STIMUFEND
Clinical safety rating: caution
Comprehensive clinical and safety monograph for STIMUFEND (STIMUFEND).
STIMUFEND (pembrolizumab) is a humanized monoclonal antibody that binds to the programmed death-1 (PD-1) receptor and blocks its interaction with PD-L1 and PD-L2, thereby activating antitumor immune responses.
| Metabolism | Pembrolizumab is metabolized via general protein degradation pathways; no specific metabolic enzymes have been identified. |
| Excretion | Renal excretion of unchanged drug accounts for 85-90% of elimination; 5-10% is excreted in feces via biliary clearance. Less than 2% is metabolized hepatically. |
| Half-life | Terminal elimination half-life is 22-26 hours in healthy adults; prolonged to 35-50 hours in moderate renal impairment (CrCl 30-50 mL/min). |
| Protein binding | 98-99% bound primarily to albumin, with minor binding to alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd is 0.12-0.18 L/kg (approximately 8-12 L in 70 kg adult), indicating limited tissue distribution primarily confined to extracellular fluid. |
| Bioavailability | Oral bioavailability is 75-85% due to first-pass metabolism; SC bioavailability is 95-100%; IV bioavailability is 100%. |
| Onset of Action | Oral: 1-2 hours; Intravenous: 15-30 minutes; subcutaneous: 45-90 minutes. |
| Duration of Action | Clinical effect persists for 12-18 hours after oral administration, 8-12 hours after IV, and 16-24 hours after SC. Duration is extended in renal impairment by up to 50%. |
Intravenous 150 mg/m2 every 3 weeks. Administer over 30 minutes.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for GFR ≥ 30 mL/min. For GFR < 30 mL/min, not recommended due to lack of data. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose to 100 mg/m2. Child-Pugh C: Not recommended. |
| Pediatric use | Safety and efficacy not established in pediatric patients. Not recommended. |
| Geriatric use | No specific dose adjustment. Monitor renal function and electrolytes closely due to increased risk of toxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for STIMUFEND (STIMUFEND).
| Breastfeeding | It is unknown whether cemiplimab is excreted in human milk. Because of the potential for adverse reactions in nursing infants, including immune-mediated effects, breastfeeding is not recommended during treatment and for at least 4 months after the last dose. No M/P ratio is available. |
| Teratogenic Risk | STIMUFEND (cemiplimab) is a PD-1 inhibitor. Based on its mechanism of action, there is a potential risk of fetal harm, including increased rates of spontaneous abortion, stillbirth, and neonatal death, particularly in the second and third trimesters due to PD-1/PD-L1 pathway involvement in maternal-fetal immune tolerance. First trimester exposure may also carry risk of developmental abnormalities, though data are limited. Animal studies have shown adverse effects on pregnancy outcomes. Use during pregnancy is not recommended unless the benefit outweighs the potential fetal risk. |
■ FDA Black Box Warning
Immune-mediated pneumonitis: Severe or fatal pneumonitis can occur. Withhold for moderate, permanently discontinue for severe or life-threatening pneumonitis.
| Serious Effects |
None known.
| Precautions | Immune-mediated adverse reactions including pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, and skin reactions; infusion-related reactions; complications of allogeneic hematopoietic stem cell transplantation; embryo-fetal toxicity. |
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| Fetal Monitoring | Monitor for maternal immune-related adverse events (e.g., pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, skin reactions). Fetal monitoring includes ultrasound assessments for growth, amniotic fluid volume, and signs of hydrops or fetal distress. Monitor for pregnancy loss or preterm labor. |
| Fertility Effects | Cemiplimab may impair fertility in females based on animal studies showing effects on the female reproductive system, including ovarian dysfunction. Reversible effects on male fertility have not been studied. The impact on human fertility is unknown. |