Gingival sequestration of nifedipine in nifedipine-induced gingival overgrowth

Drug-induced gingival hyperplasia: An in vitro study using amlodipine and human gingival fibroblasts

Gingival overgrowth is a serious side effect that accompanies the use of amlodipine. Several conflicting theories have been proposed to explain the fibroblast’s function in gingival overgrowth. To determine whether amlodipine alters the inflammatory responses, we investigated its effects on gingival fibroblast gene expression as compared with untreated cells. Fragments of gingival tissue of healthy volunteers (11 years old boy, 68 years old woman, and 20 years old men) were collected during operation. Gene expression of 29 genes was investigated in gingival fibroblast cell culture treated with amlodipine, compared with untreated cells. Among the studied genes, only 15 (CCL1, CCL2D, CCL5, CCL8, CXCL5, CXCL10, CCR1, CCR10, IL1A, IL1B, IL5, IL7, IL8, SPP1, and TNFSF10) were significantly deregulated. In particular, the most evident overexpressed genes in treated cells were CCR10 and IL1A. These results seem to indicate a possible role of amlodipine in the inflammatory response of treated human gingival fibroblasts.

Molecular Aspects of Drug-Induced Gingival Overgrowth: An In Vitro Study on Amlodipine and Gingival Fibroblasts

Gingival overgrowth is a serious side effect that accompanies the use of amlodipine. Several conflicting theories have been proposed to explain the fibroblast’s function in gingival overgrowth. To determine whether amlodipine alters the fibrotic response, we investigated its effects on treated gingival fibroblast gene expression as compared with untreated cells. Materials and Methods: Fibroblasts from ATCC^® Cell Lines were incubated with amlodipine. The gene expression levels of 12 genes belonging to the “Extracellular Matrix and Adhesion Molecules” pathway was investigated in treated fibroblasts cell culture, as compared with untreated cells, by real time PCR. Results: Most of the significant genes were up-regulated. (CTNND2, COL4A1, ITGA2, ITGA7, MMP10, MMP11, MMP12, MMP26) except for COL7A1, LAMB1, MMP8, and MMP16, which were down-regulated. Conclusion: These results seem to demonstrate that amlodipine has an effect on the extracellular matrix of gingival fibroblast. In the future, it would be interesting to understand the possible effect of the drug on fibroblasts of patients with amlodipine-induced gingival hyperplasia.

Drug-induced gingival hyperplasia: a retrospective study using spontaneous reporting system databases

Background

Drug-induced gingival hyperplasia (DIGH) causes problems with chewing, aesthetics, and pronunciation, and leads to the deterioration of the patient’s quality of life (QOL). Thus, the aim of this study was to evaluate the incidence of DIGH using spontaneous reporting system (SRS) databases.

Methods

We analyzed reports of DIGH from SRS databases and calculated the reporting odds ratios (RORs) of suspected drugs (immunosuppressants, calcium channel blockers, and anticonvulsants). The SRS databases used were the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) and the Japanese Adverse Drug Event Report (JADER) database. With the data, we evaluated the time-to-onset profile and the hazard type using the Weibull shape parameter (WSP). Furthermore, we used the association rule mining technique to discover undetected relationships such as possible risk factors.

Results

The FAERS contained 5,821,716 reports. The RORs (95% confidence interval: CI) for cyclosporine, everolimus, sirolimus, mycophenolate mofetil, amlodipine, nifedipine, carbamazepine, clobazam, levetiracetam, phenobarbital, phenytoin, primidone, topiramate, and valproic acid, were 39.4 (95% CI: 30.3–51.2), 4.2 (1.7–10.0), 6.6 (2.5–17.7), 13.1 (7.2–23.2), 94.8 (80.0–112.9), 57.9 (35.7–94.0), 15.1 (10.3–22.3), 65.4 (33.8–126.7), 6.5 (3.6–11.8), 19.7 (8.8–44.0), 65.4 (52.4–82.9), 56.5 (21.1–151.7), 2.9 (1.1–7.7), and 17.5 (12.6–24.4), respectively. The JADER database contained 430,587 reports. The median time-to-onset of gingival hyperplasia values for immunosuppressants, calcium channel blockers, and anticonvulsants use were 71, 262, and 37 days, respectively. Furthermore, the 95% CI of the WSP β for anticonvulsants was over and excluded 1, which meant that they were wear-out failure type.

Conclusions

Our results suggest that DIGH monitoring of patients administered immunosuppressants, calcium channel blockers, or anticonvulsants is important. We demonstrated the potential risk of DIGH following the long-term use of calcium channel blocker over approximately 260 days. Based on the results of the association rule mining approach, patients with intellectual disability who are administered phenytoin should be monitored carefully. We recommend that patients who experience symptoms related to DIGH should be closely monitored.

Amlodipine-induced Gingival Hyperplasia - A Case Report and Review

Anticonvulsants, antihypertensive calcium channel blockers and immunosuppressants are the three main classes of drugs known to cause drug-induced gingival hypertrophy or hyperplasia. Among the calcium channel blockers, nifedipine administration has most frequently been associated with medication-related gingival hyperplasia. The incidence with amlodipine, which has a mode of action pharmacodynamically comparable to nifedipine, has rarely been reported. Here, we present a rare case of amlodipine-induced gingival hyperplasia in a hypertensive patient.

Amlodipine Induced Gingival Hyperplasia

Calcium channel blockers are one of the most commonly used drugs for the management of cardiovascular disorders and are known for causing gingival over growth as adverse effects. Now a days, a new drug in this family Amlodipine, is being widely used, because of its duration of action. But it is of concern to the dental practitioner that this drug too has a similar effect on gingival tissues. This paper aims at drawing the attention of dentists towards the adverse effects of amlodipine along with providing a brief review of the pharmacologic profile of this drug, its effects on the gingiva and the management of hyperplasia.

Gingival overgrowth in children: epidemiology, pathogenesis, and complications. A literature review

Gingival overgrowth is the enlargement of the attached gingiva due to an increased number of cells. The most prevalent types of gingival overgrowth in children are drug-induced gingival overgrowth, hereditary gingival fibromatosis (HGF), and neurofibromatosis I (von Recklinghausen disease). Gingival overgrowth induced by drugs such as phenytoin, nifedipine, and cyclosporin develops due to an increase in the connective tissue extracellular matrix. According to epidemiologic studies, it is more prevalent in male children and adolescents. There is an additive effect of those drugs on the degree of gingival overgrowth. Genetic heterogeneity seems to play an important role in the development of the disease. Functional difficulties, disfigurement, increased caries, and delayed eruption of permanent teeth are the main complications of drug-induced gingival overgrowth. HGF is the most common syndromic gingival enlargement in children. This autosomal dominant disease usually appears at the time of eruption of permanent dentition. Histologically, it is characterized by highly collagenized connective tissue. The most important complications are drifting of teeth, prolonged retention of primary dentition, diastemata, and poor plaque control. Neurofibromatosis I is an autosomal dominant disease more common in mentally handicapped individuals. Gingival overgrowth is caused by the formation of plexiform neurofibromas in the connective tissue of the gingiva. Plexiform neurofibromas are pathognomonic of the disease and consist of hypertrophic nerves arranged as lobules in the connective tissue. Complications of the disease are multiple and severe due to neurofibromas and their occasional malignant transformation.

The effect of IL-l.ALPHA. and nifedipine of cell proliferation and DNA synthesis in cultured human gingival fibroblasts

The effect of nifedipine and interleukin-alpha (IL-1alpha) on the cell proliferation and DNA synthesis was studied in human gingival fibroblasts derived from 5 patients who developed gingival overgrowth (nifedipine responders) and 5 patients who did not develop gingival overgrowth (nifedipine non-responders) in response to nifedipine. Epidermal growth factor was used as a positive control. The fibroblasts derived from nifedipine responders tended to have a numerically greater rate of cell proliferation and DNA synthesis (3H-thymidine incorporation) than those from nifedipine nonresponders in the presence of nifedipine and IL-lalpha. Fibroblasts derived from nifedipine responders showed significantly higher cell proliferation rate in the presence of nifedipine and IL-1alpha, than nifedipine or IL-lalpha alone on both the second and the fourth day of incubation (P < 0.05). A combination of IL-1alpha and epidermal growth factor also showed significantly greater cell proliferation than IL-lalpha alone on the second day (P < 0.05). The DNA synthesis rate with a combination of nifedipine and IL-1alpha was higher than that for nifedipine alone on the second day (P < 0.01), and IL-1alpha alone on the fourth day (P < 0.05) in gingival fibroblasts originating from nifedipine responders. These results suggest that the interaction between nifedipine and gingival inflammation might play an important role in the pathogenesis of nifedipine-induced gingival overgrowth.

Dentistry and the medically compromised patient

Certain medical conditions and their accompanying drug treatment do have an impact upon oral structures and the delivery of dental care. Recent evidence suggests that oral health could be a significant risk factor for coronary artery disease. Many medical conditions can affect dental care are often over-stated and lack an evidence base. Examples include the need for antibiotic cover in patients at risk from infective endocarditis and the necessity to provide supplementary corticosteroids for those patients on longterm steroid therapy. By contrast, certain systematic drug treatments can have a profound affect on the oral tissue. The most obvious is drug-induced gingival overgrowth. Drugs frequently implicated in this unwanted effect include phenytoin, ciclosporin and the calcium channel blockers. Several risk factors for drug-induced overgrowth have been identified and include age, sex, peridontal variables and a range of drug pharmacokinetic variables. The relationship between oral health and coronary artery disease opens up a potentially new vista for the delivery of oral care. Although the association is convincing, casualty has not been established. If casualty for this relationship can be confirmed then the delivery of dental care and the promotion of oral health will receive a significant impetus.

Synergistic enhancement of collagenous protein synthesis by human gingival fibroblasts exposed to nifedipine and TNF-alpha in vitro

BACKGROUND

Gingival overgrowth occurs in patients receiving nifedipine. Gingival inflammation may be an etiologic factor.

METHODS

Gingival fibroblasts were either exposed to (i) 0-500 ng/ml TNF-alpha or 10(-7) M nifedipine or (ii) 0-500 ng/ml TNF-alpha + 10(-7) M nifedipine for 7 days. 3H-proline was used to quantify collagenous protein synthesis.

RESULTS

Both TNF-alpha and 10(-7) M nifedipine significantly decreased cell proliferation, and 10(-7) M nifedipine + 500 ng/ml TNF-alpha reversed these effects. Collagenous protein synthesis was significantly reduced by TNF-alpha and was significantly enhanced by either 10(-7) M nifedipine or 5-500 ng/ml TNF-alpha + 10(-7) M nifedipine.

CONCLUSIONS

Our data report that nifedipine reverses the primary effects of TNF-alpha on collagenous protein synthesis. Patients with gingivitis could be susceptible to gingival overgrowth during nifedipine therapy as a result of synergistic effects of these agents on fibroblast metabolism, which occurs irrespective of reduced cell numbers.

Cardiovascular diseases and periodontology

BACKGROUND

Cardiovascular diseases represent a widespread heterogeneous group of conditions that have significant morbidity and mortality. The various diseases and their treatments can have an impact upon the periodontium and the delivery of periodontal care.

AIM

In this paper we consider three main topics and explore their relationship to the periodontist and the provision of periodontal treatment.

METHOD

The areas reviewed include the effect of cardiovascular drugs on the periodontium and management of patients with periodontal diseases; the risk of infective endocarditis arising from periodontal procedures; the inter-relationship between periodontal disease and coronary artery disease.

RESULTS AND CONCLUSIONS

Calcium-channel blockers and beta-adrenoceptor blockers cause gingival overgrowth and tooth demineralisation, respectively. Evidence suggests that stopping anticoagulant therapy prior to periodontal procedures is putting patients at a greater risk of thromboembolic disorders compared to the risk of prolonged bleeding. The relationship between dentistry and infective endocarditis remains a controversial issue. It would appear that spontaneous bacteraemia arising from a patient's oral hygiene practices is more likely to be the cause of endocarditis than one-off periodontal procedures. The efficacy of antibiotic prophylaxis is uncertain (and unlikely to be proven), and the risk of death from penicillin appears to be greater than the risk of death arising from infective endocarditis. Finally, the association between periodontal disease and coronary artery disease has been explored and there seem to be many issues with respect to data handling interpretation. Many putative mechanisms have been suggested; however, these only further highlight the need for intervention studies.

Nifedipine induces gingival epithelial hyperplasia in rats through inhibition of apoptosis

BACKGROUND

Nifedipine is used as a long-acting vasodilator; one of its side effects is gingival overgrowth, characterized by an accumulation of collagenous components within the gingival connective tissue and epithelial hyperplasia with elongated, branched rete pegs penetrating into the connective tissue. We investigated the effect of nifedipine on apoptosis of gingival keratinocytes of rats to elucidate the mechanism of nifedipine-induced gingival epithelial hyperplasia.

METHODS

Twenty-day-old rats were fed a powdered diet containing or lacking nifedipine for 8 to 30 days. The mandibular gingiva and palatal mucosa were removed on days 8, 15, or 30, and epithelial thickness was examined by light microscopy. In situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay was used to examine apoptosis of keratinocytes in the epithelium. In addition, we examined the effects of nifedipine on proliferation of keratinocytes and epithelial cell life on day 8 by 5-bromo-2'-deoxyuridine (BrdU) staining.

RESULTS

Microscopic examination showed gingival epithelial hyperplasia in nifedipine-treated rats after day 15. Apoptosis of gingival keratinocytes was seen to be inhibited in nifedipine-treated rats on day 8 and 15. Also, nifedipine did not induce an increase of keratinocyte proliferation activity in terms of the number of cells showing positive staining with BrdU. Prolongation of cell life by nifedipine was observed on day 8 in gingival epithelium through a delay of upward cell movement compared to controls. However, epithelial hyperplasia was not detected in palatal mucosa, and there were no significant differences in apoptotic rates of keratinocytes and cell life between nifedipine-treated rats and control rats.

CONCLUSIONS

These results suggest that nifedipine induces epithelial hyperplasia in gingival overgrowth not by an increase in keratinocyte proliferation, but by prolongation of cell life through reduction of apoptosis before epithelial hyperplasia is detectable.

Inhibition by nifedipine of adherence- and activated macrophage-induced death of human gingival fibroblasts

The effects of nifedipine on the death and proliferation of gingival fibroblasts were investigated to elucidate the mechanism of gingival overgrowth that is associated with chronic administration of Ca2+ channel blockers. The number of adhered viable and dead fibroblasts obtained from healthy human gingiva increased after confluence, whereas cell death was inhibited by nifedipine in a concentration-dependent manner. A similar inhibition was also observed in the presence of other calcium channel blockers, such as nicardipine, diltiazem, and verapamil. When gingival fibroblasts were co-cultured with RAW264 (macrophage-like) cells, lipopolysaccharide (LPS) caused the concentration-dependent death of fibroblasts. Nifedipine significantly inhibited the LPS-induced cell death. Although neither LPS nor N-ethyl-2-(1-ethyl-2-hydroxy-2-nitroso-hydrazino)-ethanamine, a nitric oxide donor, directly caused fibroblast death, 3-morpholino-sydnonimine (SIN-1), a peroxynitrite donor, induced fibroblast death, regardless of the presence of RAW cells. The cell death induced by SIN-1 was not affected by nifedipine treatment. LPS stimulation caused an increase in the immunoreactivity of inducible nitric oxide synthase (iNOS) and in the nitrite concentration in the incubation medium of RAW cells. The induction of iNOS was completely prevented by the incubation with nifedipine. The inhibition by nifedipine of nitrite production in RAW cells was also observed after treatment with nicardipine, but not with either diltiazem or verapamil. Therefore, the inhibition by nifedipine of both adherence- and LPS-stimulated macrophage-induced death of fibroblasts may be the mechanism of gingival overgrowth seen during chronic treatment with Ca(2+) channel blockers.

Keratinocyte growth factor is upregulated by the hyperplasia-inducing drug nifedipine

Keratinocyte growth factor (KGF) is the seventh member of the fibroblast growth factor (FGF) family. It is produced by mesenchymal cells and its activity is specific for epithelial cells, controlling epithelial homeostasis and wound repair in a paracrine manner. Although KGF has been implicated in a number of hyperplastic pathologies, it has not previously been investigated in gingival hyperplasia (GH), an adverse side-effect of three pharmacologically different types of drugs, including the anti-hypertensive drug nifedipine (NIF). The mechanism by which NIF causes GH is not yet known, but we have recently shown that KGF mRNA transcripts are elevated in drug-induced GH in vivo (manuscript submitted). It is therefore possible that the action of NIF is mediated via KGF and, in the present study, using the enzyme-linked immunosorbent assay (ELISA) and the semi-quantitative reverse transcribed-polymerase chain reaction (RT-PCR), we found that NIF upregulates KGF secretion and gene transcription by gingival fibroblasts in vitro. Our results thus suggest that KGF may have an important role in the molecular pathology of GH in vivo.

Effects of tobacco products on the attachment and growth of periodontal ligament fibroblasts

BACKGROUND

Cigarette smoking is one of the most significant risk factors in the development and further advancement of inflammatory periodontal disease, however, the role of either nicotine or its primary metabolite cotinine in the progression of periodontitis is unclear. This study aimed to investigate the effects of nicotine and cotinine on the attachment and growth of fibroblasts derived from human periodontal ligament (PDL).

METHODS

Primary cultures were prepared from the roots of extracted premolar teeth. Cells were used at both low (P3 to P5) and high (P11 to P13) passage. Cell numbers were determined over 14 days using either the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay or with a Coulter counter. Cultures were exposed to culture medium supplemented with 1) 15% fetal calf serum (FCS) only; 2) 1% FCS only; 3) 1% FCS and nicotine (concentration range 5 ng/ml to 10 mg/ml); or 4) 1% FCS and cotinine (concentration range 0.5 ng/ml to 10 microg/ml).

RESULTS

Nicotine significantly (P <0.05, by ANOVA) inhibits attachment and growth of low passage cells at concentrations >1 mg/ml and high passage PDL fibroblasts at concentrations >0.5 mg/ml. Cotinine, at the highest concentration used (10 microg/ml), appeared to inhibit attachment and growth of both low and high passage fibroblasts but this was not statistically significant (P >0.05, by ANOVA).

CONCLUSIONS

Tobacco products inhibit attachment and growth of human PDL fibroblasts. This may partly explain the role of these substances in the progression of periodontitis.

Prevalence of gingival overgrowth induced by calcium channel blockers: a community-based study

BACKGROUND

The prevalence of gingival overgrowth induced by chronic medication with calcium channel blockers is uncertain. Although there have been several studies examining this question, the results are conflicting, with previous estimates ranging from 20% to 83%. There have been only 2 studies examining the prevalence of overgrowth induced by diltiazem and amlodipine, with estimates of 74% and 3.3%, respectively.

METHODS

The current study aimed to address the problems associated with these studies by examining a sample of patients taking one of 3 calcium channel blockers, who were drawn from a community-based population in northeastern England. Nine hundred eleven (911) subjects were recruited from general medical practices in the area. Of these, 442 were taking nifedipine, 181 amlodipine, and 186 diltiazem. In addition, 102 control subjects were examined. Drug and demographic data for each subject were recorded. The periodontal condition of all subjects was assessed including plaque index, papillary bleeding index, and a photograph of the anterior gingivae for subsequent analysis of overgrowth severity.

RESULTS

More than six percent (6.3%) of subjects taking nifedipine were seen to have significant overgrowth. This overgrowth was statistically greater than the amount of overgrowth seen in either of the other 2 drug groups or the control population. The prevalence of gingival overgrowth induced by amlodipine or diltiazem was not statistically significant when compared to the control group. The severity of overgrowth within the nifedipine group was found to be related to the amount of gingival inflammation and also to the gender of the subject, with males being 3 times as likely to develop overgrowth than females.

CONCLUSIONS

The prevalence of clinically significant overgrowth related to chronic medication with calcium channel blockers is low, i.e., 6.3% for nifedipine. Males are 3 times as likely as females to develop clinically significant overgrowth. The presence of gingival inflammation is an important cofactor for the expression of this effect.

Medication induced gingival overgrowth

A number of idiopathic, pathological and pharmacological reactions may result in an overgrowth of the gingiva. This review concentrates on those overgrowths associated with various pharmacological agents. The pharmaco-kinetics and side effects of each drug associated with gingival overgrowth are discussed along with the clinical and histological features and treatment. By examining the possible pathogeneses for these overgrowths we propose a unifying hypothesis for the causation based around inhibition of apoptosis and decreased collagenase activity modulated by cytoplasmic calcium.

The clinical effects of nifedipine on periodontal status

The present study was conducted to determine the clinical effects of nifedipine on the gingiva of 97 patients. Patients were examined for changes in periodontal status and divided into subgroups, based on their age, gender, duration of drug intake, presence/absence of plaque and gingival inflammation, and according to the presence and severity of gingival overgrowth. Gingival overgrowth was noticed in 29% of the patients. Among the recorded parameters, duration of drug intake, presence/severity of gingival inflammation, and gender seemed to have the greatest effect on the development of gingival overgrowth. Patients with higher gingival inflammation scores, those on nifedipine medication for more than 4 years, and males were likely to have an increased tendency for higher incidence and severity of gingival overgrowth. The findings of the present study suggest that nifedipine medication induces gingival overgrowth and that certain local factors are involved in the pathogenesis of drug-induced gingival overgrowth. However, individual ability and sensitivity to metabolize the drug and its metabolites also seem to be important etiological factors.

Prevalence of amlodipine-related gingival hyperplasia

Calcium channel blockers are known to contribute to gingival hyperplasia. The vast majority of reports discuss patients taking the drug nifedipine. During the past few years a newer calcium channel blocker, amlodipine, has been used with increasing frequency. To date, six cases have been published indicating that amlodipine may also promote gingival hyperplasia; however, no data have been reported regarding the prevalence of this phenomenon. The purpose of this study was to examine a large group of patients taking amlodipine and determine the prevalence of gingival hyperplasia. One hundred fifty dentate patients who had been taking amlodipine, 5 mg per day for at least 6 months, volunteered to undergo a screening examination for gingival hyperplasia. Mild hyperplasia (< 1/3 clinical crown) was found in five patients-a prevalence of 3.3%. This is significantly less (P < .001) than rates reported for patients taking nifedipine, and not significantly different from rates previously reported in control groups of cardiac patients not taking calcium channel blockers. The results from this group of patients indicated that amlodipine, 5 mg per day, did not induce gingival hyperplasia.

Periodontal implications: medically compromised patients

The presence of systemic disease in patients requiring periodontal therapy creates challenges for management. Alteration of treatment plans, with emphasis on physician consultation and preventive periodontal care, is frequently needed to minimize the impact of periodontal disease on the systemic condition. Conversely, detection and treatment of systemic disorders may impact upon the status of the periodontium and the success of periodontal therapy. The goal of holistic patient management is facilitated by a free flow of information between the patients and their medical and dental health care providers.

Plasma and saliva concentrations of phenytoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin in relation to the incidence and severity of phenytoin-induced gingival overgrowth in epileptic patients

This study examined the relationships between plasma and saliva concentrations of phenytoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH), the major metabolite of phenytoin in man, and the prevalence and severity of gingival overgrowth. Thirty-six adult epileptic patients who had been receiving phenytoin for greater than 6 months without a recent change in dosage were assessed for signs of periodontal disease and gingival overgrowth. Plasma and saliva samples were analyzed by high performance liquid chromatography for the determination of phenytoin and HPPH concentrations. Seventeen patients demonstrated clinically significant gingival over-growth (responders; overgrowth index > or = 30%). There were significant correlations between the gingival overgrowth index and both the papillary bleeding index (r = 0.495; P < 0.005) and probing depth (r = 0.632; P < 0.005). The plaque index correlated with the papillary bleeding index (r = 0.420; P < 0.05) and the probing depth (r = 0.301; P < 0.005), but not with the gingival overgrowth index. The extent of gingival overgrowth did not correlate significantly with either plasma or saliva concentrations of phenytoin or HPPH. Mean plasma and saliva concentrations of phenytoin and HPPH did not differ significantly between non-responders and responders, nor did the mean plaque index. The mean papillary bleeding index (32.5 +/- 21.2 vs. 63.8 +/- 37.7; P < 0.01) and mean probing depth (12.4 +/- 14.4% vs. 35.9 +/- 25.3%; P < 0.02) were significantly greater in the responders. This study found no evidence of a relationship between phenytoin or HPPH concentrations in plasma or saliva and the extent, or prevalence of phenytoin-induced gingival overgrowth. Further studies with larger populations may be necessary to establish the relationship, if any, between phenytoin or HPPH levels and gingival overgrowth.

Automated gas chromatographic assay for amlodipine in plasma and gingival crevicular fluid

This paper describes an automated capillary gas chromatographic method for the determination of amlodipine in plasma, and in sub-microlitre volumes of gingival crevicular fluid (GCF), in order to assess if amlodipine is present in GCF under conditions of gingival overgrowth, as has been shown for nifedipine, another dihydropyridine drug. Liquid-liquid extraction followed by derivatisation was employed to isolate amlodipine and render it suitable for gas chromatography. Amlodipine was analysed in plasma and GCF of four patients undergoing amlodipine therapy for cardiovascular disorders, three of whom had significant gingival overgrowth. Amlodipine was detected in the plasma of all patients and in massive concentrations in the GCF of those patients with overgrowth, 23- to 290-fold greater than in their plasma. Like nifedipine, amlodipine sequestration into GCF appears to be linked with gingival overgrowth.

The distribution of gingival overgrowth in organ transplant patients

The distribution of gingival overgrowth was investigated in a cohort of organ transplant patients, who were medicated with cyclosporin or the combination of cyclosporin and a calcium channel blocking drug. Gingival overgrowth scores were significantly higher at buccal sites than lingual-palatally (p < 0.0001). There was no significant difference between upper and lower overgrowth scores (p = 0.88). The most severe overgrowth was seen in the canine region. Overgrowth between the central incisors was significantly less than in the canine region (p > or = 0.044) and was similar to that in the molar and premolar region. Although raised overgrowth scores were associated with increased levels of plaque and gingival inflammation, the distribution could not be explained by this observation.

The pathogenesis of drug-induced gingival overgrowth

Gingival overgrowth is a well-documented unwanted effect, associated with phenytoin, cyclosporin, and the calcium channel blockers. The pathogenesis of drug-induced gingival overgrowth is uncertain, and there appears to be no unifying hypothesis that links together the 3 commonly implicated drugs. In this review, we consider a multifactorial model which expands on the interaction between drug and/or metabolite, with the gingival fibroblasts. Factors which impact upon this model include age, genetic predisposition, pharmacokinetic variables, plaque-induced inflammatory and immunological changes and activation of growth factors. Of these, genetic factors which give rise to fibroblast heterogeneity, gingival inflammation, and pharmacokinetic variables appear to be significant in the expression of gingival overgrowth. A more thorough understanding of the pathogenesis of this unwanted effect will hopefully elucidate appropriate mechanisms for its control.

The pharmacokinetics of phenytoin in gingival crevicular fluid and plasma in relation to gingival overgrowth

The aim of this study was to determine whether phenytoin (PHT) could be detected in gingival crevicular fluid (GCF), and to relate its concentration to both plasma level and degree of gingival overgrowth. 23 patients medicated with phenytoin for at least 6 months were clinically examined for signs of periodontal disease and gingival overgrowth. 12 patients out of these demonstrated clinically significant overgrowth and their plaque scores and gingival inflammation were greater than for the non-overgrowth group (p < 0.001). Phenytoin concentrations were determined by high performance liquid chromatography, and was detected in GCF. There was a significant correlation between the GCF and plasma phenytoin concentrations (p < 0.05), but it was not related to the extent of gingival overgrowth. Inflammation increased the GCF volume, but was not a determinant of GCF phenytoin concentration. It is concluded that effusion of phenytoin into GCF is regulated by the plasma levels of the drug, but its concentration in GCF is not related to the incidence of gingival overgrowth.

Gingival overgrowth in paediatric cardiac transplant patients: a study of 19 patients aged between 2 and 16 years

It is well established that both cyclosporin and nifedipine are associated with gingival overgrowth. However, there is little information on the prevalence of this undesirable effect in paediatric patients. The present study investigated gingival overgrowth in 19 cardiac transplant patients aged 2 years 8 months to 16 years 3 months (1.5-8.5 years post-transplant) and related such changes to variables of daily cyclosporin dosage, trough blood cyclosporin concentration and daily nifedipine dosage. Ten patients showed clinically significant gingival overgrowth and nine relatively minor overgrowth; there was no significant difference between the two groups with respect to age, length of time post-transplant, cyclosporin dosage, whole blood concentration of cyclosporin or intake of nifedipine. The expression of gingival changes therefore did not relate to any drug variable in this group of subjects.

Iatrogenic gingival overgrowth in cardiac transplantation

It is well established that both cyclosporin and nifedipine are associated with gingival overgrowth. Although both drugs are widely used in the management of organ transplant patients, there is little information on the prevalence and severity of this unwanted effect in cardiac transplant patients. This study evaluated the gingival health of 94 dentate cardiac transplant patients, all of whom were medicated with cyclosporin as a component of their immunosuppressive therapy. Sixty-three (63) of the patients were also medicated with nifedipine. Significantly higher gingival overgrowth scores (P < 0.0001) and periodontal probing depths (P = 0.001) were observed in patients medicated with the combination of cyclosporin and nifedipine than those medicated with cyclosporin alone. Likewise, there was a significantly greater need to carry out gingival surgery on patients taking the combination (62%), than those medicated with cyclosporin alone (25.8%) (P = 0.001). Patient's age, sex, duration of therapy, gingival bleeding index, and nifedipine therapy were important determinants for both the expression of gingival overgrowth and the need for surgery. Significant sequestration of nifedipine in the gingival crevicular fluid (GCF) was observed. The concentration of nifedipine in GCF did not relate to either the gingival changes or plasma concentration of the drug. Cardiac transplant patients are at risk of developing gingival overgrowth and approximately 50% require surgical intervention. This risk increases significantly when patients are medicated concomitantly with nifedipine.

Factors influencing nifedipine-induced gingival overgrowth in rats

Factors such as age, the dose of nifedipine administered in the diet, serum drug level, duration of drug administration, and sex which may influence nifedipine-induced gingival overgrowth were examined in a rat model using 20-, 50-, and 90-days-old male and female rats. Oral administration of nifedipine (50 to 250 mg/kg diet) increased the serum level of the drug in a dose-dependent manner in both males and females. However, a higher serum level was required in females than males to attain the same degree of gingival overgrowth. The minimum dietary concentrations of the drug required to elicit gingival overgrowth in males and females were 150 and 100 mg/kg, respectively, which gave respective minimum serum levels of 800 and 1100 ng/ml. The degree of overgrowth depended on the serum concentration of the drug after it had reached the required minimum in male and female animals. Administration of nifedipine (250 mg/kg diet) for 20 days was enough to induce maximal overgrowth, but this induction occurred only in rats that started to receive the drug when they were 20 days old, not in those that started at 50 and 90 days of age for the same administration period of 55 days, and the overgrowth regressed and the gingiva were normal 40 days after ceasing drug administration. These results suggest that gingival overgrowth occurred in accordance with the drug concentration in the diet, as well as that in the serum, and was more likely to occur in males and younger individuals.

Phenotypic differences in growth, matrix synthesis and response to nifedipine between fibroblasts derived from clinically healthy and overgrown gingival tissue

Gingival overgrowth is a disfiguring condition affecting 10-20% of patients on nifedipine therapy. The pathogenesis of this condition, although unclear, is thought to involve an interaction between the drug and resident gingival fibroblasts. The aim of the present study was to investigate the cellular mechanisms underlying this condition using cell culture techniques. Gingival fibroblast cell lines were derived by explant culture from two patients on long-term nifedipine therapy exhibiting gingival overgrowth ('responders') and from two patients on similar therapy with clinically healthy gingiva ('non responders'). Comparative studies showed phenotypic differences between the two cell types, 'responder' cells having an increased growth potential and producing increased levels of protein and collagen compared to 'non responder' lines. Addition of exogenous nifedipine (10-1000 ng/ml) to cultures had no effect on 'non-responder' cells but induced a significant inhibitory response in the 'responder' cells. Although adding support to the concept that nifedipine-sensitive fibroblasts reside within overgrown connective tissue, the inhibitory effect of the drug on cell growth and matrix synthesis was surprising in view of the clinical appearance of this condition.

Influence of nifedipine on the metabolism of gingival fibroblasts

Calcium antagonists are the gold standard in the therapy of coronary heart disease and hypertension. The prototype of these drugs is nifedipine which, as well as its therapeutic effects on the cells of the cardiovascular system, also has unpleasant side effects on other organ systems. One side effect can be a missive hyperplasia of the gingiva, the reason for which are unclear. In vitro experiments were designed to elucidate the influence of nifedipine on the growth of human gingival fibroblasts in short and long term (72 hours, 6 weeks) cell culture. The following cellular parameters were determined quantitatively: cell proliferation (cell count, [3H]thymidine incorporation), protein synthesis ([3H]glucosamine incorporation) and viability (release of lactate dehydrogenase). A significant increase in cell proliferation (up to 1 microgram/ml nifedipine) was observed in the short-term experiments (72 hours, 0.001-10 micrograms/ml nifedipine), no other parameters were altered or were even depressed at higher concentrations. A significant increase in the cell proliferation and a decrease in the proteoglycan synthesis was found in the long term experiments (6 weeks, 1 microgram/ml nifedipine). Our results indicate that nifedipine has a direct effect on the cell proliferation of the gingival fibroblast in cell culture. The effect of nifedipine on the gingival fibroblasts are therefore similar to those observed earlier by the widely used immunosuppressant drug cyclosporin A on human gingival fibroblast in culture.

Nifedipine aggravates cyclosporine A-induced gingival hyperplasia

Gingival hyperplasia is a common side-effect of immunosuppression with cyclosporine A. Nifedipine is often used to control hypertension in kidney graft recipients. Analysis of gingival status in 106 children transplanted at our centre, and treated either with azathioprine, cyclosporine A or both, revealed significantly higher degrees of gingival overgrowth in those children receiving a combination of cyclosporine A and nifedipine compared with those children treated with cyclosporine A or nifedipine alone. Seven children undergoing gingivectomy at our centre over the past few years had received this combination. After a change in the antihypertensive regimen, avoiding long-term nifedipine medication, and improved dental care with chlorhexidine gel, we noted a reduction in the degree of gingival hyperplasia. In the majority of patients, nifedipine could be replaced by a single drug, usually hydralazine. We therefore recommend avoiding calcium channel blockers in the long-term management of hypertension in patients receiving cyclosporine.

Amlodipine-induced gingival overgrowth

Amlodipine is a calcium channel blocker used in the management of angina and hypertension. We report 3 cases of gingival overgrowth in adult dentate patients associated with chronic usage of this drug. Gingival changes occurred within 3 months of dosage and appeared to be compounded by the patient's existing periodontal condition. In all 3 patients, there was sequestration of amlodipine in their crevicular fluid. The significance of this finding in relation to the pathogenesis of this unwanted effect remains to be elucidated.

Effect of calcium-channel blockers on cell proliferation, DNA synthesis and collagen synthesis of cultured gingival fibroblasts derived from human nifedipine responders and non-responders

Human gingival fibroblasts from six patients who developed gingival hyperplasia as a result of nifedipine medication and five who did not were studied for the effects of calcium-channel blockers (nifedipine, diltiazem, verapamil and nicardipine) on cell proliferation, DNA synthesis and collagen synthesis. Phenytoin was used as a positive control. The fibroblasts from reactive patients gave trends toward better cell proliferation rates, DNA synthesis ([3H]-thymidine incorporation), and collagen synthesis ([3H]-proline incorporation) than those from non-reactive patients in the presence of 1 microM of calcium-channel blockers or phenytoin.

Determination of nifedipine in gingival crevicular fluid: a capillary gas chromatographic method for nifedipine in microlitre volumes of biological fluid

This paper describes a sensitive capillary gas chromatographic (GC) method for the determination of nifedipine in sub-microliter samples of gingival crevicular fluid (GCF) in order to assess if nifedipine is present in the GCF and if so, whether the local tissue concentrations of this drug are an important determinant in the development of gingival overgrowth. Liquid-liquid and solid-phase extraction were combined to give adequate sample clean-up and concentration for measurement by automated capillary GC with electron capture detection. Nifedipine and its principal metabolite, M-I, were analysed in both plasma and GCF in 9 adult male patients who had been taking nifedipine for over six months. M-I could not be measured in GCF. Plasma nifedipine and M-I levels were normal, but the nifedipine levels found in the GCF of 7 patients (including all those with overgrowth) were remarkably elevated, 15 to 316-fold greater. This massive concentration of nifedipine into the GCF is therefore linked with gingival overgrowth. This is the first time that a GC method has been developed which permits determination of GCF pharmacokinetics of a drug which causes gingival overgrowth, and further investigation will lead to a better understanding of the tissue mechanisms involved.

Calcium channel blockers in current medical practice: an update for 1993

Calcium channel blocking drugs (CCB) have been used to lower blood pressure since 1970. Three classes are currently available, the phenylalkylamines, the benzothiazepines, and the dihydropyridines. The structure of the L-type, voltage dependent calcium channel has been elucidated with molecular techniques and the different binding sites of the various CCB described. CCB have specific effects at the site of target organs. In the kidney, all classes produce natriuresis. Their action appears independent of the level of salt intake. CCB may favorably influence the course of chronic renal disease; the results of a trial comparing nifedipine to the converting enzyme inhibitor captopril showed no difference between the two drugs. CCB may impede the progression of atherosclerosis in the coronary arteries; a prospective study of nifedipine on coronary artery morphology supports this view. In the brain, nimodipine improves the outcome of patients with stroke from subarachnoid hemorrhage. Positive effects on patients with ischemic stroke have not been corroborated. CCB are approved primary treatment for patients with hypertension and are readily combined with other antihypertensive agents. They are well tolerated and have no adverse metabolic side effects. The advent of molecular pharmacology will advance current efforts to develop new CCB, which are highly selective in their site and mode of action.