemia by 60%. When administered ip (100 mumol/kg), the synthesis inhibitor decreased the beta-END response 50%, but did not affect ACTH secretion significantly. Pretreatment of the rats with the H3-receptor agonist R(alpha)methylhistamine (50 mumol/kg, ip, twice) inhibited the secretory responses of ACTH and beta-END to insulin/hypoglycemia by 60-80%. This inhibitory effect of R(alpha)methylhistamine was reversed by prior administration of the specific H3-receptor antagonist thioperamide. Administration of the H1-antagonists mepyramine and cetirizine dose-dependently inhibited the ACTH and beta-END responses to insulin/hypoglycemia, with the highest dose (mepyramine, 350 nmol, icv; cetirizine, 40 mumol/kg, ip) inhibiting the response by 80-100%. The H1-antagonist SKF-93944 (226 nmol, icv) inhibited the ACTH response, but had no effect on the beta-END response. Administration of the H2-antagonists cimetidine (400 nmol, icv) and ranitidine (400 nmol, icv) inhibited the ACTH and beta-END responses to insulin/hypoglycemia by 50-80%. We conclude that histaminergic neurons are involved in the mediation of the insulin/hypoglycemia-induced release of ACTH and beta-END and that the effect is mediated via activation of primarily postsynaptic H1-receptors and, to a lesser extent, H2-receptors.

Pharmacological treatment of allergies.

According to recent literature, the "anti-allergy" properties of antihistamines are linked to their antagonistic ability on receptor H1. In the majority of experimental models the immediate allergic responses is followed by a late phase. Especially at the pulmonary level, the presence of a late response after an allergic provocation is considered to correlate with the severity of asthma. The reference anti-allergy drugs, such as the inhaled corticosteroids or the cromones, without anti H1 activity, inhibit this late pulmonary response. Azelastine, ketotifen and cetirizine, three substances that are antagonistic to the anti-H1 receptor reduce the late pulmonary response. In addition, these three substances have other "anti-allergy" characteristics. Azelastine inhibits production of superoxide by the pulmonary neutrophils and eosinophils after PAF provocation in animals. Cetirizine significantly inhibits eosinophil infiltration in the bronchoalveolar lavage liquid in asthmatics with a late allergic bronchospasm. The presence of anti-histaminic and anti-allergy characteristics on the same molecule may perhaps convey a supplementary therapeutic benefit in the treatment of allergic symptoms.