Effect of vitamin D2 and D3 on bone-mineral content in carbamazepine-treated epileptic patients

Effects of new antiseizure medication on bone metabolism and bone mineral density in children: A meta-analysis

Objective

To explore the effect of new antiseizure medication on bone metabolism and bone mineral density in children.

Methods

The Chinese and English databases (PubMed, EMBASE, Cochrane Library, CNKI, Wanfang and VIP) were systematically searched for observational studies evaluating the effects of new antiseizure medication on bone metabolism and bone mineral density in children with epilepsy. The effects of new antiseizure medication on serum calcium, phosphorus, alkaline phosphatase, bone alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D and bone mineral density in children were systematically evaluated.

Results

After systematic retrieval and screening, 12 studies with high literature quality (including 629 epileptic children and 627 control subjects) were included in the systematic evaluation. Meta-analysis showed that new antiseizure medication decreased bone mineral density (MD: -0.05, 95%CI, -0.09, -0.02; P = 0.004). From different kinds of antiseizure medication, levetiracetam can reduce blood phosphorus concentration in children (MD: -0.04; 95%CI, -0.07, -0.01). Oxcarbazepine increased serum alkaline phosphatase in children (MD:17.98; 95%CI, 10.43,25.53; P < 0.00001), and the increase intensity was significantly higher than that of levetiracetam (MD: 7.66; 95%CI, 0.29, 15.02; P = 0.04). In addition, oxcarbazepine can cause a significant increase in parathyroid hormone in children (MD: 7.52; 95%CI, 3.37,11.66; P = 0.0004), and 25 - hydroxyvitamin D was reduced, and the difference was statistically significant (MD:-2.18; 95%CI, -3.23, -1.13; P = 0.00006). However, the effects of new antiseizure medication on serum calcium and bone alkaline phosphatase in children were not statistically significant.

Conclusion

New antiseizure medication have different effects on bone metabolism and bone mineral density in children with epilepsy, and the effects of different types of new antiseizure medication are different.

Impact of carbamazepine on vitamin D levels: A meta-analysis

PURPOSE

There are longstanding concerns about the impact of enzyme-inducing anti-seizure medications (ASMs) on vitamin D, an important molecule in both bone metabolism and inflammation pathways. The relationship between chronic use of carbamazepine and vitamin D levels has been studied, but no comprehensive review to inform practitioners and policymakers is currently available. We performed a meta-analysis on studies that measured 25-hydroxyvitamin D (25OHD) levels in persons taking carbamazepine to determine whether this drug significantly reduces circulating 25OHD.

PRINCIPAL RESULTS

From a literature search of the terms "carbamazepine" and "vitamin D", we identified 12 studies that measured 25OHD levels in persons on carbamazepine monotherapy groups and controls. Persons taking carbamazepine had significantly lower 25OHD levels than persons not taking carbamazepine. The average 25OHD levels of carbamazepine-treated patients across all studies was 21.8 ng/mL (IQR 15.4,26.0) whereas 25OHD levels of control subjects was 28.0 ng/mL (IQR 20.8,30.4). The weighted difference of means was 4.00 ng/mL of 25OHD. Neither age nor sex nor duration of carbamazepine therapy had a significant impact on this finding. The effect was similar irrespective of whether the comparator group consisted of healthy controls or epilepsy patients taking non-inducing medications.

MAJOR CONCLUSIONS

Carbamazepine use is associated with a reduction of 25OHD levels. In combination with other literature establishing the problematic metabolic effects of carbamazepine, this meta-analysis provides additional evidence in favor of the use of alternative ASMs as first-line agents. At minimum, vitamin D supplementation should be strongly considered for patients prescribed carbamazepine.

A Cross-Sectional Study to Assess the Modulation of Wnt Inhibitors following Anti-Epileptic Drug Therapy and their Correlation with Vitamin D and Receptor Activator of Nuclear Factor κ B Ligand in Indian Women with Epilepsy

Long-term anti-epileptic drug (AED) therapy compromises bone health. Although vitamin D deficiency is proposed to be involved, it alone is not held responsible. This accounts for investigating other mechanisms in bone accrual. Recent studies have shown modulation of inhibitors of wnt pathway, sclerostin and dickkopf-1 (DKK-1), in glucocorticoids-induced osteoporosis. We investigated whether AED monotherapy modulates wnt inhibitors in Indian women with epilepsy. Women of age > 20-40 years with the diagnosis of epilepsy and receiving AEDs (carbamazepine, valproate and levetiracetam) for at least a year were enrolled. The results were compared with age-matched healthy controls with no evidence of metabolic bone disease. Women undergoing treatment with AEDs (mean duration: 50.59 ± 37.929 months) exhibited higher serum sclerostin and receptor activator of nuclear factor κ B ligand (RANKL) and lower vitamin D (25-hydroxy vitamin D) and DKK-1 levels when compared to age-matched healthy controls. Sclerostin showed a positive correlation with RANKL, while DKK-1 presented no such relationship. However, no association was evident after adjusting for age, duration of treatment and total daily dose. Although a correlation between wnt inhibitors and RANKL could not be obtained, AEDs displayed changes in serum levels of wnt inhibitors in persons with epilepsy and hence these drugs may compromise bone health through a disturbance in wnt signalling mechanisms.

Vitamin D supplementation for bone health in adults with epilepsy: A systematic review

OBJECTIVE

Several antiepileptic drugs (AEDs) have been associated with a detrimental effect on bone health through a reduction in serum vitamin D. Subsequently, several studies have investigated the effect of vitamin D supplementation in persons with epilepsy being treated with AEDs. The present systematic review of published literature was conducted to determine the effect of vitamin D intervention on bone health in adults with epilepsy.

METHODS

The following databases were searched using keywords including but not limited to epilepsy, bone, and vitamin D: PubMed, Medline, Embase, Scopus, Cochrane Clinical Trials, International Pharmaceutical Abstracts, Health Canada Clinical Trials Database, ClinicalTrials.gov, EU Clinical Trials, and Google. Studies were eligible if there was an epilepsy diagnosis, participants were adults (18+ years old), and vitamin D treatment and bone outcome were provided. Articles were screened independently by 2 reviewers. Methodological quality was assessed using the Cochrane Collaboration's tool and a modified Newcastle Ottawa Scale for nonrandomized studies.

RESULTS

Nine studies were found to be eligible for this review. After vitamin D treatment, there appeared to be positive changes in bone turnover markers; 3 of 8 studies found the increase in serum calcium to be significant, 6 of 8 studies found the decrease in alkaline phosphatase to be significant, and 2 of 4 studies found the decrease in parathyroid hormone to be significant. All 6 studies that investigated bone mineralization had significant findings; however, due to varying methodologies, the impact of vitamin D on bone mineralization was inconclusive.

SIGNIFICANCE

Vitamin D does appear to have some benefit to bone health in adults with epilepsy, and therefore supplementation could potentially be a requisite to using some AEDs. To clarify the role of vitamin D supplementation to manage the adverse effect of AEDs on bone health in adults with epilepsy, long-term trials that use higher doses (>1800 IU) and measure bone mineral density are necessary.

Survey of risk factors for osteoporosis and osteoprotective behaviors among patients with epilepsy

The prevalence of risk factors for osteoporosis in persons with epilepsy, patients' awareness of their risk, and their engagement in osteoprotective behaviors were assessed in this study. Two hundred and sixty patients with epilepsy (F=51.5%, average age=42) completed a survey tool. Of 106 patients with a dual energy X-ray absorptiometry (DXA) result, 52% had low bone mineral density, and 11% had osteoporosis. The results suggest that the majority of patients with epilepsy do not engage in bone-protective behaviors. Those who have undergone a DXA scan may be more likely to take calcium and vitamin D supplementation compared with those who did not undergo a DXA scan, but they do not engage in other osteoprotective behaviors. Many patients did not accurately report their DXA results, indicating that better patient education is warranted.

The problem of osteoporosis in epileptic patients taking antiepileptic drugs

INTRODUCTION

Epilepsy is a common neurological disorder associated with recurrent seizures. Therapy with antiepileptic drugs (AEDs) helps achieve seizure remission in approximately 70% of epileptic patients. Treatment with AEDs is frequently lifelong and there are reports suggesting its negative influence on bone health. This is especially important in terms of general occurrence of osteoporosis, affecting over 50 million people worldwide.

AREAS COVERED

This study refers to two main groups of AEDs: hepatic enzyme inducers (carbamazepine, oxcarbazepine, phenobarbital, phenytoin, primidone and topiramate) and non-inducers (clobazam, clonazepam, ethosuximide, gabapentin, lacosamide, lamotrigine, levetiracetam, pregabalin, tiagabine, valproate, vigabatrin and zonisamide). Some reports indicate that enzyme inducers may exert a more negative influence on bone mineral density (BMD) compared to non-inducers. Bone problems may appear in both sexes during AED therapy, although women are additionally burdened with postmenopausal osteoporosis. Supplementation of vitamin D and calcium in patients on AEDs is recommended.

EXPERT OPINION

Apart from enzyme inducers, valproate (an even enzyme inhibitor) may also negatively affect BMD. However, the untoward effects of AEDs may depend upon their doses and duration of treatment. Although the problem of supplementation of vitamin D and calcium in epileptic patients on AEDs is controversial, there are recommendations to do so.

Effect of carbamazepine therapy on vitamin D and parathormone in epileptic children

Evidence suggests that carbamazepine affects bone metabolism by altering vitamin D status. We prospectively compared 25-hydroxyvitamin D, parathormone, calcium, phosphorus, and alkaline phosphatase levels at initiation and 6 months of carbamazepine therapy in children, and correlated them with carbamazepine levels. We included 47 children newly diagnosed with partial epilepsy, initiated on carbamazepine therapy. Of these, 32 were studied for 6 months. Children were managed according to standard protocol. Various parameters were measured at initiation and at 6 months. Carbamazepine levels were estimated after 6 months. Mean age was 6.72 ± 2.22 years S.D. Mean 25-hydroxyvitamin D was 14.45 ± 9.77 ng/mL S.D. and 11.31 ± 9.15 ng/mL S.D. at baseline and 6 months (P = 0.023), respectively (21.7% decline). Mean parathormone increased from 34.24 ± 21.38 pg/mL S.D. to 45.01 ± 24.46 pg/mL S.D. (P = 0.001). Change in vitamin D correlated negatively with change in parathormone (r = -0.404, P = 0.022). Serum alkaline phosphatase increased from 283.50 ± 100.10 IU/L S.D. to 364.25 ± 126.98 IU/L S.D. (P < 0.001). Changes in vitamin D and parathormone did not correlate significantly with carbamazepine level. Carbamazepine therapy decreased levels of vitamin D. Hence vitamin D monitoring and supplementation may help prevent alterations in bone metabolism.

The effect of oxcarbazepine on bone metabolism

OBJECTIVE

Long term use of several antiepileptic drugs is known to cause alteration in bone metabolism. Therefore, we investigated the effect of new antiepileptic drug, oxcarbazepine, on bone metabolism.

METHODS

Twenty eight patients who were on oxcarbazepin therapy (18 female, 10 males; mean age: 27.82 +/- 10.98 years (range: 15-45)) with no additional antiepileptic drug use history in one year period prior to the study and 28 control subjects were involved in the study. Measurement of calcium, phosphate, alkaline phosphatase and Vitamin D3 levels and bone density measurements with DEXA method were performed in patient and age-matched control groups. The baseline parameters were compared with the control group and with those measured at the end of one year.

RESULTS

The biochemical (calcium, phosphate, alkaline phosphatase and Vitamin D3) parameters and densitometry values after one year of therapy were not different than the baseline values indicating that those were not affected by the therapy (P > 0.05).

CONCLUSIONS

In previous studies, anticonvulsant drugs that induce enzymes increase bone degradation by causing vitamin D deficiency. According to the results of this study, oxcarbazepin with little effect on enzyme induction was shown not to affect bone mineral metabolism.

Evaluation of bone turnover in epileptic children using oxcarbazepine

This study evaluated the effects of oxcarbazepine monotherapy on bone turnover in prepubertal and pubertal children. Thirty-four newly diagnosed pediatric patients with normal bone mineral density, serum biochemical markers of bone formation, and hormonal markers participated. Levels of 25-hydroxyvitamin D were significantly decreased after therapy compared with baseline values. Levels of gamma-glutamyl transferase, phosphorus, alkaline phosphatase, osteocalcin, parathyroid hormone, and calcitonin had increased. However, only changes in osteocalcin and gamma-glutamyl transferase levels were statistically significant compared with baseline values. Drug-induced osteopenia was evident in 3 patients with z scores of bone-mineral density less than -2.0, whereas these patients had z scores of less than -1.5 before treatment. Although 18 months of oxcarbazepine treatment exerted slightly adverse effects on bone metabolism, the effect seems insignificant in children with normal bone-mineral density. Although alterations in bone metabolism do not always suffice to explain the decrease in bone-mineral metabolism, we think that patients with osteopenia before the initiation of oxcarbazepine therapy should be followed carefully, especially in long-term treatment.

A 6-month longitudinal study of bone mineral density with antiepileptic drug monotherapy

Antiepileptic drugs (AEDs) can affect bone metabolism, but the exact mechanisms or differences in individual drugs are still unknown. The purpose of this study was to prospectively investigate the alterations in bone mineral density (BMD) and markers of bone metabolism induced by different AEDs in Koreans with epilepsy. Subjects included 33 drug-naïve, newly diagnosed patients with epilepsy aged between 18 and 50. BMD at right calcaneus and various markers for bone metabolism were measured before and after 6months of AED monotherapy including carbamazepine, valproic acid, and lamotrigine. Carbamazepine caused a significant decrease in BMD, which was accompanied by a decrease in the level of vitamin D (25-OHD(3)). BMD and vitamin D were not affected by 6months of valproic acid or lamotrigine therapy. Interestingly, valproic acid and lamotrigine, but not carbamazepine, significantly increased osteocalcin, a marker of bone formation. All AEDs almost doubled the parathyroid hormone level, whereas urinary Pyrilinks, a marker of bone resorption, was not affected by those AEDs. These findings suggest that carbamazepine, a hepatic enzyme-inducing drug, decreases BMD.

Bone mineral status in pediatric outpatients on antiepileptic drug monotherapy

Drug-induced osteopenia has been reported in institutionalized children on chronic antiepileptic drug therapy. The aim of this study was to assess longitudinally bone mineral status in pediatric outpatients on antiepileptic drug monotherapy. The study group consisted of 30 ambulatory children on a normal diet: 15 on valproic acid, 11 on carbamazepine, and 4 on phenobarbital monotherapy. Bone mineral density, serum active vitamin D (1,25-dihydroxyvitamin D), and certain biochemical markers of bone formation (calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone, osteocalcin, calcitonin, and urinary calcium to serum creatinine and urinary phosphorus to serum creatinine ratios) were studied at the beginning of antiepileptic drug monotherapy and at the end of 2 years of treatment. Age- and sex-specific Z-scores of bone mineral density were measured at anterior-posterior L2-L4 by dual-energy x-ray absorptiometry. Drug-induced osteopenia was defined in only two patients (one on carbamazepine and the other on phenobarbital monotherapy), with Z-scores of bone mineral density less than -1.5. Serum levels of active vitamin D and biochemical markers were not significantly correlated with the Z-scores of bone mineral density. We detected a frequency of antiepileptic drug-induced osteopenia of 6.7% in pediatric outpatients after 2 years of monotherapy. However, osteopenia was not attributed to a defect in serum active vitamin D production owing to hyperparathyroidism in children on antiepileptic drug monotherapy.

Epilepsy, osteoporosis and fracture risk - a meta-analysis

This meta-analysis assesses the effects of epilepsy on fracture risk and changes in bone mineral density (BMD) in patients with epilepsy. A search of PubMed was conducted using the key words epilepsy, fracture, and bone mineral. A weighted estimate of relative risk of fractures and changes in BMD (Z-score) was calculated. From the changes in BMD, expected increase in relative fracture risk was calculated. A total of 11 studies on fracture risk and 12 studies on BMD were retrieved. The relative risk of any fracture was increased (2.2, 95% CI: 1.9-2.5, five studies), as was the risk of hip (5.3, 3.2-8.8, six studies), forearm (1.7, 1.2-2.3, six studies), and spine fractures (6.2, 2.5-15.5, three studies). A large proportion of fractures (35%) seemed related to seizures. Spine (mean +/- SEM: -0.38 +/- 0.06) and hip (-0.56 +/- 0.06) BMD Z-scores were significantly decreased, hip more than spine (2P < 0.05). The expected increases in relative risk of any fracture from BMD Z-scores were 1.2-1.3, and significantly lower than observed (2P < 0.05). The deficit in BMD in patients with epilepsy is too small to explain the observed increase in fracture risk. The remainder of the increase in fracture risk may be linked to seizures.

Induction of endogenous pathways by antiepileptics and clinical implications

The aim of this study was to review modifications of the endogenous pathways (e.g. enzyme elevations, normal body constituent depletion or higher formation/excretion of endogenous metabolites) which could be ascribed to enzyme induction by antiepileptic drugs (AEDs). Information on older (e.g. phenobarbital, phenytoin and carbamazepine) and newer drugs (where information is available) is discussed together with clinical implications. The enzymes involved in the endogenous pathways and induced by the AEDs will not be limited to the hepatic microsomal enzymes; extrahepatic enzymes and/or enzymes present in other subcellular fractions will also be discussed, if pertinent. The induction of endogenous pathways by AEDs has been taken into account in the past, but much less emphasis has been given compared with the extensive literature on induction by AEDs of the metabolism of concomitantly administered drugs, either of the same or of different classes. Not all of the endogenous pathways examined and induced by AEDs appear to result in serious clinical consequences (e.g. induction of hepatic ALP, increased excretion of d-glucaric acid or of 6 beta-hydroxycortisol). In some cases, induction of some pathways (e.g. increase of high-density lipoprotein cholesterol or of conjugated bilirubin) might even be a beneficial side-effect, however enzyme induction is considered rather a detrimental aspect for an AED, as induction is generally a broad and a non-specific phenomenon. The new AEDs have generally less induction potential than the older agents. Yet some (felbamate, topiramate, oxcarbazepine and lamotrigine) have the potential for inducing enzymes, whereas others (levetiracetam, gabapentin and vigabatrin) appear to be completely devoid of enzyme inducing characteristics, at least as far as the enzymes investigated are concerned.

Effect of carbamazepine and valproate on bone mineral density

The objective of this study was to examine the effect of carbamazepine and valproate monotherapy on bone mineral density in children. Femoral neck area bone mineral density was measured by dual-energy x-ray absorptiometry in 31 healthy children and 33 children with idiopathic epilepsy treated with either carbamazepine (n = 17) or valproate (n = 16) for more than 6 months. There were no significant differences between the control and study patients in age, height, weight, and physical activity. No patient had dietary restrictions or neurologic impairment. Serum levels (as mean +/- S.D.) of valproate and carbamazepine were 53.75 +/- 23.94 microg/mL and 6.26 +/- 2.00 microg/mL, respectively, and the duration of treatment for each drug was 24.38 +/- 10.58 months and 31.76 +/- 16.33 months, respectively. Calcium intake in the diet was similar in both the control and study groups. In the valproate-treated group, 25% of the patients were hypocalcemic, 6% had elevated alkaline phosphatase levels, and 50% were hypophosphatemic. In the carbamazepine-treated group, 17.6% of the patients were hypocalcemic and 35.3% were hypophosphatemic. Children treated with valproate had 31.9% reduction in bone mineral density at the femoral neck area (P < 0.05); the 20% reduction in bone mineral density in this anatomic location in carbamazepine-treated children was not significant. In conclusion, valproate monotherapy, but not carbamazepine therapy, significantly reduces femoral neck area bone mineral density in children with idiopathic epilepsy.

Antiepileptic drugs and reduced bone mineral density

There is a growing interest in recognizing the association between antiepileptic drugs and reduced bone mineral density. Although the literature regarding this association has been available for more than three decades, the management of this complication remains unclear. We review the relevant literature regarding antiepileptic drugs and reduction in bone mineral density with the aim of developing some guidelines for practical management of this problem. This review focuses on the mechanism of antiepileptic drug-induced bone loss, its recognition, and its management.

Epilepsy and bone health in adults

Adults taking antiepileptic drugs (AEDs) have an augmented risk for osteopenia and osteoporosis because of abnormalities of bone metabolism associated with AEDs. The increased fracture rates that have been described among patients with epilepsy may be related both to seizures and to AEDs. The hepatic enzyme-inducing AEDs phenytoin, phenobarbital, and primidone have the clearest association with decreased bone mineral density (BMD). Carbamazepine, also an enzyme-inducing drug, and valproate, an enzyme inhibitor, may also adversely affect bone, but further study is needed. Little information is available about specific effects of newer AEDs on bone. Physicians are insufficiently aware of the association between AEDs and bone disease; a survey found that fewer than one-third of neurologists routinely evaluated AED-treated patients for bone disease, and fewer than 10% prescribed prophylactic calcium and vitamin D. Physicians should counsel patients taking AEDs about good bone health practices, and evaluation of bone health by measuring BMD is warranted after 5 years of AED treatment or before treatment in postmenopausal women.

Analysis of the musculoskeletal system in children and adolescents receiving anticonvulsant monotherapy with valproic acid or carbamazepine

OBJECTIVE

To examine bone development in children and adolescents who have uncomplicated idiopathic epilepsy and had received monotherapy with carbamazepine or valproic acid for at least 1 year.

METHODS

Thirty-nine patients from 6 to 19 years of age (18 girls) were studied. Total bone mineral content (BMC) and trabecular volumetric bone mineral density were measured at the distal radius using peripheral quantitative computed tomography. Maximum isometric grip force was determined with a standard dynamometer. Alkaline phosphatase activity and deoxypyridinoline (a marker of bone resorption) were assessed in serum and urine, respectively.

RESULTS

Trabecular volumetric bone mineral density was significantly decreased in the entire group (z score mean +/- standard deviation: -0.62 +/- 1.04) and in the subgroup using valproic acid (-0.75 +/- 1.18). In the carbamazepine subgroup, there was a similar but nonsignificant trend (-0.50 +/- 0.90). Total BMC and isometric maximum grip force were normal in the entire study population (0.10 +/- 1.22) and in the 2 subgroups. The relationship between BMC and grip force was similar between patients and healthy participants. Urinary levels of deoxypyridinoline were significantly elevated above normal in the whole study population (1.35 +/- 2.00) and in both the valproic acid and the carbamazepine subgroups.

CONCLUSIONS

Bone turnover can be increased, but bone mass is adequate in children and adolescents who have uncomplicated idiopathic epilepsy and who receive monotherapy with carbamazepine or valproic acid.

Adverse effects of antiepileptic drugs on bone structure: epidemiology, mechanisms and therapeutic implications

Antiepileptic drugs (AEDs) were first associated with disorders of bone in both adults and children in the late 1960s. The most severe manifestations of these disorders are osteopenia/osteoporosis, osteomalacia and fractures. Bone disease has been described in several groups of patients receiving AEDs. Groups identified as being more vulnerable to AED-associated bone disease include institutionalised patients, postmenopausal women, older men and children. Radiological and histological evidence of bone disease is found in patients taking AEDs. Numerous biochemical abnormalities of bone metabolism have also been described. The severity of bone and biochemical abnormalities is thought to correlate with the duration of AED exposure and the number of AEDs used. In monotherapy, the AEDs most commonly associated with altered bone metabolism are phenytoin, primidone and phenobarbital (phenobarbitone). To date there have been no reports of altered bone metabolism in individuals receiving the newer anticonvulsants (specifically lamotrigine, topiramate, vigabatrin and gabapentin). The mechanisms of AED-associated bone disease are not clearly elucidated; however, several theories have been proposed to explain the link. No definitive guidelines for evaluation or treatment have yet been determined.

Effects of antiepileptic drugs on hormones

A hormone is an intrinsic substance carried via the blood to a target organ which is then functionally stimulated. Similar to extrinsically administered medications, the metabolism and function of the hormones may be altered by antiepileptic drugs (AEDs). The proposed mechanisms are (a) enhanced metabolism (natural steroids, synthetic steroids, e.g., decadron and birth control pills, thyroxine, and vitamin D3), (b) altered protein bonding (thyroxine, sex hormones), (c) impaired release into the systemic circulation (calcitonin, insulin, vitamin K clotting factors) and (d) altered end-organ effect. The AEDs most likely to interact with hormones are barbiturates, carbamazepine, and phenytoin.

Effects of carbamazepine on serum electrolytes in affectively ill patients

The effects on serum electrolytes of carbamazepine, an acute and prophylactic treatment for manic-depressive illness, were assessed in subjects with primary affective disorder. Carbamazepine caused statistically significant, but clinically insubstantial, reductions in serum sodium and calcium, but not in the other electrolytes measured. Decreases in serum sodium and calcium were not related to carbamazepine dose, blood levels, or the degree of clinical improvement. The theoretical implications of these findings are discussed.

Different metabolism of vitamin D2 and vitamin D3 in epileptic patients on carbamazepine

Serum concentrations of vitamin D metabolites were measured in 30 epileptic outpatients on monotherapy with carbamazepine before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks. Vitamin D2 treatment increased the serum concentration of 25OHD2, but a corresponding decrease in 25OHD3 resulted in an unchanged serum value of total 25OHD. Vitamin D3 treatment increased the serum concentration of 25OHD3. The resulting serum level of 25OHD was consequently twice the level of that in the D2-treated group. The serum concentrations of the dihydroxy metabolites showed a similar difference between the 2 treatment groups. We conclude that treatment with vitamins D2 and D3 in the same doses produces considerably different serum concentrations of vitamin D metabolites. If the present findings can be extrapolated to normal subjects, it is important to consider more carefully which D-vitamin should be used, both with regard to therapy and supplementation.