title: A novel formulation of L-thyroxine (L-T4) reduces the problem of L-T4 malabsorption by coffee observed with traditional tablet formulations.
abstract: The purpose of this work is to evaluate if the coffee-associated malabsorption of tablet levothyroxine (L-T4) is reduced by soft gel capsule. We recruited 8 patients with coffee-associated L-T4 malabsorption including one hypothyroid patient. For 6 months, the patients were switched to the capsule maintaining the L-T4 daily dose. Patients took the capsule with water, having coffee 1 h later (proper habit, PH) on days 1-90, or with coffee ≤ 5 min later (improper habit, IH) on days 91-180. After 6 months, 2 patients volunteered for an acute loading test of 600 μg L-T4 (capsule) ingested with water (PH) or with coffee (IH). In the single hypothyroid patient, the post-switch TSH ranged 0.06-0.16 mU/L (PH) versus 5.8-22.4 mU/L pre-switch (PH) and 0.025-0.29 mU/L (IH) versus 26-34 mU/L pre-switch (IH). In the other 7 patients, post-switch TSH was 0.41 ± 0.46 (PH) versus 0.28 ± 0.20 pre-switch (PH) (P = 0.61) and 0.34 ± 0.30 (IH) versus 1.23 ± 1.47 pre-switch (IH) (P < 0.001). Importantly, TSH levels in PH versus IH habit did not differ post-switch (P = 0.90), but they did pre-switch (P < 0.0001). The proportions of post-switch TSH levels <0.10 mU/L with PH (33.3 %) or with IH (33.3 %) were borderline significantly greater than the corresponding pre-switch levels with PH (10.3 %) (P = 0.088) or with IH (0 %) (P = 0.0096). In the two volunteers, the L-T4 loading test showed that coffee influenced L-T4 pharmacokinetics minimally. Soft gel capsules can be used in patients who are unable/unwilling to change their IH of taking L-T4.
authors.affiliation: Section of Endocrinology, Department of Clinical and Experimental Medicine & Pharmacology, University of Messina, A.O.U. Policlinico G. Martino, Viale Gazzi Padiglione H, 4 piano, 98125, Messina, Italy. roberto.vita@yahoo.it
authors.forename: Roberto
authors.initials: R
authors.lastname: Vita
authors.forename: Giovanna
authors.initials: G
authors.lastname: Saraceno
authors.forename: Francesco
authors.initials: F
authors.lastname: Trimarchi
authors.forename: Salvatore
authors.initials: S
authors.lastname: Benvenga
mesh_terms: D000328:Adult; D013956:Antithyroid Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D002214:Capsules; D002626:Chemistry, Pharmaceutical; D003069:Coffee / Q000009:adverse effects*; D018592:Cross-Over Studies; D004337:Drug Carriers / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D005260:Female; D018565:Food-Drug Interactions; D005782:Gels; D006044:Goiter, Nodular / Q000188:drug therapy; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy / Q000378:metabolism; D007408:Intestinal Absorption; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D016606:Thyroid Nodule / Q000188:drug therapy; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism; D013974:Thyroxine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D013956:Antithyroid Agents; D002214:Capsules; D003069:Coffee; D004337:Drug Carriers; D005782:Gels; D013972:Thyrotropin; D013974:Thyroxine