Cipro & Thyroid Hormone

News about fluorinated drugs
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Cipro & Thyroid Hormone

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1) Ciprofloxacin and rifampin have opposite effects on levothyroxine absorption

Dr. Alyse S Goldberg, Dr. Rommel G Tirona, Ms. Linda J Asher, Dr. Richard B Kim, and Dr. Stan HM Van Uum. Thyroid. -Not available-, ahead of print. doi:10.1089/thy.2013.0014.

Online Ahead of Editing: May 7, 2013

Background: Levothyroxine (T4) absorption varies between individuals, and can be affected by various concomitantly administered drugs. Case reports have indicated an association between co-treatment with ciprofloxacin or rifampin with hypothyroidism in patients with stable T4 dose.

Methods: The effects of two antibiotics on T4 absorption were prospectively assessed in double blind-randomized, crossover fashion. Eight healthy volunteers received 1000 microgram T4 combined with placebo, ciprofloxacin 750 mg or rifampin 600 mg as single doses. We measured total plasma T4 concentrations over a 6 hour period after dosing using liquid chromatography-tandem mass spectrometry (LC-MS/MS). For each study arm, T4 areas under the plasma concentration-time curve (AUC) were compared.

Results: Co-administration of ciprofloxacin significantly decreased the T4 AUC by 39% (p=0.035), while, surprisingly, rifampin significantly increased T4 AUC by 25% (p=0.003).

Conclusion: Intestinal absorption of T4 is differentially affected by acute co-administration of ciprofloxacin or rifampin. Mechanistic studies focused on intestinal, and possibly hepatic thyroid hormone transporters are required to explain the observed drug interactions with T4.

2) Ciprofloxacin interacts with thyroid replacement therapy
Case Reports - BMJ 2005;330:1002.1

3) Ciprofloxacin induced hormonal changes in the thyroid gland of
rats and Anti-oxidant vitamin A, C and E as rescue agents
Dr.G.Vanithakumari., and *Dr. K.M.Priyadharshin ... 531218.pdf

T3 and T4 levels were raised especially in the long durational groups. Vitamins supplemented along with the drug were found to restore the T3 and T4 levels to control values more effectively in long duration treatment groups than in the short duration groups. By drug withdrawal the T3 level was restored to normalcy and T4 level to near normalcy.
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