Dosing and uses of Thyrogen (thyrotropin alfa)
Adult dosage forms and strengths
powder for injection
- 1.1mg/vial
Serum Thyroglobulin Testing
Indicated as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without radioiodine imaging in the follow-up of patients with well-differentiated thyroid cancer who have previously undergone thyroidectomy
2 dose regimen: 0.9 mg IM in buttock, followed by 2nd 0.9 mg IM injection 24 hr later
Obtain serum Tg sample 72 hr after final injection
If indicated, oral radioiodine should be given 24 hr after the second injection
Diagnostic scanning should be performed 48 hr after the radioiodine administration
Limitations of use
- Thyrotropin-stimulated Tg levels are generally lower than, and do not correlate with Tg levels after thyroid hormone withdrawal
- Even when thyrotropin-Tg testing is performed in combination with radioiodine imaging, there remains a risk of missing a diagnosis of thyroid cancer or underestimating the extent of the disease
- Anti-Tg antibodies may confound the Tg assay and render Tg levels uninterpretable
Remant Thyroid Tissue Ablation
Indicated as adjunctive treatment for radioiodine ablation of thyroid tissue remnants in patients who have undergone a near-total or total thyroidectomy for well-differentiated thyroid cancer and who do not have evidence of distant metastatic thyroid cancer
2 dose regimen: 0.9 mg IM in buttock, followed by 2nd 0.9 mg IM injection 24 hr later
Oral radioiodine should be given 24 hr after the second injection
Pediatric dosage forms and strengths
<16 years: Safety and efficacy not established
Thyrogen (thyrotropin alfa) adverse (side) effects
>10%
Nausea (11%)
1-10%
Headache (6%)
Fatigue (2%)
Vomiting (2%)
Dizziness (2%)
Asthenia (1%)
Warnings
Contraindications
None
Cautions
Known to cause a transient (over 7 to 14 days) but significant rise in serum thyroid hormone concentration when given to patients who have substantial thyroid tissue still in situ or functional thyroid cancer metastases
Sudden, rapid and painful tumor enlargement reported
CHF, hypopituitarism, concurrent use of corticosteroids
Anaphylactic reaction may occur after repeated use of thyrotropin
Radioiodine testing 24 hr after final thyrotropin dose
Reports of death within 24 hr after administration; patients for whom thyrotropin-induced hyperthyroidism could have serious consequences (eg, heart disease, extensive metastatic disease), consider hospitalization for administration and postadministration observation
Reports of neurologic events, including acute hemiplegia or hemiparesis, occurring 1-3 days after administration to patients with CNS metastases; these events associated with sudden rapid tumor enlargement
Postmarketing reports of stroke or unilateral weakness occurring within 72 hr (range 20 minutes to 3 days) of administration to women without known CNS metastases
Tumor enlargement that is sudden, rapid and painful reported within 12-48 hr of administration; symptoms include dyspnea, stridor, or dysphonia; rapid clinical improvement occurred following glucocorticoid therapy (consider pretreatment with glucocorticoids if local tumor expansion may compromise vital anatomic structures)
Use caution in patients with known history of heart disease
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown if distributed in human 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 Thyrogen (thyrotropin alfa)
Mechanism of action
Recombinant thyroid stimulating hormone (TSH); increases iodine uptake by thyroid & formation, secretion, or release of thyroid hormones; stimulates the secretion of Tg from any remaining thyroid tissue remenants; elevated Tg levels suggest the presence of remmnant thyroid tissues
Pharmacokinetics
Half-life: 15-35 hr
Peak plasma time: 3-24 hr after injection
Administration
IM Preparation
Add 1.2 mL of sterile water for injection to the vial containing lyophilized powder
Do not shake the solution; swirl the contents of the vial until all the material is dissolved
Reconstituted solution concentration is 0.9 mg/mL
IM Administration
Visually inspect the reconstituted solution for particulate matter and discoloration prior to administration; it should be clear and colorless (do not use if particulate matter present, or solution is cloudy or discolored)
Inject 1 mL (0.9 mg) IM in the buttocks
Discard unused portions
Do not mix with other substances
Storage
Protect from light
Refrigerate at 2-8ºC (36-46ºF)
Reconstituted viaL
- Room temperature: Use within 3 hr
- Refrigerated (2-8ºC [36-46ºF]): Use within 24 hr
