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)

None · Indication-specific · 40 mg/d · 10 mg/d · 20 mg/d · 80 mg/d · 10 mg/d (adults) · 100 mg/d · 4 g/d · 400 mg/d · 40 mg/d typical; up to 240 mg/d for Zollinger-Ellison · 5 mg/d · 50 mg/d · 600 mg/d · No fixed ceiling; titrate to clinical effect and tolerability with CDC opioid prescribing guidance constraints on morphine-milligram-equivalent (MME) totals · No fixed maximum; titrated to TSH target · TID per eye · Titrated to glucose; no fixed ceiling · Titrated to glucose; no fixed maximum · '''20 mg/day in adults >60 years''' per FDA's 2011-2012 QT-prolongation warning; 40 mg/day in adults ≤60

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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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Steady-state at 4-6 weeks (1)

~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)