The paper below clearly refers to taking the cipro with levothyroxine - but without knowing the mechanism, we have no idea if taking them separately by hours could have a similar effect - or not.
Thyroid. 2013 Nov;23(11):1374-8. doi: 10.1089/thy.2013.0014. Epub 2013 Oct 16.
Ciprofloxacin and rifampin have opposite effects on levothyroxine absorption.
Goldberg AS1, Tirona RG, Asher LJ, Kim RB, Van Uum SH.
Levothyroxine (L-T4) absorption varies between individuals, and can be affected by various concomitantly administered drugs. Case reports have indicated an association between cotreatment with ciprofloxacin or rifampin and hypothyroidism in patients on a stable L-T4 dose.
The effects of two antibiotics on T4 absorption were prospectively assessed in a double-blind, randomized, crossover fashion. Eight healthy volunteers received 1000 μg L-T4 combined with placebo, ciprofloxacin 750 mg, or rifampin 600 mg as single doses. We measured total plasma thyroxine (T4) concentrations over a 6-hour period after dosing using liquid chromatography-tandem mass spectrometry. For each study arm, areas under the T4 plasma concentration-time curve (T4 AUCs) were compared.
Coadministration of ciprofloxacin significantly decreased the T4 AUC by 39% (p = 0.035), while, surprisingly, rifampin significantly increased T4 AUC by 25% (p = 0.003).
Intestinal absorption of L-T4 is differentially affected by acute coadministration of ciprofloxacin or rifampin. Mechanistic studies focused on intestinal and possibly hepatic thyroid hormone transporters are required to explain the observed drug interactions with L-T4.
PMID: 23647409 [PubMed - indexed for MEDLINE]