Teratogenicity of zonisamide and other little-used antiseizure medications.

PURPOSE: To investigate the risk of teratogenesis occurring in relation to intrauterine exposure to infrequently used antiseizure medications in Australia. METHODS: Analysis of data contained in the Raoul Wallenberg Australian Pregnancy Register of Antiepileptic Drugs. RESULTS: There was statistically significant evidence that zonisamide, but not any other of nine infrequently used antiseizure medications in Australia, was associated with a risk of teratogenesis related to the maternal dose of the drug taken in at least the earlier half of pregnancy. CONCLUSIONS: The teratogenesis associated with zonisamide, like that associated with topiramate and possibly acetazolamide, may be an expression of a class effect shared among sulphonamide-derived carbonic anhydrase inhibitors that possess anti-seizure activity.

The teratogenesis risk associated with antiseizure medication duotherapy in women with epilepsy.

PURPOSE: To investigate rates of occurrence of pregnancies associated with a foetal malformation (FM pregnancy rates) following simultaneous intrauterine exposure to two antiseizure medications in 524 pregnancies in women with epilepsy from the Australian Pregnancy Register who were treated simultaneously with various combinations and dosages of two antiseizure medications (duotherapy). RESULTS: FM pregnancy rates tended to be higher in those exposed simultaneously to two antiseizure medications, each of which was a statistically significant teratogen (valproate, topiramate, or carbamazepine), than when there was exposure to only one such teratogen. When there was exposure to only one such teratogen together with clonazepam or levetiracetam, for neither of which there was statistically significant evidence of heightened teratogenicity, the FM pregnancy rates also tended to be higher, but less so. When lamotrigine was the other component of the duotherapy with an established teratogen, FM pregnancy rates tended to be lower than that for the teratogen used as monotherapy. CONCLUSION: Leaving aside issues in relation to seizure control, our data suggest that it would be best to avoid using established teratogenic antiseizure medications (carbamazepine, valproate and topiramate) in combination with each other due to the increased FM risks. When combining an established teratogenic medication with a less teratogenic one, i.e. lamotrigine, levetiracetam or clonazepam, lamotrigine appears to be the safer option.

Seizure control in successive pregnancies in Australian women with epilepsy.

OBJECTIVES: To investigate control of epileptic seizures during pairs of successive pregnancies in antiseizure medication (ASM)-treated women with epilepsy. MATERIALS AND METHODS: Analysis of seizure freedom rates during 436 pairs of successive pregnancies in Australian women with epilepsy, in nearly all instances long-standing epilepsy. RESULT: There was a higher rate of seizure-free second pregnancies compared with first paired pregnancies (63.1% vs. 51.4%; Relative Risk (R.R.) = 1.2277; 95% CI 1.0930, 1.3789) and of seizure-free pre-pregnancy years before second as compared with first paired pregnancies in the same women (63.6% vs. 52.4%; R.R. = 1.2616; 95% CI 1.1337, 1.4040). In 108 women whose ASM therapy was unaltered throughout both of their pregnancies, the seizure-freedom rate was higher in the second of the paired pregnancies (82.4% vs. 69.4%; R.R. = 1.1867, 95% CI 1.0189, 1.3821). CONCLUSIONS: Altered ASM therapy after the first of a pair of successive pregnancies did not fully account for the better overall seizure control in the corresponding second pregnancies. Some additional factor may have been in operation, possibly a greater preparedness to undertake a further pregnancy if seizures were already fully controlled.

Epileptic seizure control during and after pregnancy in Australian women.

OBJECTIVES: To study factors that affected previous epileptic seizure control throughout pregnancy, during labour, and in the post-natal weeks. MATERIALS & METHODS: Analysis of data concerning seizure freedom that was available at various stages of 2337 pregnancies in the Raoul Wallenberg Australian Pregnancy Register of Antiepileptic Drugs, mainly employing multiple variable logistic regression techniques. RESULTS: Based on data available at the outset of pregnancy, the risk of seizure-affected that is, not seizure-free pregnancy was statistically significantly (p < .05) higher in pregnancies where there was previously uncontrolled epilepsy (78.1% vs. 20.8%) and focal epilepsy (51.3% vs. 39.7%), and decreased with later onset-age epilepsy (41.8% vs. 52.2% with onset before age 13 years), The risk did not differ between initially antiseizure medication (ASM)-treated or untreated pregnancies. For epilepsy receiving ASM therapy, 90.6% of 160 pregnancies of women with uncontrolled focal epilepsy that began before the age of 13 were seizure-affected. None of the above factors influenced the risk of seizures during labour, though having seizures during pregnancy increased the hazard (3.93 vs. 0.6%). Either ASM-treated pregnancy or labour being seizure-affected increased the risk of post-partum period seizures (33.0% vs. 6.67% for both stages being seizure-free). Use of particular ASMs had no statistically significant effect on the seizure control situation at any of the pregnancy stages studied. CONCLUSIONS: Obtaining full seizure control before pregnancy appeared to be the main factor in maintaining seizure freedom during pregnancy, labour and the post-natal weeks.

The control of treated generalized and focal epilepsies during pregnancy.

OBJECTIVES: To examine factors contributing to failure to achieve full seizure control during pregnancy in women with anti-seizure medication (ASM) treated generalized epilepsy compared with focal epilepsy. RESULTS: Full seizure control was not attained in 51.4% of 1223 pregnancies of women with focal epilepsies in the Australian Pregnancy Register, and in 38.7% of 1026 pregnancies in women with generalized epilepsy (P < 0.05). For convulsive seizures only, the corresponding figures of 20.8% and 22.9% were reasonably similar. Where seizures had occurred in the pre-pregnancy year, 82.5% of the focal epilepsy pregnancies were seizure affected, and 70.1% of the generalized epilepsy ones (P < 0.05). Where the pre-pregnancy year was seizure free, the corresponding figures were 22.6% and 16.4% (P < 0.05), a roughly four-fold lower rate. Maternal age, epilepsy onset age, and epilepsy duration also differed between the focal and generalized epilepsy pregnancies. Multivariate regression analysis showed that generalized epilepsy and younger maternal age were associated with statistically significant decreased risks of seizure-affected pregnancy, and having seizure-affected pre-pregnancy years with an increased risk. However, for convulsive seizures only, the risk of seizure-affected pregnancy appeared increased in generalized epilepsy. CONCLUSIONS: The risk of seizure-affected pregnancy appears lower in women with generalized epilepsy, independently of pre-pregnancy seizure control, itself a major determinant of the risk. The risk of having only convulsive seizures in pregnancy was not lower in generalized epilepsy than in focal epilepsy. ASM therapy seemed less effective in controlling focal than generalized epileptic seizures during pregnancy.

Pregnancy outcomes in women with surgically treated epilepsy.

OBJECTIVE: To ascertain whether epileptic seizure control during pregnancy differed between Australian women with previously surgically treated epilepsy, and those with only medically treated epilepsy. MATERIALS/METHODS: Analysis of data for 74 pregnancies of women with surgically treated focal epilepsy, compared with that from 1013 pregnancies in women with medically treated focal epilepsy, both groups drawn from the Australian Register of Antiepileptic Drugs in Pregnancy between 1999 and 2020. RESULTS: Seizures of all types, and also convulsive seizures, were less well controlled during pregnancy in the previously surgically treated cases, the difference for seizures of all types (68.9% versus 50.1%) being statistically significant (p < .05). This result was contrary to the outcome of a previously published study of the same question carried out in India. CONCLUSIONS: At present, it may be premature to conclude that previous epilepsy surgery will be associated with a better chance of seizure-free, or seizure-controlled, pregnancy.

The contribution of non-drug factors to fetal malformation in anti-seizure-medication-treated pregnancy.

PURPOSE: To assess the possible contribution of factors in additional to intrauterine anti-seizure medication (ASM) exposure in the occurrence of fetal malformation in women with ASM-treated epilepsy. RESULTS: Logistic regression analysis showed that maternal age over 31 years, family histories of fetal malformation, and conception after assisted fertility treatment, and also dosage of valproate, carbamazepine, and topiramate, made statistically significant (P<0.05) contributions to the fetal malformation rate in 2223 pregnancies in Australian women with epilepsy. The malformation rates were lower in pregnancies where the non-ASM-associated contributory factors were not present: statistically significantly so for all ASM-exposed pregnancies, and those pregnancies exposed to the more potent teratogenic drugs. CONCLUSION: It is important to consider the possible roles of identified, and also possible non-identified, non-ASM factors in relation to the occurrence of fetal malformations in the pregnancies of women with ASM-treated epilepsy.

Folic acid dose, valproate, and fetal malformations.

OBJECTIVE: To determine whether there is a relationship between folic acid dose and the degree of protection against valproate-associated and other antiepileptic drug (AED)-associated fetal structural malformations in women with AED-treated epilepsy. METHODS: Statistical analysis of data from the Raoul Wallenberg Australian Register of Antiepileptic Drugs in Pregnancy involving 2104 folic acid-treated pregnancies in women with epilepsy. RESULTS: Multiple variable logistic regression failed to demonstrate any statistically significant effect of folic acid dosage in reducing overall fetal malformation rates in women taking folic acid either before and during pregnancy (P = 0.640) or during early pregnancy only (P = 0.801), and in reducing spina bifida occurrence rates (P = 0.409). CONCLUSIONS: In the present state of knowledge, it would seem misguided to hope that a folic acid dose of 5 mg/day taken before and during pregnancy would protect against the occurrence of valproate-associated and other AED-associated fetal structural malformations. Future studies are required to determine whether high-dose periconceptional folate use may decrease the risk of other valproate-associated adverse fetal outcomes, including impaired post-natal neurobehavioral development.

Antiepileptic drugs and depression during pregnancy in women with epilepsy.

OBJECTIVES: To assess the possibility that the occurrence of seizures or the use of antiepileptic drug (AED) therapy might have influenced the rate of occurrence of volunteered histories of patient-recognized depression during pregnancy in women with epilepsy. MATERIALS AND METHODS: Analysis of data from 2039 pregnancies in the Raoul Wallenberg Australian Register of Antiepileptic Drugs in Pregnancy (APR) followed during pregnancy and to the end of the year after its end. RESULTS: Patient-recognized depression occurrence rates during pregnancy were a little lower rather than higher in seizure-affected than in seizure-free pregnancies (5.67% vs 6.41%), though higher in AED-treated than AED-untreated pregnancies (6.24% vs 5.26%; RR = 1.185, 95% CI 0.612, 2.295). Logistic regression analysis showed that carbamazepine dosage had a statistically significant relationship with a decreasing rate of patient-recognized depression occurring during pregnancy and topiramate dosage with an increasing rate. CONCLUSIONS: Carbamazepine and topiramate both have established potentials for causing teratogenesis, and it is possible that replacement of carbamazepine with a less teratogenic AED, for example levetiracetam, might result in any subsequent depression that occurs in pregnancy being inappropriately attributed to the newly introduced agent.

Twin pregnancy in women with epilepsy.

OBJECTIVE: We report data from the Raoul Wallenberg Australian Register of Antiepileptic Drugs in Pregnancy (APR) to see if there are significant differences in relation to the courses and outcomes of the twin pregnancies contained in the register, as compared with the singleton ones. METHODS: The APR has been under the oversight of Melbourne institutional Human Ethics Research Committees; all women enrolled in the APR have provided written informed consent. Data from the APR were transferred to a spreadsheet and then analyzed using simple statistical techniques including logistic regression. RESULTS: The population studied comprised 44 twin and 2261 singleton pregnancies; thus, twin pregnancies accounted for 1.91% of all pregnancies studied. The women carrying twins tended to be older than the women with singleton pregnancies to a statistically significant extent, their pregnancies more often originated from assisted fertilization techniques, and their babies were more often delivered by cesarean section. There were no statistically significant differences in relation to antiepileptic drug (AED) therapy. Individual twins had statistically significantly lower mean birthweights than singleton babies and they were statistically significantly more often involved structurally malformed foetuses. In the first year of life, the twin pregnancies statistically significantly more often produced offspring that were affected by seizures in infancy. SIGNIFICANCE: The data suggest that there may be an increased hazard of fetal malformation in the offspring of twin pregnancy in women with epilepsy, but that with contemporary standards of management of epilepsy and pregnancy, there is unlikely to be an increased hazard of seizure-affected pregnancy.

The outcome of altering antiepileptic drug therapy before pregnancy.

We investigated the outcome of altering antiepileptic drug (AED) therapy in the year before pregnancy on 2233 occasions in Australian women in the 20-year period of functioning of the Raoul Wallenberg Australian Pregnancy Register (APR). Therapy had been altered in 358 instances (16%) in the months prior to the pregnancy (median interval: 18 weeks). Antiepileptic drug doses had been changed in 141 pregnancies (39.4%), being decreased in 94; drugs changed in 151 (42.2%); drugs withdrawn without replacement in 66 (18.4%) but resumed in 40 before pregnancy ended. The main drugs involved were valproate (34%), phenytoin (16.5%), topiramate (12.6%), and carbamazepine (11.4%). Antiepileptic drug doses were increased significantly more often (16.9% vs. 6.4%) when epilepsy before pregnancy was not controlled, and AED treatment ceased significantly less often (13.6% vs. 24.0%). The alterations were more often made in women with generalized epilepsies and in those whose seizure disorders were not fully controlled in the prepregnancy year, suggesting that avoidance of teratogenicity and achieving improved seizure control often motivated the changes. Overall, the alterations did not result in improved rates of seizure freedom during pregnancy, as compared with pregnancies where therapy was unchanged; however, fetal malformation rates were lower 3.6% vs. 5.4%, but this difference did not attain statistical significance. The same trends regarding seizure control and malformations persisted after pregnancies involving valproate exposure were excluded. In conclusion, this analysis of the APR cohort did not demonstrate that altering AEDs before pregnancy produced a significant improvement in seizure control and the reduction in fetal malformation rate that occurred was not statistically significant.

Pregnancy after valproate withdrawal-Fetal malformations and seizure control.

OBJECTIVE: To assess the outcomes in women with epilepsy in relation to fetal malformation and epileptic seizure control during pregnancy when valproate (VPA) intake was ceased, or the drug's dose was reduced before pregnancy. METHODS: Statistical analysis of data collected in the Australian Pregnancy Register between 1999 and 2018 concerning 580 pregnancies previously treated with VPA, with the VPA dose reduced or the drug withdrawn prior to pregnancy in 158 cases. RESULTS: Although the available data have limitations, fetal malformation rates in the pregnancies studied were lower in the VPA changed pregnancies (4.5%) than in the VPA unchanged comparator pregnancies (10.9%, hazard ratio [HR] 0.412, 95% confidence interval [CI] 0.190-0.892), and were only 2.7% where VPA intake was ceased before pregnancy (HR 0.262, 95% CI 0.083-0.826). Seizure-affected pregnancies were more frequent in the VPA changed pregnancies than in the VPA unchanged ones (46.2% vs 30.8%, HR 1.500, 95% CI 1.203-1.870). Convulsive seizure-affected pregnancies also were increased, but the difference was not statistically significant. SIGNIFICANCE: Prepregnancy reduction in VPA dosage reduced the hazard of fetal malformations, whereas ceasing intake of the drug decreased the hazard to one similar to that which applies in the general population, but at a cost of decreased control of epileptic seizures during the pregnancies studied. Further investigations are needed to see whether such findings apply more widely in women with epilepsy.

Seizures in infancy in the offspring of women with epilepsy.

OBJECTIVES: To assess (a) the incidence of seizures in the first year of life in infants born to mothers with epilepsy and (b) factors that might contribute to the seizure incidence. MATERIALS & METHODS: Analysis of data collected in the Australian Register of Antiepileptic Drugs in Pregnancy during and at the end of the year after pregnancy. RESULTS: By the end of a year following pregnancy, seizures had occurred in the progeny of 47 pregnancies (2.40%), including febrile seizures in 18 (0.92%), the latter rate being higher than the 0.40% and 0.59% rates for the same situation in the general population reported in the recent literature. Seizures in infancy were more likely in the offspring of mothers with generalized as compared with focal epilepsies (3.65% vs 1.56%; RR = 2.332; P < .05) and within the generalized epilepsy mothers in those who were not seizure free during pregnancy (4.83% vs 2.89%). Seizures were also more likely in infants with foetal malformations, especially ones not discovered until after the first post-natal month. CONCLUSIONS: These findings may help in advising mothers with epilepsy regarding the chance of their offspring experiencing seizures in the first year of life; they also suggest the desirability of achieving maternal seizure control throughout pregnancy.

Valproate-associated foetal malformations-Rates of occurrence, risks in attempted avoidance.

OBJECTIVES: To gain insight into the main advantages and disadvantages that might result from valproate being unavailable for women who intend to become pregnant. MATERIALS AND METHODS: Analysis of data from the Australian Pregnancy Register concerning pregnancies exposed to valproate (N = 501) and pregnancies where previous valproate intake had been ceased before pregnancy (N = 101). RESULTS: The risk of foetal malformation associated with valproate exposure during pregnancy was dose-related, and there was a tendency for the more major malformations, including those often managed by therapeutic abortion, for example spina bifida, to occur at higher valproate doses. Had there been no exposure to valproate during pregnancy, some 80% of the foetal malformations that occurred might have been avoided. Cessation of previous valproate therapy before pregnancy was associated with an increased hazard of seizure-affected pregnancy. This was particularly the case for women with generalized epilepsies, in whom the incidence of seizure-affected pregnancy was increased by 50% to nearly 100%. CONCLUSIONS: Avoiding valproate intake during pregnancy is likely to reduce the incidence of foetal malformation, but at a cost of worsened maternal epilepsy control. Individualization of treatment is particularly important in considering withdrawal of valproate in the light of the fact that it is much more widely used in generalized epilepsy, there being fewer alternative drugs than for focal epilepsy and withdrawal is not without risk for both mother and baby. This study may provide a quantitative basis for assessing the balance between benefit and disadvantage for individual women with valproate-treated epilepsy who are considering pregnancy.

The prescribing of antiepileptic drugs for pregnant Australian women.

BACKGROUND: It is not clear how widely it is appreciated in Australia that certain antiepileptic drugs, particularly valproate, are teratogenic. AIM: The aim of the study is to assess trends in the pattern of antiepileptic drug prescribing for pregnant women in Australia to determine whether drug use is optimal, particularly from the fetal viewpoint. METHODS: Analysis of data contained in the Australian Register of Antiepileptic Drugs, assessing trends in antiepileptic drug use correlated with pregnancy outcomes. RESULTS: Valproate was the only significant teratogen among the antiepileptic drugs in common use. There was a fetal malformation rate of 14.5% associated with its use in monotherapy, as compared with a rate of 3.15% in antiepileptic drug-unexposed pregnancies in women with epilepsy (OR = 5.23, 95% CI = 1.81, 15.09). The highest malformation rate associated with any other antiepileptic drug used in monotherapy was 5.0%, for carbamazepine. Neurologists had progressively prescribed valproate less frequently and in lower dosage than other classes of practitioner over the 10-year study period, with a parallel decrease in occurrence of fetal malformations in pregnancies referred to the Register. Other prescribers of valproate did not seem to have adopted these practices to the same extent and had not obtained similar degrees of reduction in the occurrence of fetal malformations. CONCLUSIONS: Contemporary Australian obstetricians, even though they may not be valproate prescribers, when managing pregnancies in women taking valproate, need to be alert to the possibility that it may not be being used optimally from the fetal point of view, especially when not prescribed by neurologists.

The teratogenic risk of antiepileptic drug polytherapy.

PURPOSE: To compare the risks of fetal malformation during pregnancy associated with antiepileptic drug (AED) polytherapy and monotherapy. METHODS: Statistical analysis of malformation rate and antiepileptic drug exposure data from the Australian Register of Antiepileptic Drugs in Pregnancy, and from the literature. RESULTS: The calculated relative risk (RR) value for AED polytherapy compared with monotherapy was below 1.0 in only 3 of 14 literature publications. In the register, at 1 year postnatally there were fetal malformations in 5.32% of 282 AED polytherapy pregnancies, and in 7.84% of 791 AED monotherapy pregnancies, an RR of 0.68 [95% confidence interval (CI) 0.39-1.17). For pregnancies exposed to valproate, the RR of fetal malformation (0.39, 95% CI 0.20-0.89) was lower in polytherapy (7.26%) than in monotherapy (17.9%); the difference did not depend on valproate dosage. The RR values for fetal malformation were not significantly different for AED polytherapy and monotherapy when valproate was not involved. Logistic regression suggested that coadministration of lamotrigine may have reduced the malformation risk from valproate. DISCUSSION: The fetal hazard of AED polytherapy relative to monotherapy may depend more on the degree of exposure to valproate than on the fact of polytherapy per se. Coadministration with lamotrigine may lower the fetal risk of valproate therapy.