Metformin induced adverse drug reaction: A case of severing itching and chills associated with the single overdose

Abstract

Type 2 diabetes affects more than 10% of the adult population worldwide and the prevalence is increasing. Metformin is the drug of first choice in patients with type 2 diabetes, although it can cause various side effects and severe reactions when taken irrationally. This case study emphasizes the significance of adhering to recommended dosage guidelines when prescribing medications, as well as the need to review a patient's current clinical status and treatment strategy when they present with specific medical complaints. A 64-year-old female presented to her family physician complaining of a severely itching rash on her body. She also noted feeling chills, shivering and mentioned that the symptoms exacerbate after taking 2000 mg of metformin once daily in the evening as prescribed by the Endocrinologist, MD for type 2 diabetes. From the medical anamnesis, it was known that the patient was also taking semaglutide, spironolactone, bisoprolol/perindopril, rilmenidine, ezetimibe, clopidogrel, atorvastatin, aspirin, latanoprost and timolol. Medical examination revealed a maculopapular rash on her trunk spreading to the extremities and after the dermatologist's assessment, the patient was referred to the clinical pharmacologist with the suspected adverse drug reaction. During the Clinical pharmacologist‘s, MD consultation, no clinically significant drug interactions were observed, therefore an adverse reaction of metformin‘s too high single dose was suspected prompting a recommendation to adjust the dosage to 1000 mg twice daily. Considering that the patient's myocardial infarction episode occurred over a year ago, it was additionally advised to discontinue the administration of clopidogrel. After two weeks the patient no longer felt previously mentioned symptoms, the rash almost disappeared, confirming the adverse effects of metformin consequent to an excessive single-use dosage and possibly due to taking clopidogrel. It was recommended to monitor renal function and continue the treatment as prescribed. It is important to remember that metformin can cause severe dermatological and other adverse reactions when taken more than 1500 mg as a single dose. Rational drug use is essential to achieve the best therapeutic outcomes and to minimize potential side effects and risks.