ZINPLAVA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZINPLAVA (ZINPLAVA).
Bezlotoxumab is a human monoclonal antibody that binds to Clostridioides difficile toxin B, neutralizing its activity and preventing damage to colonic epithelial cells.
| Metabolism | Bezlotoxumab is a monoclonal antibody; it is degraded via general protein catabolism into small peptides and amino acids. No specific metabolic enzymes are involved. |
| Excretion | Primarily eliminated via fecal excretion as unchanged drug (approximately 79% of dose), with minimal renal excretion (about 15% as unchanged drug). |
| Half-life | Mean terminal elimination half-life is approximately 19 days (range 14–22 days), supporting a 6-week dosing interval. |
| Protein binding | Approximately 79–86% bound, primarily to human serum albumin. |
| Volume of Distribution | Volume of distribution at steady state is approximately 0.21 L/kg, indicating limited extravascular distribution and primarily intravascular space. |
| Bioavailability | Intravenous administration only; bioavailability is 100% by the IV route. Not administered orally or by other routes. |
| Onset of Action | Onset of clinical effect (reduction in Clostridioides difficile infection recurrence) is observed within 2–3 days after a single IV infusion, correlating with attainment of therapeutic serum concentrations. |
| Duration of Action | Duration of action is approximately 12 weeks after a single 10 mg/kg IV infusion, providing protection against recurrence throughout the high-risk period. |
| Molecular Weight | 145746 |
10 mg/kg intravenously over 60 minutes, single dose.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment necessary for any degree of renal impairment, including end-stage renal disease. |
| Liver impairment | No adjustment necessary for mild, moderate, or severe hepatic impairment (Child-Pugh A, B, or C). |
| Pediatric use | Safety and efficacy not established in pediatric patients. |
| Geriatric use | No specific dose adjustment required; clinical studies included patients ≥65 years with no overall differences in safety or efficacy. |
| 1st trimester | Limited human data; no known risk based on animal studies. Bezlotoxumab is a monoclonal antibody, IgG1, which is actively transported across placenta, especially in late pregnancy. Expected fetal exposure minimal in first trimester due to lack of FcRn expression. |
| 2nd trimester | Similar to t1; increasing placental transfer as pregnancy progresses. |
| 3rd trimester | Significant placental transfer expected due to active FcRn-mediated transport. No known adverse fetal effects in animal studies, but human data insufficient. |
Clinical note
Comprehensive clinical and safety monograph for ZINPLAVA (ZINPLAVA).
| Placental transfer | Bezlotoxumab is an IgG1 monoclonal antibody; placental transfer occurs via FcRn-mediated transport, increasing throughout gestation. Expected to cross placenta, especially in third trimester. |
| Breastfeeding | Bezlotoxumab is a monoclonal antibody and likely excreted into breast milk in small amounts. Due to high molecular weight, absorption by infant is limited. Consider benefits of breast-feeding, risk of potential adverse effects in infant, and mother's need for drug. |
■ FDA Black Box Warning
None.
| Serious Effects |
History of hypersensitivity to bezlotoxumab or any excipients
| Precautions | Heart failure: Use with caution in patients with a history of congestive heart failure; adverse reactions including death have been reported in clinical trials., Infusion-related reactions: Monitor for signs of hypersensitivity, including anaphylaxis and serum sickness. |
| Food/Dietary | No known food interactions. ZINPLAVA is administered intravenously and does not interact with oral medications or dietary components. However, general nutritional support during C. difficile infection may be recommended. |
| Clinical Pearls |
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| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | No adequate and well-controlled studies in pregnant women. Animal reproduction studies have not been conducted. Based on mechanism of action (monoclonal antibody), negligible placental transfer expected; however, IgG antibodies cross placenta, especially in third trimester. Risk cannot be ruled out. |
| Fetal Monitoring | No specific monitoring required. As with any biologic, observe for hypersensitivity reactions. Monitor for signs of infection. |
| Fertility Effects | No data on fertility impairment. Animal studies not conducted. Based on mechanism, effects on fertility are unlikely. |
| ZINPLAVA (bezlotoxumab) is a human monoclonal antibody that neutralizes Clostridium difficile toxin B. Administer as a single IV infusion over 1 hour, 10 mg/kg. Use only in patients aged ≥18 years receiving antibacterial drug treatment for C. difficile infection (CDI) and at high risk for recurrence. Does not treat active CDI; must be co-administered with antibacterial therapy. Contraindicated in patients with a history of systemic hypersensitivity reactions to bezlotoxumab. Common adverse reactions include nausea, pyrexia, and headache. Monitor infusion reactions; discontinue infusion for severe reactions. No dose adjustment needed for renal or hepatic impairment. |
| Patient Advice | ZINPLAVA is given as a single intravenous infusion to help prevent your C. difficile infection from coming back. · Do not use ZINPLAVA as a treatment for active C. difficile diarrhea; you will also need antibiotics for your current infection. · Common side effects include nausea, fever, and headache. Tell your healthcare provider if you have any signs of an allergic reaction (rash, itching, difficulty breathing). · You may receive ZINPLAVA during or after your antibiotic treatment. The infusion takes about 1 hour. · Contact your healthcare provider if your diarrhea does not improve or worsens after treatment. |