Synthetic prostaglandin E1 misoprostol as a treatment for tinnitus

Randomised Controlled Clinical Study of Injection Caroverine and Ginkgo Biloba Extract in Cochlear Synaptic Tinnitus

Tinnitus, also known as phantom auditory perception, is an annoying symptom and 13-17% of population reports bothersome tinnitus. Cochlear synaptic tinnitus is the most common type. Many treatments have been tried but none is yet considered to be well established. To evaluate effect of Inj.Caroverine and Ginkgo Biloba extract in cochlear synaptic tinnitus in terms of improving tinnitus grading, tinnitus matching and quality of life of patient. It is Randomised controlled study, conducted in department of ENT, on 86 patients, who met inclusion criteria, divided into 4 groups. Gr1-Inj Caroverin, Gr2-Inj Placebo, Gr3-Ginkgo Biloba extract, Gr4-Placebo as extract. A single dose infusion of caroverine immediately improves tinnitus grading and matching and provides immediate relief in reducing severity of tinnitus in 54.54% cases but improvement was not sustained in caroverine group at 3 month and 6 month follow-up after infusion. Ginkgo biloba also is effective in improving tinnitus grading and matching in 31.8% cases and improvement was sustained in ginkgo biloba group even after 3 month of cessation of treatment i.e. at 6 month follow-up. It is suggested that Inj.Caroverine as intravenous infusion should be given in severe cases of tinnitus to reduce its severity immediately and then patient should be put on Tab.Ginkgo biloba for a period of 3 months to provide sustained and long lasting relief. Thus combination therapy of Inj.Caroverin and Tab.Ginkgo Biloba, appropriately tailored to the need of patient will provide better results in greater majority of patients.

Protective role of misoprostol in prevention of gentamicin ototoxicity

OBJECTIVES

To demonstrate potential protective effect of misoprostol on cochlear toxicity caused by gentamicin with electrophysiological tests and histopathological studies.

MATERIALS AND METHODS

The study included 80 ears of 40 rats with normal hearing threshold and DPOAE value in both ears. Animals were assigned into 4 groups. The rats were randomized into 4 groups. Group I (n = 10): Gentamicin, Group II (n = 10): Gentamicin plus misoprostol, Group III (n = 10): Saline; Group IV (n = 10): Misoprostol. All drugs used in the study were given once daily for 15 days. DPOAE and ABR measurements were repeated after drug administration. Subsequently, the rats' cochleae were examined histopathologically. Baseline DPOAE and ABR values were compared to those obtained after drug exposure and cochlear toxicity was evaluated in electrophysiological manner.

RESULTS

When At baseline, there were no significant differences in DPOAE responses at frequencies of 1001, 1501, 2002, 3003, 4004, 6006 and 7996 Hz among groups. However In DPOAE test, statistically significant difference was observed between the pre-study basal values and post-study results in groups other than gentamicin + misoprostol group. Additionally, It was found that there was a significant difference in DPOAE response at frequency of 4004 Hz obtained at baseline and after drug exposure according to measurements of epithelial vacuolization in stria vascularis. While ABR threshold values were compared at baseline, there were no significant difference in ABR threshold values of left and right ear between groups. Histopathologically it was also found that there were significant differences measurements of epithelial vacuolization in stria vascularis and inflammation among groups (p < 0.05).

CONCLUSION

By these results, misoprostol, a potent antioxidant, has protective effect against cochlear damage, and that may be a safe alternative.

Emerging pharmacotherapy of tinnitus

Tinnitus, the perception of sound in the absence of an auditory stimulus, is perceived by about 1 in 10 adults, and for at least 1 in 100, tinnitus severely affects their quality of life. Because tinnitus is frequently associated with irritability, agitation, stress, insomnia, anxiety and depression, the social and economic burdens of tinnitus can be enormous. No curative treatments are available. However, tinnitus symptoms can be alleviated to some extent. The most widespread management therapies consist of auditory stimulation and cognitive behavioral treatment, aiming at improving habituation and coping strategies. Available clinical trials vary in methodological rigor and have been performed for a considerable number of different drugs. None of the investigated drugs have demonstrated providing replicable long-term reduction of tinnitus impact in the majority of patients in excess of placebo effects. Accordingly, there are no FDA or European Medicines Agency approved drugs for the treatment of tinnitus. However, in spite of the lack of evidence, a large variety of different compounds are prescribed off-label. Therefore, more effective pharmacotherapies for this huge and still growing market are desperately needed and even a drug that produces only a small but significant effect would have an enormous therapeutic impact. This review describes current and emerging pharmacotherapies with current difficulties and limitations. In addition, it provides an estimate of the tinnitus market. Finally, it describes recent advances in the tinnitus field which may help overcome obstacles faced in the pharmacological treatment of tinnitus. These include incomplete knowledge of tinnitus pathophysiology, lack of well-established animal models, heterogeneity of different forms of tinnitus, difficulties in tinnitus assessment and outcome measurement and variability in clinical trial methodology.

PHARMACOLOGICAL TREATMENTS FOR TINNITUS: NEW AND OLD

Subjective tinnitus, the phantom ringing or buzzing sensation that occurs in the absence of sound, affects 12-14% of adults; in some cases the tinnitus is so severe or disabling that patients seek medical treatment. However, although the economic and emotional impact of tinnitus is large, there are currently no FDA-approved drugs to treat this condition. Clinical trials are now underway to evaluate the efficacy of N-methyl-d-aspartate (NMDA) and dopamine D(2) antagonists, selective serotonin reuptake inhibitors (SSRIs), γ-aminobutyric acid (GABA) agonists and zinc dietary supplements. Previous off-label clinical studies, while not definitive, suggest that patients with severe depression may experience improvement in their tinnitus after treatment with antidepressants such as nortriptyline or sertraline. A small subpopulation of patients with what has been described as "typewriter tinnitus" have been shown to gain significant relief from the anticonvulsant carbamazepine. Preliminary studies with misoprostol, a synthetic prostaglandin E1 analogue, and sulpiride, a dopamine D(2) antagonist, have shown promise. Animal behavioral studies suggest that GABA transaminase inhibitors and potassium channel modulators can suppress tinnitus. Additionally, improvements in tinnitus have also been noted in patients taking melatonin for significant sleep disturbances. Like other complex neurological disorders, one drug is unlikely to resolve tinnitus in all patients; therapies targeting specific subgroups are likely to yield the greatest success.

Efficacy of misoprostol in the treatment of tinnitus in patients with diabetes and/or hypertension

OBJECTIVE

To determine the efficacy of the prostaglandin E1 analogue misoprostol in the treatment of tinnitus in diabetic and/or hypertensive patients.

DESIGN

Double-blind, randomized, placebo-controlled trial.

SETTINGS

Tertiary care referral center.

METHODS

The subjects were 42 patients with hypertension and/or diabetes mellitus who had chronic tinnitus and had experienced tinnitus symptoms for a minimum of 6 months. Twenty-eight patients were randomly assigned to Group I (misoprostol treatment), and 14 patients to the Group II (placebo treatment). Misoprostol therapy was started at 200 microg per day, and was increased 200 microg every 7 days until a dose of 800 microg per day was reached. The same numbers of placebo tablets were given to the control group using the same schedule. Both groups were treated for 1 month. The changes in objective and subjective tinnitus findings from baseline to 1 month were assessed, and the group results were compared. The chi(2)-test, student's t-test and paired-samples t-test were used to analyze the study.

RESULTS

At the completion of treatment, objective assessment showed that tinnitus loudness decreased in 13 (46%) of the 28 patients in the experimental group, whereas this was observed in only two (14%) of the 14 subjects in the placebo group. Subjective tinnitus scoring revealed improvement rates of 29 and 14% for the misoprostol and placebo groups, respectively. When t-test relating to difference between rates were performed, the difference between improvement rate for tinnitus loudness of the experimental group and control group was found to be statistically significant (P = 0.05), but difference between improvement rate based on subjective tinnitus scoring was insignificant (P = 0.22).

CONCLUSION

Misoprostol is an effective and safe treatment for chronic tinnitus in hypertensive and/or diabetic patients. Our results are encouraging, but further studies of larger series are needed.

Misoprostol in the treatment of tinnitus: a double-blind study

OBJECTIVE

To test the efficacy of misoprostol as a treatment for tinnitus.

DESIGN

A prospective, placebo-controlled, double-blind study.

SETTING

Başkent University Otolaryngology Clinic.

PATIENTS

Forty adult patients who had had tinnitus for a minimum of 6 months and were free of systemic or otolaryngologic disease. Twenty-eight patients were randomly assigned to the experimental group (group I) and 12 to the control group (group II).

INTERVENTION

The respective groups received active drug and placebo in increasing doses for 4 months. The effect of medications on tinnitus were evaluated by determining improvement rates in tinnitus loudness and subjective tinnitus scoring.

RESULTS

In the experimental group, 18 of 28 patients showed improvement in tinnitus loudness, representing an improvement rate of 64%. The improvement rate based on subjective tinnitus scoring was 36% (10 of 28 patients). In the control group, the improvement rate for tinnitus loudness was 33% (n = 4), and the rate for subjective tinnitus scoring was 17% (n = 2). The difference between improvement rate for tinnitus loudness of the experimental group and control group was found to be statistically significant (P = 0.039), but difference between improvement rate based on subjective tinnitus scoring was insignificant (P = 0.119). When results in the experimental group were analyzed according to etiological factors, the improvement rate was highest in the sudden-onset subgroup (77%).

CONCLUSIONS

Misoprostol provided therapeutic relief for some patients with tinnitus we studied, but further investigation of larger groups is needed.

Misoprostol therapeutics revisited

Misoprostol, a prostaglandin E1 analog, is a racemate of four stereoisomers. On administration it rapidly de-esterifies to its active form, misoprostolic acid. Misoprostolic acid is 85% albumin bound and has a half-life of approximately 30 minutes. It is excreted in urine as inactive metabolites. No significant drug interactions have been reported. Besides its gastrointestinal protective and uterotonic activities, misoprostol regulates various immunologic cascades. It inhibits platelet-activating factor and leukocyte adherence, and modulates adhesion molecule expression. It protects against gut irradiation injury, experimental gastric cancer, enteropathy, and constipation. It improves nutrient absorption in cystic fibrosis. Misoprostol has utility in acetaminophen and ethanol hepatotoxicity, hepatitis, and fibrosis. It is effective in asthmatics and aspirin-sensitive asthmatic and allergic patients. It lowers cholesterol and severity of peripheral vascular diseases, prolongs survival of cardiac and kidney transplantation, synergizes cyclosporine, and protects against cyclosporine-induced renal damage. It works against drug-induced renal damage, interstitial cystitis, lupus nephritis, and hepatorenal syndrome. It is useful in periodontal disease and dental repair. Misoprostol enhances glycosoaminoglycan synthesis in cartilage after injury. It prevents ultraviolet-induced cataracts and reduces intraocular pressure in glaucoma and ocular hypertension. It synergizes antiinflammatory and analgesic effects of diclofenac or colchicine and has been administered to treat trigeminal neuralgic pain. It reduces chemotherapy-induced hair loss and recovery time from burn injury, and is effective in treating sepsis, multiple sclerosis, and pancreatitis.

A review of randomized clinical trials in tinnitus

OBJECTIVES

Review reports of randomized clinical trials (RCTs) in tinnitus to identify well-established treatments, promising developments, and opportunities for improvement in this area of clinical research.

STUDY DESIGN

Literature review of RCTs (1964-1998) identified by MEDLINE and OLD MEDLINE searches and personal files.

METHODS

Studies were compared with the RCT criteria of Guyatt et al. for quality of design, performance, and analysis; "positive" results were critically examined for potential clinical relevance.

RESULTS

Sixty-nine RCTs evaluated tocainide and related drugs, carbamazepine, benzodiazepines, tricyclic antidepressants, 16 miscellaneous drugs, psychotherapy, electrical/magnetic stimulation, acupuncture, masking, biofeedback, hypnosis, and miscellaneous other nondrug treatments. No treatment can yet be considered well established in terms of providing replicable long-term reduction of tinnitus impact, in excess of placebo effects.

CONCLUSIONS

Nonspecific support and counseling are probably helpful, as are tricyclic antidepressants in severe cases. Benzodiazepines, newer antidepressants, and electrical stimulation deserve further study. Future tinnitus therapeutic research should emphasize adequate sample size, open trials before RCTs, careful choice of outcome measures, and long-term follow-up.

Recent advances in the pharmacological treatment of tinnitus

Tinnitus is an extremely prevalent condition that impinges on the lives of sufferers to varying degrees. In some people, it is a fairly minor irritation but, for many, the tinnitus intrudes to such a degree that it affects their ability to lead a normal life, and in some very extreme cases has resulted in suicide. Insomnia, inability to concentrate and depression are commonly reported to accompany the condition. Relief can be reliably obtained using intravenous lignocaine, which indicates that pharmacology can provide a route for effective alleviation of the condition. In this article, Julie Simpson and Ewart Davies review the potential pharmacological therapies, and emphasize that clinical research has been hampered by the absence of a reliable objective assessment of the tinnitus and by the variable nature of the complaint.

Evaluation of tinnitus patients by peroral multi-drug treatment

To evaluate patients complaining of subjective tinnitus, this study examined their response to peroral betahistine mesilate, vitamin B complex and diazepam in combination. Because three drugs were used together, it remains to be seen whether a single drug or a combination of drugs was effective. We issued questionnaires to 67 patients with tinnitus associated with sensorineural hearing loss of unknown etiology or tinnitus, despite normal hearing in pure tone audiometry and lack of distinct systemic disorders. Our original questionnaire contained seven items and allotted points for each item to facilitate evaluation. After prescribing the above drugs and observing patients' progress for 5 weeks, 50 of the 67 subjects were evaluated again by the same questionnaire. The present study evaluates tinnitus of patients as an example of clinical applications; this was not a controlled double blind study. It was found that, after patients took the prescribed medication, the total number of points were significantly reduced (paired t-test, P < 0.001). After medication, cases of bilateral tinnitus were significantly reduced from 27 to 14, and cases of two types of tinnitus sound, were significantly decreased from 22 to 11 (chi 2-test, P < 0.05). After 5 weeks of administration, 54% of patients felt treatment had been effective. Preliminary results suggest this peroral multi-drug treatment may provide relief for some patients with subjective tinnitus. However, long-term efficacy of the treatment was not investigated.

Current concepts in the clinical management of patients with tinnitus

The current management in tinnitus of sensorineural origin is reviewed. Epidemiological data demonstrates that 90% of patients with hearing loss experience some tinnitus. Approximately 1% of the population suffer from a chronic tinnitus that causes severe distress and requires some type of management intervention. Present non-surgical therapies include masking techniques, psychological counseling, and biofeedback. There are also a number of drugs that have been applied, the most common being antidepressants. These have had the most success in managing patients with tinnitus, although it is currently felt that antidepressants treat underlying psychological problems rather than directly affect the tinnitus. The other large class of drugs include benzodiazopans, in addition to a new synthetic analog of a natural prostaglandin E1, misoprostol. Despite the many drugs now available, none has been approved by the United States Food and Drug Administration for the treatment of tinnitus. Many surgical therapies have been advocated but are directed towards the treatment of concurrent vertigo or for tumors of the cerebellopontine angle, with tinnitus sometimes being relieved by the operation. Specific surgical procedures such as cochlear resection and microvascular decompressions lack clear-cut efficacy. Despite author bias and a myriad of treatment modalities at present, there is still no specific therapy that definitively relieves tinnitus clinically.

Misoprostol for tinnitus

Practitioners should realize that further study of misoprostol in larger patient populations must be undertaken to determine its efficacy and safety in the treatment of tinnitus. Previous approaches to treating tinnitus have included carbamazepine, phenytoin, lidocaine, tocainide, flecainide acetate, alprazolam, and nortriptyline. Studies using lidocaine, nortriptyline, or alprazolam have shown encouraging results. The relative contribution of misoprostol remains to be seen; however, it may offer a new treatment option to patients who have experienced adverse effects or have contraindications to the pharmacologic agents currently available.