Drilldown: Medicines

Levothyroxine (1)

Synthroid, Levoxyl, Tirosint, Unithroid, Euthyrox (1)

[[:Category:Hormone_replacement|Hormone replacement]] (1) · [[:Category:Thyroid_hormones|Thyroid hormone]] (1)

Synthetic T4 (thyroxine); peripherally deiodinated to T3 (triiodothyronine), the active hormone. '"`UNIQ--vote-00000031-QINU`"' Narrow therapeutic index; brand-to-generic switches can shift TSH and require re-titration'"`UNIQ--ref-00000032-QINU`"'. (1)

'"`UNIQ--vote-00000033-QINU`"', '"`UNIQ--vote-00000034-QINU`"', '"`UNIQ--vote-00000035-QINU`"' (1)

1.6 mcg/kg/d in young healthy adults; 25-50 mcg/d in elderly or cardiac disease, titrated by TSH at 6-8 weeks (1)

25, 50, 75, 88, 100, 112, 125, 137, 150, 175, 200, 300 mcg tablets; oral capsule and IV/IM also available (1)

No fixed maximum; titrated to TSH target (1)

IV (1) · Oral (1)

None · Hours · 30-60 minutes · 1-2 hours · ~30 min · LDL lowering at 2 weeks, max by 4 weeks · ~1 hour · 15-30 minutes · 15–30 min · 1–2 h · 30–60 min · Antidepressant effect emerges over 1-2 weeks · BP and symptomatic LUTS improvement within 1-2 weeks · BP effect within 1-2 weeks · Clinical improvement within 24-72 hours · Days · Motor improvement over days at therapeutic dose · Over weeks · Postprandial glucose effect within days; HbA1c by 12 weeks · Sleep effect from first dose; antidepressant effect over 1-4 weeks

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None · 24 hours · 4-6 hours · 12 hours · 6-8 hours · Daily dosing · 8-12 hours · 12-24 hours · Hours · Hours per application · 24 hours (HS dosing) · 24 hours (once-daily dosing) · 24 h · N/A · N/A (replacement) · Variable · ~7-8 hours · 3-5 hours · 4-6 hours (IR); 24 hours (ER) · 6-12 hours

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~7 days (euthyroid); longer in hypothyroidism (~9-10 days), shorter in hyperthyroidism'"`UNIQ--ref-00000036-QINU`"' (1)

40-80% (oral); reduced by food, calcium, iron, PPIs, fiber; take fasting with water'"`UNIQ--ref-00000037-QINU`"' (1)

First-line in pregnancy; dose typically increased 25-30% due to estrogen-driven rise in TBG and fetal demand. Lactation safe at physiologic doses.<sup class="pcp-cn" title="This claim needs a citation.">&#91;[[Pharmacopedia:Citation needed|citation&nbsp;needed]]&#93;</sup> (1)

[[USLegal:Prescription only|Rx-only]] in US (1)