Metformin and Tinnitus

• Metformin is an effective hypoglycaemic agent considered as first line therapy in people with type 2 diabetes.
• Based on Malaysian Adverse Drug Reaction (ADR) database, there are reports of tinnitus following use of metformin.
• WHO ADR database also revealed 51 reports pertaining tinnitus linked to metformin.

Possible Pharmacological Correlation

• Higher dose and longer duration of metformin use increases the risk for vitamin B12 deficiency in people with diabetes.
• Consequences of clinically important decreases in vitamin B12, such as macrocytic anaemia, neuropathy and mental changes, can be profound.

Signs and symptoms of vitamin B12 deficiency

• Neurologic – difficulty walking, loss of vibratory sense, impaired sense of touch, peripheral neuropathy
• Psychiatric – irritability, personality changes, depression, psychosis, mild memory impairment
• Cardiovascular – possible increased risk of myocardial infarction and stroke, palpitation
• Aneorexia, mild weight loss diarrhoea, atrophic glossitis
• Urologic – difficulty in urination
• Dyspnoea
• VertigoTinnitus

References:

1. http://npra.moh.gov.my/images/Publications/Newsletter_MADRAC_Bulletin/Bulletin-MADRAC-August2014.pdf
2. http://www.webstercare.com.au/files/wcconteduoct13.pdf