Effects of drugs and chemicals on the fetus and newborn (1)

Chemical-induced craniofacial anomalies caused by disruption of neural crest cell development in a zebrafish model

Background

Craniofacial anomalies are among the most frequent birth defects worldwide, and are thought to be caused by gene‐environment interactions. Genetically manipulated zebrafish simulate human diseases and provide great advantages for investigating the etiology and pathology of craniofacial anomalies. Although substantial advances have been made in understanding genetic factors causing craniofacial disorders, limited information about the etiology by which environmental factors, such as teratogens, induce craniofacial anomalies is available in zebrafish.

Results

Zebrafish embryos displayed craniofacial malformations after teratogen treatments. Further observations revealed characteristic disruption of chondrocyte number, shape and stacking. These findings suggested aberrant development of cranial neural crest (CNC) cells, which was confirmed by gene expression analysis of the CNC. Notably, these observations suggested conserved etiological pathways between zebrafish and mammals including human. Furthermore, several of these chemicals caused malformations of the eyes, otic vesicle, and/or heart, representing a phenocopy of neurocristopathy, and these chemicals altered the expression levels of the responsible genes.

Conclusions

Our results demonstrate that chemical‐induced craniofacial malformation is caused by aberrant development of neural crest. This study indicates that zebrafish provide a platform for investigating contributions of environmental factors as causative agents of craniofacial anomalies and neurocristopathy.

Gastroesophageal reflux disease in pregnancy

Gastroesophageal reflux disease during pregnancy is common. Altered structure and function of the normal physiological barriers to reflux of gastric contents into the oesophagus explain the high incidence of this problem in pregnant women. For the majority of patients, life-style modifications are helpful, but are not sufficient to control symptoms and medication is required. The optimum management of reflux in pregnant patients requires special attention and expertise, since the safety of the mother, foetus and neonate remain the primary focus. Gastroenterologists and obstetricians should work together to optimise treatment. Typically, one utilises a step-up program that starts with life-style modifications and antacids. If those methods fail, histamine-2 receptor antagonists and proton pump inhibitors are tried. Rarely, promotility agents are used. Initiation of these medications must be undertaken after a careful discussion of risks and benefits with patients. In patients without a prior history of reflux, symptoms usually abate after delivery.

[Alcohol, tobacco and cannabis: Review of teratogenicity studies in animals]

Despite an intensive national campaign of information, the drugs most frequently consumed by young adults undoubtedly continue to be alcohol, tobacco and cannabis. If the impact of these drugs on the health of the consumers can be evaluated in conjunction with the clinical and epidemiologic data, the consequences on the embryo due to their consumption by the pregnant women can be appreciated thanks to the abundant literature describing their effects in the gravid animal. Taking into account the abundant literature available in multiple animal species, the zero drug recommendation should be widely diffused to pregnant women.

Use of over-the-counter medications during pregnancy

The use of over-the-counter medications by pregnant women is common. Over-the-counter medications are widely assumed to be harmless because they may be purchased without prescription. Some consumers do not consider them to be drugs. Women may not realize that over-the-counter medications have the potential to harm them or their fetuses. This article reviews selected over-the-counter medications commonly used by pregnant women, including pharmacology, risks, Food and Drug Administration risk classifications, and strategies for counseling clients.

Treating gastro-oesophageal reflux disease during pregnancy and lactation: what are the safest therapy options?

Gastro-oesophageal reflux and heartburn are reported by 45 to 85% of women during pregnancy. Typically, the heartburn of pregnancy is new onset and is precipitated by the hormonal effects of estrogen and progesterone on lower oesophageal sphincter function. In mild cases, the patient should be reassured that reflux is commonly encountered during a normal pregnancy: lifestyle and dietary modifications may be all that are required. In a pregnant woman with moderate to severe reflux symptoms, the physician must discuss with the patient the benefits versus the risks of using drug therapy. Medications used for treating gastro-oesophageal reflux are not routinely or vigorously tested in randomised, controlled trials in women who are pregnant because of ethical and medico-legal concerns. Safety data are based on animal studies, human case reports and cohort studies as offered by physicians, pharmaceutical companies and regulatory authorities. If drug therapy is required, first-line therapy should consist of nonsystemically absorbed medications, including antacids or sucralfate, which offer little, if any, risk to the fetus. Systemic therapy with histamine H2 receptor antagonists (avoiding nizatidine) or prokinetic drugs (metoclopramide, cisapride) should be reserved for patients with more severe symptoms. Proton pump inhibitors are not recommended during pregnancy except for severe intractable cases of gastrooesophageal reflux or possibly prior to anaesthesia during labour and delivery. In these rare situations, animal teratogenicity studies suggests that lansoprazole may be the best choice. Use of the least possible amount of systemic drug needed to ameliorate the patient's symptoms is clearly the best for therapy. If reflux symptoms are intractable or atypical, endoscopy can safely be performed with conscious sedation and careful monitoring the mother and fetus.

Adverse effects of drugs and chemicals in breast milk on the nursing infant

Breastfeeding is an essential physiologic process that provides nutrition to the infant and protects the child against infection and immunologic disorders. The incidence of various diseases and metabolic disorders is known to be less in a breastfed infant compared with a child given a milk substitute. Psychologically, a breastfed infant forms a maternal bond that enables adaptation more readily to a social environment. It is well-established that all drugs are excreted into breast milk and are bioavailable to the infant. In general the majority of drugs do not pose a significant problem to the nursing infant and breastfeeding should be encouraged. The physician should be aware of which drugs are contraindicated during lactation and which drugs should be used with caution. There are also environmental chemicals that readily enter breast milk and may induce adverse effects. At present, the advantages of breastfeeding for infant development outweigh the potential adverse consequences and this physiologic process should be encouraged. With the use of available data on pharmacokinetics, milk-to-plasma ratio, excretion, etc. a supportive approach can be delineated by the pediatrician to reassure the nursing mother that they can safely breastfeed and continue therapy with minimal effects on the infant. It is thus imperative to document the extent to which a drug or chemical appears in breast milk and any apparent effects in the infant.

Congenital malformations caused by psychotropic drugs in pregnancy

After a description of the harmful effects of psychotropic drugs as well as of the moments of vulnerability to any teratogenic effect, this paper reviews prospective, retrospective and epidemiological studies of the teratogenic effects of anticonvulsants (phenytoin, valproic acid, carbamazepine and barbiturates), lithium, anti-psychotics, benzodiazepines and anti-depressive agents. It is found that the results of these studies are not unequivocal. Only lithium and valproic acid are shown to be teratogenic. In cases where malformations of the fetus are observed, the treatment often consisted in a combination of various psychotropic drugs. The review is completed with data on the psychopharmacological problems during delivery and their side-effects on the newborn.

A survey on the use of alternative drugs during pregnancy

OBJECTIVE

To describe the use of alternative drugs during pregnancy.

DESIGN

A trial including 3 surveys on drug use during pregnancy in maternity centers in one area of Finland in 1985-86 (study 1), and a retrospective survey in 2 maternity hospitals in Finland in 1988 (study 2).

PATIENTS AND METHODS

Study 1: 2912 pregnant women (about 94% of pregnant women in the area during the study period); 97-88% returned questionnaires. Study 2: 180 out of 181 consecutive women giving birth. In study 1, drug use (including drug-like products) in the last two weeks was asked by questionnaires around 12th, 28th, and 36th gestation weeks. In study 2, women were interviewed 2-3 days after birth asking about any drugs used during pregnancy. Due to the method of asking, our studies underestimate the level of using alternative drugs.

RESULTS

In study 1, a total of 97 (3.6%) pregnant women reported use of alternative drugs. Most drugs were dietary supplements, and by current knowledge harmless. But a few women had used (potentially) dangerous drugs. The users were from the higher social class and they had also used pharmaceutical specialties more often than non-users. In study 2, 14% had used alternative drugs at some time during pregnancy.

CONCLUSION

Because our surveys showed that alternative drugs are used, possibly with increasing frequency, during pregnancy, further studies on safety are needed.

Treatment guidelines for psychotropic drug use in pregnancy

Despite the apparent risks of psychotropic drug exposure in pregnancy, many pregnant women receive psychotropics. The major concerns associated with the use of antipsychotics, antidepressants, benzodiazepines, and lithium carbonate in pregnancy are reviewed, with clinical approaches for assessing the relative risks and benefits of treatment of psychiatrically ill pregnant patients and for choosing and instituting therapy with these agents.

Current concepts in the treatment of rheumatoid arthritis

The treatment of RA is complex and often frustrating. The pathologic process of RA is composed of acute inflammation, chronic immunologic phenomenon, and chronic connective tissue degradation. It is important to understand not only the pathophysiology of RA but also the mechanism of action of our therapeutic drugs so that treatment can be tailored to affect the important aspects of the process leading to end-organ damage. Despite the many drugs available, therapy is still unsatisfactory. Many drugs work in only certain patients. This could be secondary to variability in the disease state or to difference in drug metabolism. A better understanding of both disease and therapeutic agents may lead to better use of our present agents and development of new, more effective treatment modalities.