LOCAMETZ
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LOCAMETZ (LOCAMETZ).
Metformin hydrochloride is a biguanide antihyperglycemic agent that improves glucose tolerance in patients with type 2 diabetes mellitus. It primarily decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
| Metabolism | Metformin undergoes minimal hepatic metabolism; approximately 90% is excreted unchanged in the urine via tubular secretion. It is not metabolized by cytochrome P450 enzymes. |
| Excretion | Primarily renal excretion (70% unchanged), with 20% fecal elimination via biliary secretion; 10% metabolized. |
| Half-life | Terminal elimination half-life of 14 hours (range 12-16 h); clinically, steady-state achieved after 3 days. |
| Protein binding | 98% bound to albumin. |
| Volume of Distribution | Vd 0.8 L/kg; indicates extensive tissue distribution with accumulation in lung and liver. |
| Bioavailability | Oral bioavailability 60% due to first-pass metabolism. |
| Onset of Action | Oral: 1-2 hours; intravenous: within 5 minutes. |
| Duration of Action | 8-12 hours for oral dose; 6-8 hours for intravenous dose; prolonged in hepatic impairment. |
Locametz (gallium Ga 68 gozetotide) is administered intravenously at a dose of 3-5 mCi (110-185 MBq) as a single injection for PET imaging. No repeated dosing schedule is defined.
| Dosage form | POWDER |
| Renal impairment | No formal renal dose adjustment is required; however, in patients with severe renal impairment (eGFR <30 mL/min/1.73m²), the imaging quality may be reduced due to altered clearance. |
| Liver impairment | No specific dose adjustment is needed for hepatic impairment based on Child-Pugh classification. |
| Pediatric use | Pediatric dosing is not established; safety and efficacy in patients under 18 years have not been studied. |
| Geriatric use | No specific dose adjustment is recommended for elderly patients; however, caution is advised due to higher prevalence of renal impairment and comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LOCAMETZ (LOCAMETZ).
| Breastfeeding | No data on human milk excretion. Due to radioactivity, breastfeeding should be discontinued prior to therapy and not resumed until radiation clearance is confirmed. M/P ratio is unknown. |
| Teratogenic Risk | Locametz (lutetium Lu 177 vipivotide tetraxetan) is a radiopharmaceutical. In pregnancy, radiation exposure poses significant fetal risk. First trimester: high risk of teratogenesis including CNS and cardiac defects. Second and third trimesters: increased risk of fetal growth restriction, microcephaly, and childhood malignancies. Use is contraindicated in pregnancy. |
■ FDA Black Box Warning
Lactic acidosis is a rare but serious metabolic complication that can occur due to metformin accumulation. Risk factors include renal impairment, concomitant cardiovascular collapse, acute myocardial infarction, sepsis, hepatic impairment, and excessive alcohol intake. Discontinue metformin immediately if lactic acidosis is suspected.
| Serious Effects |
["Severe renal impairment (eGFR <30 mL/min/1.73 m²)","Acute or chronic metabolic acidosis, including diabetic ketoacidosis","History of lactic acidosis","Severe hepatic impairment","Acute unstable heart failure","Hypersensitivity to metformin or any component of the formulation"]
| Precautions | ["Lactic acidosis risk: assess renal function before starting and annually; discontinue if renal impairment or acute conditions develop.","Monitor renal function; avoid in patients with eGFR <30 mL/min/1.73 m².","Hypoglycemia risk when used with insulin or insulin secretagogues.","Vitamin B12 deficiency: monitor hematologic parameters annually.","Temporary discontinuation for radiologic studies with iodinated contrast or surgical procedures.","Avoid in acute conditions that may compromise renal function (e.g., dehydration, severe infection)."] |
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| Fetal Monitoring |
| Monitor complete blood counts (CBC), renal function (serum creatinine, eGFR), and liver function tests (ALT, AST, bilirubin) at baseline and periodically. Assess for signs of myelosuppression. In pregnancy, if unavoidable, perform serial fetal ultrasounds and consider fetal dosimetry. |
| Fertility Effects | Radiation exposure may cause gonadal damage and impair fertility. In males, oligospermia or azoospermia; in females, ovarian failure and premature menopause. Long-term reproductive function may be permanently compromised. |