[india-drug] Re: Metallic taste with nitroimidazoles (2)

["Sampada Patvardhan" <dicmspc@yahoo.co.in>]

Metallic taste with nitroimidazoles (2)
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Dear Dr Anupam Aggarwal,

Here is information in response to your query about: reason for metallic taste with nitroimidazoles (metronidazole etc)?

Metronidazole is readily and almost completely absorbed from the gastrointestinal tract. Bioavailability is nearly 100%. Maximum concentrations occur in the serum after about one hour and traces are detected after 24 hours. Metronidazole is almost completely metabolized in liver. Principal metabolites result from oxidation of side chain and formation of glucuronides. A small amount of reduced metabolites, including ring cleavage products, is formed by gut flora. A metallic taste often occurs in people taking metronidazole.
   
  Several medications can cause an abnormal taste in the mouth, either by changing the chemical composition of your saliva or by affecting the taste sensors in your mouth. Any condition that affects the ability to taste is referred to as dysgeusia. While dysgeusia is often used to describe any change in the sense of taste, more specific terms include ageusia (complete loss of the sensation of taste); hypogeusia (decreased sense of taste); parageusia (bad taste in the mouth); and dysgeusia (distorted sense of taste, such as a metallic taste in the mouth). Dysgeusia occurs as an altered perception of taste (i.e.,markedly sweet, bitter, salty, or metallic taste). Drugs may alter taste by a number of potential mechanisms. They may be tasted in the mouth upon initial ingestion or when re-secreted in saliva. 
   
  A wide variety of conditions can cause a deficit in the sense of taste, including any conditions that interfere with the functioning of the taste buds (the nerve cells on the tongue that process information about taste), conditions that interrupt the taste signal that is sent to the brain, or conditions that interfere with the normal brain processing of those signals. Processes that affect the functioning of the lingual nerve or the glossopharyngeal nerve may impair the sense of taste. Furthermore, the sense of taste is frequently dulled or impaired due to dysfunction of the sense of smell. So, Complaints of impaired taste are usually due to smell disturbances.
   
  To know in details about this please visit: 
  https://www.pharmacists.ca/content/cpjpdfs/mar_apr06/Drug-InducedDisease.pdf
   
    Drug-induced change in taste is the second most common cause of taste disturbance among patients, accounting for , 25% of cases. About 170 drugs including metronidazole have been associated with taste disturbances, either when used alone or in combinations. There are a number of possible mechanisms for drug-related taste disturbance and that zinc plays a key role. To know about mechanisms you may access research paper titled ?Drug-Related Taste Disturbances?  by Hiroshi Tomita and Takuma Yoshikawa published in Acta Oto-Laryngologica, Volume 122, Number 4 Supplement 546 / 2002, pp 116-121 (only to subscribers)

   
Dr. (Mrs.) Sampada Patvardhan (Ph.D.Tech. Pharmacology)                                                
Director, Maharashtra State Pharmacy Council?s Drug Information Centre  E.S.I.S. Hospital Compound, L.B.S. Marg, Mulund (W), Mumbai-400 080   Phone: 25930607  Telefax: 25684291/25684418  
e-mail: dicmspc@yahoo.co.in  OR    dicmspc@hathway.com