Risk of Major Congenital Malformations and Exposure to Antiseizure Medication Monotherapy

Importance

Women with epilepsy (WWE) require treatment with antiseizure medications (ASMs) during pregnancy, which may be associated with an increased risk of major congenital malformations (MCMs) in their offspring.

Objective

To investigate the prevalence of MCMs after prenatal exposure to 8 commonly used ASM monotherapies and changes in MCM prevalence over time.

Design, Setting, and Participants

This was a prospective, observational, longitudinal cohort study conducted from June 1999 to October 2022. Since 1999, physicians from more than 40 countries enrolled ASM-treated WWE before pregnancy outcome was known and followed up their offspring until 1 year after birth. Participants aged 14 to 55 years who were exposed to 8 of the most frequently used ASMs during pregnancy were included in this study. Data were analyzed from April to September 2023.

Exposure

Maternal use of ASMs at conception.

Main Outcomes and Measures

MCMs were assessed 1 year after birth by a committee blinded to type of exposure. Teratogenic outcomes across exposures were compared by random-effects logistic regression adjusting for potential confounders and prognostic factors.

Results

A total of 10 121 prospective pregnancies exposed to ASM monotherapy met eligibility criteria. Of those, 9840 were exposed to the 8 most frequently used ASMs. The 9840 pregnancies occurred in 8483 women (mean [range] age, 30.1 [14.1-55.2] years). MCMs occurred in 153 of 1549 pregnancies for valproate (9.9%; 95% CI, 8.5%-11.5%), 9 of 142 for phenytoin (6.3%; 95% CI, 3.4%-11.6%), 21 of 338 for phenobarbital (6.2%; 95% CI, 4.1%-9.3%), 121 of 2255 for carbamazepine (5.4%; 95% CI, 4.5%-6.4%), 10 of 204 for topiramate (4.9%; 95% CI, 2.7%-8.8%), 110 of 3584 for lamotrigine (3.1%; 95% CI, 2.5%-3.7%), 13 of 443 for oxcarbazepine (2.9%; 95% CI, 1.7%-5.0%), and 33 of 1325 for levetiracetam (2.5%; 95% CI, 1.8%-3.5%). For valproate, phenobarbital, and carbamazepine, there was a significant increase in the prevalence of MCMs associated with increasing dose of the ASM. Overall prevalence of MCMs decreased from 6.1% (153 of 2505) during the period 1998 to 2004 to 3.7% (76 of 2054) during the period 2015 to 2022. This decrease over time was significant in univariable logistic analysis but not after adjustment for changes in ASM exposure pattern.

Conclusions and Relevance

Of all ASMs with meaningful data, the lowest prevalence of MCMs was observed in offspring exposed to levetiracetam, oxcarbazepine, and lamotrigine. Prevalence of MCMs was higher with phenytoin, valproate, carbamazepine, and phenobarbital, and dose dependent for the latter 3 ASMs. The shift in exposure pattern over time with a declining exposure to valproate and carbamazepine and greater use of lamotrigine and levetiracetam was associated with a 39% decline in prevalence of MCMs, a finding that has major public health implications.

Changes over 24 years in a pregnancy register - Teratogenicity and epileptic seizure control

OBJECTIVES

To trace (i) changes in Australian Pregnancy Register (APR) records concerning antiseizure medications (ASMs) prescribed for women with epilepsy (WWE) over the course of 24 years and correlate the changes with (ii) rates of occurrence of pregnancies involving foetal malformations, (iii) the body organs involved in the malformations, and (iv) freedom from epileptic seizures.

RESULTS

Use of valproate and carbamazepine decreased progressively, use of lamotrigine remained relatively static, and the use of levetiracetam increased progressively, whereas the use of topiramate first increased and then fell again, associated with a temporary increase in malformation-associated pregnancy rate. More serious malformations, such as spina bifida, became less frequent, whereas more trivial ones tended to increase, whereas epileptic seizure freedom rates improved.

CONCLUSIONS

The increasing use of newer ASMs in pregnant women has been associated with overall advantages in relation to the frequency and severity of foetal malformation and with advantages in relation to freedom from epileptic seizures.

Specific fetal malformations following intrauterine exposure to antiseizure medication

OBJECTIVE

To investigate in the Australian Pregnancy Register of Antiepileptic Drugs patterns of fetal malformation associated with intrauterine exposure to particular currently available antiseizure medications taken by women with epilepsy.

RESULTS

There was statistically significant evidence (P < 0.05) of an increased hazard of fetal malformation associated with exposure to valproate, carbamazepine, topiramate, zonisamide, and with conception after assisted fertilization, but a reduced hazard in the offspring of women who continued to smoke during pregnancy. Valproate exposure was associated with malformations in a wide range of organs and organ systems, carbamazepine and topiramate with hydronephrosis, topiramate also with hypospadias, zonisamide with spina bifida and assisted fertilization with heart and great vessel maldevelopment.

CONCLUSIONS

Prenatal valproate exposure appears to interfere with the development of many if not all, fetal tissues. It seems likely that prenatal exposure to carbamazepine and topiramate, and possibly exposure to zonisamide, but also some process related to in vitro fertilization, may more selectively affect the normal development of particular fetal tissues or organs.

Proposal for reference values for the developmental effects of valproate based on human data using a benchmark dose approach

Following accidental release of valproate into ambient air during manufacture at a French production site in 2018, concerns were raised for inhabitants of the surrounding area. As no toxicological reference value (TRV) was available, the risks could not be properly assessed. The French Agency for Food, Environmental and Occupational Health and Safety (ANSES) was mandated to determine a TRV by inhalation to be used for risk assessment. Major congenital malformations (MCMs) in offsprings of mothers exposed to valproate during pregnancy have been reported in international scientific literature. As these adverse effects were the most sensitive effect identified, they were retained as the critical effect to be used for the TRV. The data from a robust registry on MCMs established by the International Registry of Antiepileptic Drugs and Pregnancy (EURAP) were modellized and support a strong DRR between the prevalence of MCMs in the fetus and in utero exposure. A benchmark dose (BMD) was then calculated as the dose that may trigger a 5% increase in this risk. A lower 95% confidence limit (BMD5%L95%) of 2.26 mg/kg/day, leading to an oral TRV of 0.08 mg/kg/day and a respiratory TRV of 0.26 mg.m-3 after applying an uncertainty factor of 30, was determined.

Fetal malformations in successive pregnancies in Australian women with epilepsy

OBJECTIVES

To utilize data from the Australian Register of Antiepileptic Drugs in Pregnancy (APR) to determine the hazard of fetal malformation in the subsequent pregnancy or pregnancies in women with epilepsy following a pregnancy associated with a fetal malformation, and to identify factors relevant to the hazard.

RESULTS

There was a 7.4% initial pregnancy fetal malformation rate. The subsequent pregnancy malformation rate was 4.2% if there was no initial pregnancy malformation, but 21.2% if there was an initial pregnancy malformation (O.R. = 6.1448, 95% C.I. 2.3396, 16.1386). For pregnancies where antiseizure medication (ASM) therapy was unchanged between pregnancies (N = 196), the initial pregnancy malformation rate was 10.2%, but 30.0% in the subsequent pregnancy if there was a malformation in the initial pregnancy, and 2.35% if there was none (O.R. = 17.7857, 95% C.I. 4.4847, 70.5361). A cohort comprising 24% of the women with fetal malformations in their initial pregnancies seemed to be intrinsically vulnerable to fetal malformation during successive pregnancies: when their seizure disorder type had been recorded all had genetic generalized epilepsies, compared with a 45.8% generalized epilepsy rate in women with initial but not subsequent pregnancy malformations (P = 0.0121).

CONCLUSIONS

If fetal malformation had occurred in an initial ASM-treated pregnancy there was a significantly increased hazard of fetal malformation in the subsequent pregnancy, particularly if the woman involved had a genetic generalized epilepsy.

Declining malformation rates with changed antiepileptic drug prescribing

Objective

Changes in prescribing patterns of antiepileptic drugs (AEDs) in pregnant women with epilepsy would be expected to affect the risk of major congenital malformations (MCMs). To test this hypothesis, we analyzed data from an international pregnancy registry (EURAP).

Methods

EURAP is an observational prospective cohort study designed to determine the risk of MCMs after prenatal exposure to AEDs. The Cochrane-Armitage linear trend analysis was used to assess changes in AED treatment, prevalence of MCMs, and occurrence of generalized tonic-clonic seizures (GTCs) over 3 time periods: 2000–2005 (n = 4,760), 2006–2009 (n = 3,599), and 2010–2013 (n = 2,949).

Results

There were pronounced changes in the use of specific AEDs over time, with a decrease in the use of valproic acid and carbamazepine and an increase in the use of lamotrigine and levetiracetam. The prevalence of MCMs with monotherapy exposure decreased from 6.0% in 2000–2005 to 4.4% in 2010–2013. The change over time in MCM frequency after monotherapy exposure showed a significant linear trend in the crude analysis (p = 0.0087), which was no longer present after adjustment for changes in AED treatment (p = 0.9923). There was no indication of an increase over time in occurrence of GTCs during pregnancy.

Conclusions

There have been major changes in AED prescription patterns over the years covered by the study. In parallel, we observed a significant 27% decrease in the prevalence of MCMs. The results of adjusting the trend analysis for MCMs for changes in AED treatment suggest that changes in prescription patterns played a major role in the reduction of teratogenic events.

Development of EpiRisk: An online clinical tool for estimating the risk of major congenital malformations in pregnant women treated for epilepsy

Antiepileptic drugs (AEDs) are known to associate with an increased risk of major congenital malformations (MCMs) in children born to women who become pregnant while taking them. As the indications for AEDs continue to diversify, novel AEDs emerge, and polytherapy becomes more prevalent, the volume and complexity of the information relating to teratogenic risk can become unmanageable for the clinician. This in turn makes accurate education of pregnant women treated with AEDs regarding the risk of MCMs challenging. To enable clinicians to provide better information regarding the potential teratogenic risk of AEDs, we outline here the method we have employed to underpin a new system of real-time risk analysis, "EpiRisk." When launched, EpiRisk will offer a user-friendly, online clinical tool, compatible with all modern Internet browsers, smart phones, and personal computers. Using the most current published data, as well as "real world" data from the UK and the Australian Pregnancy Registers, EpiRisk will enable clinicians to quickly and accurately assess the teratogenic risk of AEDs in mono- and polytherapy. EpiRisk may thus provide a future-proof central hub for empowering patients, clinicians, and registries by delivering evidence-based information on the teratogenic risk of the AEDs in pregnant women with epilepsy through an easily accessible platform.

Comparative risk of major congenital malformations with eight different antiepileptic drugs: a prospective cohort study of the EURAP registry

BACKGROUND

Evidence for the comparative teratogenic risk of antiepileptic drugs is insufficient, particularly in relation to the dosage used. Therefore, we aimed to compare the occurrence of major congenital malformations following prenatal exposure to the eight most commonly used antiepileptic drugs in monotherapy.

METHODS

We did a longitudinal, prospective cohort study based on the EURAP international registry. We included data from pregnancies in women who were exposed to antiepileptic drug monotherapy at conception, prospectively identified from 42 countries contributing to EURAP. Follow-up data were obtained after each trimester, at birth, and 1 year after birth. The primary objective was to compare the risk of major congenital malformations assessed at 1 year after birth in offspring exposed prenatally to one of eight commonly used antiepileptic drugs (carbamazepine, lamotrigine, levetiracetam, oxcarbazepine, phenobarbital, phenytoin, topiramate, and valproate) and, whenever a dose dependency was identified, to compare the risks at different dose ranges. Logistic regression was used to make direct comparisons between treatments after adjustment for potential confounders and prognostic factors.

FINDINGS

Between June 20, 1999, and May 20, 2016, 7555 prospective pregnancies met the eligibility criteria. Of those eligible, 7355 pregnancies were exposed to one of the eight antiepileptic drugs for which the prevalence of major congenital malformations was 142 (10·3%) of 1381 pregnancies for valproate, 19 (6·5%) of 294 for phenobarbital, eight (6·4%) of 125 for phenytoin, 107 (5·5%) of 1957 for carbamazepine, six (3·9%) of 152 for topiramate, ten (3·0%) of 333 for oxcarbazepine, 74 (2·9%) of 2514 for lamotrigine, and 17 (2·8%) of 599 for levetiracetam. The prevalence of major congenital malformations increased with the dose at time of conception for carbamazepine (p=0·0140), lamotrigine (p=0·0145), phenobarbital (p=0·0390), and valproate (p<0·0001). After adjustment, multivariable analysis showed that the prevalence of major congenital malformations was significantly higher for all doses of carbamazepine and valproate as well as for phenobarbital at doses of more than 80 mg/day than for lamotrigine at doses of 325 mg/day or less. Valproate at doses of 650 mg/day or less was also associated with increased risk of major congenital malformations compared with levetiracetam at doses of 250-4000 mg/day (odds ratio [OR] 2·43, 95% CI 1·30-4·55; p=0·0069). Carbamazepine at doses of more than 700 mg/day was associated with increased risk of major congenital malformations compared with levetiracetam at doses of 250-4000 mg/day (OR 2·41, 95% CI 1·33-4·38; p=0·0055) and oxcarbazepine at doses of 75-4500 mg/day (2·37, 1·17-4·80; p=0·0169).

INTERPRETATION

Different antiepileptic drugs and dosages have different teratogenic risks. Risks of major congenital malformation associated with lamotrigine, levetiracetam, and oxcarbazepine were within the range reported in the literature for offspring unexposed to antiepileptic drugs. These findings facilitate rational selection of these drugs, taking into account comparative risks associated with treatment alternatives. Data for topiramate and phenytoin should be interpreted cautiously because of the small number of exposures in this study.

FUNDING

Bial, Eisai, GlaxoSmithKline, Janssen-Cilag, Novartis, Pfizer, Sanofi-Aventis, UCB, the Netherlands Epilepsy Foundation, and Stockholm County Council.

Withdrawal of valproic acid treatment during pregnancy and seizure outcome: Observations from EURAP

Based on data from the EURAP observational International registry of antiepileptic drugs (AEDs) and pregnancy, we assessed changes in seizure control and subsequent AED changes in women who underwent attempts to withdraw valproic acid (VPA) during the first trimester of pregnancy. Applying Bayesian statistics, we compared seizure control in pregnancies where VPA was withdrawn (withdrawal group, n = 93), switched to another AED (switch group, n = 38), or maintained (maintained-therapy group, n = 1,588) during the first trimester. The probability of primarily or secondarily generalized tonic-clonic seizures (GTCS) was lower in the maintained-therapy group compared with the other two groups, both in the first trimester and for the entire duration of pregnancy. GTCS were twice as common during pregnancy in the withdrawal (33%) and switch groups (29%) compared with the maintained-treatment group (16%). Limitations in the data and study design do not allow to establish a cause-effect relationship between treatment changes and seizure outcome, but these observations provide a signal that withdrawal of, or switch from, VPA during the first trimester could lead to loss of seizure control, and highlight the need for a specifically designed prospective observational study.

Dose-dependent teratogenicity of valproate in mono- and polytherapy: an observational study

OBJECTIVE

To assess the risk of major congenital malformations (MCMs) in association with maternal use of valproic acid (VPA) in monotherapy or adjunctive therapy, and its relationship with dose.

METHODS

The analysis was based on prospectively acquired data from EURAP, a registry enrolling women treated with antiepileptic drugs (AEDs) in early pregnancy, in which the primary outcome is presence of MCMs at 1 year after birth. Exposure was defined as type and dose of AEDs at time of conception. A comparison was made among 3 exposure types: (1) VPA monotherapy (n = 1,224); (2) VPA combined with lamotrigine (LTG) (n = 159); and (3) VPA combined with another AED but not LTG (n = 205).

RESULTS

The frequency of MCMs at 1 year after birth was 10.0% for VPA monotherapy, 11.3% for exposures to VPA and LTG, and 11.7% for exposures to VPA + another (non-LTG) AED. Regardless of exposure group, the frequency of MCMs increased with dose of VPA, being highest at doses ≥1,500 mg/d (24.0% for monotherapy, 31.0% for VPA + LTG, and 19.2% for VPA + other AEDs), and was similar across treatment groups at the lowest VPA dose level of <700 mg/d (5.9% for monotherapy, 7.0% for VPA + LTG, and 5.4% for VPA + other AEDs).

CONCLUSIONS

The risk of MCMs associated with VPA exposure increases with increasing VPA dose, both in the presence and in the absence of one concomitant AED, and appears to be related primarily to the dose of VPA.

Altered cortical thickness following prenatal sodium valproate exposure

Prenatal exposure to sodium valproate (VPA) is associated with neurodevelopmental impairments. Cortical thickness was measured in 16 children exposed prenatally to VPA and 16 controls. We found increased left inferior frontal gyrus (IFG; BA45) and left pericalcarine sulcus (BA18) thickness, an association between VPA dose and right IFG thickness, and a close relationship between verbal skills and left IFG thickness. A significant interaction between group and hemispheric IFG thickness showed absence of the normal asymmetry in the IFG region of VPA-exposed children. These data provide preliminary insights into the putative neural basis of difficulties experienced by some VPA-exposed children.

Seizure control and treatment changes in pregnancy: observations from the EURAP epilepsy pregnancy registry

PURPOSE

To analyze seizure control, dose adjustments, and other changes of antiepileptic drug (AED) treatment during pregnancy in a large cohort of women with epilepsy entering pregnancy on monotherapy with carbamazepine, lamotrigine, phenobarbital, or valproate.

METHODS

Seizure control and AED treatment were recorded prospectively in 3,806 pregnancies of 3,451 women with epilepsy taking part in European and International Registry of Antiepileptic Drugs and Pregnancy (EURAP), an international AED and pregnancy registry.

KEY FINDINGS

Of all cases, 66.6% remained seizure-free throughout pregnancy. Generalized tonic-clonic seizures (GTCS) occurred in 15.2% of the pregnancies. Women with idiopathic generalized epilepsies were more likely to remain seizure-free (73.6%) than women with localization-related epilepsy (59.5%; p < 0.0001). Worsening in seizure control from the first to second or third trimesters occurred in 15.8% of pregnancies. The AED dose was increased during pregnancy in 26.0% and a second AED added to the initial monotherapy in 2.6% of all pregnancies. Seizures were more likely to occur in the first trimester in pregnancies with an increased drug load (35%; increased dose and/or addition of another AED) than in pregnancies without an increased drug load (15.3%) (p < 0.0001). Compared with other monotherapies, pregnancies exposed to lamotrigine were less likely to be seizure-free, 58.2% (p < 0.0001); had more GTCS, 21.1% (p < 0.0001); had a greater likelihood of deterioration in seizure control from first to second or third trimesters, 19.9% (p < 0.01), and were more likely to require an increase in drug load, 47.7% (p < 0.0001). The mean dose increases from the first to third trimesters were 26% for lamotrigine, 5% for carbamazepine, 11% for phenobarbital, and 6% for valproate. There were 21 cases of status epilepticus (10 convulsive): none with maternal mortality and only one with a subsequent stillbirth.

SIGNIFICANCE

Although the majority of women remain seizure-free throughout pregnancy, our data suggest that a more proactive approach to adjusting the dose of all AEDs in pregnancy should be considered, in particular for those pregnancies with seizures occurring in the first trimester and those exposed to lamotrigine, to reduce the risk of deterioration in seizure control.

Dose issues in antiepileptic therapy

Antiepileptic drug (AED) therapy is complex, with numerous traditional drugs and more than 10 second-generation drugs being approved since the mid-1990s. The burden of epilepsy is compounded by the adverse effects of these drugs, which comprise a variety of manifestations, the most devastating of which is their association with physical and cognitive foetal malformations in babies exposed to these agents in utero. Many effects are dose-related - a clear understanding of these adverse effects is desirable to be able to adjust medications and medication regimens to suit individual patient needs and to try to prevent them, by a careful introduction, slow escalation, well-considered combination and possible pre-exposure testing of patients for their tolerance, to each proposed AED. The overall problem and the profiles of the main agents are outlined from the perspective of dose-related issues.

Neurobehavioral consequences of prenatal antiepileptic drug exposure

Despite elevated rates of birth defects associated with prenatal antiepileptic drug exposure, pharmacotherapy is typically continued throughout pregnancy because of the risks posed to mother and child by recurrent seizures. Emerging data suggest that prenatal exposure to valproate or polytherapy may also be associated with increased risk of cognitive impairment. However, our understanding of the longer-term sequelae of prenatal antiepileptic drug exposure remains incomplete. Improved understanding of the neurobehavioral consequences of prenatal antiepileptic drug exposure is essential to ensure accurate information is available for women with epilepsy planning a pregnancy, and to achieve optimal outcomes for mothers and children.

Antiepileptic drug exposure and major congenital malformations: the role of pregnancy registries

The use of antiepileptic drugs (AEDs) in pregnancy is associated with an increased risk of fetal malformations. Although it is known that AEDs may differ with respect to the type of malformations they can induce, earlier studies have generally lacked the power to demonstrate differences between AEDs in their overall teratogenic potential. Furthermore, there is an urgent need to assess the clinical teratogenic potential of the newer-generation AEDs. Epilepsy and pregnancy registries have been established to provide such information, which is essential for the rational management of women with epilepsy with childbearing potential. The registries also provide opportunities for additional studies of seizures observed during pregnancy and labor and, with the enrolled woman's consent, for separate studies on cognitive outcomes and pharmacogenetics. Although most are prospective, the existing registries vary somewhat in design, which needs to be considered when their results are compared. Some registries are driven by pharmaceutical companies (often compelled by national or international drug licensing agencies) and provide data on pregnancy outcome related to the sponsor's own product. Others are organized by independent research groups and are potentially more useful in that they publish comparative data. This review provides a critical discussion and comparison of important methodological aspects of AED and pregnancy registries along with a summary of results published so far.

Role of valproate across the ages. Treatment of epilepsy in adults

A workshop was held in Göteborg in June 2005 to discuss the place of valproate in treating adult epilepsies. Consensus positions were developed on the epilepsy types for which the drug is most suitable and the use of valproate in women of child-bearing age, in men and in patients with psychiatric comorbidity. Valproate was considered to be effective across a broad variety of epilepsy syndromes and seizure types and should be considered a suitable choice for first-line monotherapy of juvenile myoclonic epilepsy and other idiopathic generalized epilepsies. The use of valproate by women of child-bearing age is associated with potential harm to the foetus. A conservative approach to treatment is recommended in these patients whereby alternative antiepileptic drugs should be proposed to women planning pregnancies wherever satisfactory seizure control can be thereby maintained. In cases where valproate is used during pregnancy, either because the pregnancy was unplanned or because alternative treatment options of equivalent efficacy are unavailable, appropriate counselling, precautionary measures and monitoring should be provided. The evidence for an impact of valproate on male reproductive health is equivocal and considerations of male fertility should not be taken into account in deciding whether to prescribe valproate to men. Valproate can be proposed safely to patients with comorbid psychiatric disease or underlying psychiatric vulnerability.

A double-blind, placebo-controlled trial of diclofenac/misoprostol in Alzheimer's disease

BACKGROUND

Previous studies suggest a potential benefit from nonsteroidal anti-inflammatory drugs (NSAIDs) in Alzheimer's disease (AD). Prescribing NSAIDs, however, carries the risk of significant gastrointestinal adverse events.

OBJECTIVES

To study whether treatment with an NSAID prevents expected decline in AD patients and evaluate whether co-administration of the gastro-protective agent, misoprostol, with an NSAID is safe in AD.

METHODS

The efficacy and safety of diclofenac in combination with misoprostol (D/M) was evaluated in 41 patients with mild-moderate AD in a prospective 25-week, randomized, double-blind placebo-controlled trial. Efficacy measures comprised the Alzheimer's Disease Assessment Scale cognitive and noncognitive subsections, Global Deterioration Scale, Clinical Global Impression of Change, Mini-Mental State Examination, Instrumental Activities of Daily Living, Physical Self-Maintenance Scale, and a caregiver-rated Global Impression of Change.

RESULTS

There were no group differences with any of the outcome measures in an intent-to-treat analysis. There were some nonsignificant trends for the placebo group to have deteriorated more than the D/M-treated patients. Withdrawal rates were 12 of 24 in the D/M group and 2 of 17 in the placebo group. There were no serious drug-related adverse events.

CONCLUSIONS

This pilot study, with small treatment numbers, did not demonstrate a significant effect of NSAID treatment in AD, but the trends observed justify further investigations with a larger number of participants. D/M is safe in AD patients, but its tolerability is not optimal.

Serum interleukin-6 and interleukin-6 soluble receptor in Alzheimer's disease

Serum levels of interleukin-6 (IL-6) and interleukin-6 soluble receptor (IL-6sR) were measured in 41 patients (23 female and 18 male, mean age 72.5 years) with Alzheimer's disease (AD) and in 32 controls (14 women and 18 men, mean age 69.2 years) using enzyme-linked immunosorbent assays (ELISA). Proportions of individuals with detectable serum IL-6 concentrations did not differ significantly between patients and controls. There was however, a significant decrease in IL-6sR levels in Alzheimer's patients when compared with controls. Our results suggest that there is a dysregulation of IL-6 and its soluble receptor in AD.

A double-blind, placebo-controlled crossover study of vigabatrin 2 g/day and 3 g/day in uncontrolled partial seizures

The efficacy and tolerability of vigabatrin as add-on therapy was assessed in patients with uncontrolled partial seizures. Ninety-seven patients entered this seven-centre, double-blind, placebo-crossover study. Vigabatrin (2 g or 3 g) or placebo was administered daily. Vigabatrin was well-tolerated and did not cause clinically significant adverse drug effects when added to established anticonvulsant therapy. No significant differences were observed between dose groups for the overall incidence of adverse events, although drowsiness and visual disturbances (diplopia, ataxia, visual abnormalities) showed a dose-related increase with vigabatrin treatment. The results of this study indicate that vigabatrin, given in a daily dose of either 2 g or 3 g is significantly more effective than placebo in reducing seizure frequency among patients with partial seizures.

Comparison of liquid- and gas-liquid chromatographic assays of 5-fluorouracil in plasma

A liquid-chromatographic assay of 5-fluorouracil in plasma is described. Advantages of this procedure over gas chromatography are the simpler extraction procedure, elimination of the need for a derivitization step with silylating agents, and a 20-fold greater sensitivity. The minimum detectable concentration of 5-fluorouracil in plasma is 25 microgram/L. The enhanced sensitivity enabled measurement of the concentrations of 5-fluorouracil found in plasms of patients receiving continuous intravenous infusions of the drug; such concentrations are generally unmeasurable by gas-chromatographic methods. We compared liquid-chromatographic and gas-chromatographic measurements on 36 plasma samples obtained from patients after rapid intravenous injection of 5-fluorouracil. The resulting correlation coefficient was 0.97, with a regression slope of 0.94. The liquid-chromatographic method is free of interference from other cytotoxic agents, anti-emetics, and folate derivatives that are frequently combined with 5-fluorouracil therapy.

Comparison of liquid- and gas-liquid chromatographic assays of 5-fluorouracil in plasma

A liquid-chromatographic assay of 5-fluorouracil in plasma is described. Advantages of this procedure over gas chromatography are the simpler extraction procedure, elimination of the need for a derivitization step with silylating agents, and a 20-fold greater sensitivity. The minimum detectable concentration of 5-fluorouracil in plasma is 25 microgram/L. The enhanced sensitivity enabled measurement of the concentrations of 5-fluorouracil found in plasms of patients receiving continuous intravenous infusions of the drug; such concentrations are generally unmeasurable by gas-chromatographic methods. We compared liquid-chromatographic and gas-chromatographic measurements on 36 plasma samples obtained from patients after rapid intravenous injection of 5-fluorouracil. The resulting correlation coefficient was 0.97, with a regression slope of 0.94. The liquid-chromatographic method is free of interference from other cytotoxic agents, anti-emetics, and folate derivatives that are frequently combined with 5-fluorouracil therapy.

Acute conduction velocity changes in guinea-pigs after administration of diphenylhydantoin

Motor nerve conduction velocity was measured after dosing guinea-pigs with 200-400 μmol/kg diphenylhydantoin (DPH) daily for three to four days. Conduction velocity fell by a mean value of 13% in animals that achieved plasma DPH levels over 200 μmol/l. There was no change in velocity with DPH levels below this value.

Plasma carbamazepine determinations: a simple gas chromatographic method

1. A simple, rapid and specific gas chromatographic method for the measurement of plasma carbamazepine concentration is presented. 2. The extraction is a single step method, and the drug is measured by derivatization using on column methylation and standard instrumentation. 3. Other anticonvulsant agents do not co-extract. Other drugs do not interfere in the chromatogram. 4. Stability, recovery and reproducibility make this procedure suitable for routine carbamazepine measurements.

Prevalence and treatment of vitamin D deficiency in children on anticonvulsant drugs

Bone metabolism was studied in a group of adolescent epileptic children given anticonvulsant drugs and compared with a matched group of nonepileptic children living in the same institutional environment. Biochemical evidence of vitamin D deficiency was more common in treated children than in controls, and 3 out of 60 children taking anticonvulsants had radiological evidence of rickets. The signs of vitamin D deficiency could not be corrected by giving 5 μg (200 IU) cholecalciferol daily for 12 weeks, but disappeared after treatment with 75 μg (3000 IU) cholecalciferol weekly for a further 12 weeks. Thus, in a residential home in southeast England the increased nutritional requirement for vitamin D caused by the administration of anticonvulsants to adolescent epileptic children was of the order of 10 μg cholecalciferol per day. It is likely that all epileptic subjects on anticonvulsants have increased needs for vitamin D and we advise regular supplementation of their diets. It is also shown that serum concentrations of γ-glutamyl transpeptidase, 5′nucleotidase, and leucine aminopeptidase are raised in children taking anticonvulsants. It seems likely that this is caused by drug induction of membrane-bound enzymes in the liver.