In vitro embryotoxicity of carbamazepine and carbamazepine-10, 11-epoxide

Teratogenic Effects of Carbamazepine in Mice

Objectives:

The aim of this study was to determine the teratogenic effects of carbamazepine (CBZ) in BALB/c mice.

Materials and Methods:

Mature female and male BALB/c mice (25–30 g) were used for all experiments. After standardization of administration and dose of CBZ, animals in the CBZ-treated groups (CBZ 450 mg/kg and 600 mg/kg) were fed on medicinal diet. The dams in the control group were mated on the same day as that of the CBZ-treated dams. After cesarean section (CS), fetal viability status and weights were recorded. Gross histopathological examination of fetuses was conducted to identify alterations in morphology and external or internal organs due to in utero exposure of CBZ.

Results:

Out of the nine female animals (three treated on CBZ 450 mg/kg, three treated on CBZ 600 mg/kg and three controls), seven were pregnant, and two (one each from the two CBZ-treated groups) were nonpregnant. All fetuses of the control group (n = 31) and CBZ 450 mg/kg treated group (n = 24) were live, but eight out of the twenty fetuses (40%) of CBZ 600 mg/kg treated group were dead at CS. The birth weight of the fetuses antenatally exposed to CBZ was drastically reduced (0.71 ± 0.06) when compared to control fetuses (1.67 ± 0.12) (P < 0.0001). All the fetuses of the CBZ-treated groups showed stunted physical development.

Conclusion:

Although oral administration of CBZ to mice is a convenient model to study the effect of CBZ to pregnancy, higher oral dose was associated with increased fetal loss. Some of the fetuses exposed to CBZ demonstrated structural abnormalities and low body weight.

Carbamazepine

This chapter includes the aspects of carbamazepine. The drug is synthesized by the use of 5H-dibenz[b,f]azepine and phosgene followed by subsequent reaction with ammonia. Carbamazepine is generally used for the treatment of seizure disorders and neuropathic pain, it is also important as off-label for a second-line treatment for bipolar disorder and in combination with an antipsychotic in some cases of schizophrenia when treatment with a conventional antipsychotic alone has failed. Other uses may include attention deficit hyperactivity disorder, schizophrenia, phantom limb syndrome, complex regional pain syndrome, borderline personality disorder, and posttraumatic stress disorder. The chapter discusses the drug metabolism and pharmacokinetics and presents various methods of analysis of this drug such electrochemical analysis, spectroscopic analysis, and chromatographic techniques of separation. It also discusses its physical properties such as solubility characteristics, X-ray powder diffraction pattern, and thermal methods of analysis. The chapter is concluded with a discussion on its biological properties such as activity, toxicity, and safety.

Teratogenic effects of carbamazepine on embryonic eye development in pregnant mice

BACKGROUND

Carbamazepine is an antiepileptic drug used widely for the treatment of epileptic seizures and neuropathic pain. Several malformations in humans, mainly neural tube defects, have been reported as a consequence of its use during pregnancy. The association between maternal use of carbamazepine and congenital eye malformations is not very well understood.

OBJECTIVE

The purpose of this study was to examine this association after intraperitoneal injection of carbamazepine during the period of organogenesis in mice.

METHODS

Balb/c timed-pregnant mice were divided into 4 experimental and control groups. Two experimental groups received daily intraperitoneal injections of 15 mg/kg (group I) or 30 mg/kg (group II) of carbamazepine on gestational days 6 to 15. Two control groups received normal saline or Tween 20 (polysorbate 20). Dams underwent Cesarean section on gestational day 18 and embryos were harvested. External examination for eye malformations, routine histological processing of malformed fetuses to study eye morphology, and skeletal staining were performed.

RESULTS

The mean weight and crown-rump of the fetuses in both experimental groups were significantly reduced compared with those of the control groups. Various malformations were detected such as brachygnathia, calvarial deformity, vertebral deformity, short tail, and brachydactyly. Premature opening of one or both eyes with mild to severe exophthalmos occurred in the 2 experimental groups. Deformed lens, retinal folds with undeveloped layers, and corneal folds with absence of surface epithelium were detected in both experimental groups.

CONCLUSIONS

This study, to the best of our knowledge, showed for the first time that intraperitoneal administration of carbamazepine at clinically comparable doses during organogenesis can induce several eye malformations in mice. The implication of these results needs to be considered when carbamazepine is administered during human pregnancy.

The significance of folic acid for epilepsy patients

The following is a comprehensive review of the current understanding of the many important roles of folic acid in the health of patients with epilepsy. A review of past and current literature reveals that folic acid plays important roles in the areas of hematology, neurology, development, and reproduction. Also highlighted are new areas for exploration.

Chemical teratogenesis in humans: biochemical and molecular mechanisms

In this review, an attempt has been made to summarize our current understanding of the mechanisms whereby certain chemicals cause birth defects. The chemicals selected for consideration were those that have been designated as established or recognized human teratogens. It is clear that our current understanding of mechanisms whereby these agents cause teratogenic effects (birth defects) can vary dramatically from one agent to the next. Extremes include the folic acid antagonists, which are now well established as agents that produce birth defects by virtue of potent inhibition of dihydrofolate reductase as a primary biochemical mechanism. An example at the other extreme is ethanol, for which very few definitive statements can be made with regard to teratogenic mechanisms, and the probability exists that a large number of interacting, contributory mechanisms can be invoked. For nearly all chemical teratogens, the critical links in the chains of events between the initial, primary biochemical and molecular mechanistic event (e.g. dihydrofolate reductase inhibition) and the manifestations of specific abnormalities (pathogenic mechanisms) remain to be delineated. This will provide an enormous challenge for investigators for years to come.