Ciprofloxacin interacts with thyroid replacement therapy
1 Department of Medicine, Stavanger University Hospital, PO Box 8100, 4068 Stavanger, Norway,2 Department of Orthopaedic Surgery, Stavanger University Hospital,3 Department of Medical Biochemistry, Stavanger University Hospital,4 Regional Drug Information Centre, Haukeland University Hospital, 5021 Bergen, Norway
Introduction
Unexplained hypothyroidism in patients taking oral ciprofloxacin
Case reports
Increasing levothyroxine to 200 μg daily had no effect. We reduced levothyroxine to 125 μg daily and stopped ciprofloxacin, and thyroid function tests rapidly became normal. Other drugs (alfacalcidiol, propranolol, ranitidine, furosemide, methenamine hippurate, paracetamol, morphine, and ondansetron) were unchanged. We continued to give dicloxacillin and heparin as thyroid function returned to normal (figure). The patient died of metastatic thyroid cancer three weeks after discharge.
Case 2
A 79 year old woman with rheumatoid arthritis, manic depression, cardiac failure, chronic obstructive airways disease, and hypothyroidism was admitted with a wound infection after a transfemoral amputation. She had maintained stable thyroid function tests on a daily dose of 150 μg levothyroxine. After three weeks' treatment with oral ciprofloxacin (500 mg twice a day), her concentration of thyroid stimulating hormone had increased from 1.6 to 19 mIU/l and free thyroxine had fallen from 22 to 13 pmol/l. Switching from concomitant administration of levothyroxine and ciprofloxacin to administering the drugs with a six hour gap resulted in rapid normalisation of the thyroid function tests (figure). Other drugs (zuclopenthixol, enalapril, bumetanide, prednisolone, folic acid, lactulose, acetylcysteine, hydroxychloroquine, paracetamol, ipratropium bromide, salbutamol, nystatin) remained unchanged.
Discussion
Funding: None. Competing interests: None declared.
References
Mersebach H, Rasmussen AK, Kirkegaard L, Feldt-Rasmussen U. Intestinal adsorption of levothyroxine by antacids and laxatives: case stories and in vitro experiments. Pharmacol Toxicol 1999;84: 107-9.
Surks MI, Sievert R. Drugs and thyroid function. N Engl J Med 1995;333: 1688-94.
Siraj ES, Gupta MK, Reddy SS. Raloxifene causing malabsorption of levothyroxine. Arch Intern Med 2003;163: 1367-70., http://www.100md.com(John G Cooper, Knut Harbo)
Introduction
Unexplained hypothyroidism in patients taking oral ciprofloxacin
Case reports
Increasing levothyroxine to 200 μg daily had no effect. We reduced levothyroxine to 125 μg daily and stopped ciprofloxacin, and thyroid function tests rapidly became normal. Other drugs (alfacalcidiol, propranolol, ranitidine, furosemide, methenamine hippurate, paracetamol, morphine, and ondansetron) were unchanged. We continued to give dicloxacillin and heparin as thyroid function returned to normal (figure). The patient died of metastatic thyroid cancer three weeks after discharge.
Case 2
A 79 year old woman with rheumatoid arthritis, manic depression, cardiac failure, chronic obstructive airways disease, and hypothyroidism was admitted with a wound infection after a transfemoral amputation. She had maintained stable thyroid function tests on a daily dose of 150 μg levothyroxine. After three weeks' treatment with oral ciprofloxacin (500 mg twice a day), her concentration of thyroid stimulating hormone had increased from 1.6 to 19 mIU/l and free thyroxine had fallen from 22 to 13 pmol/l. Switching from concomitant administration of levothyroxine and ciprofloxacin to administering the drugs with a six hour gap resulted in rapid normalisation of the thyroid function tests (figure). Other drugs (zuclopenthixol, enalapril, bumetanide, prednisolone, folic acid, lactulose, acetylcysteine, hydroxychloroquine, paracetamol, ipratropium bromide, salbutamol, nystatin) remained unchanged.
Discussion
Funding: None. Competing interests: None declared.
References
Mersebach H, Rasmussen AK, Kirkegaard L, Feldt-Rasmussen U. Intestinal adsorption of levothyroxine by antacids and laxatives: case stories and in vitro experiments. Pharmacol Toxicol 1999;84: 107-9.
Surks MI, Sievert R. Drugs and thyroid function. N Engl J Med 1995;333: 1688-94.
Siraj ES, Gupta MK, Reddy SS. Raloxifene causing malabsorption of levothyroxine. Arch Intern Med 2003;163: 1367-70., http://www.100md.com(John G Cooper, Knut Harbo)