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PubMed1981

Interaction between ethanol and antihistamines: 3. mebhydrolin.

We used 17 student volunteers in an experiment to investigate the effects of orally administered mebhydrolin (0.71 mg/kg), alone and in combination with ethanol (0.75 g/kg), on perceptual, cognitive and motor functions. Mebhydrolin did not significantly modify performance when given alone, but showed evidence of enhancing ethanol-induced performance deficits. Histamine challenge experiments indicated that the dose of mebhydrolin used exerted an antihistaminic effect over the period of the ethanol interaction study.

Administration, Oral↗
PubMed2002

Ventricular tachycardia following ingestion of a commonly used antihistamine.

This report describes ventricular tachycardia, likely to have been torsade de pointes, following ingestion of the non-sedating antihistamine loratadine. Documentation of the arrhythmia was made possible by the automatic electrogram storage facility of an implanted defibrillator in a patient with no prior history of cardiac arrhythmia.

Adult↗
PubMed1990

Segmenting the antihistamine market: an investigation of consumer preferences.

The authors combine conjoint analysis and contingent valuation into a single model to estimate the value of product attributes for antihistamine drugs. One hundred forty-three allergic rhinitis suffers were examined. The results show evidence of validity in the data. Cluster analysis reveals five segments of patients with various patterns of preference for product attributes.

Cluster Analysis↗
PubMed1997

Considerations in pharmaceutical conversion: focus on antihistamines.

The practice of pharmaceutical conversion, which encompasses three types of drug interchange (generic, brand, and therapeutic substitution), is increasing in managed care settings. Pharmaceutical conversion has numerous implications for managed care organizations, their healthcare providers, and their customers. Although drug cost may be a driving consideration in pharmaceutical conversion, a number of other considerations are of equal or greater importance in the decision-making process may affect the overall cost of patient care. Among these considerations are clinical, psychosocial, and safety issues; patient adherence; patient satisfaction; and legal implications of pharmaceutical conversion. Patient-centered care must always remain central to decisions about pharmaceutical conversion. This article discusses the issues related to, and implications of, pharmaceutical conversion utilizing the antihistamines class of drugs as the case situation.

Automobile Driving↗
PubMed1999

Why are non-sedating antihistamines non-sedating?

In this paper several factors which may influence the potential of a certain antihistamine to cause CNS-related side-effects are discussed. It is shown by pharmacological studies that the H1 receptors occurring in CNS tissue or in peripheral organs do not differ with regard to their affinity for H1 blockers. There is also no other evidence for subtypes of the H1 receptor. The sedating properties are caused by H1 blockade. The level of brain penetration (passage of the blood-brain barrier) is not fully determined by the lipophilicity (log P) of an individual compound. Compounds with a low or a high lipophilicity (log P) do not penetrate. For compounds with a basic centre the log D should be applied, replacing the log P; the log D corrects for the level of ionization of such compounds, as neutral species only readily enter into the CNS. For compounds with an intermediate log P or log D a Deltalog P is introduced; a Deltalog P indicates a large hydrogen binding capacity. A strong hydrogen binding capacity means a strong (serum) protein binding and consequently a poor brain penetration. Also the role of the P-glycoprotein as a transporter out of the CNS is introduced. Finally the influence of histamine on the permeability of the blood-brain barrier is discussed; it is shown that histamine increases the extravasation of, for example, albumin.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

Effects of H1 antihistamines on adhesion molecules: a possible rationale for long-term treatment.

Our knowledge of the mechanisms underlying the allergic reaction has increased rapidly and has revealed a complex network of cells, mediators and cytokines. The intercellular adhesion system (and the ICAM-1 molecule in particular) appeared to play a pivotal role in the accumulation of inflammatory cells at the site of allergic reaction. The new antihistamines have been demonstrated to be capable of affecting several phenomena of the allergic inflammation, including mediator release, cellular activation and adhesion molecule expression. Taking into consideration the central role of adhesion molecules, the modulation of their expression may represent an important therapeutic target. The nasal and the conjunctival challenges represent two useful models for the in vivo study of the antiallergic activity of drugs, as they allow investigation of a wide variety of parameters: inflammatory infiltrate, ICAM-1 expression, concentration of soluble mediators.

Animals↗
PubMed1999

Stereoselectivity of the phase-II-metabolism of the H1 antihistaminic drug dimethindene investigated by capillary electrophoresis.

Two capillary electrophoretic (CE) methods for the determination of conjugated metabolites of the antihistaminic drug dimethindene were developed. These methods allow the determination of the diastereomeric ratios of both Phase II glucuronides, 6-hydroxy dimethindene glucuronide (5) and 6-hydroxy-N-demethyl dimethindene glucuronide (6). Furthermore, after enzymatic deconjugation of both glucuronides, enantiomeric ratios of the hydroxylated Phase I metabolites 3 and 4 were determined. For comparison, glucuronides 5 and 6 were prepared by enzymatic synthesis and identified by MALDI-TOF mass spectrometry and deconjugation with beta-glucuronidase to the corresponding phenols 3 and 4. The assay of the glucuronides in rat urine and serum was performed by a combination of liquid/liquid extraction followed by solid phase extraction. After a high dose treatment with racemic dimethindene the diastereomeric glucuronides 5 and 6 could be directly determined in the urine of a guinea pig by CE without prior extraction or preconcentration of the urine sample. In all cases, stereoselectivities of the formation of Phase I as well as Phase II metabolites were observed.

Animals↗
PubMed1999

Modification of antihistaminic activity of cetirizine by nimesulide.

OBJECTIVE: To study the effect of nimesulide (4-nitro-2-phenoxymethane sulfonanilide) a non-steroidal anti-inflammatory drug, on antihistaminic activity of cetirizine. METHOD: A randomized, double blind, cross over study was conducted in ten healthy male volunteers. Wheal and flare responses to histamine were measured by performing intradermal injection of histamine (2 micrograms base) diluted in 100 microliters volume of saline on the volar surface of forearm, on four occasions (0, 2, 4, and 6 hrs. post-dosing). Each volunteer was randomized to receive either treatment A (cetirizine 10 mg + placebo) or treatment B (cetirizine 100 mg + nimesulide 100 mg), with one week wash out period in between each administration. Wheal and flare responses were measured ten minutes after each histamine injection. RESULTS: Both cetirizine 10 mg alone and cetirizine 10 mg + nimesulide 100 mg, decreased wheal and flare responses significantly at 2 hrs. and this continued till 6 hrs. post-dosing. This decrease was highly significant when cetirizine was given along with nimesulide. CONCLUSION: The results suggest a synergistic effect exhibited by the combined use of cetirizine with nimesulide.

Adult↗
PubMed2000

[Antihistamines].

The H1-receptor antagonists (H1-antihistamines) are among the most widely used medications in the world. We review the molecular basis of action, pharmacology, efficacy in allergic disorders (rhinoconjunctivitis, asthma, urticaria, atopic dermatitis) and adverse effects. Special advices are given for the young children, the elderly, in case of liver or renal insufficiency and during pregnancy and breast-feeding.

Adult↗
PubMed2000

[Acceptability of local treatment of allergic rhinitis with a combination of a corticoid (beclomethasone) and an antihistaminic (azelastine)].

A prospective multicentre study involving 219 patients with seasonal or aperiodic rhinitis was performed to assess the acceptability of a local treatment combining antihistamine (azelastine) and corticoid (beclomethasone) drugs. The drugs were administered either together (morning and evening, with a 5-minute interval) or separately (azelastine in the morning and evening, and beclomethasone later during the morning and in the afternoon) for 15 days. Treatment acceptability was measured by a nine-fold questionnaire (7-point scale, mean score per question). Patient participation, protocol and therapy compliance, and treatment efficacy and tolerance were also studied. The acceptability of the association was satisfactory (mean score for general facility of treatment: 4.7/6) and did not differ between administration schedules. Patients found treatment easy, and were not bothered by the bulk of the bottles or the risk of mixing them up. This acceptability was confirmed by the low percentage (4%) of patients refusing to be included in the study (refusing any treatment by nasal spray). The general acceptability was confirmed by the results for therapy compliance, general efficacy and tolerance: 94.9% of the patients took more than 75% of the administrations prescribed, 77.6% of the patients and 85.2% of the practitioners judged treatment efficacy as good or excellent, and 84.6% of the patients and 91.4% of the practitioners judged tolerance as good or excellent. Moreover, most of the adverse events consisted of minor signs of local intolerance, and were identical to those observed when the two treatments were administered alone.

Administration, Inhalation↗
PubMedDate not supplied

Quantitation of antihistamines in pharmaceutical preparations by liquid chromatography with a micellar mobile phase of sodium dodecyl sulfate and pentanol.

A reversed-phase liquid chromatographic procedure with a micellar mobile phase of sodium dodecyl sulfate (SDS), containing a small amount of pentanol, was developed for the control of 7 antihistamines of diverse action in pharmaceutical preparations (tablets, capsules, powders, solutions, and syrups): azatadine, carbinoxamine, cyclizine, cyproheptadine, diphenhydramine, doxylamine, and tripelennamine. The retention times of the drugs were <9 min with a mobile phase of 0.15M SDS-6% (v/v) pentanol. The recoveries with respect to the declared compositions were in the range of 93-110%, and the intra- and interday repeatabilities and interday reproducibility were <1.2%. The results were similar to those obtained with a conventional 60 + 40 (v/v) methanol-water mixture, with the advantage of reduced toxicity, flammability, environmental impact, and cost of the micellar-pentanol solutions. The lower risk of evaporation of the organic solvent dissolved in the micellar solutions also increased the stability of the mobile phase.

Chromatography, Liquid↗
PubMedDate not supplied

Antihistamines and the torsade de point in children with allergic rhinitis.

Allergic rhinitis (AR) is a very common disease, occurring in approximately 10% of children and up to 20% of adolescents. It is often underdiagnosed and its importance as a cause of morbidity is also underestimated, especially in asthmatic children. It has been estimated that 75% of asthmatic children suffer from AR, and its prevalence has increased during the last years, due to changes in environmental factors. AR may be a cause of serious discomfort for the child as well as for the family. AR may cause several complication, including serous otitis media, abnormal facial development with orthodontic problems, eustachian tube dysfunction and sinusitis. The frequent association of paranasal sinusitis in children with asthma has been observed and sinusitis has been considered a contributing factor in bronchial asthma Second-generation antihistamines are the golden therapy for AR. However, reports of potentially life-threatening dysrhythmias, specifically torsades de pointes, were described. In conclusion, we comment the in vitro inhibition of several ion channels, in particular predisposing the heart to dysrhythmias by terfenadine and astemizole. In this paper we examine recent reports on safety of both cetirizine and loratadine.

Adolescent↗
PubMed2002

H1-antihistamines in asthma.

Histamine released from mast cells and basophils is an important mediator of airway inflammation in asthma, particularly in the development of the early allergic response. Although histamine has been shown to contribute significantly to the bronchoconstrictor response to allergen or exercise, leukotrienes are likely to play a more prominent role in these responses in asthma. The improved specificity, tolerability, and safety profile of the second-generation H1-antagonists associated with anti-inflammatory activities and bronchodilator activities, may contribute to relieve the symptoms of the upper and lower airways in patients with coexistent mild seasonal asthma and allergic rhinitis. Considering the global rise in the prevalence of allergy and asthma, the suggestion that H1-antagonists may delay the onset of asthma in infants is of considerable interest and merits further assessment. Although it is unlikely that monotherapy with most currently available H1-antagonists will provide significant clinical benefit in asthma, the potential of combined antihistamine and antileukotriene therapy may prove useful, particularly in subjects with poor compliance to inhaled corticosteroid therapy.

Asthma↗
PubMed2002

H1-antihistamines in pregnancy and lactation.

Antihistamines may be used for the treatment of allergic rhinitis, upper respiratory infections, urticaria/angioedema, atopic dermatitis, and, rarely, as adjunctive treatment for anaphylaxis, during pregnancy. Because these illnesses may affect maternal comfort and safety as well as threaten the fetus directly (anaphylaxis) or indirectly, they often require therapy during pregnancy. Based on the information available to date, in this chapter we have attempted to provide rational guidelines for the gestational use of H1-receptor antagonists in a manner that will lead to the optimal well-being of both the mother and her infant. As more information becomes available, the recommendations herein may require modification. Although this chapter has dealt specifically with gestational management, a case can be made for considering this information when making therapeutic decisions in all women of childbearing potential. First, most pregnancies are unplanned, and the peak period of fetal vulnerability to drug-induced teratogenesis begins the day a woman's period is due. Second, during gestation, substantial alterations in a previously successful but not optimal-for-pregnancy chronic therapeutic regimen may be psychologically threatening to the patient and may lead to either uncontrolled disease or unanticipated side effects. Thus, pregnancy-appropriate regimens should ideally be discussed with all women of childbearing age as part of the informed therapeutic decision-making process.

Animals↗
PubMedDate not supplied

[The secondary effects of the antihistamine chlorpheniramine on the central nervous system].

OBJECTIVE: The objective of this study is to review the main investigations into the secondary effects of the antihistamine chlorpheniramine on the central nervous system (CNS). DEVELOPMENT: The antagonists of the H1 receptors of histamine, usually used in the treatment of symptoms of allergy or the common cold, have many adverse effects on the CNS. They cause day time drowsiness, cause poorer performance of tasks involving visuo motor coordination and make it more difficult to detect target auditory stimuli in tasks involving sustained concentration. When using evoked potentials (EP) it has been observed that they alter the system for maintaining auditory attention. They cause increased P300 latency, an EP related to the voluntary ability to discriminate between relevant stimuli, a reduction in the amplitude of mismatch negativity (MMN), an EP which is seen as a pre attention mechanism for automatic detection of environmental acoustic changes and alters selective attention capacity, reflected by a reduction in the amplitude of processing negativity (PN). CONCLUSIONS: These studies show that chlorpheniramine has major adverse effects on the CNS, and the patient may not be subjectively aware of this (e.g. selective attention). This means that in certain situations it is a dangerous substance. The characteristics of these adverse effects should lead to a review of the prescription of chlorpheniramine, and stimulate the search for other substances with similar therapeutic actions but fewer side effects on the CNS.

Attention↗
PubMed2003

Studies on performance and sleepiness with the H1-antihistamine, desloratadine.

INTRODUCTION: The purpose of this study was to establish whether the H1-antihistamine desloratadine (5 mg), the active metabolite of loratadine, is free of effects on performance and sleepiness. METHOD: Effects of desloratadine (5 mg) on psychomotor performance, daytime sleep latencies, subjective sleepiness, and memory were studied in nine healthy volunteers (four men, five women) between the ages of 20 and 39 yr (mean 28.2). Assessments were made 1.0 h pre-ingestion and from 0.5 to 8.0 h post-ingestion. The study was placebo-controlled and double blind with a crossover design, using promethazine (25 mg) as an active control. RESULTS: Promethazine impaired tracking (3.5-5.5 h), choice reaction time (3.5-5.5 h), digit symbol substitution (3.5-5.5 h), and attention (2.0-5.5 h). There was increased objective and subjective sleepiness (2.0-5.5 h) and subjective fatigue (3.5-8.0 h). There were no changes in any of these measures with desloratadine (5 mg). With promethazine, memory was impaired from 2.0-5.0 h. Analysis failed to establish a consistent effect on memory with desloratadine, as there was a change in only one (digit memory recall reaction time) of the twelve memory test measures at only one time point (5.5 h). The change was significant with respect to placebo, but not with respect to the pre-ingestion value. CONCLUSIONS: Desloratadine (5 mg) appears to be free of adverse effects on psychomotor performance, daytime sleep latencies, and subjective sleepiness, and could prove suitable for those involved in skilled activity and transportation.

Adult↗
PubMed1992

Use of cetirizine to investigate non-H1 effects of second-generation antihistamines.

In addition to their increased potency as H1 blockers and their nonsedating effects, the second-generation antihistamines have other unusual and potentially beneficial properties. Evidence is accumulating from several laboratories that at least one of these agents under investigation, cetirizine, may be effective in inhibiting the late reaction. The Johns Hopkins group showed that during the cutaneous late phase response (LPR), histamine release was not altered by cetirizine, 20 mg, pretreatment. The most dramatic effect of cetirizine was attenuation of inflammatory cell migration into the chamber. Eosinophils, neutrophils, and basophils were reduced by about 75% during hours 6 to 8. It can be concluded that cetirizine influences the LPR by causing a reduction in the inflammatory cell infiltrate. Cetirizine, 10 mg, orally once a day also induced a significant decrease in the wheal and flare skin reactions caused by pollen, histamine, and compound 48/80. Cetirizine inhibited eosinophil recruitment and platelet-activating factor (PAF) in skin chambers 24 hours after pollen challenge. We and others have studied the mechanisms of this effect. The release of eosinophil peroxidase induced by PAF and formyl-methionyleucyl/phenylalanine was not attenuated by cetirizine. At therapeutic concentrations, however, cetirizine has a potent inhibitory action in vitro on eosinophil chemotaxis induced either by formyl-methionyleucyl/phenylalanine or PAF and also on IgE-dependent stimulation of platelets. In a separate study in patients with chronic urticaria, cetirizine markedly reduced both the immediate wheal and flare induced by PAF and the delayed reaction at six hours. These results suggest that cetirizine acts on eosinophil migration to inhibit the late reaction.

Cetirizine↗