Year : 2006 | Volume
: 17 | Issue : 4 | Page : 190--198
Pentoxifylline therapy : A new adjunct in the treatment of oral submucous fibrosis
R Rajendran, Vidya Rani, Saleem Shaikh
Department of Oral Pathology & Microbiology, Govt Dental College, Trivandrum 695 001, Kerala, India
Department of Oral Pathology & Microbiology, Govt Dental College, Trivandrum 695 001, Kerala
OBJECTIVE : This study was designed to determine the effect of pentoxifylline (Trental) on the clinical and pathologic course of oral submucous fibrosis. This drug is a methylxanthine derivative that has vasodilating properties and was envisaged to increase mucosal vascularity. STUDY DESIGN : This investigation was conducted as a randomized clinical trial incorporating a control group (Standard drug group SDG, multivitamin, and local heat therapy) in comparison to pentoxifylline test cases (Experimental drug group EDG, 400mg 3 times daily, as coated, sustained release tablets). The stipulated treatment period was 7 months and a total of 29 cases of advanced fibrosis (14 test subjects and 15 age and sex matched diseased controls) were included in this study and 100% compliance was reported at the end ofthe test period. RESULTS : Mild gastric irritation that could be managed by diet protocols was the only untoward symptom reported during this trial. Review of the patients and controls was done at an interval of 30 days and subjective and objective measurements were recorded. The follow up data at each visit with respect to each other and to base-line values was calibrated using a nonparametric test of Mann-Whitney (Kruskal-Wallis test). Significant comparisons with regard to improvement were recorded as objective criteria of mouth opening (t=11.285, p= 0.000), tongue protrusion (t= 3.898, p = 0.002), and relief from perioral fibrotic bands (p = 0.0001554). Subjective symptoms of intolerance to spices (p = 0.0063218), burning sensation of mouth (p = 0.0005797), tinnitus (p=0.000042), difficulty in swallowing (p=0.0000714). and difficulty in speech (p=0.0000020) were also recorded significant improvement at the end of the trial period. CONCLUSION : This pilot investigation points to the effectiveness of pentoxifylline as an adjunct therapy in the routine management of oral submucous fibrosis.
|How to cite this article:|
Rajendran R, Rani V, Shaikh S. Pentoxifylline therapy : A new adjunct in the treatment of oral submucous fibrosis.Indian J Dent Res 2006;17:190-198
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Rajendran R, Rani V, Shaikh S. Pentoxifylline therapy : A new adjunct in the treatment of oral submucous fibrosis. Indian J Dent Res [serial online] 2006 [cited 2021 Dec 2 ];17:190-198
Available from: https://www.ijdr.in/text.asp?2006/17/4/190/29865
Oral submucous fibrosis (OSF) remains enigmatic and characterization of its pathogenesis is still met with difficulties, caused primarily due to the inability to prove a cause-effect relationship in ascribing any known agent in its causation. The fibrogenic potential of areca- nut alkaloids and tanning had been studied extensively and was proved to have an effect in its causation, backed with epidemiological and experimental evidences . But this remains inconclusive against the backdrop of clinical cases, sizable in proportion, of patients who refrain from any such habits . The reality of "non-arecanut cases" cannot be overlooked and the majority of investigators now uphold the multifactorial origin of this disorder with probable genetic predisposition in its causation. This uncertainty as regards its causation is reflected primarily in its management protocols and it, still at best, remains empirical.
The degree of vascularity of the diseased mucosa in OSF has always been a matter of dispute while good casecontrol studies on the integrity and patency of microvasculature still lacking. Histological evidence goes against the concept of decreased vascularity and the often reported epithelial "atrophy" in OSF is based on the assumption of an ischemic epithelium resultant to poorly vascularised stroma. The atrophic epithelium is envisaged to pre-dispose to malignant transformation when brought in contact with oral carcinogens.
The objective of this clinical study was to evaluate the efficacy of pentoxifylline, a methylxanthine derivative, that has vasodilating properties and may decrease platelet aggregation on the clinical and pathologic course of this disease. This controlled investigation was carried as a randomized clinical trial incorporating a control group (multi-vitamin and localized heating protocols) in comparison with pentoxifylline (400mg thrice daily) administered in the form of coated sustained release tablets.
PATIENTS AND METHODS
Study design and sample
The study comprised a prospective clinical analysis of 29 randomly selected OSF patients, graded as clinically advanced, judged by established clinico-pathologic parameters and evaluated in randomized clinical trial. All the patients recruited to the study were of comparable disease progression and share the common demographic features of ethnicity , geographic localization, and socioeconomic status and all of them were habitual chewers of 'areca-quid'. The patient stock was fragmented into experimental drug group (EDG, n=14) where the active treatment option was pentoxifylline, (Trental asub 400mg tablets) and the standard drug group (SDG, n=15) was managed with multi-vitamin capsules (one capsule before sleep daily). Local heating therapy (hot water exercise and forceful mouth opening) was practiced uniformly by both the groups of patients. The EDG before administration of pentoxifylline, underwent detailed hematological and clinical tests to rule out systemic ailments of hypertension, diabetes mellitus, cardiac diseases, malignant ulcers, duodenal and gastric peptic ulcers, bleeding diatheses, and the like. The hematological work up comprised recording of total leukocyte count (TC), differential count (DC), hemoglobin values (Hb), platelet count (PC), clotting and bleeding times (CT, BT), recordings of blood pressure (systolic and diastolic), and pulse characters of the patients.
The drug pentoxifylline was administered as an inductive regime for the initial 30 days at a reduced dosage of 2 tablets daily and at the end of the period, all the test cases underwent routine blood and systemic examinations to record untoward effect(s), if any. Thereafter the dose was hiked to 3 tablets daily (400mg) for all the patients in the EDG. The drop out figure recorded was zero and the clinical symptoms reported were mild gastritis and gastric irritation, peripheral flushing, and warmth of upper trunk, that could be managed easily. One patient who complained of continued gastric irritation was dropped from the EDG after the induction period of one month. No other reportable complications or side effects were recorded from any of the patients included in the study design and the clinical trial was carried out further for 6 more months (total of 7 months). Clinical follow up and review of all the patients included in the EDG and SDG was carried out at 30 days intervals for the whole trial period of 7 months. During each visit, recordings to evaluate the objective and subjective improvement from disease of both the groups were assessed and scored and entered in a specially designed' proforma' drawn for the purpose. To prevent bias due to interpersonal variability, the same investigator (RR) measured all the patients during each visit (all the measurements were recorded in centimeters).
The clinical recordings were made under two headings during each visit:
Improvement in mouth opening (measurement in centimeters of inter- incisal / alveolar clearance),Tongue protrusion (measurement in centimeters from the reference point of lip vermillion)Relieffrom fibrotic bands (digitalpalpation)
Relief from intolerance to spicy foodRelief from burning sensationImprovement in salivation, mucosal rigidity, depapillation of tongueRelief from tinnitus (ringing in the ear)Relief from difficulty in swallowing (especially of solid food)Relief from difficulty of speech (phonation)
Statistical comparision of EDG and SDG at each visit with respect to each other and to base-line values (pretreatment measurements) was done using a non parametric test of Mann Whitney (Kruskal Wallis test).
Follow up period
All the patients included in this clinical trial are at different stages of follow up; the period ranges from 6 months to one year after cessation of active medication. The base-line therapy of localized heating and mouth exercise continues until the time of this reporting.
Age and Sex
The mean age of the patients in the study group was 39.64±7.2years and that of the controls was 41.13 ± 5.51 (t = -0.62, p = 0.54, NS). The male to female ratio of the study group was 9:5 and that of the control group was 9:6 (X 2 = 0.02, p=0.88, NS). Therefore both the patient groups were comparable with respect to age and sex ratio.
Assessment of objective criteria of disease progression measured at interval of 30 days
1) Improvement in mouth opening
(V= number of visit, d= the relative difference between visits) in inter-incisal / alveolar clearance recorded between the follow up visits (of 30 days) of study and control groups of patients with respect to base-line values was analyzed using the test of Mann Whitney (Kruskal Wallis test). The comparisons made were highly significant for all the visits [Table 1]
2) Improvement in tongue protrusion base-line reference to vermillion lip
The relative difference in tongue protrusion was compared between study and control groups at each visit with respect to base-line value using modified 't' test. The comparisons were erratic with significant levels achieved during V5 and V6 visits. When analyzed separately the test cases recorded better overall improvement when compared to control [Table 2]
3) Relief from fibrotic bands (Peri-oral, anterior and posterior buccal mucosa, junction of hard and soft palate)
The values recorded and the comparisons made were inconsistent and therefore rated as 'inconclusive'. The patients who reported no palpable bands at the perioral location at first visit (n = 7) were not included in the analysis. The relief from perioral and buccal mucosal fibrous bands reported at the end of the clinical trial in EDG was highly significant (p = 0.000 1554). [Table 3],[Table 4],[Table 5],[Table 6]
Assessment of subjective criteria
All the subjective symptoms were recorded on a scale of 0-2, based on severity. Any improvement in the severity of symptoms when compared to initial visit was considered to be `improved', and the rest `non improved'. Chi-square test / Fisher's exact test was used wherever appropriate.
1) Relief from intolerance to spicy food
Comparison of improvement (based on interview data) in the symptom was made at each visit between EDG and SDG and recorded as 'highly significant'. 'Spicy food' denotes seasoning with red chilly, a common culinary item of the area. [Table 7]
2) Relief from' burning mouth'
Comparison of improvement of the symptom was made at each visit between EDG and SDG. The comparisons were 'highly significant' in all the visits. [Table 8]
3) Improvement in salivation, rigidity of the mucosa and de-papillation of dorsum tongue
The values recorded were erratic and the effect of the drug was assessed to be `inconclusive'. [Table 9],[Table 10],[Table 11].
4) Improvement from tinnitus ('ringing in the ear')
Comparisons were 'highly significant' statistically in all the visits [Table 12].
5) Improvement from difficulty in swallowing, speech
The comparisons were 'highly significant' in all the visits. [Table 13],[Table 14]
Pentoxifylline is a tri-substituted methylxanthine derivative, the biologic activities of which are numerous. This includes increasing red cell deformability, leukocyte chemotaxis, antithrombin and anti- plasmin activities, and more importantly to the present context, its fibrinolytic activity. Pentoxifylline decreases red cell and platelet aggregation, granulocyte adhesion, fibrinogen levels, and whole blood viscosity . Recent work has delineated pentoxifylline's ability to decrease production of tumor necrosis factor alpha and reduce some of the systemic toxicities mediated by interleukin-2 ,,. These two cytokines are important mediators of the inflammatory response. In addition, pentoxifylline has been shown to increase the production of PGE2 and PGI2 by vascular epithelium, important in maintaining cellular integrity and homeostasis after acute injury ,,. Because this drug has proved effective in treating intermittent claudication caused by chronic peripheral arterial occlusion, we surmised that it might also be effective in treating OSF, having a putative association with mucosal ischemia and resultant epithelial atrophy. The submucosal fibrosis, which is the hallmark of the disorder, is envisaged to be the result of a defective inflammatory reparative response culminating in fibrotic healing .
The degree of vascularity of the diseased mucosa in OSF has always been a matter of dispute. While good case control studies on the integrity and patency of microvasculature of the mucosa in OSF are still lacking, histological evidence goes against the concept of decreased vascularity in this disease . An evidence in support of this was the recent demonstration of the status of vascular patency in OSF, by image analysis (OPTIMAS ver 6.0), that the mean vascular luminal diameter recorded an increasing trend as the disease progresses (Rajendran et al. unpublished observation). This was a significant conceptual deviation from the common wisdom, as regards to the pathogenesis of this disease. Against this backdrop the concept of ischemic atrophy was disputed by these authors who held that the usual tissue reaction resultant to ischemia / hypoxia does not seem to operate in this disease; which is preconditioned by significant stromal changes as part of the disease process. These authors demonstrated a mean vascular dilatation, instead of a generalized vasoconstriction, which they assumed to be an adaptive response to tissue ischemia due to the physical effects of pathological fibrosis. It is speculative therefore to evaluate the role of a peripheral vasodilator pentoxifylline, in the treatment of OSF. The beneficial effect recorded by pentoxifylline in managing advanced OSF, prompt us to explore further with the biological effects of this drug, and also to elucidate the effectiveness of this drug in dealing with this rather prototype of pathologic fibrosis.
Because OSF is a chronic mucosal inflammatory disease (persistent stomatitis and glossitis), control of the inflammation or the factors influencing the inflammatory process should form the basis of definitive management. Primary immunologic abnormalities have been reported with OSF and that these immune abnormalities probably mediate local tissue damage and that they appear to be the final common pathway in the pathogenesis of OSF. But there is no unifying explanation for this immunological basis of OSF . The drug pentoxifylline is said to have the property of suppressing leucocyte function while altering fibroblast physiology and stimulating fibrinolysis. Its immuno-modulating actions include increasing leucocyte adhesion. It also causes neutrophil degranulation and the release of peroxides, promotes natural killer cell activity and the production of tumor necrosis factor, and inhibits T and B cell activation . The subjective improvement in clinical outcome recorded in this study may probably be attributed to these pharmacological effects of the drug. The anti inflammatory and immunomodulatory actions of'Trental' seems to have definite therapeutic advantages in the management of OSF but the long term effects of which is difficult to speculate now. Some of our patients are being followed up for a period of more than 12 months and the beneficial effects seemed to be holding, is regarded as a desirable effect of the drug.
The property of pentoxifylline that may be far-reaching in the management of OSF is perhaps its effect on the fibroblast and the role it assumed in fibrinolysis. There are some features exclusive to skin and the subcutaneous tissue that may also be important in the oral mucosal sites, particularly in the context of wound healing and connective tissue diseases in general. Berman and Duncan (1989)  showed that fibroblasts cultured in the presence of pentoxifylline produce twice as much collagenase activity and decreased amount of collagen, glycosaminoglycans and fibronectins. IL-1 induced fibroblast proliferation was inhibited by the addition of pentoxifylline. In another series by Berman et al (1992)  pentoxifylline blocked TNF-a induced synthesis of fibroblast collagen, glycosaminoglycans and collagenolytic activity. It was determined that these selective inhibitory effects occurred without altering TNF-a receptor mRNA, the number of cell receptors, or affinity for TNF-a receptors compared with untreated controls. These results suggest that the inhibitory activities of pentoxifylline on fibroblasts are mediated at a locus other than TNF-a receptors.
Most side effects caused by pentoxifylline involve the gastrointestinal tract and central nervous system. In initial placebo-controlled clinical trials, the overall incidence of adverse effects was higher in patients who received pentoxifylline in capsule form than in those who received a commercially available sustained release tablet (SRT) . The latter formulation slows drug delivery and minimizes gastric intolerance. The most frequent gastrointestinal complaints include dyspepsia, nausea and /or vomiting in less then 3% of the patients receiving 1200mg per day in sustained release form. Approximately 1% report bloating, flatus, and bleeding. Principal central nervous system side effects include dizziness and headache in a small percentage of patients, whereas tremor, anxiety, and confusion occur in some. Both central nervous system and gastro-intestinal side effects are dose related and are therefore minimized by dose reduction. The adverse side effects which warrant ceasation of therapy occurred in only one patient in this clinical trial and this low frequency of untoward effects was attributed mainly to adherence to the threshold dosage and SRT form of medication.
Although primary or adjunctive therapy with pentoxifylline has been suggested for a multitude of disorders that include cases of pathological fibrosis, there are few controlled clinical trials to confirm its efficacy. It is hoped that future double blind placebo- controlled clinical studies that use pentoxifylline and its derivatives will determine if the many beneficial pharmacokinetic properties of pentoxifylline are effective in treating this enigmatic human disease of oral submucous fibrosis.
The authors would like to acknowledge with gratitude the discussion held on this topic with Dr. Bobby Collins, University of Pittsburgh, United States, which paves way for this clinical trial. The statistical help by way of analysis and interpretation of raw clinical data done by Mr. S. M. Nair, Clinical Epidemiology Unit, Medical College Hospital, Trivandrum is gratefully acknowledged.
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