Drilldown: Medicines
Medicines > fda max 
:
4 g/d in healthy adults; 3 g/d conservative limit; 2 g/d in cirrhosis or chronic alcohol use or
No fixed maximum; titrated to TSH target
:
4 g/d in healthy adults; 3 g/d conservative limit; 2 g/d in cirrhosis or chronic alcohol use or
No fixed maximum; titrated to TSH target Use the filters below to narrow your results.
brand:
classes:
mechanism:
None (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-00000032-QINU`"' Brand-to-brand and lot-to-lot variability in T3:T4 ratio is greater than with synthetic levothyroxine, which is why endocrine guidelines prefer the synthetic'"`UNIQ--ref-00000033-QINU`"'. (1)
uses:
starting dose:
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) ·
30 mg PO daily (1/2 grain); titrate by TSH at 6-8 weeks; 60 mg desiccated thyroid is approximately equivalent to 88-100 mcg levothyroxine (1) ·
325-1000 mg PO every 4-6 hours as needed; maximum 4 g/d in healthy adults, 3 g/d in regular users or hepatic risk; pediatric 10-15 mg/kg every 4-6 hours (1)
preparations:
15, 30, 60, 90, 120, 180, 240, 300 mg tablets (1/4 to 5 grains; 1 grain = 60 mg) (1) ·
25, 50, 75, 88, 100, 112, 125, 137, 150, 175, 200, 300 mcg tablets; oral capsule and IV/IM also available (1) ·
325, 500, 650 mg tablets; 80, 160 mg chewables; 160 mg/5 mL pediatric liquid; 325 mg suppository; 1000 mg/100 mL IV (Ofirmev); fixed-dose combinations with opioids, decongestants, antihistamines (1)
fda max: (Click arrow to add another value)
routes:
onset:
duration:
halflife:
1-3 hours (normal liver); markedly prolonged in overdose with glutathione depletion'"`UNIQ--ref-000006A5-QINU`"' (1) ·
T4 ~7 days; T3 ~1 day'"`UNIQ--ref-00000036-QINU`"' (1) ·
~7 days (euthyroid); longer in hypothyroidism (~9-10 days), shorter in hyperthyroidism'"`UNIQ--ref-00000036-QINU`"' (1)
bioavailability:
pregnancy:
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.">[[[Pharmacopedia:Citation needed|citation needed]]]</sup> (1) ·
Long the preferred analgesic-antipyretic in pregnancy; recent observational studies have raised speculative neurodevelopmental signals that remain under investigation.<sup class="pcp-cn" title="This claim needs a citation.">[[[Pharmacopedia:Citation needed|citation needed]]]</sup> (1) ·
Synthetic levothyroxine is the standard-of-care in pregnancy; desiccated thyroid use in pregnancy is not well studied<sup class="pcp-cn" title="This claim needs a citation.">[[[Pharmacopedia:Citation needed|citation needed]]]</sup> (1)
Showing below up to 3 results in range #1 to #3.