Dosing and uses of Armour Thyroid, Thyroid USP (thyroid desiccated)
Adult dosage forms and strengths
tablet
- 15mg, 16.25mg, 30mg, 32.5mg, 48.75 mg, 60mg, 65mg, 81.25, 90mg, 97.5 mg, 113.75 mg
- 120mg, 130mg, 146.25, 162.5mg, 180mg, 195mg, 240mg, 260 mg, 300mg, 325 mg
Hypothyroidism
Mild: initial 15-30 mg PO qDay, may increase by 15 mg/day q2-3Weeks (or 30 mg/day q30Days)
Myxedema: start 15 mg PO qDay, THEN after 2 weeks 30 mg PO qDay, THEN after 2 weeks 60 mg PO qDay
Maintentance: 60-120 mg PO qDay
Administration: before breakfast
Other Indications & Uses
As diagnostic agents in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy
Pediatric dosage forms and strengths
tablet
- 15mg, 16.25mg, 30mg, 32.5mg, 48.75 mg, 60mg, 65mg, 81.25, 90mg, 97.5 mg, 113.75 mg
- 120mg, 130mg, 146.25, 162.5mg, 180mg, 195mg, 240mg, 260 mg, 300mg, 325 mg
Hypothyroidism
6 months: 4.8-6 mg/kg PO qDay
6-12 months: 3.6-4.8 mg/kg PO qDay
1-5 years: 3-3.6 mg/kg PO qDay
6-12 years: 2.4-3 mg/kg PO qDay
12 years or older: 1.2-1.8 mg/kg PO qDay
Geriatric dosage forms and strengths
Not recommended
Armour Thyroid, Thyroid USP (thyroid desiccated) adverse (side) effects
Frequency not defined
Tachycardia
Alopecia
Myalgia
Arrhythmias
Nervousness
Tremor
Diarrhea
Cramps
Warnings
Contraindications
Hypersensitivity to thyroid hormone
AMI uncomplicated by hypothyroidism, untreated thyrotoxicosis, untreated adrenal insufficiency
Cautions
Angina, cardiovascular disease, HTN, endocrine disorders, elderly
Judicious use in AMI complicated or caused by hypothyroidism may be considered
Ineffective in the treatment of obesity or of infertility uncomplicated by hypothyroidism
Myxedemous patients are very sensitive to thyroid hormone; start at low dosage
Pregnancy and lactation
Pregnancy category: A
Lactation: small amount excreted into breast milk, use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Armour Thyroid, Thyroid USP (thyroid desiccated)
Mechanism of action
Natural thyroid hormone from animals; increase basal metabolic rate, increase utilization and mobilization of glycogen store, promotes gluconeogenesis
Pharmacokinetics
Onset: Initial effect: 3hr
Bioavailability: 48-80%
Protein Bound: >99%
Metabolism: Hepatic; also in kidney and intestinal walls
Metabolites: Levothyroxine (T4), liothyronine (T3), reverse triiodothyronine (rT3)
Excretion: Urine (major), feces (partially)
Time to peak
- T4: 2-4 hr
- T3: 2-3 days
Half-Life
- T4: 6-7 days (euthyroid); 3-4 days (hyperthyroid); 9-10 (hypothyroid)
- T3: 2.5 days
