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This document discusses the management of vertigo through pharmacotherapy, adaptation exercises, and surgery. It focuses on the pharmacotherapy options including antihistamines, phenothiazines, anxiolytics, diuretics, and betahistine. Betahistine is highlighted as a treatment for vertigo and Meniere's disease that works as a H1 agonist and H3 antagonist to improve microcirculation, regulate neural activity, and relieve vertigo symptoms with dosages of 24-48 mg per day and no significant side effects, contraindications, or interactions with antihistamines.
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2 vertin
- 2. 2 Management of vertigo Pharmacotherapy Adaptation exercises Surgery
- 3. 3 A Vertigo Patient I WANT .. Fewer attacks every month Attacks should not be as bad as before Attacks should not last long
- 5. 5 Anti- emetics Antihistamines Anti Phenothiazines Miscellaneous Cholinergics Large overlap between the effects produced by antihistamines, anticholinergics and phenothiazines.
- 6. 6 Phenothiazines (Prochlorperazine, Thiethylperazine) Prochlorperazine is less sedating than some other phenothiazines but drowsiness still occurs Also causes hypotension, Parkinsonian side effects --Betts T et al, Brit. J. Clin. Pharmac, 1991, 32, 455-8, --Curley JWA, E N T Journal, 1984, 65, 555-560 “The drug which most commonly causes parkinsonism in general practice is Prochlorperazine” --Chaplin S, Geriatric Medicine, 1989, Feb, 13-14
- 7. 7 Anxiolytics (Tranquilizers) (Benzodiazepines such as diazepam, Lorazepam) No effect on the underlying vertigo Helps patient endure the symptoms by allaying anxiety Many side effects drowsiness and sedation, dependence and addiction abuse potential, psychomotor impairment, memory loss, interactions with alcohol Harris T, Ear Nose Throat J, 1984, 65, 551-5
- 8. 8 Diuretics (e.g. Furosemide, Hydrochlorthiazide) Used in vertigo and meniere’s disease Reduce the volume of endolymph by promoting urine flow and reducing fluid retention. Use mainly associated with electrolyte imbalance Ludman H, Brit. Med. J., 1981, 282, 454-457, Harris T, Ear Nose Throat J, 1984, 65, 551-5
- 9. 9 Cinnarizine, Collin Dollery Therapeutic Drugs, C240-3, Godfraind T et al, Drugs of Today, 1982, XVIII(1), 27-42, Venkataraman S, Neurosciences Today, 1997, Vol. I, 3&4, 205-6, Norre M E, Crit Rev. Phy. Rehab. Med., 1990, 2,2,101-20 Antihistamines Cinnarizine, Flunarizine, Cyclizine Drowsiness and blurred vision (Difficult for patients who drive or operate machinery) Delay normal vestibular compensation process Cinnarizine and Flunarizine act via calcium antagonism, unspecific action may cause side effects Weight gain & depression (serotonergic effects) Extrapyramidal symptoms (dopaminergic effects) G.I. upset
- 10. 10 * SOLVAY PHARMA INDIA LTD. Betahistine 8, 16 & 24 mg tablets
- 11. 11 Betahistine The original research product of Solvay Available Worldover as Betaserc® Serc® Vasomotal® Urutal® Available in India as Vertin *
- 12. 12 Data on file Betahistine Trusted therapy for more than 41 million Vertigo patients worldwide
- 14. 14 Betahistine - Chemistry Histamine Betahistine N N H CH2CH2NH2 N CH2CH2NHCH3 Histamine analogue, can be given orally with no histamine like side effects Van Cauwenberge P B, et al, Acta Otolaryngol, 1997, suppl. 526, 43-6, Venkataraman S, Neurosciences Today, 1998, II, 1 & 2, 56-8
- 15. 15 Betahistine : Pharmacokinetics Oral administration Rapid and complete absorption Mean plasma half life :- 3-4 Hrs. Complete excretion via urine in 24 hours Very low plasma protein binding One metabolite (2-aminoethyl pyridine) is found to be active
- 17. 17 Betahistine : Mode of Action Vascular Effects Neurological Effects (in inner ear & brain) (in brain)
- 18. 18 H3-AUTORECEPTORS … CONTROLLING THE RELEASE OF HISTAMINE Adapted Van Cauweneberge PB, Acta Otolaryngol, 1997, suppl. 526, 43-6, Venkataraman S, Neurosciences Today, 1998, II, 1 & 2, 56-8 H1 H2 H3 autoreceptor Histaminergic Neuron
- 19. 19 Venkataraman S, Neurosciences Today, 1998, II (1 & 2), 56-8 EFFECTS OF BETAHISTINE
- 20. 20 Betahistine - Vascular Effects H3 autoreceptors antagonist H1 agonist Inhibits autoregulation of histamine release Venkataraman S, Neurosciences Today, 1998, II (1 & 2), 56-8 Improves cochlear microcirculation Improves cerebral / vertebrobasilar blood flow
- 21. 21 Blocks H3 heteroreceptors Increases release of other neurotransmitters e.g. serotonin Regulates firing activity of vestibular nuclei Venkataraman S, Neurosciences Today, 1998, II (1 & 2), 56-8, Biswas A, Ind. J. Otolaryngol H N S, 1997, 49(2), 179-81 Betahistine - Neurological Effects
- 22. 22 Betahistine : Mode of action Blocks H3 heteroreceptors H3 autoreceptors stimulates release of other neurotransmitter e.g. serotonin Stimulates release of histamine Regulatory effect on vestibular nuclei H1 receptor Symptomatic relief of vertigo Prophylactic effect of vertigo improvement of cochlear & cerebral blood flow direct stimulatory effect
- 23. 23 BETAHISTINE Therapeutic Indications Vertigo Meniere’s Syndrome Dosage Recommendations 24-48 mg /day
- 24. 24 Betahistine -Tolerance No sedation No gastric side effects No anticholinergic effects No extrapyramidal side effects Bradoo RA et al, Ind. J. Otolaryngol HNS, 2000, 52(2), 151-8, Biswas A, Ind. J. Otolaryngol H N S, 1997, 49(2), 179-81
- 25. 25 Betahistine: No affinity for H2 receptors H2 receptors predominate in stomach and control gastric secretion Betahistine has no effect on H2 receptors. Betahistine is generally free of gastric side effects Betahistine, Collin Dollery Therapeutic Drugs, B 62-5 Van Cauwenberge PB, Acta Otolaryngol, 1997, Suppl. 526, 43-6
- 26. 26 Betahistine Contraindications - Not known Precaution / Caution for use Betahistine, being a histamine analogue, should be used with caution in patients with pheochromocytoma, peptic ulcer, bronchial asthma, concurrent use of antihistamines Bradoo RA et al, Ind. J. Otolaryngol HNS, 2000, 52(2), 151-8
- 27. 27 Betahistine No antagonistic effect on H1 receptors Antihistamines block H1 receptors in brain, causing sedation or drowsiness Betahistine, stimulates H1 receptors Betahistine, does not slow down vestibular compensation, unlike antihistamines. Hence is suitable for use with vestibular habituation therapy. Kirtane MV, Ind. J. Otolaryngol HNS, 1999, 51(2),27-36
- 28. 28 Betahistine - Summary Pharmacokinetics: Rapid and complete absorption after oral route Pharmacology: It is a H1 agonist and H3 receptor antagonist. It increases cochlear and cerebral blood flow and regulates firing activity of vestibular nuclei. Dose: 24-48 mg /day Indication: vertigo, meniere’s syndrome Contraindications: not known Precaution for use: pheochromocytoma, peptic ulcer, bronchial asthma
Editor's Notes
- Vertigo patients often have a great fear of vertigo attacks. They are generally scared of attacks in future. They always wish lesser no. of attacks will occur in future & which will be less severe & of shorter duration.
- Side effects of Prochlorperazine include dry mouth, fall in B.P. ( hypoptension), rapid heart beat (Tachycardia), extrapyramidal symptoms (parkinsonism), jaundice (rarely). Parkinsonism is the most common side effect. In a study of patients referred to a specialist unit in U.K. with drug -induced parkinsonism, 44% cases were due to Prochlorperazine. (Lancet, 1984, ii, 1082-3)
- Anxiolytics and tranquilisers have no direct effect on vertigo. They may some patients with vertigo by reliving the underlying anxiety and apprehension. They do not affect pathology of the disease but merely enable the patient to endure the symptoms. They have a lot of side effects as noted above.
- Antihistamines mainly control nausea and vomiting along with vertigo. They have depressive effect on the brain, including the vomiting centre. There are various side effects as given above. Cinanrizine and Flunarizine are used as antivertigo drugs. They act through calcium antagonistic properties. Their sedating properties affects the patients normal lifestyle.
- Betahistine is the original research product of Solvay-Duphar & was first registered in Europe in 1970 for the treatment of Meniere’s disease. Some of the countries in which Betahistine is available are mentioned below: Vertin (India) Betaserc (Belgium, Denmark, Netherlands, U.A.E.etc. ) Serc (France, Spain, U.K.etc. ) Vasomotal (Chile, German Fed. Repub. etc. ) Urutal (Yugoslavia etc. )
- More than an estimated 41 million patients have so far been received Betahistine ( as of January 1995). Hence till today this figure must have increased very high.
- Chemically, Betahistine is 2-[2-(methylamino)ethyl] pyridine & is formulated as dihydrochloride salt . As shown in the above fig. , there is a close resemblance between the structures of Betahistine & histamine. Histamine caused a number of side effects & must be administered intravenously to avoid breakdown in liver. Betahistine overcame all these disadvantages since it had no serious side-effects & could be taken orally.
- Studies in man using 14-C labeled Betahistine have shown that Betahistine is rapidly absorbed (within 30 min) following oral administration of drug. Plasma radio activity reaches its peak within 1 hour. Mean half-life was 3-4 hrs. & excretion is virtually complete in urine within 24 hours.
- For many years principle mechanism of action of betahistine was believed to be due to its direct agonistic effect on H 1 receptors located in blood vessel of inner ear. This would give rise to local vasodilation and increased permeability. Recently research is focussed on H3 receptors. H3 receptors are located on th presynaptic membranes of histaminergic and other neurons in the brain. There are two types of H 3 receptors. H3 autoreceptors on histaminergic nerve endings and H3 heterorecpotrs controlling release of other neurotransmitter. They appear to control the release on histamine and other neurotransmitter by negative feedback mechanism. Excess Histamine released from nerve endings will bind on presynpatic H 3 receptors. This will inhibit further release of histamine. Thus H3 autoreceptors execute negative feed back control on histamine release.
- Betahistine has a powerful antagonistis effects on H 3 autoreceptors. It blocks H3 autorecepotrs so that negative feedback to control histamine release in blocked. Thus more histamine will be released at nerve endings. This increased amount of histamine released from histaminergic nerve endings can stimulate H1 receptors, thus augmenting direct agonistic effect of Betahistine on these receptors.
- Betahistine for past many years is known to be the drug of choice in Meniere’s disease. It is interesting to know that it is effective in various other forms of vertigo. It offers both prophylactic as well as symptomatic effect. Betahistine is also used for vertebrobasilar insufficiency because of its effect on cerebral blood flow.
- Clinical studies have shown Betahistine to be well tolerated. The low level of side effects is due to its specific action on H1 & H3 receptors. Betahistine does not cause sedation / drowsiness which is the classical side effect of many antihistaminic drugs. In fact, Betahistine restores normal lifestyle in patients. Betahistine does not cause gastric side effects since it has very little affinity for H2 receptors. Betahistine is shown not to increase gastric acid secretion in man. Betahistine has no anticholinergic action hence it is very unlikely to cause anticholinergic side effects. Since Betahistine has no antidopaminergic activity, it does not cause extrapyramidal side effects like parkinsonism .
- Pheochromocytoma is a rare condition, in which tumors of adrenal glands secrete liberate excess adrenaline and noradrenaline into blood stream causing headcahe, blurred vision, rapid heart beat, raised blood pressure. Histamine is known to stimulate the release of noradrenaline and adrenaline from the tumor. Theoretically, Betahistine being histamine analogue could also make the condition worse. Hence it to be used with caution. Betahistine, being a histamine analogue,to be used with care in petic ulecr patients. Intolerance to Betahistine in patients with bronchial asthma is not shown. But care should be taken in bronchial asthma, since Betahistine is a histamine analogue.