|Year : 2013 | Volume
| Issue : 4 | Page : 358-366
Risk assessment of folic acid supplementation in phenytoin-treated epileptic patients: A pilot study
Abhishek Singh Nayyar1, Mubeen Khan2, GT Subhas3, B Nataraju3, M Anitha4
1 Department of Oral Medicine and Radiology, Saraswati-Dhanwantari Dental College and Post-Graduate Research Institute, Parbhani, Maharashtra, India
2 Department of Oral Medicine and Radiology, Government Dental College and Research Institute, Bangalore, Karnataka, India
3 Department of Neurology, Bangalore Medical College and Research Institute, Bangalore, Karnataka, India
4 Department of Clinical Biochemistry, Bangalore Medical College and Research Institute, Bangalore, Karnataka, India
|Date of Submission||11-Jun-2013|
|Date of Acceptance||21-Jul-2013|
|Date of Web Publication||15-Oct-2013|
Abhishek Singh Nayyar
H.No. 44, Behind Singla Nursing Home, New Friends'Colony, Model Town, Panipat - 132 103, Haryana
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: There have been studies that report clinical benefits of the use of folic acid as an adjuvant to the antiepileptic therapy in the prevention of antiepileptic drug-induced gingival enlargement. However, studies conducted in the past have also reported precipitation of epileptic attacks in patients on folic acid adjuvant therapy due to fall in sera levels of phenytoin due to drug interactions. The study was planned to investigate the association of phenytoin-induced gingival enlargement and sera levels of folic acid in epileptic patients on phenytoin therapy. Subjects and Methods: A total of 25 patients aged between 18 and 50 years clinically diagnosed with epilepsy prior to the start of phenytoin therapy were included based on selection criteria and written informed consents were obtained. Assessment of serum folic acid levels and gingival enlargement was done prior to the start of and after 6 months of phenytoin therapy. The statistical analysis was done using t-test and the baseline serum folate levels and the serum folate levels obtained after 6 months of phenytoin therapy were correlated with the respective grades of gingival enlargement using Pearson's coefficient formula. Results: The results of the study confirmed a significant association between low serum folate levels with increasing severity as well as an early onset of phenytoin-induced gingival enlargement justifying the judicious use of folate supplementation to prevent this inadvertent side effect of phenytoin administration. Conclusions: The results of the study suggest a higher incidence of gingival enlargement in phenytoin-treated epileptic patients with a positive correlation with falling serum folic acid levels as the duration of the therapy increases.
Keywords: Epilepsy, folic acid, gingival enlargement, phenytoin
|How to cite this article:|
Nayyar AS, Khan M, Subhas G T, Nataraju B, Anitha M. Risk assessment of folic acid supplementation in phenytoin-treated epileptic patients: A pilot study. Int J Nutr Pharmacol Neurol Dis 2013;3:358-66
|How to cite this URL:|
Nayyar AS, Khan M, Subhas G T, Nataraju B, Anitha M. Risk assessment of folic acid supplementation in phenytoin-treated epileptic patients: A pilot study. Int J Nutr Pharmacol Neurol Dis [serial online] 2013 [cited 2019 Aug 22];3:358-66. Available from: http://www.ijnpnd.com/text.asp?2013/3/4/358/119846
| Introduction|| |
Despite the tremendous advances in the management of epilepsy, phenytoin still remains the drug of choice; however, the long-term administration of phenytoin has been seen to lead to a number of adverse effects. Gingival enlargement is a frequently reported adverse effect of phenytoin. , Approximately, 40%-50% of the patients treated with phenytoin develop esthetically disfiguring enlargement of the gingivae. Whenever occurs, this adverse effect of phenytoin lasts throughout the period of therapy and continues further with a severe reduction in the quality of life of the affected individual. ,
The etiopathogenesis of phenytoin-induced gingival enlargement is still not clearly understood; however, many studies indicate its multifactorial etiology. , It has also been seen that phenytoin is not only responsible for the initiation of the enlargement of the gingival tissue but has also been noted to interfere with folic acid metabolism especially, absorption thereby leading to a significant decrease in the plasma as well as the tissue levels of folates. 
Folates administered at pharmacological doses, on the contrary, though have been seen to lead to a substantial decrease in the incidence of gingival enlargement,  have been blamed for a significant decrease in the serum concentration of phenytoin severe enough to precipitate seizures. ,, The use of folates as an adjuvant to the antiepileptic therapy in the prevention of gingival enlargement, therefore, mandates further clinical and laboratory evaluation.
On the basis of the conclusions drawn from the various studies correlating decreased plasma and tissue folate levels with phenytoin-induced gingival enlargement, folic acid has been tried, both topically and systemically, to prevent this inevitable adverse effect of long-term phenytoin therapy.  There has been consistent void, however, in research in assessing serum folic acid levels in epileptic patients and their correlation with the onset and severity of phenytoin-induced gingival enlargement starting from the beginning of phenytoin treatment. Hence, the present study was designed to investigate the association of phenytoin-induced gingival enlargement with serum folate levels in phenytoin-treated epileptic patients. The aim of the study was to find an etiological role, if any, of folic acid behind antiepileptic drug, phenytoin-induced gingival enlargement so as to initiate research on an important question that has been raised in the past regarding the safety of the use of folate adjuvants in the prevention of this inevitable side effect of the drug, although associated with a risk of precipitation of epileptic attacks due to a significant propensity for drug interactions leading to decreased sera phenytoin levels, severe enough to precipitate seizures. The objectives of the study were to study the incidence and assess the scores of gingival enlargement in epileptic patients before and after 6 months of phenytoin therapy; to assess serum folic acid levels before and after 6 months of phenytoin therapy and to correlate the scores of gingival enlargement with serum folic acid levels in patients on phenytoin therapy.
| Subjects and Methods|| |
Source of data
A total of 25 patients visiting the Department of Neurology, Victoria Hospital, Bangalore during the period of Jan 2009 to Dec 2009 clinically diagnosed with epilepsy were selected prior to the start of phenytoin therapy based on the defined inclusion and exclusion criteria.
Method of collection of data
Selected epileptic patients in the age group of 18-50 years, who were clinically diagnosed with epilepsy and being started with phenytoin therapy and who were with full complement of teeth without any carious or periodontal involvement or any other pathological process in the teeth and the jaws, were explained in detail about the planned study and written informed consents were obtained. The patients were exclusively being started on phenytoin therapy and were not supposed to take any other medication apart from phenytoin throughout the course of the study. The patients who required polytherapy with other drugs in combination with phenytoin were excluded from the study. These patients were subjected to a detailed history and a thorough clinical examination using a specially prepared proforma.
Epileptic patients with other systemic diseases; with preexisting gingival enlargements due to any reasons as idiopathic, inflammatory, neoplastic, endocrinal, chronic vitamin C deficiency, mouth breathing or pregnancy; epileptic patients on any type of pharmacologic therapy including multivitamins or, folate antagonists; and who had history of dental treatment and trauma to teeth were excluded from the study.
On the basis of the selection criteria, 25 patients clinically diagnosed with epilepsy were enrolled in the study with their written informed consents and then subjected to a thorough oral prophylaxis, routine hematological examination, and serum folic acid level assessment. Before the start of study, the ethical clearance was obtained by the ethical committee of the institution as well as from Bangalore Medical College and Research Institute and Associated Hospitals.
Assessment of serum folic acid
Assessment of serum folic acid level was done by chemiluminiscent method [Figure 1] using Immulite kit [Figure 2] prior to the start of phenytoin therapy. A gap of a minimum of 10 h after the last meal followed by intake of drug was considered as the standard fasting period in the patients. Following this, 5 mL of venous blood was taken from patients from the antecubital vein using a sterile disposable syringe in the sitting position between 8 A.M. and 10 A.M. Serum was immediately separated by ultracentrifugation. The supernatant was discarded and the rest of the sample was stored at −20°C [Figure 3]. The flurometer was set at 370 nm excitation with emission monitored at 470 nm. Flow rate was adjusted as 1.3 mL/min [Figure 4].
|Figure 1: Immulite 1000 system, siemens ref LKFO1, lot 0305, smn 10380902 equipment for assessment of serum folic acid levels by chemiluminiscent immunoassay system|
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|Figure 2: Immulite 1000 folic acid chemiluminiscent immunoassay kit with sera samples|
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|Figure 4: Immulite 1000 system, siemens ref LKFO1, LOT 0305, and smn 10380902 equipment for assessment of serum folic acid levels by chemiluminiscent immunoassay system with running samples|
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Controls were assessed only once based on their inclusion according to age and sex. They were free of any systemic disease process and were not on any drugs including supplementation with synthetic vitamin supplements or the drugs which could have interfered with the absorption of such nutrients.
After a gap of 1 week, these patients were thoroughly examined and their gingival status assessed using the index originally described by Angelpoulous and Goaz , and later, modified by Miller and Damm (GO INDEX) ,, [Figure 5].
|Figure 5: Clinical picture of gingival status in a male epileptic patient before the start of phenytoin therapy, after 1 week of oral prophylaxis|
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Assessment of gingival enlargement
The gingival status was assessed using the [GO INDEX]. ,, There were a total of four investigators who assessed gingival enlargements and were blinded to the purpose of the study as well as blinded to the sera levels of folic acid. The height of gingival tissue was measured from the cementoenamel junction to the free gingival margin. The grades for gingival enlargement were assessed in relation to the six anterior teeth in both the maxillary and mandibular arches based on the findings of the previous studies of the more common involvement of the anterior segments of the jaws, both on the mesial and the distal interproximal aspects and the greater score among them was selected to be included to refer to the peak effect of the drug. ,,
After a period of 2 months, the patients were reviewed and their gingival scores reassessed [Figure 6], using the same criteria. The same procedure was repeated at the end of 6 months [Figure 7] and [Figure 8] of phenytoin therapy and serum folic acid levels assessed before the morning dose of phenytoin. Results were tabulated and subjected to statistical analysis.
|Figure 6: Clinical picture of gingival enlargement in a male epileptic patient (Grade 1) after 2 months of initiation of phenytoin therapy|
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|Figure 7: Clinical picture of gingival enlargement in a male epileptic patient (Grade 2) after 6 months of phenytoin therapy|
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|Figure 8: Clinical picture of bulbous gingival enlargement in a female epileptic patient with more prominent involvement of the interdental papillae (Grade 3) after 6 months of phenytoin therapy|
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Method of statistical analysis
The statistical analysis was done using t-test and the baseline serum folate levels, and the serum folate levels obtained after 6 months of phenytoin therapy were correlated with the respective grades of gingival enlargement using Pearson's coefficient formula.
| Results|| |
The present study was designed in the Department of Oral Medicine and Radiology, Government Dental College and Research Institute, Bangalore during the period of Jan 2009 to Dec 2009 to assess the correlation between phenytoin-induced gingival enlargement and serum folate levels. Selected epileptic patients to be enrolled in the study based on defined inclusion and exclusion criteria were explained in detail about the planned study and written informed consents were obtained.
The study consisted of a total of 25 patients with 19 males (76%) and 6 females (24%) patients. The mean age of the study group was 30.08 years with an age range of 18-50 years. The mean age of the 19 male patients included in the study was 30.26 years with an age range of 18-50 years, while for the 6 female patients with an age range of 20-36 years, the mean age was calculated to be 29.5 years.
The study revealed a higher incidence of gingival enlargement in phenytoin-treated epileptic patients with the observation of gingival enlargement in all patients in the test group after 6 months of phenytoin administration, though to varying grades.
The study also observed serum folic acid levels in selected epileptic patients prior to the start of and after 6 months of phenytoin therapy in addition to the age- and sex-matched controls. Assessment of serum folic acid level was done by chemiluminiscent method using Immulite kit.
Average serum folate level in our study was 7.48 ± 3.91 ng/mL prior to the start of phenytoin therapy with an average serum folate level of 7.16 ± 2.19 ng/mL and a range of 3.87−10.9 ng/mL for the male and 8.49 ± 1.06 ng/mL with a range of 6.62-9.39 ng/mL for the female patients. The average serum folate level for the age- and sex-matched 10 control samples was found to be 14.46 ± 2.81 ng/mL.
The gingival status was assessed using the index originally described by Angelopoulos and Goaz and later, modified by Miller and Damm (GO INDEX) prior to the start of and after 6 months of phenytoin therapy.
The average score of gingival enlargement prior to the start of phenytoin therapy in our study was found to be 1.7 ± 0.23. In our study, an average grade of 1.74 ± 0.21 was obtained for the gingival enlargement in the 19 male patients included in the study with a range of 1.33-2.17 and 1.58 ± 0.26 with a range of 1.33-2.08 for the 6 female patients. Among these, 22 patients were found to have an approximate grade 2, while 3 patients were seen with grade 1 gingival enlargement.
After 6 months of phenytoin therapy, the average serum folate level in the study group was found to be 3.9 ± 5.31 ng/mL with an average 3.63 ± 2.01 ng/mL for the male, while 4.77 ± 1.58 ng/mL for the female patients with a range of 2.02-8.71 ng/mL and 2.46-7.43 ng/mL, respectively.
After 6 months of phenytoin treatment, average grade for gingival enlargement was found to be 2.04 ± 0.38 with a range of 1.17-2.67 in the male patients, while 2.14 ± 0.23 with a range of 1.83-2.42 for the female patients. Among these, 20 patients were found to have nearing grade 2; 2 patients, grade 1; and 3 patients, grade 3 gingival enlargement.
The statistical analysis was done using t-test and the baseline serum folate levels and the serum folate levels obtained after 6 months of phenytoin therapy were then correlated with the respective grades of gingival enlargement using Pearson's coefficient formula.
The results arrived found the reduction in mean serum folate levels before and after 6 months of phenytoin treatment to be statistically significant [Table 1]. The increase in mean gingival enlargement from before to after 6 months of phenytoin therapy was also found to be statistically significant [Table 2]. In either case, the P value came out to be less than 0.001 with the level of significance kept at 0.05.
|Table 1: Table depicting comparison of mean serum folate levels in the test group before and after 6 months of phenytoin treatment|
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|Table 2: Table depicting comparison of mean grades for gingival enlargement in the test group before and after 6 months of phenytoin treatment|
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A positive correlation was also noted between the mean serum folate levels and the mean gingival enlargement before [Figure 9] and after 6 months of phenytoin treatment [Figure 10].
|Figure 9: Scatter diagram comparing mean serum folate levels and grades for gingival enlargement before initiation of phenytoin treatment Along X-axis- Mean serum folate levels in ng/mL, Along Y-axis- Grades for gingival enlargement|
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|Figure 10: Scatter diagram comparing mean serum folate levels and grades for gingival enlargement after 6 months of phenytoin treatment|
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| Discussion|| |
Despite tremendous advances in the management of epilepsy in the recent decade, the antiepileptic drug phenytoin still remains the prime drug of choice in the management of epileptic patients in India. ,
Chronic administration of phenytoin has been associated with a number of adverse effects. , Phenytoin-induced gingival overgrowth is one such most frequently reported gingival lesion which was first described in 1939, although the exact etiology still remains controversial and deficient sera and tissue level folates being ascribed as one of the most important causes. ,
Phenytoin administered at therapeutic dosages has been shown to deplete plasma folate concentrations in humans (Pisciotta, 1982). This has been later confirmed in other studies as well. While the details of these interactions remain obscure, several potential mechanisms have been proposed as explanations. One of the first hypotheses suggested that phenytoin increased the pH of the small intestine inhibiting the intestinal conjugase activity (Hoffbrand and Necheles, 1968) impairing the intestinal absorption of folates by the anticonvulsant drugs (Meynell, 1966; Dahlke and Mertens-Roesler, 1967). A total of 80% of the folates are present in the diet in the form of nonabsorbable polyglutamates (Butterworth, Santini and From Meyer, 1963) which are deconjugated by the intestinal enzyme conjugase into absorbable monoglutamates during absorption (Rosenberg and Streiff, 1967). The phenytoin-generated increase in gut pH was hypothesized to decrease the driving force of the proton pump which supplied the energy for at least one folate transporter in the gut (Schron, 1991). Other hypotheses include direct competition between folate and phenytoin for uptake sites (Rosenberg et al., 1979), inhibition of folate interconverting enzymes by phenytoin (Carl and Smith, 1983), increased catabolism of folates by phenytoin induction of folate catabolic enzymes (Chanarin, 1979), and inhibition of central appetite centers by phenytoin decreasing food intake and thereby leading to decreased tissue folate concentrations (Hoppner and Lampi, 1989).
The fact that anticonvulsant drugs are known to induce hepatic enzymes led to a further series of hypotheses. Richens and Waters have suggested that folate deficiency in long-term phenytoin users might arise due to induction of enzymes involved in folate metabolism. Maxwell et al., proposed that folate deficiency in phenytoin users might be a result of an increase in the demand for the folate coenzymes required either for the anticonvulsant drug hydroxylations or for other hepatic enzymes induced by these drugs.
A number of possible explanations are also cited to account for the gingival enlargement seen in long-term phenytoin users correlating them with folate levels at serum and tissue levels. Phenytoin is not only responsible for the initiation of gingival enlargement but also for the interference of folic acid absorption thereby leading to a significant decrease in the folate levels (Norris and Pratt, 1974, Mallek and Nakamato, 1981, Lewis et al., 1995) suggested to be one of the important promoters of phenytoin-induced gingival enlargement (Vogel, 1977), a hypothesis later corroborated by Backman et al., (1989). There have been studies that report clinical benefits of systemic and/or topical usage of folic acid in delaying the onset and reducing the incidence as well as severity of phenytoin-induced gingival enlargement. It is also hypothesized that folic acid interferes with the production of p-HPPH, a major byproduct of phenytoin metabolism known to lead to phenytoin-induced gingival enlargement in epileptic patients. 
Numerous studies in the past suggest the possible role of folic acid in the prevention of phenytoin-induced gingival enlargement as well as its recurrence following a surgical removal. ,, In a study conducted by Arya et al., 120 pediatric patients that developed gingival hyperplasia due to phenytoin use were included and followed up for 6 months. During the study, 62 patients were treated with folic acid against 58 patients who were kept on placebo. Gingival hyperplasia was found to be significantly reduced in patients treated with folic acid. However, a limitation of the study was that folate levels were not measured in either the control or treatment groups.  To add, the results of most of the studies indicate that topical folates lead to a significantly inhibited gingival hyperplasia than either systemic folate or placebo group.  A recent study, however, has also concluded that systemic folic acid prescribed along with phenytoin reduces the incidence and delays the onset and severity of phenytoin-induced gingival enlargement. 
The impact of adding folic acid to a stable regimen of phenytoin to correct folate deficiency is often underrated. While correction of folate deficiency is required in such case, administration of large doses of folic acid has been seen to decrease blood levels of phenytoin, potentially interfering with seizure control. ,,,,, The mean decrease in total serum phenytoin level after addition of 1 mg of daily folic acid given orally is about 20%, while it might reach as high as 40% in case of a daily 5 mg supplementation, a reduction severe enough to lead to breakthrough seizures in a stable epileptic patient. Pharmacokinetic studies of this interaction strongly suggest that folic acid is a cofactor in the metabolism of phenytoin. Higher levels of folic acid appear to increase the affinity of the metabolizing enzymes, thus greatly increasing the efficiency of phenytoin degradation.  In addition to interfering with the anticonvulsant drug metabolism, high dose folic acid itself may be epileptogenic, the exact mechanism behind this too although remains obscure. Intravenous administration of 14.4 mg of folic acid has been seen to induce a tonic-clonic seizure in an epileptic patient although other patients experienced no adverse effects even when administered 75 mg of folic acid in one dose.  Precipitation of epileptic seizures has been seen in a female epileptic patient prescribed 0.8 mg of folic acid on a daily basis so as to correct folate deficiency in view of her expected future pregnancy  although a dose of 100−1,000 mcg/day has been found by most of the neurophysicians to be sufficient to prevent folate deficiency without impairing seizure control.  On the basis of these observations, it can be concluded that modest doses of folic acid can be used to treat folate deficiency in epileptic patients; however, larger clinical trials with greater sample sizes and an adequate representation of patients from different age and sex are required to arrive at a definitive conclusion before folic acid could be declared as a safer and standardized adjuvant to conventional antiepileptic therapy.
The study revealed a high incidence of gingival enlargement in epileptic patients on phenytoin therapy with the observation of varying grades of gingival enlargement in all patients in test group after 6 months of phenytoin administration.
Numerous reports suggest that phenytoin-induced gingival enlargement is more commonly seen in younger age groups. This is in concordance with the observations of the several epidemiological studies conducted by Thomason et al., 1992, Steinberg and Steinberg, 1982, Dahllof and Modeer, 1986, and Stinnett et al., 1987. Also, both genders have been reported to be equally susceptible to phenytoin-induced gingival enlargement in the literature.  The above-mentioned observations were confirmed in our study as well.
The incidence of phenytoin-induced gingival enlargement as reported by a study conducted by Kimball was found to be 57%, while other studies conducted in relation to incidence of phenytoin-induced gingival enlargement have revealed wide incidence ranges of 20-40%, , in some studies to 6-79% in others, ,,,,, while 3-93% in few other studies , and 50% in institutionalized epileptic patients (Seymour, 1993) as reported in the literature. The incidence of gingival overgrowth in the normal population has been reported to be between 4% and 7.5%.  This wide range of variability may be attributed to the small number of the cases reported in some publications to large variations in phenytoin dosages to variations in the length of phenytoin exposure and to differences in the age of the patients included in the various studies as well.
Drug-induced gingival enlargement normally begins at the interdental papillae and is more frequently found in the anterior segments of the jaws, though it often involves all the surfaces of teeth and is generalized in its distribution. ,, Gradually, gingival lobulations are formed that may appear inflamed or more fibrotic in nature depending on the degree of local factors' induced secondary inflammatory changes.
All the clinical features of phenytoin-induced gingival enlargement were confirmed in our study, wherein we observed a predominantly firm and fibrotic nature of the gingival enlargement in most of the patients with local factors' induced secondary inflammatory changes having a minor role, if any, to play in the clinical picture of the phenytoin-induced lesions of gingival enlargement as the oral hygiene was meticulously maintained. The observations of our study also revealed that interdental papillae were the most common sites of involvement for the phenytoin-induced gingival enlargements. The tissues affected were though not subjected to a detailed histopathological analysis as the patients were not subjected to surgical therapeutic options for the treatment that carries a high probability for recurrence. ,,
Also, significant was the observation that the gingival enlargement induced by phenytoin was usually generalized with involvement of all surfaces of the teeth in all the quadrants but was more severe in the anterior segments of the jaws as per the observations of the prior studies possibly because of a relative lack of oral hygiene maintenance in these areas of the jaws.
A review of the gingival enlargement indices proposed in the literature clearly demonstrates their diversity, from the most simple gingival enlargement index proposed to the most elaborate one. Different authors have used different criteria for grading the gingival enlargement in their studies; however, there are no universal criteria that can be adopted for the same as every criteria has a more or less subjective methodological approach for the assessment of gingival enlargement and depends on the author's discretion for following the same. The majority of the indices used to quantify gingival enlargement are difficult to reproduce because they lack an objective criteria to differentiate between the degree of horizontal and vertical overgrowth.
In our study, the gingival status was assessed using the index originally described by Angelopoulos and Goaz , and later, modified by Miller and Damm [GO INDEX]. ,, Other criteria for assessing the gingival enlargement were not followed for their being with too extensive methodologies and yet with highly subjective nature of assessment of gingival enlargements.
The results obtained could not be compared with the observations of other studies as the indices followed were either different, modified Harris and Ewalt index in a study conducted by Prasad et al.,  on the role of folic acid in the prevention of phenytoin-induced gingival enlargement on 60 epileptic children in the age range of 8-13 years or even using the same index in a cross sectional study conducted by Brunet et al.,  on 59 patients on antiepileptic medications using the vertical gingival overgrowth (GO) index horizontal Miranda and Brunet (MB) index in the inter-dental area, owing to the subjectivity of the assessment procedure and a lack of reproducibility with local factors further playing a confounding role in the observations.
In our study, assessment of serum folic acid was done by chemiluminiscent method using Immulite kit prior to the start and after 6 months of phenytoin therapy. Other methods used to assess serum folates that have been described in the literature include the one of immunoassay method and the less reliable and a relatively less sensitive assay of serum folate levels using Lactobacillus casei as the test organism. Average range of serum folate levels in normal controls as standardized by few studies has been found to be 3-17 ng/mL.
Serum folate levels were earlier quantified by means of a radioimmunoassay method using a SimulTRAC Radioassay kit in a study conducted by Majola et al.,  involving a total of 134 patients on the factors influencing phenytoin-induced gingival enlargement. The average serum folate levels in the study ranged from 1.2 to 14.7 ng/mL with a mean value of 4.6 ng/mL.
The mean serum folate level as assayed with the help of L. casei method was found to be 4.76 ng/mL in the normal controls and 3.96 ng/mL in the epileptic patients in the study conducted by Reynolds et al.,  involving 33 normal controls, 34 epileptic outpatients, 19 of whom also suffered from psychiatric illness, 33 epileptic inpatients with psychiatric illness and 30 nonepileptic inpatients with psychiatric illness on folate metabolism in epileptic and psychiatric patients.
Serum folate levels were on the contrary found to be 8.8 ± 3.6 ng/mL with a range of 2.9-16.1 ng/mL in controls, while 4.1 ± 1.6 ng/mL with a range of 1.2-6.7 ng/mL in 16 among a total of 75 epileptic patients on phenytoin therapy in the study conducted by Sener et al.,  on the effects of common antiepileptic drug monotherapy on serum levels of homocysteine, vitamin B12, folic acid, and vitamin B6. Serum folate levels in this study were measured by the immunoassay method using commercial kit, Immulite, DPC, United States. Normal range of serum folates in healthy adults as estimated by L. casei method has been standardized to be 2.5-15 ng/mL.
The wide variations found in the mean and average range of serum folate levels in different age groups and genders from the previous studies likely reflected the differences among the study samples in terms of age and health status as well as differences in the assessment procedures.
This is, however, preliminary study; the results of the study suggest a higher incidence and severity of gingival enlargement in phenytoin-treated epileptic patients with a positive correlation between serum folic acid levels and gingival enlargement before and after 6 months of phenytoin administration. No available published reports with similar methodology have been found in the literature. However, the study requires further evaluation in larger clinical trials with supplementation of folates in phenytoin-treated epileptic patients to check this side effect simultaneously decreasing the propensity of folates to precipitate seizures in such patients by decreasing the sera levels of the drug.
| Conclusion|| |
This is a preliminary study which aims at the assessment of serum folate levels in epileptic patients who are on long-term phenytoin therapy and their association with phenytoin-induced gingival enlargement.
The statistical analysis of the results suggests the following:
Thus, the use of folic acid as an adjuvant to phenytoin therapy in the prevention of phenytoin-induced gingival enlargement calls for further analysis in future keeping in mind the precipitation of epileptic attacks seen in a significant number of patients on folic acid adjuvant therapy, secondary to fall in the sera levels of phenytoin due to the propensity of drug interactions between the two. Since, this is only a baseline study, the results of the study encourage for further studies with larger sample size and estimation of tissue level folates to conclude the results.
- A high incidence and increased severity of gingival enlargement in epileptic patients on phenytoin therapy
- A positive correlation between gingival enlargement and average serum folate levels before and after phenytoin administration; and
- A significant drop in serum folate levels after 6 months of phenytoin treatment.
| Acknowledgment|| |
The authors would like to thank all the people who directly and indirectly contributed for the study as the study required intense efforts from the people outside our Department including Department of Neurology and Department of Clinical Biochemistry, Bangalore Medical College and Research Institute and Associated Hospitals.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
[Table 1], [Table 2]