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PubMed1978

Bronchodilatation after inhalation of the antihistamine clemastine.

H1 receptor blocking antihistamines administered by mouth have not found a clear place in the management of bronchial asthma. We investigated the possibility that higher concentrations of these drugs, administered directly to the bronchial tree, might produce bronchodilatation. Twelve asthmatic patients inhaled aerosols generated from solutions of clemastine (0.05%), salbutamol (0.5%), and placebo. Bronchodilatation was assessed by changes in the forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR) over four hours. Both clemastine and salbutamol caused significant bronchodilatation. The mean maximum percentage increases in FEV1 for clemastine and salbutamol were 21.1% and 29.2% respectively. The mean maximum percentage increases in PEFR were 31.2% and 35.2% respectively. There was no significant difference in the maximum bronchodilatation produced by the two drugs. Clemastine, when administered by aerosol inhalation, appears to be an effective bronchodilator.

Adult↗
PubMed1978

Inhaled antihistamines--bronchodilatation and effects on histamine- and methacholine-induced bronchoconstriction.

To assess further the bronchodilator activity of inhaled antihistamines ten stable asthmatic subjects inhaled aerosols of clemastine, 1 mg/ml, and saline placebo administered double blind. Subjects underwent bronchial challenge with increasing concentrations of histamine and methacholine, and specific airways conductance was measured by whole body plethysmography at each concentration. There was a significant 21.9% increase in specific airways conductance after inhalation of clemastine. Subjects could tolerate significantly higher mean concentrations of histamine when treated with clemastine than with saline. The shift of the cumulative log histamine dose-reponse curve suggests that such protection is due to competitive antagonism to the inhaled clemastine. Clemastine did not protect subjects against methacholine-induced bronchoconstriction, which suggests that its bronchodilator properties are not related to any anticholinergic action.

Adult↗
PubMed1984

Effect of antihistamines and antiallergic drugs on responses to allergen and histamine provocation tests in asthma.

The inhibition of immediate allergen or histamine induced airflow obstruction by inhaled ketotifen, clemastine, sodium cromoglycate, and placebo was studied in two groups of asthmatic subjects. Single doses of ketotifen (0.5 mg), clemastine (0.5 mg), sodium cromoglycate (20 mg), or placebo were administered by inhalation 45 minutes before bronchial provocation testing at weekly intervals, double blind and in random order. Inhalation of ketotifen and clemastine, but not sodium cromoglycate, caused an increase in the amount of histamine which had to be administered to cause a 20% fall in FEV1 from control levels (PD20-FEV1) compared with placebo. The PD20-FEV1 for allergen increased significantly after inhalation of clemastine and sodium cromoglycate. Clemastine, primarily an H1 receptor antagonist, inhibited airflow obstruction after inhalation of both histamine and allergen. Its inhibitory effect on allergen induced asthma did not differ significantly from that of sodium cromoglycate. Ketotifen, when inhaled in a single dose of 0.5 mg before bronchial provocation testing, showed potent antihistamine activity, but there was no evidence of any additional "antianaphylactic" activity.

Adult↗
PubMed1976

Circulatory effects of prolonged hypoxia before and during antihistamine.

Five chronically instrumented healthy dogs were exposed to a 5-day period of breathing 10% oxygen in a chamber. The response to hypoxia was found to be time dependent. During the first 24 h of hypoxia the circulatory response was characterized by increases in cardiac output, heart rate, pulmonary and systemic arterial blood pressures, and pulmonary vascular resistance. Systemic vascular resistance increased; left atrial pressure decreased. During the early part of hypoxia the animals became hypocapnic; the arterial blood pH rose significantly. During the rest of the hypoxic period cardiac output, heart rate, and arterial blood pH returned to the control values; pulmonary and systemic arterial pressures and pulmonary vascular resistance remained significantly elevated. Systemic vascular resistance rose; left atrial pressure remained below control. This response to hypoxia was not substantially modified when the experiment was repeated during the administration of the antihistamine promethazine, an H1-receptor blocking agent, in a dose which blocked the pulmonary vasoconstrictor response to small doses of exogenous histamine. The circulatory response to acute hypoxia in five anesthetized dogs was not modified by intravenous administration of metiamide, an H2-receptor blocking agent.

Animals↗
PubMedDate not supplied

Hypothetical mechanisms of action of an H1-antihistamine in asthma.

Some recent clinical studies carried out with the potent H1-antihistamine cetirizine (CTZ) suggest that this drug could be useful for the treatment of mild to moderate asthma and even for the prevention of the disease. Besides a potent antagonism of H1-receptors at bronchial level, this drug was also shown to exert a large series of anti-inflammatory effects in in vitro, ex vivo and in vivo pharmacological models and also in clinical situations in atopic subjects. All the data collected up to now suggest the possible existence in the molecule of a central key mechanism of action on resident cells especially involved in cell trafficking and bronchial inflammation, i.e a down-regulating effect on the nuclear factorKappaB (NFkappaB). This hypothesis was tested on human endothelial cells and a human epithelial pulmonary cell line using different experimental methods. The results showed that CTZ down-regulates the TNF-alpha-induced hyperactivation of NFKappaB in these two different resident cells at physiological concentrations.

Adult↗
PubMed1977

Exercise-induced bronchoconstriction in patients with bronchial asthma. Its prevention with an antihistaminic agent.

14 asthmatic patients developing regularly exercise-induced bronchoconstriction were subjected to a submaximal exercise on a bicycle ergometer. On the first day the exercise was not preceded by any medication; on the second, 50 mg thiazinamium was given, and on the third day 2 mg atropine was given before the exercise. The changes in the calibre of the bronchi were assessed with a Wright peak flow meter. With thiazinamium a complete protection against the bronchoconstriction was observed in 12 patients, in one the protection was partial and in an other no beneficial effect of the drug was found. It seems that protection given by thiazinamium was due to its antihistaminic property and not to the anticholinergic one, as among 10 patients protected by thiazinamium, only 2 were also protected by the atropine.

Adult↗
PubMed1997

Experimentally induced pruritus and cutaneous reactions with topical antihistamine and local analgesics in atopic eczema.

We investigated the antipruritic effect of a 15-min application of dimethindene maleate (Fenistil gel) and other local analgesics (Optiderm, EMLA, Xylocain ointment 5%) on subsequent focal histamine stimulus (20 mC) given by iontophoresis in 12 patients suffering from acute atopic eczema (AE). The results were compared to histamine after pretreatment with the respective placebo and to non-pretreated skin. Wheal and flare areas were planimetrically evaluated. Itch or pain ratings were performed over a 24-min period using a rating scale. The examination also comprised alloknesis, i.e. induction of a perifocal itch sensation by a non-itching mechanical stimulus. None of the antihistaminic and anaesthetic agents reduced the itch intensity significantly. Three of the AE patients had a total lack of alloknesis. We conclude that these substances, when applied for 15 min, are not sufficiently effective in atopic skin suppressing histamine-induced reactions under experimental conditions. The diminished elicitation of alloknesis in these patients may be a result of central nervous system alteration.

Administration, Topical↗
PubMed1996

Systemic complement system depletion does not inhibit cellular accumulation in antihistamine pretreated allergic guinea pig lung.

The present study was designed to determine if depletion of the complement system in the circulation with cobra venom factor (CVF) prevented the cellular infiltration in a guinea pig model of asthma. Guinea pigs were sensitized with ovalbumin (OA) alone or OA with complete Freund's adjuvant. Animals were pretreated with CVF and challenged with OA aerosol for 15 min in the presence of the antihistamine pyrilamine. Either 6 or 20 h later, bronchoalveolar lavage (BAL) was collected and the numbers of white blood cells and red blood cells and amount of protein were determined. In addition, eosinophil peroxidase and myeloperoxidase activity of the lavage and lung homogenate was measured as an indicator of eosinophil and neutrophil infiltration. Aerosol OA challenge caused cellular infiltration in the lung and BAL. CVF treatment did not inhibit the OA-induced cellular infiltration but resulted in an enhanced accumulation of eosinophils 6 h after OA and increased protein in the lavage at 20 h after OA compared to animals not treated with CVF and challenged with OA. Total hemolytic complement activity in the serum was reduced by more than 98% and local complement activity (C3 in the BAL) by more than 95% by CVF treatment. However, after OA challenge in CVF-treated animals, the C3 content of the BAL was not different from control. Thus, leakage of plasma proteins or local synthesis of C3 induced by OA was sufficient to maintain C3 at normal levels in the BAL despite drastic reductions in C3 in the circulation (> 98%) by CVF treatment. Our studies indicate that the systemic complement system is not essential for the cellular infiltration in this guinea pig model of asthma. Complement in local compartments may have an important role in inflammatory events in the lung. In addition, complement system depletion and/or activation may be an important determinant of the severity of a subsequent allergic reaction.

Adjuvants, Immunologic↗
PubMed1988

Comparison of the new antihistamine acrivastine (BW 825C) versus cyproheptadine in the treatment of idiopathic cold urticaria.

A double-blind, crossover trial with a new triprolidine derivative, acrivastine (BW 825C; 8 mg 3 times daily), cyproheptadine (4 mg 3 times daily) and placebo was carried out in 18 patients suffering from idiopathic cold urticaria. Acrivastine and cyproheptadine significantly (p less than 0.01) reduced weal areas following ice cube challenge when compared to placebo. Acrivastine was found to be significantly more effective (p less than 0.01) than cyproheptadine in reducing weal areas. Furthermore, cyproheptadine caused significantly more drowsiness than acrivastine (p = 0.021) or placebo (p = 0.013), which did not differ from each other. This study shows that acrivastine is an effective agent in the treatment of cold urticaria and suggests that acrivastine in the dose used lacks adverse effects, such as drowsiness, traditionally associated with antihistamine therapy.

Adult↗
PubMed1982

Does mast cell protection plus mediator antagonism surpass the effect of a classic antihistaminic in the treatment of chronic urticaria? A double-blind comparison of oxatomide and mequitazine.

A new type of antiallergic drug, oxatomide (60 mg daily), was compared with the antihistaminic, mequitazine (10 mg daily), in a 5-week double-blind randomized study involving 26 patients with chronic urticaria. In the 13 oxatomide-treated patients, papules, erythema and pruritus were significantly suppressed after 2 weeks, which was markedly more rapid than with mequitazine. Slight somnolence was reported by 3 patients on oxatomide and 1 on mequitazine; in the latter case, severe urine retention was also reported. Another patient on mequitazine had to discontinue treatment because of severe drowsiness.

Adolescent↗
PubMed1978

Evaluation of the local antihistaminic activity of dimetindene maleate by a quantitative method.

The topical application of a 0.1% dimetindene maleate gel on the forearms of 11 subjects reduces the areas of both erythema and wheal produced by the intradermal injection of 0.025 mg of histamine hydrochloride to a statistically greater degree than 1% d-chlorpheniramine maleate cream (p less than 0.005 and p less than 0.0005, respectively). The quantitative method employed in this study has proved to be an excellent means for the evaluation of the antihistaminic activity of topical preparations.

Administration, Topical↗
PubMedDate not supplied

The effect of an oral combined preparation (antihistamine and decongestant) on Eustachian tube function in the common cold.

In this randomized double-blind study the effect of an oral, combined preparation (antihistamine + decongestant) on Eustachian tube function was compared with that of placebo in 80 adults with common cold. Tubal patency was measured by sonotubometry and indirectly by tympanometry. Sonotubometry clearly showed the Eustachian tube gradually returning to normal as the infection resolved. The tubal opening measurements revealed a slight tendency towards improved tubal function with the active drug, but the differences between the treated and the placebo group were statistically insignificant.

Acoustic Impedance Tests↗
PubMed1992

Canine in vivo tracheal chemotaxis of eosinophils to antigen in sensitized dogs: inhibition by a steroid, a systemic lazaroid U-78517F, and several topical H1 antihistamines.

Inflammation of the airways contributes to the multicomponent disease known as asthma. The primary cells that infiltrate the airway in response to antigen exposure are neutrophils and eosinophils. Eosinophils have been implicated in much of the histopathology of the airway following infiltration and degranulation. We used topical antigen exposure in the trachea of sensitized beagle dogs to study the kinetics of eosinophil infiltration with a modified double balloon endotracheal tube technique. After establishment of the eosinophilia, we used inhibitors with known actions to implicate certain mediators in the cellular response. Beagle dogs were sensitized to ascaria ova by feeding them orally by gavage. After 6 wk, challenge with 2.0 micrograms/ml ascaris antigen protein via the tracheal chamber resulted in a rapid (maximal in 4 h) and repeatable influx (p less than 0.05 versus vehicle) of eosinophils that was faster and larger than that of exogenously added LTB4 or PAF exposure. After 4 to 6 separate (every 2 wk) antigen challenges in which the response varied by (SEM +/- 13 to 50%), the individual dogs were rechallenged in the presence of various inhibitors administered either topically in the perfusate or systemically. The inhibitors that were effective in blocking the eosinophil influx by a statistically significant amount were: (1) the lazaroid U-78517F orally 0.5 to 30 mg/kg-18 h (2) Medrol acetate 5 mg/kg intramuscularly-18 h, (3) H1-antihistamines topically (10(-6) M) Astemizole, Cetirizine, and Mepyramine, also orally 30 mg/kg, and Azelastine. Inhibitors falling to inhibit influx topically were a LTB4 receptor antagonist (U-75302) and U-80271 (Merck L-652731), a PAF antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1976

Effects of antihistamines on the lung vascular response to histamine in unanesthetized sheep. Diphenhydramine prevention of pulmonary edema and increased permeability.

To see whether antihistamines could prevent and reverse histamine-induced pulmonary edema and increased lung vascular permeability, we compared the effects of a 4-h intravenous infusion of 4 mug/kg per min histamine phosphate on pulmonary hemodynamics, lung lymph flow, lymph and plasma protein content, arterial blood gases, hematocrit, and lung water with the effects of an identical histamine infusion given during an infusion of diphenhydramine or metiamide on the same variables in unanesthetized sheep. Histamine caused lymph flow to increase from 6.0+/-0.5 to 27.0+/-5.5 (SEM) ml/h (P less than 0.05), lymph; plasma globulin concentration ratio to increase from 0.62+/-0.01 to 0.67+/-0.02 (P less than 0.05), left atrial pressure to fall from 1+/-1 to -3+/-1 cm H2O (P less than 0.05), and lung lymph clearance of eight protein fractions ranging from 36 to 96 A molecular radius to increase significantly. Histamine also caused increases in lung water, pulmonary vascular resistance, arterial PCO2, pH, and hematocrit, and decreases in cardiac output and arterial PO2. Diphenhydramine (3 mg/kg before histamine followed by 1.5 mg/kg per h intravenous infusion) completely prevented the histamine effect on hematocrit, lung lymph flow, lymph protein clearance, and lung water content, and reduced histamine effects on arterial blood gases and pH. 6 mg/kg diphenhydramine given at the peak histamine response caused lymph flow and lymph: plasma protein concentration ratios to fall. Metiamide (10 mg/kg per h) did not affect the histamine lymph response. We conclude that diphenhydramine can prevent histamine-induced pulmonary edema and can prevent and reverse increased lung vascular permeability caused by histamine, and that histamine effects on lung vascular permeability are H1 actions.

Animals↗
PubMedDate not supplied

Diagnostic and therapeutic studies in childhood serous otitis media. Results of treatment with an antihistamine-adrenergic combination.

Fifty-five children with their first recognized episodes of serous otitis media were followed over a three-month period. The efficacy of an antihistamine-adrenergic combination (diphenhydramine and pseudoephedrine), the comparative value of various diagnostic studies of middle ear function, and the prognostic importance of information obtained at the first visit were assessed. Compared double-blindly to a placebo, the pharmaceutical preparations did not appear to influence the clinical course, although more drug patients experienced lethargy or relief of symptoms not directly concerned with middle ear function (mainly upper respiratory congestion). The color and extent of motility of the tympanic membrane, but no other pneumatic otoscopic findings, were related to audiometry, whereas tympanometry correlated with the amount of motility and the presence or absence of visible fluid behind the membrane. The patients with the most severe hearing losses or with visible middle ear fluid at their initial visits improved the most, and those who began to be followed in the summer the least. The last finding may be due to a general but unexplained deterioration of childhood serous otitis media during the fall.

Acoustic Impedance Tests↗
PubMed1982

Childhood serous otitis media: fifteen months' observations of children untreated compared with those receiving an antihistamine-adrenergic combination.

Of 55 patients who had received, in a previously reported double-blind study, either an antihistamine-adrenergic combination or a placebo for three months for serous otitis media, 48 were followed without drug therapy for an additional year. During the follow-up period no differences were detected between the patients who had initially been treated with drugs and those who had received the placebo, as detected by audiometry, tympanometry, parental concern about hearing loss (as detected by the parents themselves or by their children's teachers or primary health care providers), school performance, or recurrences of serous otitis media.

Child↗
PubMed1994

Cardiovascular toxicity of antihistamines.

The efficacy of individual antihistamines is similar for most indications. The primary difference between traditional (first-generation) and nonsedating (second-generation) histamine1-receptor antagonists is the incidence and severity of adverse reactions. The first-generation drugs are associated with sedation, decreased psychomotor function, anticholinergic side effects, and other adverse reactions that are not observed with usual doses of second-generation agents. Since 1990 evidence has accumulated demonstrating that high doses of the second-generation drugs terfenadine and astemizole prolonged the cardiac QT interval and produced torsades de pointes, a rare but potentially lethal arrhythmia. Some first-generation agents also cause torsades de pointes. Concomitant administration of some drugs that inhibit the hepatic drug-metabolizing enzymes with either terfenadine or astemizole prevents the metabolism and increases the serum concentration of unchanged terfenadine and astemizole; this results in prolonged cardiac QT intervals and torsades de pointes. Interacting drugs include the macrolides (erythromycin and troleandomycin) and imidazole antifungals (ketoconazole and itraconazole). Also discussed are other factors that increase the likelihood of torsades de pointes after administration of terfenadine or astemizole and the pathophysiology of torsades de pointes, current therapy, and ways to avoid its occurrence. Preliminary studies indicate that two other second-generation agents, loratadine and cetirizine (an investigational agent), do not produce torsades de pointes.

Astemizole↗
PubMed1978

Comparative trial of an antihistamine, mequitazine, and placebo.

Forty patients suffering from a dermatological condition suitable for treatment with an antihistamine were studied in a double-blind randomized trial to compare the effectiveness and tolerance of mequitazine and placebo. Over a period of 2 weeks, patients received either 5 mg mequitazine twice daily or placebo. Where justified, patients were also given concomitant topical treatment but only with a hydrating cream or ichthyol paste. Patients' overall response to treatment was significantly better in the mequitazine group, whether the results were analyzed for all patients or those receiving just the trial drugs without topical treatment. Few side-effects were reported and there was no significant difference between the levels of drowsiness experienced with mequitazine compared with placebo.

Adolescent↗