Table of Contents  
CASE REPORT
Year : 2014  |  Volume : 5  |  Issue : 2  |  Page : 163-165  

A case of tinnitus induced by chlorpromazine in a pediatric patient


1 Department of Biomedical and Clinical Sciences, Luigi Sacco University Hospital, Milan, Italy
2 Department of Pediatrics, Luigi Sacco Hospital, University of Milan, Milan, Italy
3 Scientific Institute for Research, Hospitalization and Health Care Eugenio Medea, Bosisio Parini, Lecco, Italy
4 Department of Biomedical and Clinical Sciences, Luigi Sacco University Hospital, Milan; Scientific Institute for Research, Hospitalization and Health Care Eugenio Medea, Bosisio Parini, Lecco, Italy

Date of Submission02-May-2013
Date of Decision29-Jun-2013
Date of Acceptance01-Nov-2013
Date of Web Publication7-Apr-2014

Correspondence Address:
Sonia Radice
Unit of Clinical Pharmacology, Luigi Sacco University Hospital, Via GB Grassi, 74 20157 Milan
Italy
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-500X.130110

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   Abstract 

Chlorpromazine is a well-known antipsychotic agent that binds with a variety of receptors in the central nervous system. To date, chlorpromazine has never been associated with onset of hearing disorders and tinnitus. We report on an unexpected suspect adverse reaction to chlorpromazine that occurred in a 12-year-old boy, affected by severe generalized anxiety disorder. After treatment with chlorpromazine, the patient experienced an enhanced sensitivity to sounds accompanied by perception of noises of the buzzing or ringing type. This clinical case is of great clinical interest as chlorpromazine is not currently included among potentially ototoxic drugs.

Keywords: Adverse drug reaction, chlorpromazine, tinnitus


How to cite this article:
Carnovale C, Pellegrino P, Beretta S, Zuccotti GV, Perrone V, Antoniazzi S, Pozzi M, Clementi E, Radice S. A case of tinnitus induced by chlorpromazine in a pediatric patient. J Pharmacol Pharmacother 2014;5:163-5

How to cite this URL:
Carnovale C, Pellegrino P, Beretta S, Zuccotti GV, Perrone V, Antoniazzi S, Pozzi M, Clementi E, Radice S. A case of tinnitus induced by chlorpromazine in a pediatric patient. J Pharmacol Pharmacother [serial online] 2014 [cited 2019 Dec 9];5:163-5. Available from: http://www.jpharmacol.com/text.asp?2014/5/2/163/130110


   Introduction Top


Chlorpromazine is a phenothiazine antipsychotic drug. Its effect is mediated via interactions with several receptors in the central nervous system and results from a combination of antidopaminergic, anticholinergic, antihistaminic, and weak antiadrenergic actions. The therapeutic effects of chlorpromazine are frequently accompanied by unwanted side effects that include sedation, autonomic, endocrine, and neurological effects. [1] To date, chlorpromazine has never been associated with onset of hearing disorders and tinnitus.

Tinnitus is a common adverse reaction (ADR) to several drugs and may occur during long-term therapies or after a single drug administration. [2] Even though not life threatening, tinnitus may be discomforting; it may also be irreversible despite drug withdrawal. To date, over 130 drugs have been described to be potentially ototoxic, among which the most common inducers of tinnitus are aminoglycosides and other antimicrobials. [3]


   Case Report Top


We report on a suspect ADR to chlorpromazine that occurred in a 12-year-old boy, affected by severe generalized anxiety disorder.

He received initially a benzodiazepine therapy, which was switched to chlorpromazine (6.25 mg/day orally) because of the absence of a significant clinical response. The patient received no other concomitant drug or herbal treatment.

Ten days after treatment with chlorpromazine, the patient experienced an enhanced sensitivity to sounds accompanied by perception of noises of the buzzing or ringing type.

Information about the patient's medical history did not report conditions that may have predisposed to the onset of the disturbance manifested. Moreover, the patient was in overall good health and had never suffered from hearing disorders.

In view of the medical history, an iatrogenic nature was suspected. No instrumental exams for hearing disorder were performed.

The inability to discontinue therapy with chlorpromazine resulted in an objective worsening of the patient's symptoms, which are still present to date.

The Naranjo ADR probability scale identified the relationship between the patient's development of ADR and the drug as "possible."


   Discussion Top


This is the first report on a case of tinnitus related to the administration of chlorpromazine. Several different mechanisms may explain this clinical development. Chlorpromazine is an antagonist of several dopamine cochlear receptors that play an important role in the sensory process by modulating afferent auditory nerve activity. Dopamine, released from the terminals of lateral olivocochlear efferent fibers, is protective against acoustic trauma, hypoxia, and ototoxicity. In this context, the dopamine antagonist activity of chlorpromazine may result in a higher risk of ototoxicity. [4],[5] A second possible mechanism is the antagonist activity of chlorpromazine on histamine receptors. Histamine has physiological roles in the homeostasis of the inner ear and the cochlea. [6] It controls the cochlear blood flow, acting on the precapillary sphincters and increasing the microcirculatory flow. Clinical evidence indicates that H1 histamine agonists are effective in reducing tinnitus via improving vestibular compensation of the microcirculation. Chlorpromazine antagonism on H1-receptors may thus play a role in counteracting the vessel modulatory effect of histamine and by this means have contributed to tinnitus development in our patient.

Chlorpromazine has also anticholinergic effects. Acetylcholine is the major neurotransmitter in the olivocochlear efferent pathway, which is a feedback control system to the inner ear comprising a medial olivocochlear pathway projecting to outer hair cells and a lateral olivocochlear pathway projecting to dendrites of cochlear nerve fibres. [7] In this context, the anticholinergic effects of chlorpromazine may have inhibited efferent signalling via the α9/α10 nicotinic acetylcholine receptor complex in the outer hair cells which is known to be protective against acoustic injury. [8]

Another action of chlorpromazine that may have contributed to generate tinnitus in our patient is its antagonism of serotonergic receptors. Serotonin is one of the neurotransmitters acting on the auditory pathways; in particular it is involved in sound detection, location, and interpretation. Serotonin is currently believed to be one of the most important neurotransmitter involved in the perception of tinnitus. [9] Indeed, serotonin reuptake inhibitor drugs reduce the intensity of tinnitus acting directly on nerve conduction of the auditory stimulus, particularly in the central auditory pathways. [10] In this scenario, it is thus conceivable that antagonism at serotonin receptor levels caused by chlorpromazine causes auditory disorders leading to tinnitus.

Finally, a role for an action of chlorpromazine on gamma amino butyric acid (GABA) cannot be excluded. GABA inhibits auditory system and systemic administration of a GABA transaminase inhibitor improves tinnitus by suppressing hyperactivity in the auditory system. [11]

The neurotransmitter serotonin, involved in a large variety of physiological functions, behaves as a neuromodulator by strengthening the GABA system. [12] Chlorpromazine, by decreasing the availability of serotonin, may lead to decreased GABAergic activity and this action may have contributed to tinnitus development. We cannot establish which among the actions of chlorpromazine described above has been predominant in the tinnitus-inducing action we observed, and the most likely possibility is that tinnitus resulted from a synergism among these different actions. A predisposition of the patient to develop tinnitus following chlorpromazine cannot also be ruled out. Receptors for serotonin, histamine, dopamine, and GABA are polymorphic and the presence of specific single nucleotide polymorphisms that acted as predisposing factors may be present in this specific patient. [13],[14],[15] In addition chlorpromazine is substrate of cytochrome P4502D6 (CYP2D6), a highly polymorphic isoform of cytochrome. Genetically determined functional variations of this cytochrome may be present in the patient and may also have contributed to the onset of tinnitus. [16]


   Conclusion Top


To our knowledge, this is the first report on the development of tinnitus following chlorpromazine administration. Although there is no information on dechallenge and rechallenge, the inability to discontinue therapy with chlorpromazine resulted in an objective worsening of the patient's symptoms. This clinical case is of great clinical interest as chlorpromazine is not currently included among potentially ototoxic drugs; paradoxically phenothiazines can be prescribed to alleviate symptoms related to disorders of the vestibular system.

 
   References Top

1.Carpenter WT, Koenig JI. The evolution of drug development in schizophrenia: Past issues and future opportunities. Neuropsychopharmacology 2008;33:2061-79.  Back to cited text no. 1
    
2.Cooper JC Jr. Health and Nutrition Examination Survey of 1971 - 1975: Part II. Tinnitus, subjective hearing loss, and well being. J Am Acad Audiol 1994;5:37-43.  Back to cited text no. 2
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3.Cianfrone G, Pentangelo D, Cianfrone E, Mazzei F, Turchetta R, Orlando MP, et al. Pharmacological drugs inducing ototoxicity, vestibular symptoms and tinnitus: A reasoned and updated guide. Eur Rev Med Pharmacol Sci 2011;15:601-36.  Back to cited text no. 3
    
4.Niu X, Canlon B. The signal transduction pathway for the dopamine D1 receptor in the guinea-pig cochlea. Neurosci 2006;137:981-90.  Back to cited text no. 4
    
5.Maison SF, Liu XP, Eatock RA, Sibley DR, Grandy DK, Liberman MC. Dopaminergic signaling in the cochlea: Receptor expression patterns and deletion phenotypes. J Neurosci 2012;32:344-55.  Back to cited text no. 5
    
6.Azuma H, Sawada S, Takeuchi S, Higashiyama K, Kakigi A, Takeda T. Immunohistochemical localization of histamine receptors in rat cochlea. Laryngoscope 2004;114:2249-51.  Back to cited text no. 6
    
7.Eybalin M. Neurotransmitters and neuromodulators of the mammalian cochlea. Physiol Rev 1993;73:309-73.  Back to cited text no. 7
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8.Maison SF, Luebke AE, Liberman MC, Zuo J. Efferent protection from acoustic injury is mediated via alpha9 nicotinic acetylcholine receptors on outer hair cells. J Neurosci 2002;22:10838-46.  Back to cited text no. 8
    
9.Simpson JJ, Davies WE. A review of evidence in support of a role for 5-HT in the perception of tinnitus. Hear Res 2000;145:1-7.  Back to cited text no. 9
    
10.Robinson SK, Viirre ES, Bailey KA, Gerke MA, Harris JP, Stein MB. Randomized placebo-controlled trial of a selective serotonin reuptake inhibitor in the treatment of nondepressed tinnitus subjects. Psychosom Med 2005;67:981-8.  Back to cited text no. 10
    
11.Brozoski TJ, Spires TJ, Bauer CA. Vigabatrin, a GABA transaminase inhibitor, reversibly eliminates tinnitus in an animal model. J Assoc Res Otolaryngol 2007;8:105-18.  Back to cited text no. 11
    
12.Ciranna L. Serotonin as a modulator of glutamate- and GABA-mediated neurotransmission: Implications in physiological functions and in pathology. Curr Neuropharmacol 2006;4:101-14.  Back to cited text no. 12
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13.Wong AH, Buckle CE, Van Tol HH. Polymorphisms in dopamine receptors: What do they tell us? Eur J Pharmacol 2000;410:183-203.  Back to cited text no. 13
    
14.Levitan ES, Schofield PR, Burt DR, Rhee LM, Wisden W, Köhler M, et al. Structural and functional basis for GABAA receptor heterogeneity. Nature 1988;335:76-9.  Back to cited text no. 14
    
15.Faludi G, Gonda X, Bagdy G, Dome P. Pharmaco- and therapygenetic aspects in the treatment of anxiety disorders beyond the serotonergic system: A brief review. Neuropsychopharmacol Hung 2012;14:221-9.  Back to cited text no. 15
    
16.Zanger UM, Raimundo S, Eichelbaum M. Cytochrome P450 2D6: Overview and update on pharmacology, genetics, biochemistry. Naunyn Schmiedebergs Arch Pharmacol 2004;369:23-37.  Back to cited text no. 16
    



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