MYOSCINT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MYOSCINT (MYOSCINT).
Myoscint (indium In 111 imciromab pentetate) is a radiolabeled monoclonal antibody that binds to cardiac myosin, specifically targeting myosin heavy chains exposed in necrotic myocardial cells. It is used for imaging myocardial necrosis following acute myocardial infarction.
| Metabolism | The monoclonal antibody component is metabolized via catabolism into amino acids and fragments. The indium-111 label decays with a half-life of 2.8 days and is not metabolically processed. |
| Excretion | Primarily renal; approximately 70% of administered dose excreted unchanged in urine within 24 hours; minimal biliary/fecal elimination (<5%). |
| Half-life | Terminal elimination half-life is 6–8 hours; clinically, this allows same-day imaging post-injection. |
| Protein binding | Approximately 10–15% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | 0.3–0.5 L/kg; indicates distribution primarily in extracellular fluid and myocardium. |
| Bioavailability | Not applicable (administered intravenously only); 100% bioavailability via IV route. |
| Onset of Action | Intravenous injection: uptake in myocardium begins within minutes; optimal imaging at 15–30 minutes post-injection. |
| Duration of Action | Effective imaging window is 30–60 minutes post-injection; tracer washes out over several hours; no sustained therapeutic effect. |
Adults: 1-2 mCi (37-74 MBq) intravenously as a single dose. Imaging can be repeated after 6-24 hours with same dose if needed.
| Dosage form | VIAL |
| Renal impairment | No specific dose adjustment recommended based on GFR; however, elimination is renal, so use caution in severe impairment (GFR <30 mL/min). |
| Liver impairment | No specific adjustment based on Child-Pugh score; not hepatically metabolized. |
| Pediatric use | Weight-based: 0.025-0.05 mCi/kg (0.925-1.85 MBq/kg) intravenously; minimum dose 0.5 mCi (18.5 MBq). |
| Geriatric use | No specific adjustment; use the adult dose and monitor renal function due to age-related decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MYOSCINT (MYOSCINT).
| Breastfeeding | It is not known whether Myoscint is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for adverse reactions in nursing infants from the radioactive component, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. The M/P ratio is not available. |
| Teratogenic Risk | Myoscint (indium In-111 imciromab pentetate) is a monoclonal antibody fragment used for cardiac imaging. There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, no teratogenic effects were observed at doses up to 10 times the human dose. However, because animal studies are not always predictive of human response, the drug should be used during pregnancy only if clearly needed. The risk to the fetus cannot be ruled out, and exposure to ionizing radiation from the indium-111 label may carry risks, especially during the first trimester where fetal organogenesis occurs. |
■ FDA Black Box Warning
None
| Common Effects | Allergic reaction |
| Serious Effects |
["Known hypersensitivity to murine (mouse) proteins","Pregnancy (due to radiation exposure unless benefit outweighs risk)"]
| Precautions | ["Risk of hypersensitivity reactions including anaphylaxis; premedicate with antihistamines and corticosteroids","Human anti-mouse antibody (HAMA) response may occur, limiting future use of murine antibodies","Radiation exposure risk; use only when diagnostic benefit outweighs risk","Not recommended in patients with known hypersensitivity to murine proteins"] |
Loading safety data…
| Fetal Monitoring | No specific maternal or fetal monitoring is required beyond standard imaging procedures. However, pregnancy status should be assessed before administration. If the patient is pregnant, consider the potential fetal radiation dose and alternative imaging modalities. |
| Fertility Effects | No human data on fertility effects. Animal studies have not been conducted to evaluate the effect on fertility. The radioactive label may theoretically pose a risk to germ cells, but clinically relevant effects are unlikely with diagnostic doses. |