Safety of antihistamines in children

Treating Diphenhydramine Overdose: A Literature Review of Currently Available Treatment Methods

From 2019 to 2020, antihistamines were found in 15% of all US drug overdose deaths, often co-administered with fentanyl, with 3.6% of overdose deaths due to antihistamines alone. The most common antihistamine found in all these reported deaths is diphenhydramine, a ubiquitous, over-the-counter and clinically important medication. Currently, there is no antidote for diphenhydramine overdose. This review summarizes the adverse health effects and current emergency medicine treatments for diphenhydramine. Several emergency medicine case reports are reviewed, and the efficacy and outcomes of a variety of treatments are compared. The treatments reviewed include the more traditional antihistamine overdose therapeutics physostigmine and sodium bicarbonate, as well as newer ones such as donepezil, dexmedetomidine, and lipid emulsion therapy. We conclude that more study is needed to determine the ideal therapeutic approach to treating antihistamine overdoses.

Temporary prolongation of the QT interval in acute ebastine intoxication due to challenge video on TikTok in a girl

Antihistamines are among the most widely used medications in the world. Ebastine is an antihistaminic which is long-acting, second-generation, and selective H1-receptor inverse agonist. I report a twelve-year-and-six-month-old girl with temporary prolongation of the QTc interval caused by acute ebastine intoxication due to TikTok challenge. Initial electrocardiogram showed sinus arrhythmia (72 beats/min) and prolongation of the QTc interval (QTc 482 milliseconds). Gastric lavage was performed. Intravenous fluid was administered, and activated charcoal (1 g/kg/per dose) was given. Electrocardiogram 9 h after drug ingestion showed sinus rhythm and normal QTc interval (QTc 414milliseconds). During follow-up, no electrocardiogram abnormalities were detected with electrocardiogram monitoring. She was discharged on day 2 without any complications. This case report is the first in the literature to show acute intoxication with ebastine due to challenge video on TikTok, which leads to a temporary prolongation of the QTc interval. Also, with this case report, I assert the fact that it is important to properly supervise the use of social media, such as TikTok and to review the content of TikTok videos.

Diphenhydramine: Time to Move on?

Diphenhydramine is one of the most widely available, longest-used antihistamine medications but has many side effects including sedation and risk of toxicity in overdose including cardiac toxicity. It is frequently inappropriately used when newer, more favorable antihistamine medications are available. Second-generation antihistamines are also widely available and affordable, with many of the same desired effects as diphenhydramine and fewer, if any, of the undesirable side effects. Because of the negative side effects and wide availability of alternative antihistamine medications, it is definitively time to move on from diphenhydramine.

Efficacy of cationic amphiphilic antihistamines on outcomes of patients treated with immune checkpoint inhibitors

BACKGROUND

Cationic amphiphilic antihistamines have been shown to improve patient outcomes in immunogenic tumours, but whether they can augment and improve response to immunotherapy is unknown. We aim to evaluate the effect of cationic amphiphilic antihistamines in patients receiving immune checkpoint inhibitors (ICIs).

METHODS

We conducted a retrospective propensity score-matched cohort study at two tertiary referral centres in Taiwan between January 2015 and December 2021. Patients who received desloratadine, cyproheptadine, and ebastine were classified as cationic amphiphilic antihistamine users. The primary outcome was overall survival, and the secondary outcomes were progression-free survival and clinical benefit rate. Patients treated with cationic amphiphilic antihistamines were matched to patients who received non-cationic amphiphilic antihistamines based on variables including age, cancer type, stage, and history of allergic diseases.

RESULTS

A total of 734 ICI-treated patients were included. After matching, 68 cationic amphiphilic antihistamine and non-cationic amphiphilic antihistamine users remained for analysis. Compared with non-cationic amphiphilic antihistamine users, patients who received cationic amphiphilic antihistamines had a significantly longer median overall survival (24.8 versus 10.4 months; Log-rank, p = 0.018) and progression-free survival (10.6 versus 4.93 months; Log-rank, p = 0.004). The use of cationic amphiphilic antihistamines was associated with an approximately 50% lower risk of all-cause mortality (HR, 0.55 [95% CI: 0.34-0.91]). Survival benefits were not seen in patients who received cationic amphiphilic antihistamines before immune checkpoint blockade. These survival benefits were observed regardless of the generation of cationic amphiphilic antihistamines.

CONCLUSION

The use of cationic amphiphilic antihistamines was associated with improved survival among patients treated with immunotherapy.

Fexofenadine: review of safety, efficacy and unmet needs in children with allergic rhinitis

Allergic rhinitis (AR) is the most common undiagnosed chronic condition in children. Moderate/severe AR symptoms significantly impair quality of life, and cause sleep disruption, absenteeism and decreased productivity. Additionally, untreated AR predisposes children to asthma and other chronic conditions. Although intranasal corticosteroids are the most effective pharmacologic treatment for AR, oral antihistamines are often preferred. First-generation antihistamines may be chosen to relieve AR symptoms as they are inexpensive and widely available; however, they cause sedative and cardiovascular negative effects due to poor receptor selectivity. Therefore, second-generation antihistamines were developed to reduce adverse effects while retaining efficacy. There are fewer clinical trials in children than adults, therefore, efficacy and safety data is limited, particularly in children under 6 years, highlighting the need to generate these data in young children with AR. Fexofenadine, a highly selective second-generation antihistamine, effectively alleviates symptoms of AR, is non-sedating due to decreased blood-brain barrier permeability, and is devoid of cardiovascular side effects. Importantly, fexofenadine relieves the ocular symptoms of allergic conjunctivitis, which occur concomitantly with AR, improving quality of life. Overall, fexofenadine displays a favorable safety profile and results in greater treatment satisfaction in children compared with other second-generation antihistamines. This review aimed to evaluate and compare the safety and efficacy of fexofenadine with other available first- and second-generation antihistamines in children with AR.

Impact of drug formulation on outcomes of pharmaceutical poisoning in children aged 7 years or younger: A retrospective observational study in South Korea

Pharmaceutical poisoning in children is almost unintentional and there are various types of drug out of curiosity. Understanding the attractive features and formulation of drugs related to poisoning in younger children may be helpful in treatment and prevention of poisoning. To investigate the impact of drug formulation on outcomes of pharmaceutical poisoning in young children.We retrospectively reviewed the data of pharmaceutical exposures among children who were registered in a Korean 23-center, emergency department (ED) based registry from 2011 to 2016. Our study was conducted on preschool children aged 0 to 7 years. According to the formulation and category of the ingested drugs, the exposures were divided into the "tablet and capsule (TAC)" and "syrup" groups. In the TAC group, we additionally recorded data on the shape, color, and size of the drugs. The ED outcomes, such as hospitalization and length of stay, were compared between the 2 groups.Among the 970 enrolled exposures, 674 (69.5%) were classified into the TAC group. In this group, hormones/hormone antagonists (18.5%) were the most commonly ingested, followed by central nervous system drugs (17.1%). In the syrup group, antihistamines (28.4%) were the most commonly ingested, followed by respiratory drugs (24.3%). The TAC group showed a higher hospitalization and transfer rate to tertiary centers than the counterpart (TAC, 18.0% vs syrup, 11.5%, P = .03) without a significant difference in the length of stay (TAC, 173.5 minutes [interquartile range, 95.0-304.0] vs syrup, 152.5 [77.5-272.0]; P = .08). No in-hospital mortality occurred in the exposures. Round-shaped and chromatic TACs, accounting for 91.7% (618) and 56.1% (378), respectively, were more commonly ingested. The median size of the TACs was less than 1.0 cm.Young children who visited the ED ingested TACs more frequently than syrups, particularly small, round-shaped, or chromatic drugs, leading to a higher hospitalization rate. Our findings can contribute to prevention strategies and safety education on childhood drug poisoning.

Azelastine inhibits viropexis of SARS-CoV-2 spike pseudovirus by binding to SARS-CoV-2 entry receptor ACE2

A recent study have reported that pre-use of azelastine is associated with a decrease in COVID-19 positive test results among susceptible elderly people. Besides, it has been reported that antihistamine drugs could prevent viruses from entering cells. The purpose of this study is to investigate whether azelastine have antiviral activity against SARS-CoV-2 in vitro and the possible mechanism. Here, we discovered antihistamine azelastine has an affinity to ACE2 by cell membrane chromatography (CMC); Then we determined the equilibrium dissociation constant (K_D) of azelastine-ACE2 as (2.58 ± 0.48) × 10^-7 M by surface plasmon resonance (SPR). The results of molecular docking showed that azelastine could form an obvious hydrogen bond with Lys353. The pseudovirus infection experiments showed that azelastine effectively inhibited viral entry (EC₅₀ = 3.834 μM). Our work provides a new perspective for the screening method of drug repositioning for COVID-19, and an attractive and promising drug candidate for anti-SARS-CoV-2.

No Time for Lullabies Tracing down Pharmacological Effects & Uses of H1-Antihistamines in Children Younger than 6 Years

Objectives. To provide a qualitative and a quantitative analysis of H1-antihistamines pharmacological uses pattern among children (<6 years old) and to evaluate the parental-related awareness. Methods. A cross-sectional study was carried out at 5 retail pharmacies in Jordan over 5 months (October/2019-February/2020). Parents who requested any of H1-antihistmine agent for a child (<6 years) were invited to participate. Results. A total of 516 children, most of them were toddlers (1-3) years, received at least 1 H1-antihistamine. More than half of the cases received H1-antihistamine as self-medication (56.3%). Sedating antihistamine agents were the most frequently used among children (<6 years old) (77.9%) among which Chlorpheniramine maleate was the most commonly used agent (62.9%). About half of the children (47.0%) received H1-antihistamine to induce sleep. Whereas, 21.7% and 12.9% received them to manage flu, and allergic rhinitis (AR), respectively. Around 66.6% of the cases were classified as off-label use. Most of the parents (80.5%) were aware of the sedative adverse effects of H1-antihistamines, whereas a fewer number (31.9%) were aware of their cognitive effects. Finally, more than two thirds of parents (79.7%) were unfamiliar with off-label drug use in children. Conclusion. Despite the availability of less-sedating H1-antihistamines with a wide safety and efficacy record, the use of sedating H1-antihistamines remains popular in children.

Influence of ketotifen and conventional antiepileptic drugs on the exploratory and spontaneous locomotor activity in mice

Drug interactions are major problems in polytherapy, especially in epilepsy, and inappropriate drug selection may result in increased frequency of seizures.

In this study, the influence of histamine type 1 (H1) receptor antagonist ketotifen and four chosen antiepileptic drugs (AEDs) on mice activity was examined. We evaluated three parameters of locomotor activity in mice: horizontal total activity with total distance and vertical activity, as well as animal spontaneous activity. Experiments were divided into two 15-minutes studies. During the first 15 minutes, we examined exploratory activity in mice; in the second period, spontaneous activity was tested. In the experiment, Ketotifen or vehicle were administered once or for 7 days daily, whereas AEDs were given only once before test performance.

Our results show that ketotifen given alone once or for 7 days significantly increased exploratory locomotor activity in mice without affecting their spontaneous activity. However, in combination with AEDs, ketotifen given once or for 7 days differently affected spontaneous and locomotor activity in mice. Our study indicates that the combination of ketotifen with AEDs needs special attention in pharmacotherapy of epilepsy.

Non-antibiotic medication use in an Indonesian community cohort 0-18 months of age

BACKGROUND

Rational medication use for treatment is mandatory, particularly in children as they are vulnerable to possible hazards of drugs. Understanding the medication use pattern is of importance to identify the problems of drug therapy and to improve the appropriate use of medication among this population.

METHODS

A post-hoc study of the RV3-BB Phase IIb trial to children aged 0-18 months which was conducted in Indonesia during January 2013 to July 2016. Any concomitant medication use and health events among 1621 trial participants during the 18 months of follow-up were documented. Information on medication use included the frequency, formulation, indication, duration of usage, number of regimens, medication types, and therapeutic classes.

RESULTS

The majority of participants (N = 1333/1621; 82.2%) used at least one non-antibiotic medication for treatment during the 18-month observation period. A total of 7586 medication uses were recorded, mostly in oral formulation (90.5%). Of all illnesses recorded, 24.7% were treated with a single drug regimen of non-antibiotic medication. The most common therapeutic classes used were analgesics/antipyretics (30.1%), antihistamines for systemic use (17.4%), cough and cold preparations (13.5%), vitamins (8.6%), and antidiarrheals (6.6%). The main medication types used were paracetamol (29.9%), chlorpheniramine (16.8%), guaifenesin (8.9%), zinc (4.6%), and ambroxol (4.1%). Respiratory system disorder was the most common reason for medication use (51.9%), followed by gastrointestinal disorders (19.2%), pyrexia (16.9%), and skin disorders (7.0%).

CONCLUSION

A large number of children were exposed to at least one medication during their early life, including those where evidence of efficacy and safety in a pediatric population is lacking. This supports the need for further research on pediatric drug therapy to improve the appropriate use of medication in this population.

A Comparison of Pediatric and Adult Safety Studies for Antipsychotic and Antidepressant Drugs Submitted to the United States Food and Drug Administration

OBJECTIVE

To examine the differences in the adverse drug reaction (ADR) profile of antipsychotic and antidepressant agents between pediatric and adult patients in studies submitted to the Food and Drug Administration (FDA) during the drug development process.

STUDY DESIGN

Clinical trials in adult and pediatric patients were conducted by sponsors as part of the drug development programs for antipsychotic and antidepressant agents, and ADR information was collected as part of those trials and submitted to the FDA. Data collection was conducted by reviewing publicly available FDA-authored reviews and FDA-approved product labels for 10 drugs with an antipsychotic or an antidepressant indication from 2007 to 2017.

RESULTS

There were 308 drug and ADR combinations for the 10 drugs and drug combinations with 113 (36.7%) having a significantly different incidence in pediatric patients compared with adults. Sixty-eight (60.2%) of these ADRs had a significantly higher incidence in pediatric patients than in adults. Sedation was higher in 6 of the 10 drugs and drug combinations with risk differences ranging from 9.6 to 36.6%.

CONCLUSIONS

This analysis indicates that there were significant differences between the pediatric and adult safety profiles of antipsychotic and antidepressant drugs. Sedation was the major ADR associated with the use of atypical antipsychotic drugs in pediatric patients. Clinicians caring for children should consider the ADR profile when prescribing antipsychotics and antidepressants in pediatric patients.

Inappropriate prescription of cough remedies among children hospitalised with respiratory illness over the period 2002-2015 in Kenya

OBJECTIVE

To examine trends in prescription of cough medicines over the period 2002-2015 in children aged 1 month to 12 years admitted to Kenyan hospitals with cough, difficulty breathing or diagnosed with a respiratory tract infection.

METHODS

We reviewed hospitalisation records of children included in four studies providing cross-sectional prevalence estimates from government hospitals for six time periods between 2002 and 2015. Children with an atopic illness were excluded. Amongst eligible children, we determined the proportion prescribed any adjuvant medication for cough. Active ingredients in these medicines were often multiple and were classified into five categories: antihistamines, antitussives, mucolytics/expectorants, decongestants and bronchodilators. From late 2006, guidelines discouraging cough medicine use have been widely disseminated and in 2009 national directives to decrease cough medicine use were issued.

RESULTS

Across the studies, 17 963 children were eligible. Their median age and length of hospital stay were comparable. The proportion of children who received cough medicines shrank across the surveys: approximately 6% [95% CI: 5.4, 6.6] of children had a prescription in 2015 vs. 40% [95% CI: 35.5, 45.6] in 2002. The most common active ingredients were antihistamines and bronchodilators. The relative proportion that included antihistamines has increased over time.

CONCLUSIONS

There has been an overall decline in the use of cough medicines among hospitalised children over time. This decline has been associated with educational, policy and mass media interventions.

Are antihistamines effective in children? A review of the evidence

BACKGROUND AND AIMS

During the last decades, much attention has been paid to off-label and unlicensed prescriptions in paediatrics. However, on-label prescribing can also cause health issues. In this paper, the case of first-generation H₁-antihistamines is investigated, notably the range of indications for which products are licensed in different European countries and the evidence base (or lack thereof) for each indication, as well as reported adverse drug reactions.

METHODS

Review of the Summary of Product Characteristics of first-generation H₁-antihistamines with a focus on paediatric use. This is plotted against the evidence available in the literature.

RESULTS

This investigation shows a large variability in labelled indications and licensing ages when compared in five different European countries. Moreover, most of the indications are not based on clinical trials evaluating efficacy and safety of these drugs in children.

CONCLUSIONS

Many of the licensed indications of first-generation antihistamines do not appear to be evidence based.

Adverse drug reactions of systemic antihistamines in children in the Netherlands

BACKGROUND

Antihistamines are used for the treatment of allergic rhinitis, allergic conjunctivitis, chronic spontaneous urticaria and atopic eczema.

OBJECTIVE

To study the reports of adverse drug reactions (ADRs) in children using antihistamines to provide prescribers with an overview of the possible toxicity.

DESIGN

We studied ADRs in children reported to the Netherlands Pharmacovigilance Centre Lareb in the years 1991-2014, assessed the Naranjo score and, when possible, computed the reporting OR.

RESULTS

Serious ADRs included one death (malignant neuroleptic syndrome), cardiac arrhythmia (one case) and convulsions (three cases). Skin eruptions, headache and somnolence were the most frequently reported ADRs. Aggression and agitation were also reported.

CONCLUSIONS

Toxicity can occur with second-generation antihistamines. The main toxicity relates to skin eruptions and central nervous system problems.

Antihistamines prescribed off-label among paediatric patients at a tertiary care hospital setting in Malaysia

Background Antihistamines are widely prescribed to children but should be used with caution in young children. Objective To determine the paediatric prescribing pattern of antihistamines with a focus on the off-label prescribing and factors that influence such prescribing. Setting Paediatric wards of a tertiary care hospital setting in Malaysia. Methods The pharmacy-based computer system and medical records were used to collect the required data. Labelling status of each antihistamine was determined based on the information provided in the product leaflets. Main outcome measure Antihistamines prescribed off-label and factors associated with such prescribing. Results Of the 176 hospitalised children aged <18 years prescribed with an antihistamine in the year 2012, 60.8 % received it in an off-label manner. Of 292 antihistamine prescription items, 55.5 % were prescribed off-label. Loratadine (35.3 %) was the most frequently prescribed antihistamine and chlorpheniramine maleate (34.0 %) was the most common antihistamine prescribed off-label. The main reason for the off-label prescribing of antihistamines was prescribing at higher than the recommended dose (30.2 %). Binary logistic regression showed that children aged <2 years (OR 12.65; 95 % CI 2.87-55.67) and the number of medications received (OR 1.14; 95 % CI 1.00-1.29) were significant predictors for the off-label prescribing of antihistamines. Conclusion Prescribing antihistamines for children in an off-label manner was prevalent at the studied locations and warrants further investigation on the consequences of such prescribing.

Cimetidine and Clobenpropit Attenuate Inflammation-Associated Colorectal Carcinogenesis in Male ICR Mice

Histamine and histamine receptors (Hrhs) have been identified as critical molecules during inflammation and carcinogenesis. This study was conducted to determine the effects of Hrh1-Hrh3 antagonists on inflammation-associated colorectal carcinogenesis. Male ICR mice were treated with azoxymethane (AOM, 10 mg/kg bw, i.p.) and 1.5% dextran sodium sulfate (DSS, drinking water for 7 days) to induce colorectal carcinogenesis. The mice were then fed diets containing test chemical (500 ppm terfenadine, 500 ppm cimetidine or 10 ppm clobenpropit) for 15 weeks. At week 18, feeding with the diets containing cimetidine (Hrh2 antagonist) and clobenpropit (Hrh3 antagonist/inverse agonist) significantly lowered the multiplicity of colonic adenocarcinoma. Terfenadine (Hrh1 antagonist) did not affect AOM-DSS-induced colorectal carcinogenesis. Adenocarcinoma cells immunohistochemically expressed Hrh1, Hrh2, Hrh3 and Hrh4 with varied intensities. Because clobenpropit is also known to be a Hrh4 receptor agonist, Hrh2, Hrh3 and Hrh4 may be involved in inflammation-related colorectal carcinogenesis. Additional data, including the mRNA expression of pro-inflammatory cytokines and inducible inflammatory enzymes in the colonic mucosa, are also presented.

Effect of azelastine on cardiac repolarization of guinea-pig cardiomyocytes, hERG K⁺ channel, and human L-type and T-type Ca²⁺ channel

Azelastine is a second generation histamine H₁-receptor antagonist used as an anti-asthmatic and anti-allergic drug that can induce QT prolongation and torsades de pointes. We investigated the acute effects of azelastine on human ether-a-go-go-related gene (hERG) channels, action potential duration (APD), and L-type (I(Ca,L)) and T-type Ca²⁺ current (I(Ca,T)) to determine the electrophysiological basis for its proarrhythmic potential. Azelastine increased the APD at 90% of repolarization concentration dependently, with an IC₅₀ of 1.08 nM in guinea-pig ventricular myocytes. We examined the effects of azelastine on the hERG channels expressed in Xenopus oocytes and HEK293 cells using two-microelectrode voltage-clamp and patch-clamp techniques. Azelastine induced a concentration-dependent decrease of the hERG current amplitude at the end of the voltage steps and tail currents. The IC₅₀ for the azelastine-induced block of the hERG currents expressed in HEK293 cells was 11.43 nM, while the drug inhibited I(Ca,L) and I(Ca,T) with IC₅₀ values of 7.60 and 26.21 μM, respectively. The S6 domain mutations, Y652A partially attenuated and F656A abolished hERG current block. These results suggest that azelastine is a potent blocker of hERG channels rather than I(Ca,L) or I(Ca,T), providing molecular mechanisms for the arrhythmogenic side effects during the clinical administration of azelastine.

Pharmacology of antihistamines

H1-antihistamines, the mainstay of treatment for urticaria, were developed from anticholinergic drugs more than 70 years ago. They act as inverse agonists rather than antagonists of histamine H1-receptors which are members of the G-protein family. The older first generation H1-antihistamines penetrate readily into the brain to cause sedation, drowsiness, fatigue and impaired concentration and memory causing detrimental effects on learning and examination performance in children and on impairment of the ability of adults to work and drive. Their use should be discouraged. The newer second-generation H1-antihistamines are safer, cause less sedation and are more efficacious. Three drugs widely used for symptomatic relief in urticaria, desloratadine, levocetirizine and fexofenadine are highlighted in this review. Of these levocetirizine and fexofenadine are the most potent in humans in vivo. However, levocetirizine may cause somnolence in susceptible individuals, whereas fexofenadine has a relatively short duration of action and may be required to be given twice daily for all round daily protection. Although desloratadine is less potent, it has the advantages of rarely causing somnolence and having a long duration of action.

Pharmacology of antihistamines

This article reviews the molecular biology of the interaction of histamine with its H1-receptor and describes the concept that H1-antihistamines are not receptor antagonists but are inverse agonists i.e. they produce the opposite effect on the receptor to histamine. It then discourages the use of first-generation H1-antihistamines in clinical practice today for two main reasons. First, they are less effective than second generation H1-antihistamines. Second, they have unwanted side effects, particularly central nervous system and anti-cholinergic effects, and have the potential for causing severe toxic reactions which are not shared by second-generation H1-antihistamines. There are many efficacious and safe second-generation H1-antihistamines on the market for the treatment of allergic disease. Of the three drugs highlighted in this review, levocetirizine and fexofenadine are the most efficacious in humans in vivo. However, levocetirizine may cause somnolence in susceptible individuals while fexofenadine has a relatively short duration of action requiring twice daily administration for full all round daily protection. While desloratadine is less efficacious, it has the advantages of rarely causing somnolence and having a long duration of action. Lastly, all H1-antihistamines have anti-inflammatory effects but it requires regular daily dosing rather than dosing 'on-demand' for this effect to be clinically demonstrable.

Pharmacology of antihistamines

This article reviews the molecular biology of the interaction of histamine with its H₁-receptor and describes the concept that H₁-antihistamines are not receptor antagonists but are inverse agonists i.e. they produce the opposite effect on the receptor to histamine. It then discourages the use of first-generation H₁-antihistamines in clinical practice today for two main reasons. First, they are less effective than second generation H₁-antihistamines. Second, they have unwanted side effects, particularly central nervous system and anti-cholinergic effects, and have the potential for causing severe toxic reactions which are not shared by second-generation H₁-antihistamines. There are many efficacious and safe second-generation H₁-antihistamines on the market for the treatment of allergic disease. Of the three drugs highlighted in this review, levocetirizine and fexofenadine are the most efficacious in humans in vivo. However, levocetirizine may cause somnolence in susceptible individuals while fexofenadine has a relatively short duration of action requiring twice daily administration for full all round daily protection. While desloratadine is less efficacious, it has the advantages of rarely causing somnolence and having a long duration of action. Lastly, all H₁-antihistamines have anti-inflammatory effects but it requires regular daily dosing rather than dosing 'on-demand' for this effect to be clinically demonstrable.

Impact of allergic rhinitis in school going children

Allergic rhinitis (AR) is the most common chronic pediatric disorder. The International Study for Asthma and Allergies in Childhood phase III found that the global average of current rhinoconjunctivitis symptoms in the 13-14 year age-group was 14.6% and the average prevalence of rhinoconjunctivitis symptoms in the 6-7 year age-group was 8.5%. In addition to classical symptoms, AR is associated with a multidimensional impact on the health related quality of life in children. AR affects the quality of sleep in children and frequently leads to day-time fatigue as well as sleepiness. It is also thought to be a risk factor for sleep disordered breathing. AR results in increased school absenteeism and distraction during class hours. These children are often embarrassed in school and have decreased social interaction which significantly hampers the process of learning and school performance. All these aspects upset the family too. Multiple co-morbidities like sinusitis, asthma, conjunctivitis, eczema, eustachian tube dysfunction and otitis media are generally associated with AR. These mostly remain undiagnosed and untreated adding to the morbidity. To compound the problems, medications have bothersome side effects which cause the children to resist therapy. Children customarily do not complain while parents and health care professionals, more often than not, fail to accord the attention that this not so trivial disease deserves. AR, especially in developing countries, continues to remain a neglected disorder.

Histamine H1 antagonists and clinical characteristics of febrile seizures

Background

The purpose of this study was to determine whether seizure susceptibility due to antihistamines is provoked in patients with febrile seizures.

Methods

The current descriptive study was carried out from April 2009 to February 2011 in 250 infants and children who visited the Madinah Maternity and Children’s Hospital as a result of febrile convulsions. They were divided into two groups according to administration of antihistamines at the onset of fever.

Results

Detailed clinical manifestations were compared between patients with and without administration of antihistamines. The time from fever detection to seizure onset was significantly shorter in the antihistamine group than that in the nonantihistamine group, and the duration of seizures was significantly longer in the antihistamine group than in the nonantihistamine group. No significant difference was found in time from fever detection to seizure onset or seizure duration between patients who received a first-generation antihistamine and those who received a second-generation antihistamine.

Conclusion

Due to their central nervous system effects, H1 antagonists should not be administered to patients with febrile seizures and epilepsy. Caution should be exercised regarding the use of histamine H1 antagonists in young infants, because these drugs could potentially disturb the anticonvulsive central histaminergic system.

Sleep problems in children and adolescents with common medical conditions

Untreated sleep disturbances and sleep disorders pose significant adverse daytime consequences and place children at considerable risk for poor health outcomes. Sleep disturbances occur at a greater frequency in children with acute and chronic medical conditions compared with otherwise healthy peers. Sleep disturbances in medically ill children can be associated with sleep disorders, comorbid with acute and chronic conditions, or secondary to underlying disease-related mechanisms, treatment regimens, or hospitalization. Clinical management should include a multidisciplinary approach with particular emphasis on routine, regular sleep assessments and prevention of daytime consequences, and promotion of healthy sleep habits and health outcomes.

What do you tell parents when their child is sick with the common cold?

PURPOSE

To review research supporting the Food and Drug Administration's recommendation to relabel over-the-counter cough and cold medications (OTC CCMs), warning against use in young children.

CONCLUSIONS

Research has shown that the majority of OTC CCMs and antihistamines have little to no effect when used to treat the common cold and have a risky safety profile. Despite these findings, parents continue to use OTC CCMs for treatment of their children's colds.

PRACTICE IMPLICATIONS

Educating parents on the lack of scientific evidence supporting the use of OTC CCMs and the potential for harm is important in altering parental perception and decreasing the purchase of OTC CCMs.

Risk of first-generation H(1)-antihistamines: a GA(2)LEN position paper

BACKGROUND

First-generation H(1)-antihistamines obtained without prescription are the most frequent form of self-medication for allergic diseases, coughs and colds and insomnia even though they have potentially dangerous unwanted effects which are not recognized by the general public.

AIMS

To increase consumer protection by bringing to the attention of regulatory authorities, physicians and the general public the potential dangers of the indiscriminate use first-generation H(1)-antihistamines purchased over-the counter in the absence of appropriate medical supervision.

METHODS

A GA(2)LEN (Global Allergy and Asthma European Network) task force assessed the unwanted side-effects and potential dangers of first-generation H1-antihistamines by reviewing the literature (Medline and Embase) and performing a media audit of US coverage from 1996 to 2008 of accidents and fatal adverse events in which these drugs were implicated.

RESULTS

First-generation H(1)-antihistamines, all of which are sedating, are generally regarded as safe by laypersons and healthcare professionals because of their long-standing use. However, they reduce rapid eye movement (REM)-sleep, impair learning and reduce work efficiency. They are implicated in civil aviation, motor vehicle and boating accidents, deaths as a result of accidental or intentional overdosing in infants and young children and suicide in teenagers and adults. Some exhibit cardiotoxicity in overdose.

CONCLUSIONS

This review raises the issue of better consumer protection by recommending that older first-generation H(1)-antihistamines should no longer be available over-the-counter as prescription- free drugs for self-medication of allergic and other diseases now that newer second- generation nonsedating H(1)-antihistamines with superior risk/benefit ratios are widely available at competitive prices.

Drug interactions

Drugs for allergy are often taken in combination with other drugs, either to treat allergy or other conditions. In common with many pharmaceuticals, most such drugs are subject to metabolism by P450 enzymes and to transmembrane transport. This gives rise to considerable potential for drug-drug interactions, to which must be added consideration of drug-diet interactions. The potential for metabolism-based drug interactions is increasingly being taken into account during drug development, using a variety of in silico and in vitro approaches. Prediction of transporter-based interactions is not as advanced. The clinical importance of a drug interaction will depend upon a number of factors, and it is important to address concerns quantitatively, taking into account the therapeutic index of the compound.

In Vitro and In Vivo Anti-Allergic Effects of Arctium lappa L

The discovery of drugs that can be used for the treatment of allergic disease is important in human health. Arctium lappa Linne (Compositae) (AL) has been used as a traditional medicine in Brazil and throughout Asia and is known to have an anti-inflammatory effect. In this study, the inhibitory effects of AL on degranulation and the release of mediators as well as on inhibition of cys-leukotriene biosynthesis by basophils were investigated. AL was selected out of 10,000 herbal extracts in a set-up for high throughput screening in which the degree of degranulation was monitored by the release of β-hexosaminidase from rat basophil leukemia (RBL-2H3) cells. The AL extract significantly reduced degranulation and biosynthesis of cys-leukotrienes of human basophils in peripheral blood mono-nuclear cells (PBMCs) (50% inhibitory concentration [IC50] = 8.3 and 11.4 μg/ml, respectively). Viability and metabolic activity of the PBMCs were not affected. Although arctiin, the active component of AL that has been described in the literature, was not able to reduce degranulation in RBL-2H3 cells, a single high-performance liquid chromatography (HPLC) fraction from the AL extract inhibited β-hexosaminidase release (IC50 = 22.2 μg/ml). Topical administration of an aqueous extract of AL (5 mg/ear) on the ear of whey-sensitized mice 4 hrs before challenge with whey in the ear inhibited acute ear swelling by 50% in an in vivo cow’s milk allergic model. The extract had no effect in this model when administered orally. In conclusion, the active component present in the active HPLC fraction of the AL extract was able to significantly reduce the release of inflammatory mediators through inhibition of degranulation and cys-leukotriene release in vitro. In addition, this active component was able to inhibit acute skin response in mice in vivo, indicating that AL is a very promising natural component for use in anti-allergic treatment.

Cutaneous reactions to drugs in children

Cutaneous eruptions are a commonly reported adverse drug reaction. Cutaneous adverse drug reactions in the pediatric population have a significant impact on patients' current and future care options. A patient's recollection of having a "rash" when they took a medication as a child is a frequent reason for not prescribing a particular treatment. The quick detection and treatment of cutaneous adverse drug reactions, plus identification of the causative agent, are essential for preventing the progression of the reaction, preventing additional exposures, and ensuring the appropriate use of medications for both the current condition and others as the patient ages. The purpose of this review is to discuss a reasonable approach to recognition and initial management of cutaneous adverse drug reactions in children.

Current concepts and therapeutic strategies for allergic rhinitis in school-age children

BACKGROUND

Allergic rhinitis (AR) is a common debilitating disorder that can adversely affect the quality of life and the academic performance of school-age children. Symptoms during the day can hamper concentration and lead to learning problems. Nocturnal symptoms can cause sleep loss and secondary daytime fatigue, further undermining a child's ability to function well during the school day Oral antihistamines are the foundation of pharmacologic therapy, but there are important differences between the agents.

OBJECTIVE

The purpose of this review is to provide an overview of the diagnostic and treatment challenges posed by AR in school-age children. The paper discusses and compares the available treatment modalities for this age group, with a focus on their beneficial and adverse effects.

METHODS

Pertinent articles were identified in the literature through a MEDLINE search (1990-2003). Keywords used were antihistamines cetirizine fexofenadine loratadine desloratadine intranasal corticosteroids and CNS effects. Results of numerous clinical trials of first-generation early second-generation and the newer antihistamines were identified.

RESULTS

This review established that the socioeconomic costs of AR are considerable. In children aged > or =12 years, direct US expenditures (eg, physician visits, medications) in 1996 amounted to $2.3 billion. Indirect costs measured by variables such as missed school days and poor performance also have an impact Major concerns include underdiagnosis and inadequate treatment, increasing the risk of serious comorbid conditions such as asthma. Advantages and drawbacks of antihistamines show that first-generation agents (eg, hydroxyzine) are effective and readily available over the counter, but are associated with sedation and the potential for suboptimal dosing. Newer agents, such as cetirizine, loratadine, desloratadine, and fexofenadine are effective and safer than the older drugs tie, no cardiotoxicity and less sedation). Of these, fexofenadine has been shown to be beneficial and nonsedating, even at higher-than-recommended doses. Other therapies reviewed include intranasal corticosteroids and leukotriene modifiers.

CONCLUSIONS

AR has a considerable negative impact on children in terms of their physical, social, and psychological well-being and academic performance. An appropriate treatment must be effective and tolerable. Of particular importance for enhancing treatment adherence in the school-age population are pleasant taste and ease of use of medication. A drug that has minimal or no sedative or anticholinergic effects is optimal.

Hypersensitivity reactions in neonates and infants

Although rare, several hypersensitivity reactions can occur in the infant population. Several types of hypersensitivity reactions are discussed, including urticaria, drug eruptions, erythema multiforme, allergic contact dermatitis, and vasculitis (acute hemorrhagic edema of infancy); neonatal lupus also is discussed. Although most of these conditions are benign, their presentations can be dramatic and a cause of concern for both parents and physicians. Important considerations and differences in the diagnosis and management of these conditions in children under the age of 6 months are discussed.

A simple high-performance liquid chromatographic method for detection of hydroxyzine in human plasma after overdose

INTRODUCTION

Hydroxyzine, a piperazine H1-receptor antagonist, is effective in generalised anxiety disorder. For toxicological purposes, a simple reversed-phase high-performance liquid chromatographic assay was developed for the detection of hydroxyzine in human plasma.

METHODS

A liquid-liquid procedure was used to extract the drug from plasma in the presence of an internal standard (clothiapine). The analysis was performed on a Spherisorb S5 C(8) analytical column with UV detection.

RESULTS

A linear response was observed over the concentration range 20-1500 ng/ml. A good accuracy (bias<7.3%) was achieved for all quality controls, with intraday and interday variation coefficients inferior to 8.5%. The limit of detection was 10 ng/ml, without interference of endogenous components.

DISCUSSION

This rapid method (run time<13 min) is currently used for poison management involving hydroxyzine.

Cetirizine: a review of its use in allergic disorders

Cetirizine is a selective, second-generation histamine H1 receptor antagonist, with a rapid onset, a long duration of activity and low potential for interaction with drugs metabolised by the hepatic cytochrome P450 system. Cetirizine was generally more effective than other H1 receptor antagonists at inhibiting histamine-induced wheal and flare responses. Cetirizine is an effective and well tolerated agent for the treatment of symptoms of seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR) and chronic idiopathic urticaria (CIU) in adult, adolescent and paediatric patients. In adults with these allergic disorders, cetirizine was as effective as conventional dosages of ebastine (SAR, PAR, CIU), fexofenadine (SAR), loratadine (SAR, CIU) or mizolastine (SAR). This agent was significantly more effective, and with a more rapid onset of action, than loratadine in 2-day studies in environmental exposure units (SAR). In paediatric patients, cetirizine was as at least as effective as chlorphenamine (chlorpheniramine) [SAR], loratadine (SAR, PAR) and oxatomide (CIU) in the short term, and more effective than oxatomide and ketotifen (PAR) in the long term. Cetirizine was effective in reducing symptoms of allergic asthma in adults and reduced the relative risk of developing asthma in infants with atopic dermatitis sensitised to grass pollen or house dust mite allergens. It had a corticosteroid-sparing effect in infants with severe atopic dermatitis and was effective in ameliorating reactions to mosquito bites in adults. Cetirizine was well tolerated in adults, adolescents and paediatric patients with allergic disorders. In adult, adolescent and paediatric patients aged 2-11 years, the incidence of somnolence with cetirizine was dose related and was generally similar to that with other second-generation H1 receptor antagonists. Although, its sedative effect was greater than that of fexofenadine in some clinical trials and that of loratadine or fexofenadine in a postmarketing surveillance study. In infants aged 6-24 months, the tolerability profile of cetirizine was similar to that of placebo. Cetirizine did not have any adverse effects on cognitive function in adults, or cognitive function, behaviour or achievement of psychomotor milestones in paediatric patients. Cetirizine was not associated with cardiotoxicity.

CONCLUSION

Cetirizine is well established in the treatment of symptoms of SAR, PAR or CIU. It demonstrated a corticosteroid-sparing effect and reduced the relative risk of developing asthma in sensitised infants with atopic dermatitis. Cetirizine was effective in the treatment of allergic cough and mosquito bites; however, its precise role in these indications has yet to be clearly established. On the basis of its favourable efficacy and tolerability profile and rapid onset of action, cetirizine provides an important option for the treatment of a wide range of allergic disorders.

Allergic rhinitis and impairment issues in schoolchildren: a consensus report

BACKGROUND

Allergic rhinitis (AR) can have substantial negative impact on children. Most notably, it can impede learning during the school-age years. Other consequences include adverse behavioral and psychosocial effects, poor quality of life, and potential impact on serious comorbidities, such as asthma.

CONSENSUS PANEL

In February 2004, in a conference sponsored by Aventis Pharmaceuticals, a multidisciplinary group convened to review relevant clinical data for the purposes of developing consensus recommendations for the management of AR in children. The consensus panel consisted of academic, school health, and medical providers, who were identified based on previous work and publications.

CONSENSUS FINDS

The focus of discussions was to assess the degree of impact of AR in schoolchildren and, based on this information, to determine how to improve screening, diagnosis, prevention, and treatment, to help ensure quality of life and maximal school performance in this population. The group considered the most critical factor in successful management ot be communication and collaboration among parents, educators, and healthcare professionals. Knowledge of the common signs and symptoms of AR in children can help to ensure early diagnosis, appropriate intervention, and clinically favorable outcomes. Importantly, both uncontrolled symptoms of AR, as well as adverse effects from medications, can diminish cognitive function and learning. When choosing treatment for children with AR, consideration must be given to the side effects of medications. All first-generation and some second-generation antihistamines can be associated with adverse effects on cognitive function and learning, as a result of their sedative properties. Treatment with non-sedating second-generation antihistamine has been shown to improve learning potential and is an ideal choice for treatment in this population.

CONCLUSION

Existing data indicate that further studies using objective measures of impairment in children taking antihistamine medications should be conducted to evaluate the impact of disease and treatment.

Central nervous system side effects of first- and second-generation antihistamines in school children with perennial allergic rhinitis: a randomized, double-blind, placebo-controlled comparative study

OBJECTIVE

Allergic rhinitis is common and on the rise. Antihistamines are the mainstay of treatment and are the most commonly prescribed drugs in Singapore. Treatment-related sedation and its effect on cognition are a major concern. First- and second-generation antihistamines show varying degrees of sedation, but to date, objective studies in children are lacking. The objective of this study was to assess the sedating effect of cetirizine (second-generation antihistamine) and chlorpheniramine (first-generation antihistamine) compared with placebo using an objective neurophysiological test.

METHODS

This was a prospective, double-blind, placebo-controlled, randomized, single-dose, 3-way crossover study. Twenty-four children aged 7 to 14 years with allergic rhinitis completed the study. All children were randomly allocated to medication sequences and received 3 different drugs on 3 different days, at least 1 week apart. The P300 event-related potential was used as an objective test of sedation. Subjective assessment was by a visual analog scale.

RESULTS

Chlorpheniramine and cetirizine increased P300 latency when compared with baseline. No significant increase was obtained with placebo. The significant increase in P300 latency was not accompanied by significant change in subjective somnolence as measured by the visual analog scale.

CONCLUSION

We have shown that cetirizine has sedative properties in children. The lack of correlation between P300 latency and the visual analog scale indicates that sedation induced by these drugs may not be subjectively noted.

Anti-inflammatory activity of H1-receptor antagonists: review of recent experimental research

OBJECTIVE

To compare the anti-inflammatory effects of fexofenadine with other H(1)-receptor antagonists in vitro.

DATA SOURCES

Published literature.

STUDY SELECTION

Recent experimental studies on anti-inflammatory effects of H(1)-receptor antagonists. Databases searched: Medline, Medscape.

PERIOD COVERED

1990-2003. Search terms: second-, third-generation antihistamines; sedating, nonsedating antihistamines; in vitro anti-inflammatory activity; cetirizine; ebastine; loratadine; fexofenadine; desloratadine.

RESULTS

Second- and third-generation H(1)-receptor antagonists may demonstrate significant in vitro anti-inflammatory activity at concentrations considered to be clinically relevant. In some instances, higher (supraclinical) concentrations are required to achieve comparable effects.

CONCLUSIONS

Experimental research suggests that second- and third-generation H(1)-receptor antagonists may achieve anti-inflammatory effects in a clinical context. Further studies are required to support this conclusion.

Fexofenadine hydrochloride, 180 mg, exhibits equivalent efficacy to cetirizine, 10 mg, with less drowsiness in patients with moderate-to-severe seasonal allergic rhinitis

BACKGROUND

Previous studies have shown that fexofenadine and cetirizine effectively relieve symptoms of seasonal allergic rhinitis (SAR).

OBJECTIVE

To compare the effects of fexofenadine hydrochloride, 180 mg, and cetirizine, 10 mg, on symptoms, drowsiness, and motivation in patients with moderate-to-severe SAR.

METHODS

In this 2-week multicenter, double-blind, randomized study, 495 subjects with moderate-to-severe SAR received once-daily fexofenadine hydrochloride, 180 mg, or cetirizine, 10 mg, without regard to food intake. Daily 12-hour reflective (AM, PM) and instantaneous (AM) individual symptoms and total symptom score (TSS) were evaluated. Drowsiness and motivation were recorded daily using visual analog scale at 7 AM, 10 AM, and 3 PM.

RESULTS

Between-treatment differences in reduction from baseline in AM instantaneous and 24-hour reflective TSS were -0.18 [95% confidence interval (CI), -0.55 to 0.20) and -0.22 (95% CI, -0.59 to 0.15), respectively. Since CIs for reduction in TSS between treatments fell within a 0.7 margin (defined a priori), treatments were considered statistically equivalent. Patients receiving fexofenadine experienced significantly less overall drowsiness vs baseline than those receiving cetirizine [-2.33 (95% CI, -3.80 to 0.86) vs 0.37 (95% CI, -1.10 to 1.84), P = .0110]. There was a trend toward greater improvements in overall motivation with fexofenadine compared with cetirizine [-2.36 (95% CI, -3.83 to 0.90) vs -0.30 (95% CI, -1.76 to 1.17), P = .0504].

CONCLUSIONS

Once-daily fexofenadine hydrochloride, 180 mg, given for 2 weeks caused statistically and clinically equivalent improvement in symptoms and significantly less drowsiness va baseline, compared with cetirizine, 10 mg, in patients with moderate-to-severe SAR.

Safety of non-antiarrhythmic drugs that prolong the QT interval or induce torsade de pointes: an overview

The long and growing list of non-antiarrhythmic drugs associated with prolongation of the QT interval of the electrocardiogram has generated concern not only for regulatory interventions leading to drug withdrawal, but also for the unjustified view that QT prolongation is usually an intrinsic effect of a whole therapeutic class [e.g. histamine H(1) receptor antagonists (antihistamines)], whereas, in many cases, it is displayed only by some compounds within a given class of non-antiarrhythmic drugs because of an effect on cardiac repolarisation. We provide an overview of the different classes of non-antiarrhythmic drugs reported to prolong the QT interval (e.g. antihistamines, antipsychotics, antidepressants and macrolides) and discusses the clinical relevance of the QT prolonging effect. Drug-induced torsade de pointes are sometimes considered idiosyncratic, totally unpredictable adverse drug reactions, whereas a number of risk factors for their occurrence is now recognised. Widespread knowledge of these risk factors and implementation of a comprehensive list of QT prolonging drugs becomes an important issue. Risk factors include congenital long QT syndrome, clinically significant bradycardia or heart disease, electrolyte imbalance (especially hypokalaemia, hypomagnesaemia, hypocalcaemia), impaired hepatic/renal function, concomitant treatment with other drugs with known potential for pharmacokinetic/pharmacodynamic interactions (e.g. azole antifungals, macrolide antibacterials and class I or III antiarrhythmic agents). This review provides insight into the strategies that should be followed during a drug development program when a drug is suspected to affect the QT interval. The factors limiting the predictive value of preclinical and clinical studies are also outlined. The sensitivity of preclinical tests (i.e. their ability to label as positive those drugs with a real risk of inducing QT pronglation in humans) is sufficiently good, but their specificity (i.e. their ability to label as negative those drugs carrying no risk) is not well established. Verapamil is a notable example of a false positive: it blocks human ether-a-go-go-related (HERG) K(+) channels, but is reported to have little potential to trigger torsade de pointes. Although inhibition of HERG K(+) channels has been proposed as a primary test for screening purposes, it is important to remember that several ion currents are involved in the generation of the cardiac potential and that metabolites must be specifically tested in this in vitro test. At the present state of knowledge, no preclinical model has an absolute predictive value or can be considered as a gold standard. Therefore, the use of several models facilitates decision making and is recommended by most experts in the field.

QT prolongation and torsades de pointes associated with concurrent use of cisapride and erythromycin

Prolongation of QT interval may lead to serious, potentially life-threatening, ventricular tachyarrhythmia, such as torsades de pointes. The cause may be an inherited or an acquired malfunction of ion channels at the myocardial cell membrane. Metabolic abnormalities, starvation, nervous system injury, and drug administration cause the much more frequent acquired long QT syndrome (LQTS). Types Ia and III antiarrhythmic drugs account for the majority of these life-threatening events, whereas a number of drugs widely used in otolaryngology, such as antibiotics and antihistamines, have been recently implicated. A case of a life-threatening ventricular tachyarrhythmia after the concurrent administration of cisapride and erythromycin is presented. Reviewed are drugs commonly prescribed in otolaryngology, as well as the associated risk factors that potentially lead to LQTS.