Sialogogic activities of SNI-2011 compared with those of pilocarpine and McN-A-343 in rat salivary glands: identification of a potential therapeutic agent for treatment of Sjörgen's syndrome

Reactivity of human labial glands in response to cevimeline treatment

Among the pathologies affecting the salivary glands, the Sjögren's syndrome (SS), an autoimmune disease, causes progressive destruction of the glandular tissue. The effect of SS is particularly evident on the labial glands and the morphological analysis of these minor glands is considered useful for diagnosis. Cevimeline hydrochloride (SNI), a selective muscarinic agonist drug, is one of the elective treatments for the hyposalivation due to SS, acting not only on major salivary glands, but also on labial glands since their secretion is primarily under parasympathetic control. Aim of this study is to describe the morphology of human labial glands treated with SNI by light, transmission, and high-resolution scanning electron microscopy. Moreover, a morphometric analysis was applied to the light and transmission electron microscopy micrographs to obtain data that were then compared with analogous data collected on control and carbachol-treated labial glands. Following SNI administration, the mucous tubules exhibited enlarged lumina, which were filled with a dense mucous secretion. Occasionally, small broken debris of the cells were retrieved into the lumen. In the mucous secretory cells, some mucous droplets fused to form a large vacuole-like structure. Similarly, the seromucous acini showed both dilated lumina and canaliculi. These above reported signs of secretion were confirmed through morphometric analysis and a milder action of SNI than carbachol on labial parenchyma was observed. This study confirmed that SNI also evoked secretion on labial glands and that its effect is more physiologic than that of the pan-muscarinic agonists.

Diagnosis and management of xerostomia and hyposalivation

Xerostomia, the subjective complaint of dry mouth, and hyposalivation remain a significant burden for many individuals. Diagnosis of xerostomia and salivary gland hypofunction is dependent upon a careful and detailed history and thorough oral examination. There exist many options for treatment and symptom management: salivary stimulants, topical agents, saliva substitutes, and systemic sialogogues. The aim of this review is to investigate the current state of knowledge on management and treatment of patients affected by xerostomia and/or hyposalivation.

Management of radiotherapy-induced salivary hypofunction and consequent xerostomia in patients with oral or head and neck cancer: meta-analysis and literature review

OBJECTIVE

To analyze the efficacy of various treatment options for radiation-induced hyposalivation in patients with head and neck cancer.

STUDY DESIGN

A literature review and meta-analysis was performed on all appropriate literature identified via MEDLINE/PubMed.

RESULTS

Fourteen articles were identified that met inclusion criteria for review, and 8 articles qualified for inclusion in the meta-analysis. The available literature addressed both objective and subjective responses of hyposalivation, xerostomia, or both to cholinergic agonists (such as pilocarpine and cevimeline), salivary substitutes, hyperbaric oxygen, and acupuncture.

CONCLUSIONS

This analysis indicated that cholinergic agonists were more effective in treating radiation-induced hyposalivation compared with salivary substitutes, hyperbaric oxygen, and acupuncture. However, other treatment modalities, such as salivary substitutes and hyperbaric oxygen, were also found to subjectively improve patients' perception of xerostomia.

A comprehensive review of autoantibodies in primary Sjögren's syndrome: clinical phenotypes and regulatory mechanisms

Sjögren's syndrome (SS) is a systemic autoimmune disease characterized by periepithelial lymphocytic infiltrates in affected tissues and the production of plethora of autoantibodies. Among them autoimmune responses against Ro/SSA and La/SSB are of major importance since their detection is routinely used for disease diagnosis and clinical characterization. Although the exact mechanisms underlying disease pathogenesis are not fully understood, the important role of salivary gland epithelial cells (SGEC) in the initiation and development of the local immune responses is well-established. SGECs are also capable to mediate the exposure of the Ro/SSA and La/SSB autoantigens to the immune system by elevated apoptosis and autoantigen release in apoptotic bodies and/or by the secretion of autoantigen-containing exosomes. The expression of these autoantigens in epithelial cells appears to be tightly regulated. Up-to-date, signaling of certain innate immunity receptors, such as TLR3, appear to be implicated in the regulation of Ro/SSA and La/SSB expression by SGECs, whereas the deregulated expression of certain miRNAs that are predicted to target them in SS patients suggests a regulatory feedback at the post-transcriptional level. In the periphery, the humoral autoimmune responses are further regulated by the development of an active network of idiotypic-antiidiotypic antibodies. The plethora of mechanisms suggests that autoimmune humoral responses in SS are tightly regulated. In this review, the major humoral autoimmune responses, recent advances on the role of epithelial cells in their development, as well as possible regulatory mechanisms will be discussed.

Significant increase in salivary substance p level after a single oral dose of cevimeline in humans

Cevimeline is a novel muscarinic acetylcholine receptor agonist currently being developed as a therapeutic agent for xerostomia. We examined the effects of cevimeline on salivary and plasma levels of substance-P- (SP-), calcitonin-gene-related-peptide- (CGRP-), and vasoactive-intestinal-polypeptide- (VIP-) like immunoreactive substances (ISs) in humans. An open-labeled crossover study was conducted on seven healthy volunteers. Saliva volume was measured, and saliva and venous blood samples were collected before and 30–240 min after a single oral dose of cevimeline or placebo. Salivary and plasma levels of SP-, CGRP-, and VIP-IS were measured using a highly sensitive enzyme immunoassay. A single oral dose of cevimeline resulted in significant increases in salivary but not plasma SP-IS level compared to placebo. Cevimeline administration did not alter the salivary or plasma levels of CGRP-IS or VIP-IS compared to placebo. Significant increases in salivary volume were observed after cevimeline administration compared to placebo. A significant correlation was observed between the total release of SP-IS and that of salivary volume. These findings suggest an association of SP with the enhancement of salivary secretion by cevimeline.

Review of the Pharmacological Properties and Clinical Usefulness of Muscarinic Agonists for Xerostomia in Patients with Sjögren's Syndrome

The anti-xerostomia effects of muscarinic agonists (cholinomimetics) are reviewed. Cevimeline (cevimeline monohydrochloride hemihydrate) is a novel muscarinic agonist that stimulates salivary secretion in animals and humans both with normal salivary gland function and with impaired salivary secretion (xerostomia or oral dryness) as effectively as pilocarpine. Other classic and nonselective muscarinic agonists, such as arecoline, carbachol, muscarine and oxotremorine, as well as acetylcholine, failed to exhibit a sufficient salivation effect even at sublethal doses in animals.Oral administration of cevimeline 30mg to humans induces a moderate and lasting increase in salivary flow, and the effect is maintained for at least 4 to 6 hours, longer than with pilocarpine. Mean increases in salivary flow rates after cevimeline treatment were 2-fold higher than after placebo, and no evidence of tolerance of the pharmacological effect has been observed during prolonged administration for up to 12 months.The clinical efficacy of cevimeline in relieving symptoms of xerostomia, including oral dryness and difficulties in chewing, swallowing and speaking, has been demonstrated by placebo-controlled, double-blind, randomised clinical trials in the USA and Japan. In these studies, cevimeline 30mg three times daily increased salivary flow and improved the symptoms of xerostomia in a significantly higher percentage of patients compared with placebo. Some patients receiving cevimeline therapy for xerostomia experienced adverse events such as sweating, gastrointestinal symptoms (nausea, diarrhoea, abdominal pain and vomiting), dizziness and rigors; these effects were related to muscarinic activity and were generally mild and tolerable in comparison with those of pilocarpine.These findings suggest that muscarinic M3 agonists are suitable for the treatment of xerostomia. Cevimeline in particular has a long-lasting salivation effect with fewer adverse events than pilocarpine, and so is expected to be more useful for the treatment of xerostomia in patients with Sjögren's syndrome, reducing symptom severity and improving their quality of life.

Subgroups of Sjögren syndrome patients according to serological profiles

Sjögren Syndrome (SS) is a systemic, autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands. Different clinical associations have been described for each of the diverse autoantibodies found in SS patients. Antibodies directed against the Ro/La ribonucleoprotein complexes have been correlated with younger age, more severe dysfunction of the exocrine glands and a higher prevalence of extraglandular manifestations. Anti-nuclear antibodies and rheumatoid factors have been associated to extraglandular manifestations and an active immunological profile, while cryoglobulins are markers of more severe disease and correlate to lymphoma development and death. Antibodies to cyclic citrullinated peptides are scarce in SS and have been linked in some cases to the development of non-erosive arthritis. Furthermore, the presence of anti-mitochondrial antibodies and anti-smooth muscle antibodies in the sera of primary SS patients is considered indicative of primary biliary cirrhosis and autoimmune hepatitis, respectively. In addition, anti-centromere antibodies have been associated with a clinical phenotype intermediate between primary SS and systemic sclerosis, while antibodies against carbonic anhydrase have been related to renal tubular acidosis. Finally, an association of anti-muscarinic antibodies with cytopenias and a higher disease activity has also been described in primary SS. In conclusion, although not all of the above mentioned antibodies are useful for predicting distinct patient subgroups in SS, knowledge of the clinical associations of the different autoantibody specificities encountered in SS can advance our understanding of the disease and improve patient management.

Cevimeline-induced monophasic salivation from the mouse submandibular gland: decreased Na+ content in saliva results from specific and early activation of Na+/H+ exchange

Cevimeline and pilocarpine are muscarinic agonists used clinically to treat dry mouth. In this study, we explored fluid secretion from mouse submandibular glands to determine the mechanism of cevimeline, pilocarpine, and an experimentally used agent carbachol. Cevimeline evoked almost the same amount of secretion at concentrations from 30 μM to 1 mM. Pilocarpine also induced secretion at a concentration as low as 1 μM and was the most powerful secretagogue at 10 μM. Secretion was induced by carbachol at 0.1 μM, with maximum secretion at 1.0 μM. Cevimeline induced monophasic secretion at all concentrations tested, whereas higher concentrations of pilocarpine and carbachol induced secretion with variable kinetics, i.e., an initial transient high flow rate, followed by decreased secretion after 2 to 3 min. In the presence of an epithelial Na(+) channel blocker, amiloride, neither carbachol nor pilocarpine affected the Na(+) level of secreted saliva; however, it significantly increased the Na(+) content of cevimeline-induced saliva. The intracellular Ca(2+) response of acinar cells was almost identical among all three agents, although recovery after drug removal was slower for cevimeline and pilocarpine. A profound decrease in intracellular pH was observed during pilocarpine and carbachol treatment, whereas intracellular acidification induced by cevimeline was only seen in the presence of a Na(+)/H(+) exchange inhibitor. When external HCO(3)(-) was removed, cevimeline-induced saliva significantly decreased. These findings suggest that cevimeline specifically activates Na(+)/H(+) exchange and may promote Na(+) reabsorption by stabilizing epithelial sodium channel activity.

Sjögren's syndrome patients presenting with hypergammaglobulinemia are relatively unresponsive to cevimeline treatment

Sjögren's syndrome (SS) is a systemic autoimmune disease characterized by sicca symptoms, including dry eyes and dry mouth. Cevimeline is used for the treatment of dry mouth in patients with SS. Here we prospectively tested the clinical effectiveness of cevimeline at increasing saliva secretion in patients with SS, and the results were compared with the clinical parameters of the patients. Saliva secretion was increased >160% in 17 of 30 (56.7%) patients (P < 0.005). When the clinical parameters were compared between the patients who responded to cevimeline treatment and those who did not respond to the treatment, the frequency of patients presenting with hypergammaglobulinemia was significantly higher in the nonresponder group (P < 0.05). It thus appears that cevimeline is effective in SS patients with milder disease activity.

Cevimeline

Cevimeline is an orally administered muscarinic receptor agonist that is indicated for the treatment of symptoms of dry mouth in patients with Sjogren's syndrome. Several well designed placebo-controlled trials demonstrated that 4-12 weeks' therapy with cevimeline 30 mg three times daily improved symptoms of dry mouth in patients with Sjogren's syndrome. Other symptoms, such as dry eye symptoms and overall dryness, also improved to a significantly greater extent with cevimeline than with placebo. Moreover, cevimeline significantly improved the salivary flow rate in patients with Sjogren's syndrome. Increased salivary flow was maintained in the longer term with cevimeline in patients with Sjogren's syndrome and symptoms of dry mouth, according to the results of an open-label 52-week study. From week 20 onwards, rates of patient and investigator satisfaction with the cevimeline dosage were > or =88%. Oral cevimeline 30 mg three times daily was generally well tolerated in patients with Sjogren's syndrome, with many of the most commonly reported adverse events reflecting the pharmacological action of the drug.

Degradation of submandibular gland AQP5 by parasympathetic denervation of chorda tympani and its recovery by cevimeline, an M3 muscarinic receptor agonist

By chorda tympani denervation (CTD, parasympathectomy), the aquaporin 5 (AQP5), but not AQP1, protein level in the rat submandibular gland (SMG) was significantly decreased, dropping to 37% of that of the contralateral gland at 4 wk. The protein levels of AQP5 and AQP1 were not significantly affected by denervation of the cervical sympathetic trunk (sympathectomy). Administration of cevimeline hydrochloride, an M3 muscarinic receptor agonist (10 mg/kg for 7 days po), but not pilocarpine (0.3 mg/kg for 7 days po), recovered the AQP5 protein level reduced by CTD and increased the AQP1 protein level above the control one. The mRNA level of AQP5 was scarcely affected by CTD and cevimeline hydrochloride administration. Administration of chloroquine (50 mg/kg for 7 days po), a denaturant of lysosomes, increased the AQP5 protein level reduced by CTD. An extract obtained from the submandibular lysosomal fraction degraded the AQP5 protein in the total membrane fraction in vitro. These results suggest the possible regulation of the AQP5 protein level in the SMG by the parasympathetic nerves/M3 muscarinic receptor agonist and imply the involvement of lysosomal enzymes, but not a transcriptional mechanism, in this regulation.

Effect of cevimeline on radiation-induced salivary gland dysfunction and AQP5 in submandibular gland in mice

The aim of this study was to clarify the effects of the muscarinic receptor agonist, cevimeline, on saliva flow and expression of aquaporin5 (AQP5) in submandibular gland after X-ray irradiation. Using a previously established radiation-induced xerostomia model mouse, saliva flow from at 7 days before irradiation to at 28 days after irradiation was investigated in mice that were treated with cevimeline before or after irradiation. Radiation caused a significant decrease in saliva flow compared with nonirradiated salivary glands. Cevimeline post-treatment also caused a significant decrease in saliva flow. In contrast, cevimeline pre-treatment did not significantly decrease saliva flow. Expression of AQP5 fluorescent intensity and mRNA were also analyzed. Irradiation significantly decreased expression of AQP5 in submandibular gland. However, pre-treatment with cevimeline prevented this decrease in AQP5 expression. These data suggest that pretreatment with cevimeline prevents radiation-induced xerostomia and radiation-induced decrease in expression of AQP5 in submandibular gland.

Effect of a muscarinic M3 receptor agonist on gastric motility

Muscarinic M3 receptors exist in the gastrointestinal wall in humans and the muscarinic M3 agonist cevimeline hydrochloride (Evoxac) is a candidate therapeutic agent for the treatment of xerostomia in Sjögren's syndrome. However, M3 receptor agonists are not known to show efficacy for diseases associated with abnormal gastrointestinal motility. Herein the effects are reported of cevimeline on gastric motility in two patients with non-ulcer dyspepsia. The patients both received long-term proton pump inhibitor therapy for 6 months, but their symptoms persisted. Then cevimeline was administered orally for 8 weeks at 30 mg three times daily (90 mg/day) and their dyspepsia symptoms improved. Electrogastrography was performed to examine gastric motility before and after administration of the M3 agonist. The fasting or nocturnal wave rate was significantly increased after administration compared with before administration, but no significant postprandial changes were seen. No adverse effects of cevimeline were observed. This drug might be a candidate therapeutic agent for non-ulcer dyspepsia. Because its postprandial effects on gastrointestinal motility are unclear, a dose-finding clinical study should be performed in the future.

Salivary secretion, taste and hyposalivation

Saliva has many essential functions. As the first digestive fluid in the alimentary canal, saliva is secreted in response to food, assisting intake and initiating the digestion of starch and lipids. During this process, saliva acts as a solvent of taste substances and affects taste sensitivity. Clinically, a more important role is in the maintenance of oral health, including the protection of teeth and mucosa from infections, maintenance of the milieu of taste receptors, and communication ability through speech. Variations in salivary flow can be affected, reversibly or irreversibly, by numerous physiological and pathological factors. Decreased salivary flow results in clinically significant oral discomfort that may manifest as increased caries, susceptibility to oral candidiasis, altered taste sensation or as a host of other problems. Hyposalivation is a condition that is frequently encountered in dental practice. The most common cause is the use of certain systemic medications, which put the elderly at greater risk because they are usually more medicated. Other causes include high doses of radiation and certain diseases such as Sjögren's syndrome. This article reviews the mechanism of salivary secretion, effect of saliva on taste, importance of saliva in oral health, and hyposalivation in relation to ageing, medicine and/or disease and management of hyposalivation.

Cevimeline for the Treatment of Postirradiation Xerostomia in Patients With Head and Neck Cancer

PURPOSE

To study the efficacy and safety of cevimeline in two double-blind trials (Studies 003 and 004) enrolling patients with head and neck cancer in whom xerostomia developed after radiotherapy.

METHODS AND MATERIALS

Subjects were randomly assigned to receive cevimeline, 30 mg three times daily, or placebo for 12 weeks, with the possibility of dose escalation to 45 mg three times daily at 6 weeks. The primary efficacy endpoint was the patient's final global evaluation of oral dryness; change in unstimulated salivary flow was a secondary endpoint.

RESULTS

Five hundred seventy subjects (284 in Study 003 and 286 in Study 004) were randomized. Significantly more cevimeline-treated subjects than placebo recipients (47.4% vs. 33.3%, p = 0.0162) in Study 003 reported improvement in dry mouth in the final global evaluation of oral dryness. No significant difference between groups in the final global evaluation was seen in Study 004, in which a high placebo response rate of 47.6% was observed. In both studies, cevimeline-treated subjects had significantly greater increases in the objective measure of unstimulated salivary flow than placebo recipients (p = 0.0093 [Study 003] and p = 0.0215 [Study 004]), whereas no significant differences in stimulated salivary flow were observed. The most frequent adverse event was increased sweating.

CONCLUSION

Cevimeline was well tolerated by patients with xerostomia after radiotherapy for head and neck cancer, and oral administration of 30-45 mg of cevimeline three times daily increased unstimulated salivary flow.

Peroxynitrite formation in radiation-induced salivary gland dysfunction in mice

Xerostomia frequently arises in patients with head and neck malignancies that are treated by radiation. However, the mechanisms responsible for the destruction of the salivary gland remain unknown. We previously established a xerostomia model of mice and identified the pathway through which nitric oxide (NO) affects the pathogenesis of radiation-induced salivary gland dysfunction. Although the toxicity of NO alone is modest, NO with superoxide anion (O2(*-)) rapidly forms peroxynitrite (ONOO), a more powerful toxic oxidant. In this study, we used the experimental model to examine: 1) when NO and O2(*-) production is maximum in the salivary gland after irradiation;2) whether peroxynitrite, as assessed by nitrotyrosine production, is responsible for salivary gland dysfunction; and 3) the effect of the iNOS selective inhibitor, aminoguanidine (AG), on nitrotyrosine formation. The increases in production of NO and O2(*-) in the salivary gland peaked on day 7 after irradiation. Nitrotyrosine detected immunohistochemically was significantly reduced by AG in the salivary gland. On the basis of these results, we concluded that NO together with O2(*-) forms the more reactive ONOO, which might be an important pathogenic factor in radiation-induced salivary gland dysfunction.

Assessment of the use of sialogogues in the clinical management of patients with xerostomia

This study was conducted to assess the clinical efficacy and adverse effects of pilocarpine, bethanechol and cevimeline in patients with xerostomia. In this open-label crossover assessment in 20 patients with xerostomia, a one- to two-week course of each medication with a one-week washout period was prescribed. Side effects, symptoms, whole stimulated and unstimulated saliva were measured. Each sialogogue was found to increase saliva and decrease symptoms. A mixed-effects analysis showed a greater increase in stimulated saliva on bethanechol compared to pilocarpine (0.106, p = 0.0272). Increased sweating was the most common side effect, experienced more frequently with pilocarpine as compared to bethanechol (p = 0.0588) or cevimeline (p = 0.0143). A carryover effect beyond the washout period was seen. Effects on saliva and side effects vary between sialogogues, suggesting a benefit of trials with different sialogogues to determine individual patient preference. The observed carryover effect suggests that intermittent treatment may be an alternative to continuous treatment with sialogogues.

Radiation-induced xerostomia

BACKGROUND

Radiation-induced xerostomia is a frequent and usually permanent side effect of radiation therapy for head and neck cancer. We summarize recent developments in the prevention and treatment of radiation-induced xerostomia.

METHODS

The Medline database was searched for articles published within the past 10 years on the prevention and treatment of postirradiation xerostomia. Proceedings of recent important national meetings and government Web registries of clinical trials and therapeutic agents were also consulted. Priority was given to randomized controlled trials but, because of the scarcity of such trials, small open trials were included in this review. No other predetermined selection criteria were used, although articles exploring the effects of xerostomia and its treatment on quality of life were considered of special interest.

RESULTS

A variety of preventive approaches for postirradiation xerostomia exist, involving more conformal radiation delivery technology, radioprotective agents, and even preirradiation surgical techniques. Therapeutic interventions include supportive care, saliva supplementation, and the use of pro-cholinergic salivary secretagogues.

CONCLUSIONS

Radiation-induced xerostomia constitutes a significant morbidity after orofacial irradiation. Careful preventive techniques, meticulous supportive care, and new preventive and therapeutic agents may prove useful in combination.

Recent advances in the management of ocular complications of Sjögren's syndrome

Sjögren's syndrome (SS) is an autoimmune disorder, the principal ocular manifestation of which is decreased tear production leading to chronic irritation and damage to the corneal and conjunctival epithelium. The most important advance in the treatment of ocular manifestations of SS is the introduction of topical anti-inflammatory agents such as cyclosporine A, which increases tear production and decreases symptoms without any significant side effect. Stimulators of tear secretion, both topical, such as diquafosol, and systemic, such as pilocarpine and cevimeline, are also effective, although they have been associated with frequent side effects. Topical use of autologous serum is another new and effective form of treatment, but problems in the preparations prevent their widespread use. Additionally, nonpharmacologic treatments, such as insertion of punctal plugs, are beneficial in the dry eye of SS, whereas several other modalities, such as anti-CD4 monoclonal antibody eye drops and gene transfer, are still in experimental phases.

Effect of cevimeline on salivary components in patients with Sjögren syndrome

The aim of this study is to clarify the effects of cevimeline on various components in human saliva, such as immunoglobulin A (IgA), lysozyme, alpha-amylase and squamous cell carcinoma (SCC) antigen. Twelve female patients with Sjögren syndrome (SS) and 14 healthy women were enrolled. After the first saliva collection, one capsule (30 mg) of cevimeline was administered to each subject. Saliva was collected again after 90 min. The salivary flow rate and concentration of each component were measured. In both groups the salivary flow rate and amylase concentration were significantly increased by cevimeline. The lysozyme and IgA concentrations did not change significantly in both groups. The SCC antigen concentration did not change significantly in the SS group, but it decreased significantly in the control group. The secretion rates of amylase and IgA showed significant increases in both groups. The secretion rate of lysozyme significantly increased only in the control group, while the secretion rate of SCC significantly increased only in the SS group. Cevimeline augments not only the salivary flow rate but also the secretion rate of some digestive and/or defense factors from infections. It may be beneficial for SS patients to continue taking cevimeline to prevent oral infections, and other serious sequelae.

An update of the etiology and management of xerostomia

Salivary gland disease gives rise to salivary gland enlargement, pain, and prolonged xerostomia (dry mouth). Xerostomia is the most common long-standing problem for the majority of affected patients. There are many causes of dry mouth, with long-standing xerostomia being a particular problem in Sjögren's syndrome and after radiation to the head and neck region. Xerostomia is usually managed with saliva substitutes, but a large number of potential systemic therapies of long-standing xerostomia now exist. Some-particularly immunosuppressants-are of fundamental interest for the potential reduction of gland damage in Sjögren's syndrome but as yet are of limited clinical usefulness. Others, particularly pilocarpine and cevimeline, are, or have the potential to be, clinically useful in stimulating salivation by virtue of their action on cholinergic receptors.

Implants in the medically compromised patient

Dental clinicians are confronted with an increasing number of medically compromised patients who require implant surgery for their oral rehabilitation. However, there are few guidelines on dental implant therapy in this patient category, so that numerous issues regarding pre- and post-operative management remain unclear to the dental clinician. Therefore, the aim of the present review is to offer a critical evaluation of the literature and to provide the clinician with scientifically based data for implant therapy in the medically compromised patient. This review presents the current knowledge regarding the influence of the most common systemic and local diseases on the outcome of dental implant therapy, e.g., abnormalities in bone metabolism, diabetes mellitus, xerostomia, and ectodermal dysplasias. Specific pathophysiologic aspects of the above-mentioned diseases as well as their potential implications for implant success are critically appraised. In line with these implications, guidelines for pre- and post-operative management that may assist in the successful implant-supported rehabilitation of this patient category are proposed.

Possible role of nitric oxide in radiation-induced salivary gland dysfunction

In this study, we developed a murine model of xerostomia to elucidate the mechanism of radiation-induced salivary gland dysfunction and determined the levels of nitric oxide (NO) in the salivary glands to assess its involvement in the salivary dysfunction induced by radiation. In addition, an inhibitor of NO synthesis was administered to the model in vivo, and its effect on saliva secretion was investigated. Salivary gland irradiation at a dose of 15 Gy caused a significant decrease in secretion compared to unirradiated salivary glands. There were no marked differences between the irradiated mice and unirradiated mice in water or food consumption or in body weight changes. The NO levels in the cultured salivary gland epithelial cells were increased by treatment with a combination of interferon gamma (Ifng), interleukin 1-beta (Il1b), and tumor necrosis factor alpha (Tnfa). Irradiation increased the NO level in the salivary gland tissue. The presence of N(G)-monomethyl-l-arginine acetate (l-NMMA), an inhibitor of NO synthesis, caused a decrease in the NO level in cultured salivary gland tissues after irradiation. Administration of l-NMMA to irradiated mice improved saliva secretion. These results suggest that excessive production of NO induced by radiation is involved in the formation of radiation-induced xerostomia. The finding that administration of an inhibitor of NO synthesis ameliorated the dysfunction of irradiated salivary glands indicates that NO plays a role as a mediator of the dry mouth symptoms that occur after irradiation.

Sjogren's syndrome: evolving therapies

Sjogren's syndrome (keratoconjunctivis sicca) is a relatively common disorder with incidence of approximately 0.5% of adult women. It has both local (ocular and oral) features as well as systemic manifestations. There has been recent FDA approval of agents to stimulate salivation (pilocarpine and cevimeline) and studies are in progress to determine their role in the treatment of dry eye. New therapies are in clinical trials for ocular manifestations with the most interest focused on topical cyclosporin A and purinogenic receptor agonists. In oral therapy, topical human interferon has reported encouraging results in short-term studies. However, the high placebo response (probably reflecting the beneficial response of mechanical stimulation of the buccal mucosa by the lozenge) and the response to much cheaper therapies (such as acid maltose lozenges) may offer safer and cheaper alternatives. For systemic disease, there is interest in tumour necrosis factor inhibitors. However, the cost-effectiveness and safety of biological agents needs longer term follow up, as they appear much less dramatic in their effect on systemic lupus erythematosus or Sjogren's syndrome than in rheumatoid arthritis.

[Cevimeline hydrochloride hydrate (Saligren capsule 30 mg): a review of its pharmacological profiles and clinical potential in xerostomia]

Cevimeline hydrochloride hydrate is a muscarinic receptor agonist with a chemical structure of a quinuclidine. Intraduodenal administration of cevimeline hydrochloride hydrate dose-dependently increased salivary secretion in normal mice and rats, two strains of autoimmune disease mice, and X-irradiated rats. The clinical efficacy of the cevimeline hydrochlide hydrate at 30 mg t.i.d. during 4 weeks has been demonstrated in double blind comparative study with placebo. In addition, its treatments in 52 weeks have increased salivary flow and improved subjective and objective symptoms of patients with xerostomia in Sjögren's syndrome.

A double-blind, randomized, placebo-controlled study of cevimeline in Sjögren's syndrome patients with xerostomia and keratoconjunctivitis sicca

OBJECTIVE

To evaluate the safety and efficacy of 2 dosages of cevimeline for the treatment of xerostomia and keratoconjunctivitis sicca in patients with Sjögren's syndrome.

METHODS

A 12-week double-blind, randomized, placebo-controlled study was performed. Patients were randomly assigned to receive either placebo, 15 mg of cevimeline 3 times daily, or 30 mg of cevimeline 3 times daily. Patients were evaluated at baseline and throughout the study for their global assessment of dryness (mouth, eyes, overall) as well as their subjective assessment of the specific symptoms of dry mouth and dry eyes. Total saliva and tear flow also were measured.

RESULTS

Patients taking 30 mg of cevimeline 3 times daily had statistically significant improvements in their subjective global assessment of dry eyes (P = 0.0453), dry mouth (P = 0.0004), and increased salivary flow (P = 0.007). Patients receiving the 30-mg dosage also showed greater objective improvement (increased salivary and lacrimal flow rates, as measured by Schirmer's test) than did patients receiving placebo. Frequently reported adverse events included headache, increased sweating, abdominal pain, and nausea.

CONCLUSION

Treatment with cevimeline at a dosage of 30 mg 3 times daily resulted in substantive improvement by increasing the rate of saliva and tear flow in patients with Sjögren's syndrome, as well as improving subjective symptoms of dry mouth, dry eyes, and overall dryness. The 15-mg dosage relieved some symptoms, and both dosages were well tolerated.

Treatment of systemic sclerosis

Systemic sclerosis is an extremely variable disease in its manifestations and consequently, treatment needs to be individualized depending on the specific problems that each patient has. Limited scleroderma patients have a prolonged duration of Raynaud's phenomenon and puffy fingers before they develop any skin thickening, digital ulcers or gastrointestinal symptoms. They are likely to present with all the classic manifestations of scleroderma. Diffuse scleroderma patients have a much more acute systemic onset with marked whole hand swelling and may initially have only subtle skin thickening. A good understanding of the differences between the natural history of limited and diffuse scleroderma will enable the physician to treat present problems and anticipate future ones more effectively. One should determine which major subset and organ systems are involved before deciding on the appropriate therapy. Advances in organ-specific therapy, particularly calcium channel antagonists in Raynaud's phenomenon, proton pump inhibitors in esophageal reflux, intravenous iloprost and endothelin receptor antagonists in pulmonary hypertension, and ACE inhibitors in renal crisis, have decreased morbidity and mortality in patients with scleroderma. Studies of aggressive therapies to prevent or improve pulmonary fibrosis are in progress. Further clinical experience in wound healing, gastrointestinal malabsorption and physical therapy for loss of motion has helped patients to have a more comfortable life. In recent years, a significant number of controlled clinical trials have been performed and there has been improved understanding of the best way to perform studies and of which patients are most likely to respond to therapy. Penicillamine, methotrexate, photopheresis, relaxin, interferons, and cyclosporine have all been studied in controlled trials with variable outcomes. Although an overall remittive therapy has not yet been determined, new, potentially useful agents are being investigated.

Use of muscarinic agonists in the treatment of Sjögren's syndrome

Two muscarinic agonists (pilocarpine and cevimeline) have recently been approved for the treatment of symptoms of xerostomia in Sjögren's syndrome (SS). These agents stimulate the M1 and M3 receptors present on salivary glands, leading to increased secretory function. The use of these agents emphasizes the importance of neuroendocrine mechanisms in SS, which is considered an autoimmune disorder. We review recent studies on the release of cytokines and metalloproteinases in SS-affected glands and their influence on the release of and response to neurotransmitters. Also, we review the structure and function of muscarinic receptors as they may relate to SS and the potential use of novel muscarinic agonists in SS.

The management of Sjögren's syndrome in dental practice

BACKGROUND

Sjögren's syndrome, or SS, is a multisystem inflammatory disorder of the exocrine glands with a wide range of extraglandular involvement. Symptoms of dry eyes and xerostomia, although not invariably present, are characteristic features of SS. An increased risk of oral and dental diseases is a prominent consequence of SS.

TYPES OF STUDIES REVIEWED

The author reviewed recent medical and dental studies that have advanced our understanding of the causes and treatment of SS. She particularly focused on studies addressing the diagnosis and treatment of the oral component of the disease.

RESULTS

Sjögren's syndrome is a widely underdiagnosed disease. A delay in the diagnosis of SS may have a significant physical, psychological and economic impact on the affected person. The pathogenesis of SS appears to involve a number of factors: immunological, genetic, hormonal and possibly infectious. Successful management of SS requires a multidisciplinary approach, and the dentist plays an essential role in the diagnosis and treatment of the disease. ORAL IMPLICATIONS: Impairment of salivary function in SS increases the risk of developing oral diseases. Effective management of oral health comprises enhancement of salivary output (cholinergic agonist drugs such as pilocarpine or cevimeline) and prevention and treatment of dental caries, oral candidiasis and allergic mucositis. Finally, periodic evaluation of various clinical and laboratory parameters is needed to monitor disease status.

Salivary gland dysfunction: a review of systemic therapies

Xerostomia may result from salivary dysfunction secondary to a variety of conditions, including medications, autoimmune disease, and tumoricidal therapy. As the geriatric population increases, the incidence of xerostomia will increase and the oral manifestations will continue to be a challenge to the clinician. Common oral manifestations resulting from decreased salivary flow include increased dental caries, fungal infections, and dysphagia. Treatment for salivary gland dysfunction is currently limited because of a lack of controlled clinical trials. Medications that have been studied in clinical trials are emphasized in this article. The aim of this article is to briefly review salivary gland physiology and to summarize the suggested systemic treatment modalities for xerostomia that emphasize controlled clinical trials.

Sjögren's syndrome: current therapies remain inadequate for a common disease

Sjögren's syndrome (SS) is a systematic autoimmune disease characterised by dysfunction of the lacrimal and salivary glands. This dryness leads to the symptoms of dry eyes and keratoconjunctivitis sicca, which is painful and may predispose patients to ocular infections. Also, SS patients develop dry mouth, which is uncomfortable and associated with progressive dental disease. SS is divided into secondary SS (where the dryness symptoms are associated with another well defined autoimmune disorder such as rheumatoid arthritis, systemic lupus erythematosus, or scleroderma) and primary SS (where the patients do not fulfil criteria for another well defined associated autoimmune disease). Primary SS has extra glandular organ involvement including lung (interstitial pneumonitis), renal (interstitial nephritis), peripheral and central nervous system manifestations, vasculitis of skin and other organs and increased frequency of lymphoma. This review will concentrate on primary SS. Therapies are divided into agents for topical replacement of deficient secretions (artificial tears, artificial salivas), stimulation of muscarinic M3 receptors (pilocarpine, cevimeline) to increase aqueous secretions, reduction of topical inflammation (topical cyclosporin or corticosteroids for the eye and fluorides or antibacterial varnishes for the mouth) and modification of the immune response in a manner similar to treatment of systemic lupus (antimalarial drugs, methotrexate, cyclophosphamide and perhaps newer agents such as leflunomide or TNF inhibitors).

(+/-)-cis-2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine] hydrochloride, hemihydrate (SNI-2011, cevimeline hydrochloride) induces saliva and tear secretions in rats and mice: the role of muscarinic acetylcholine receptors

We investigated effects of (+/-)-cis-2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine] hydrochloride, hemihydrate (SNI-2011, cevimeline hydrochloride), a rigid analogue of acetylcholine, on saliva and tear secretions in rats and mice to evaluate its therapeutical efficacy for xerostomia and xerophthalmia in patients with Sjogren's syndrome and X-ray exposure in the head and neck. Intraduodenal administrations of SNI-2011 increased saliva secretion in a dose-dependent manner at doses ranging from 3 to 30 mg/kg in normal rats and mice, two strains of autoimmune disease mice and X-irradiated saliva secretion defective rats. The salivation elicited by SNI-2011 was completely inhibited by atropine. A similar atropine-sensitive response was observed in tear secretion. In rat submandibular/sublingual gland membranes, [3H]quinuclidinyl benzilate (QNB) binding was saturable, and Scatchard plot analysis revealed a single population of binding sites with a Kd of 22 pM and a maximal binding capacity of 60 fmol/mg protein. The competitive inhibition curve of the [3H]QNB binding by SNI-2011 was obtained, and its dissociation constant value calculated from IC50 was 1-2 microM. These results suggest that SNI-2011 increases saliva and tear secretions through a direct stimulation to muscarinic receptors in salivary and lacrimal glands, and they suggest that SNI-2011 should be beneficial to patients with Sjögren's syndrome and X-ray exposure in the head and neck.

Long-lasting salivation induced by a novel muscarinic receptor agonist SNI-2011 in rats and dogs

The sialogogic effect of SNI-2011, a novel muscarinic receptor agonist, (+/-)-cis-2-methylspilo [1,3-oxathiolane-5,3'-quinuclidine] hydrochloride, hemihydrate, was compared with that of pilocarpine hydrochloride in a dose range in which the two muscarinic agonists exhibited approximately similar efficacy in eliciting salivation. Pilocarpine (0.66-2.0 mg/kg, i.d.) induced a marked but short-lasting salivation in rats, whereas the salivation induced by SNI-2011 (20-60 mg/kg, i.d.) lasted 1.4- to 1.8-fold longer. In dogs, the sialogogic effect of SNI-2011(1-3 mg/kg, i.v.) also lasted about 2-fold longer than that of pilocarpine (0.1-0.3 mg/kg, i.v.). The plasma SNI-2011 level that caused salivation at a rate of 0.4 ml/min was about 100 ng/ml and higher rates of salivation (over 0.4 ml/min) induced by 1 mg/kg SNI-2011 lasted for about 90 min in dogs. The plasma pilocarpine level that caused salivation at a rate of 0.4 ml/min was about 25 ng/ml and the higher rate of salivation (over 0.4 ml/min) induced by 0.1 mg/kg pilocarpine lasted only for 20 min in dogs. Effective plasma levels of SNI-2011 persisted longer than those of pilocarpine. These results indicate that SNI-2011 may be useful in the treatment of xerostomia because of its long-lasting sialogogic action.