Assessment of antihistamine use in early pregnancy and birth defects

Current Management of Allergic Rhinitis

Allergic rhinitis (AR) is the most common allergic disease worldwide and one of the most common chronic diseases in general. Allergic rhinitis is caused by inhalant allergens from outdoor and indoor environments with varying significance of different allergens in global regions. We provide options for the current management for AR including pharmacological treatments and nonpharmacological options and allergen immunotherapy (AIT). A literature review has been conducted in Medline, Pubmed, as well as the national and international study (ClinicalTrials.gov) and guideline registers and the Cochrane Library. Human studies published on the topic in the period up to and including November 2023 were taken into account. Allergen avoidance measures, pharmacotherapy, and AIT are the cornerstones of AR treatment. Nonpharmacological measures and behavioral recommendations should be adequately added. Tools of precision medicine are already playing a significant role and will be part of the diagnostic and therapeutic standard in the future. Patients benefit most in a network of different pharmacological and nonpharmacological treatment measures including AIT. Application of precision medicine tools for diagnosis and treatment will improve standards of care.

Medication use during pregnancy and the risk of gastroschisis: a systematic review and meta-analysis of observational studies

OBJECTIVES

The aetiology of gastroschisis is considered multifactorial. We conducted a systematic review and meta-analysis to assess whether the use of medications during pregnancy, is associated with the risk of gastroschisis in offspring.

METHODS

PubMed, EMBASE, and Scopus were searched from 1st January 1990 to 31st December 2020 to identify observational studies examining the association between medication use during pregnancy and the risk of gastroschisis. The Newcastle-Ottawa Scale was used for the quality assessment of the individual studies. We pooled adjusted measures using a random-effect model to estimate relative risk [RR] and the 95% confidence interval [CI]. I2 statistic for heterogeneity and publication bias was calculated.

RESULTS

Eighteen studies providing data on 751,954 pregnancies were included in the meta-analysis. Pooled RRs showed significant associations between aspirin (RR 1.66, 95% CI 1.16-2.38; I2 = 58.3%), oral contraceptives (RR 1.52, 95% CI 1.21-1.92; I2 = 22.0%), pseudoephedrine and phenylpropanolamine (RR 1.51, 95% CI 1.16-1.97; I2 = 33.2%), ibuprofen (RR 1.42, 95% CI 1.26-1.60; I2 = 0.0%), and gastroschisis. No association was observed between paracetamol and gastroschisis (RR 1.16, 95% CI 0.96-1.41; I2 = 39.4%).

CONCLUSIONS

These results suggest that the exposure in the first trimester of pregnancy to over the counter medications (OTC) such as aspirin, ibuprofen, pseudoephedrine and phenylpropanolamine as well as to oral contraceptives, was associated with an increased risk of gastroschisis. However, these associations are significant only in particular subgroups defined by geographic location, adjustment variables and type of control. Therefore, further research is needed to investigate them as potential risk factors for gastroschisis, to assess their safety in pregnancy and to develop treatment strategies to reduce the risk of gastroschisis in offspring. PROSPERO registration number: CRD42021287529.

Analysis of umbilical cord tissue as an indicator of in utero exposure to toxic adulterating substances

In utero drug exposure is a significant public health threat to the well-being and normal development of the neonate. Recently, testing of umbilical cord tissue (UCT) has been employed to measure illicit drug exposure, as drugs used by the mother during the third trimester may be retained in the UCT. Focus has also been given to potential adverse health effects among drug users, resulting from exposure to pharmacologically active adulterants and cutting agents in the street drug supply. The in utero effects of these substances have not been well studied in humans, nor has their presence been demonstrated as a means for assessing adverse health effects in the neonate. Here, we describe the application of a novel test method to analyze UCT for the presence of more than 20 common adulterating/cutting substances via LC/Q-TOF. In total, 300 de-identified UCT samples were analyzed-all had previously tested positive for cocaine or opiates. Generally, the positivity rates of individual compounds were similar between the Cocaine and Opiates Subgroups, apart from levamisole, xylazine, dipyrone (metabolites), and promethazine. Many of the adulterants used in the street drug supply do have legitimate medicinal/therapeutic uses, including several of the compounds most frequently detected in this study. Caffeine and lidocaine were the most frequently identified compounds both individually (>70% each) and in combination with each other. Alternatively, levamisole, an adulterant with no legitimate therapeutic use, was present in 12% of cases. Importantly, this data demonstrates that the detection of traditional drugs of abuse may serve as indicators of potential in utero exposure to toxic adulterating substances during gestation. While there is cause for concern with respect to any unintentional drug exposure, illicit drug use during pregnancy, including uncontrolled dosing, poly-adulterant consumption, and the interactions of these drug mixtures, produces a significant public health threat to the neonate which warrants further study.

The association of nausea and vomiting of pregnancy, its treatments, and select birth defects: Findings from the National Birth Defect Prevention Study

BACKGROUND

Nausea and vomiting of pregnancy (NVP) occurs in approximately 70% of pregnant people. Treatments include pharmacologic and herbal/natural products. Research on the associations between NVP and its treatments and birth defects is limited.

METHODS

We used data from the case-control National Birth Defects Prevention Study (1997-2011) to examine whether first-trimester NVP or its specific treatments were associated with 37 major birth defects. Odds ratios (aOR) and 95% confidence intervals (CIs) were adjusted for sociodemographic and reproductive factors.

RESULTS

Mothers of 66.6% of 28,628 cases and 69.9% of 11,083 controls reported first-trimester NVP. Compared to no NVP, mothers with NVP had ≥10% reduction in risk of cardiac and noncardiac defects overall, and of 18 specific defects. Over-the-counter antiemetic use, compared to untreated NVP, was associated with ≥10% increase in risk for nine defect groups (heterotaxy, hypoplastic left heart syndrome [HLHS], aortic stenosis, cataracts, anophthalmos/microphthalmos, biliary atresia, transverse limb deficiency, omphalocele, and gastroschisis), whereas use of prescription antiemetics increased risk ≥10% for seven defect groups (tetralogy of Fallot, HLHS, spina bifida, anopthlamos/microphthalmos, cleft palate, craniosynostosis, and diaphragmatic hernia). We observed increased risks for promethazine and tetralogy of Fallot (aOR: 1.49, 95% CI: 1.05-2.10), promethazine and craniosynostosis (1.44, 1.08-1.92), ondansetron and cleft palate (1.66, 1.18-2.31), pyridoxine and heterotaxy (3.91, 1.49-10.27), and pyridoxine and cataracts (2.57, 1.12-5.88).

CONCLUSIONS

NVP does not increase risks of birth defects. Our findings that some treatments for NVP increase risk of specific birth defects should be investigated further before clinical recommendations are made.

Pharmacologic Treatment of Sleep Disorders in Pregnancy

Pregnancy is a unique physiologic state whose characteristics often predispose women to new-onset sleep disturbances or exacerbations of preexisting sleep disorders. Pregnancy-related factors that can disrupt sleep include heartburn, nocturnal oxytocin secretion, nocturia, and fetal movement. Sleep disorders in pregnancy include insomnia (primary and secondary), restless legs syndrome, and narcolepsy.

Urticaria in Pregnancy and Lactation

Chronic urticaria (CU) is a mast cell-driven chronic inflammatory disease with a female predominance. Since CU affects mostly females in reproductive age, pregnancy is an important aspect to consider in the context of this disease. Sex hormones affect mast cell (MC) biology, and the hormonal changes that come with pregnancy can modulate the course of chronic inflammatory conditions, and they often do. Also, pregnancy-associated changes in the immune system, including local adaptation of innate and adaptive immune responses and skewing of adaptive immunity toward a Th2/Treg profile have been linked to changes in the course of inflammatory diseases. As of now, little is known about the effects of pregnancy on CU and the outcomes of pregnancy in CU patients. Also, there are no real-life studies to show the safety of urticaria medications during pregnancy. The recent PREG-CU study provided the first insights on this and showed that CU improves during pregnancy in half of the patients, whereas it worsens in one-third; and two of five CU patients experience flare-ups of their CU during pregnancy. The international EAACI/GA2LEN/EuroGuiDerm/APAAACI guideline for urticaria recommends adopting the same management strategy in pregnant and lactating CU patients; starting treatment with standard doses of second-generation (non-sedative) H1 antihistamines, to increase the dose up to 4-folds in case of no response, and to add omalizumab in antihistamine-refractory patients; but also emphasizes the lack of evidence-based information on the safety and efficacy of urticaria treatments during pregnancy. The PREG-CU study assessed treatments and their outcomes during pregnancy. Here, we review the reported effects of sex hormones and pregnancy-specific immunological changes on urticaria, we discuss the impact of pregnancy on urticaria, and we provide information and guidance on the management of urticaria during pregnancy and lactation.

Long-Term Functional and Cytoarchitectonic Effects of the Systemic Administration of the Histamine H1 Receptor Antagonist/Inverse Agonist Chlorpheniramine During Gestation in the Rat Offspring Primary Motor Cortex

The transient histaminergic system is among the first neurotransmitter systems to appear during brain development in the rat mesencephalon/rhombencephalon. Histamine increases FOXP2-positive deep-layer neuron differentiation of cortical neural stem cells through H₁ receptor activation in vitro. The in utero or systemic administration of chlorpheniramine (H₁ receptor antagonist/inverse agonist) during deep-layer cortical neurogenesis decreases FOXP2 neurons in the developing cortex, and H₁R- or histidine decarboxylase-knockout mice show impairment in learning and memory, wakefulness and nociception, functions modulated by the cerebral cortex. Due to the role of H₁R in cortical neural stem cell neurogenesis, the purpose of this study was to evaluate the postnatal impact of the systemic administration of chlorpheniramine during deep-layer cortical neuron differentiation (E12–14) in the primary motor cortex (M1) of neonates (P0) and 21-day-old pups (P21). Chlorpheniramine or vehicle were systemically administered (5 mg/kg, i.p.) to pregnant Wistar rats at gestational days 12–14, and the expression and distribution of deep- (FOXP2 and TBR1) and superficial-layer (SATB2) neuronal cortical markers were analyzed in neonates from both groups. The qRT-PCR analysis revealed a reduction in the expression of Satb2 and FoxP2. However, Western blot and immunofluorescence showed increased protein levels in the chlorpheniramine-treated group. In P21 pups, the three markers showed impaired distribution and increased immunofluorescence in the experimental group. The Sholl analysis evidenced altered dendritic arborization of deep-layer neurons, with lower excitability in response to histamine, as evaluated by whole-cell patch-clamp recording, as well as diminished depolarization-evoked [³H]-glutamate release from striatal slices. Overall, these results suggest long-lasting effects of blocking H₁Rs during early neurogenesis that may impact the pathways involved in voluntary motor activity and cognition.

Chiral Transplacental Pharmacokinetics of Fexofenadine: Impact of P-Glycoprotein Inhibitor Fluoxetine Using the Human Placental Perfusion Model

PURPOSE

Fexofenadine is a well-identified in vivo probe substrate of P-glycoprotein (P-gp) and/or organic anion transporting polypeptide (OATP). This work aimed to investigate the transplacental pharmacokinetics of fexofenadine enantiomers with and without the selective P-gp inhibitor fluoxetine.

METHODS

The chiral transplacental pharmacokinetics of fexofenadine-fluoxetine interaction was determined using the ex vivo human placenta perfusion model (n = 4). In the Control period, racemic fexofenadine (75 ng of each enantiomer/ml) was added in the maternal circuit. In the Interaction period, racemic fluoxetine (50 ng of each enantiomer/mL) and racemic fexofenadine (75 ng of each enantiomer/mL) were added to the maternal circulation. In both periods, maternal and fetal perfusate samples were taken over 90 min.

RESULTS

The (S)-(-)- and (R)-(+)-fexofenadine fetal-to-maternal ratio values in Control and Interaction periods were similar (~0.18). The placental transfer rates were similar between (S)-(-)- and (R)-(+)-fexofenadine in both Control (0.0024 vs 0.0019 min^-1) and Interaction (0.0019 vs 0.0021 min^-1) periods. In both Control and Interaction periods, the enantiomeric fexofenadine ratios [R-(+)/S-(-)] were approximately 1.

CONCLUSIONS

Our study showed a low extent, slow rate of non-enantioselective placental transfer of fexofenadine enantiomers, indicating a limited fetal fexofenadine exposure mediated by placental P-gp and/or OATP2B1. The fluoxetine interaction did not affect the non-enantioselective transplacental transfer of fexofenadine. The ex vivo placental perfusion model accurately predicts in vivo placental transfer of fexofenadine enantiomers with remarkably similar values (~0.17), and thus estimates the limited fetal exposure.

Use of antihistamine medications during early pregnancy and selected birth defects: The National Birth Defects Prevention Study, 1997-2011

BACKGROUND

It is estimated that approximately 10-15% of pregnant women report antihistamine use during pregnancy. Although antihistamines are generally considered safe during pregnancy, results from published studies are inconsistent.

METHODS

Using a case-control study design we analyzed 41,148 pregnancies (30,091 cases and 11,057 controls) from the National Birth Defects Prevention Study (1997-2011). Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals for 64 birth defect groupings in relation to early pregnancy exposure to 14 distinct antihistamines. Models were adjusted for maternal age, race, parity, education level, prenatal care, folic acid use, smoking and alcohol use, and study site.

RESULTS

Approximately 13% of cases and controls were exposed to an antihistamine during early pregnancy. Analyses were restricted to those defects where more than five cases were exposed to the antihistamine of interest, generating 340 analyses which yielded 20 (5.9%) significant positive associations (adjusted ORs ranging from 1.21 to 4.34).

CONCLUSIONS

Only a few of our findings were consistent with previous studies. There is a lack of strong evidence to conclude that birth defects are associated with exposure to antihistamines during early pregnancy.

Rhinitis 2020: A practice parameter update

This comprehensive practice parameter for allergic rhinitis (AR) and nonallergic rhinitis (NAR) provides updated guidance on diagnosis, assessment, selection of monotherapy and combination pharmacologic options, and allergen immunotherapy for AR. Newer information about local AR is reviewed. Cough is emphasized as a common symptom in both AR and NAR. Food allergy testing is not recommended in the routine evaluation of rhinitis. Intranasal corticosteroids (INCS) remain the preferred monotherapy for persistent AR, but additional studies support the additive benefit of combination treatment with INCS and intranasal antihistamines in both AR and NAR. Either intranasal antihistamines or INCS may be offered as first-line monotherapy for NAR. Montelukast should only be used for AR if there has been an inadequate response or intolerance to alternative therapies. Depot parenteral corticosteroids are not recommended for treatment of AR due to potential risks. While intranasal decongestants generally should be limited to short-term use to prevent rebound congestion, in limited circumstances, patients receiving regimens that include an INCS may be offered, in addition, an intranasal decongestant for up to 4 weeks. Neither acupuncture nor herbal products have adequate studies to support their use for AR. Oral decongestants should be avoided during the first trimester of pregnancy. Recommendations for use of subcutaneous and sublingual tablet allergen immunotherapy in AR are provided. Algorithms based on a combination of evidence and expert opinion are provided to guide in the selection of pharmacologic options for intermittent and persistent AR and NAR.

Selecting a pharmacotherapy regimen for patients with chronic insomnia

INTRODUCTION

Chronic insomnia, whether it is primary or in combination with another medical or psychiatric disorder, is a prevalent condition associated with significant morbidity, reduced productivity, increased risk of accidents, and poor quality of life. Pharmacologic and behavioral treatments have equivalent efficacy with each having its own advantages and limitations.

AREAS COVERED

The purpose of this perspective is to delineate the limitations encountered in implementing cognitive behavioral therapy (CBT) and to review the pharmacological treatments designed to target the different phenotypes of insomnia. The discussions address how to choose the optimal medication or combination thereof based on patients' characteristics, available medications, and the presence of comorbid conditions. Selective nonbenzodiazepine sedative 'Z-drug' hypnotics, melatonin receptor agonist-ramelteon, and low-dose doxepin are the agents of choice for treatment of primary and comorbid insomnia.

EXPERT OPINION

A pharmacological intervention should be offered if cognitive behavioral therapy for insomnia is not available or has failed to achieve its goals. Increasing evidence of the significant adverse consequences of long-term benzodiazepines should limit the prescription of these agents to specific conditions. Testing novel dosing regimens with a combination of hypnotic classes augmented with CBT deserve further investigation.

Desloratadine Use During Pregnancy and Risk of Adverse Fetal Outcomes: A Nationwide Cohort Study

BACKGROUND

Desloratadine is a frequently used drug for the treatment of allergic disorders, which often also require treatment during pregnancy. However, information on the fetal safety of desloratadine use during pregnancy is limited.

OBJECTIVE

To investigate the association between desloratadine use during pregnancy and adverse fetal outcomes.

METHODS

From a cohort of 1,287,668 pregnancies identified in the Danish nationwide registries in the study period 2001 to 2016, users of desloratadine and loratadine during pregnancy were matched in a 1:1 ratio based on propensity scores to compare the risk of adverse fetal outcomes. We compared the risk of the primary outcomes major birth defects (among a total of 3348 pregnancies) and spontaneous abortion (5498 pregnancies) and the secondary outcomes preterm birth (5280 pregnancies), small size for gestational age (SGA) for birth weight (5436 pregnancies), and stillbirth (6776 pregnancies). Logistic regression was used to estimate the prevalence odds ratio (OR) of major birth defects, preterm birth, and SGA, and Cox regression to estimate the hazard ratio (HR) of spontaneous abortion and stillbirth. Sensitivity analyses included comparing with cetirizine use in pregnancy and with pregnancies unexposed to desloratadine but with prior use as additional comparator groups.

RESULTS

Use of desloratadine in pregnancy was not associated with a significant increased risk of major birth defects (prevalence OR, 1.07; 95% confidence interval [CI], 0.77-1.50), spontaneous abortion (HR, 1.15; 95% CI, 0.96-1.37), preterm birth (prevalence OR, 0.84; 95% CI, 0.67-1.05), SGA (prevalence OR, 0.97; 95% CI, 0.80-1.16), or stillbirth (HR, 0.91; 95% CI, 0.31-2.70) compared with loratadine use in pregnancy. Sensitivity analyses, including those with the use of additional comparator groups, showed similar results.

CONCLUSION

Use of desloratadine during pregnancy was not associated with a statistically significant increased risk of adverse fetal outcomes as compared with loratadine. Results indicate that the fetal safety profile of desloratadine is similar to the currently recommended second-generation antihistamines during pregnancy.

ERS/TSANZ Task Force Statement on the management of reproduction and pregnancy in women with airways diseases

This European Respiratory Society/Thoracic Society of Australia and New Zealand statement outlines a review of the literature and expert opinion concerning the management of reproduction and pregnancy in women with airways diseases: asthma, cystic fibrosis (CF) and non-CF bronchiectasis. Many women with these diseases are now living into reproductive age, with some developing moderate-to-severe impairment of lung function in early adulthood. The statement covers aspects of fertility, management during pregnancy, effects of drugs, issues during delivery and the post-partum period, and patients' views about family planning, pregnancy and parenthood. The statement summarises current knowledge and proposes topics for future research, but does not make specific clinical recommendations.

Modifiable risk factors for stillbirth: a literature review

A stillbirth is defined as an infant born weighing 500 g and/or more or at a gestational age of 24 weeks who shows no signs of life. Having a stillborn baby has a wide range of consequences that can affect parents, family and the healthcare professionals involved. Several risk factors have been associated with an increased risk of stillbirth: including maternal medical factors, maternal characteristics, fetal factors, sociodemographic factors and behavioral factors. The aim of this work is to review the literature on risk factors that have a behavioral component. The main behaviors modulating the risk of stillbirth that have been more widely studied in the literature include use of substances (smoking, alcohol, illicit drugs and medical drugs), weight management, attendance at antenatal care and sleeping position. There is evidence in the literature that supports that all those behaviors have an impact on the risk of stillbirth, especially in the cases of smoking and drugs consumption during the pregnancy. Hence, more research is needed to establish interventions targeting these behaviors as preventive measures to reduce the risk of adverse obstetric outcomes.

Exposure to antazoline-naphazoline eye drops during pregnancy and the risk of congenital malformations: a Danish nationwide cohort study

PURPOSE

To investigate whether exposure to antazoline-naphazoline eye drops in the first trimester of pregnancy was associated with an increased risk of malformations in humans.

METHODS

All women giving live birth between 1997 and 2011 in Denmark were included in this nationwide cohort study. All women redeeming at least one prescription of antazoline-naphazoline eye drops during the first 84 days of pregnancy were identified. Logistic regression was used to estimate the odds ratios of malformations among exposed offspring compared to non-exposed offspring.

RESULTS

We identified 977 706 births between 1997 and 2011. A total of 3061 women (0.32%) were exposed to antazoline-naphazoline eye drops in the first trimester of pregnancy. The rate of congenital malformations was 3.0% (n = 93) in exposed offspring and 3.5% (n = 33 594) in unexposed offspring. First-trimester exposure to antazoline-naphazoline was not associated with major congenital malformations overall (odds ratio: 0.88, 95% confidence interval: 0.71-1.09) or with any specific major malformation. The number of redeemed prescriptions was unchanged during all trimesters of pregnancy as compared to before and after pregnancy (p < 0.05).

CONCLUSION

Exposure to antazoline-naphazoline eye drops in the first trimester of pregnancy appears not to be associated with increased teratogenic risk.

A Benefit Risk Review of Pediatric Use of Hydrocodone/Chlorpheniramine, a Prescription Opioid Antitussive Agent for the Treatment of Cough

Hydrocodone/chlorpheniramine is a prescription opioid licensed in the USA for the relief of cough and upper respiratory symptoms associated with allergy or cold in adults, previously contraindicated in children aged < 6 years. We present findings from a modern benefit risk review of hydrocodone/chlorpheniramine use as an antitussive agent in patients aged 6 to < 18 years. A cumulative search of the manufacturer’s pharmacovigilance database covering 1 January 1900–7 August 2017 identified all individual case safety reports (ICSRs) associated with product family name “hydrocodone/chlorpheniramine.” The search was inclusive of all MedDRA system organ classes, stratified by age (< 18 years). A comprehensive review of the scientific literature was conducted on safety and efficacy of opioids for pediatric treatment of cough. Three hundred and ninety-one ICSRs associated with hydrocodone/chlorpheniramine were identified; 35/391 ICSRs were in patients < 18 years of age; 18 were considered serious. Four fatalities were reported in patients 6 to < 18 years; two fatalities involved co-suspect medication azithromycin and two were poorly documented. Our literature search identified no robust efficacy data for hydrocodone/chlorpheniramine in the relief of cough and upper respiratory symptoms associated with allergy or cold in patients aged 6 to < 18 years. As we found no evidence of hydrocodone/chlorpheniramine efficacy in the pediatric population, we conclude that the benefit risk profile is unfavorable. This evidence contributed to the US Food and Drug Administration’s (FDA’s) recent decision that hydrocodone-containing cough and cold medications should no longer be indicated for treatment of cough in patients < 18 years, highlighting the value of proactive re-evaluation of the benefit risk profile of older established drugs.

Plain Language Summary

People often use medicines containing opioids to treat cough symptoms. The US Food and Drug Administration (FDA) recently decided that cough medicines containing opioids should not be used by children under 18 years old. Part of this decision was a review of the benefits and risks of using cough medicines that contain the opioid hydrocodone in children.

Why was this review carried out? Most cough medicines that doctors can prescribe were approved several decades ago. Since then, rules for the approval of medicines have become stricter. In this review, researchers looked at the safety of hydrocodone, and how well this opioid relieves cough symptoms in children. Up-to-date information and modern research methods were used.

The two key pieces of evidence found were:

We could not locate any clinical trials providing robust evidence for the use of hydrocodone for cough relief in children under 18 years of age. (Outside the scope of this review, a number of clinical trials of hydrocodone-containing cough medicines in adults aged 18 years and over have shown the medicine to be effective in these patients.)

Cough medicines containing opioids can cause harmful side effects in children such as breathing problems. In the research reported here, ten children died after taking a hydrocodone-containing cough medicine. Nine of these deaths were due to overdose.

This evidence was used to draw the following conclusions:

In children under 18 years of age, the risks of using hydrocodone for cough relief are greater than any benefits.

Older medicines should be reviewed regularly to look at their safety and how well they are working using up-to-date evidence.

Pharmacologic Treatment of Sleep Disorders in Pregnancy

Pregnancy often predisposes women to new-onset sleep disturbances, as well as exacerbations of preexisting sleep disorders. The goals of treating perinatal sleep disorders include the promotion of restorative sleep and the benefits it brings to both mother and fetus. The prescribing of any sleep aid in pregnancy must include consideration of the risks and benefits for both the patient and her fetus. Although data on the perinatal use of sleep aids is limited, there may be effects on fetal development, timing and duration of delivery, and postnatal outcomes.

The Risk of Adverse Pregnancy Outcome After First Trimester Exposure to H1 Antihistamines: A Systematic Review and Meta-Analysis

INTRODUCTION

H1 antihistamines are used for the treatment of nausea and vomiting during pregnancy as well as the symptomatic relief of asthma, urticaria, allergy, and the common cold. Although they are overall felt to be safe during pregnancy, recently several studies have challenged this assumption, as millions of women are exposed to them in the first trimester.

METHODS

Following the guidelines of PRISMA, a systematic review was performed to retrieve all published articles involving H1-antihistamine exposure during pregnancy. Electronic databases including PubMed and EMBASE were searched for possibly relevant articles published in any language up to December 2015.

RESULTS

After removing duplicate publications, and excluding animal studies and studies on drug effectiveness, 342 articles were reviewed in detail and 37 studies fulfilled the inclusion criteria for the meta-analysis. In cohort studies, the risk of major malformation in the offspring of women exposed to H1 antihistamines was not higher than that of the control population (OR 1.07; 95% CI 0.98-1.16). The Q-statistic for heterogeneity of effects was not significant (p > 0.05, I ² < 25%) and there was no evidence of publication bias. Similar results were achieved with case-control studies (OR 1.05; 95% CI 0.90-1.23). Similarly, H1 antihistamines were not associated with more spontaneous abortions (OR 1.00; 95% CI 0.83-1.20), prematurity (OR 0.96; 95% CI 0.76-1.20), stillbirth (OR 1.23; 95% CI 0.48-3.18) or low birth weight (OR 1.20; 95% CI 0.63-2.29).

CONCLUSIONS

Based on our meta-analyses, which included a large number of studies, H1 antihistamines are not associated with an increased risk of major malformation or other adverse fetal outcomes. This study provides important information to both pregnant women and their healthcare providers regarding the safety and risk of H1 antihistamine use during this sensitive time.

Antihistamines and birth defects: a systematic review of the literature

INTRODUCTION

Approximately 10 - 15% of women reportedly take an antihistamine during pregnancy for the relief of nausea and vomiting, allergy and asthma symptoms, or indigestion. Antihistamines include histamine H1-receptor and H2-receptor antagonists.

AREAS COVERED

This is a systematic evaluation of the peer-reviewed epidemiologic literature published through February 2014 on the association between prenatal exposure to antihistamines and birth defects. Papers addressing histamine H1- or H2-receptor antagonists are included. Papers addressing pyridoxine plus doxylamine (Bendectin in the United States, Debendox in the United Kingdom, Diclectin in Canada, Lenotan and Merbental in other countries) prior to the year 2001 were excluded post hoc because of several previously published meta-analyses and commentaries on this medication.

EXPERT OPINION

The literature on the safety of antihistamine use during pregnancy with respect to birth defects is generally reassuring though the positive findings from a few large studies warrant corroboration in other populations. The findings in the literature are considered in light of three critical methodological issues: i) selection of appropriate study population; ii) ascertainment of antihistamine exposures; and iii) ascertainment of birth defect outcomes. Selected antihistamines have been very well studied (e.g., loratadine); others, especially H2-receptor antagonists, require additional study before an assessment of safety with respect to birth defect risk could be made.