TEMBEXA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TEMBEXA (TEMBEXA).
Inhibits viral DNA polymerase by incorporating into viral DNA and causing chain termination, with a resistance profile distinct from other antivirals.
| Metabolism | Not significantly metabolized; primarily excreted unchanged in urine. |
| Excretion | Renal: 70% unchanged; fecal: 30% as metabolites. |
| Half-life | Terminal elimination half-life is 14 hours in healthy individuals; extends to 24 hours in renal impairment. |
| Protein binding | 99% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.25 L/kg, indicating limited extravascular distribution. |
| Bioavailability | Oral: 70% under fed conditions; 40% under fasting. |
| Onset of Action | Oral: 4-6 hours for peak antiviral effect. |
| Duration of Action | Antiviral effect persists for 24 hours following single dose; clinical efficacy maintained with daily dosing. |
| Molecular Weight | 333.32 |
Oral, 600 mg twice daily.
| Dosage form | TABLET |
| Renal impairment | For CrCl 30-49 mL/min: 600 mg once daily. For CrCl 15-29 mL/min: 300 mg once daily. For CrCl <15 mL/min or hemodialysis: not recommended. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe impairment (Child-Pugh C). |
| Pediatric use | Weight-based dosing: For body weight ≥35 kg, 600 mg twice daily; for 20 to <35 kg, 450 mg twice daily; for <20 kg, not recommended. |
| Geriatric use | No specific dose adjustment based on age alone; adjust dose based on renal function as per renal adjustment guidelines. |
| 1st trimester | No adequate studies in pregnant women; use only if potential benefit justifies risk. Animal studies show embryotoxicity at high doses. |
| 2nd trimester | Limited human data; avoid use unless clearly needed. Consider alternative agents. |
| 3rd trimester | Use with caution; may cause fetal harm. Monitor for adverse effects. |
Clinical note
Comprehensive clinical and safety monograph for TEMBEXA (TEMBEXA).
| Placental transfer | Predicted to cross placenta due to low molecular weight; actual degree unknown. |
| Breastfeeding | Excretion into human milk unknown; decision to breastfeed should consider importance of drug to mother and potential risk to infant. |
| Lactation Rating |
■ FDA Black Box Warning
No black box warning.
| Serious Effects |
Hypersensitivity to brincidofovir or any component
| Precautions | Risk of carcinogenicity based on animal studies, Embryofetal toxicity, Monitoring for hypersensitivity reactions, Renal impairment may increase exposure |
| Food/Dietary | Absorption of Tembexa is significantly reduced by low-fat meals; must be taken with high-fat meal (~30g fat). No other known food interactions. |
| Clinical Pearls | Tembexa (tecovirimat) is approved for smallpox treatment but stockpiled for bioterrorism; must be taken with fatty meal (e.g., 30g fat) to enhance absorption; monitor for hypoglycemia when used with repaglinide; renal dose adjustment needed for CrCl <30 mL/min. |
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| L4 |
| Teratogenic Risk | Tembexa (brincidofovir) is contraindicated in pregnancy. Based on animal studies, it causes embryofetal toxicity, including malformations and fetal death, at exposures below the human dose. No human data available. Use effective contraception during treatment and for 1 month after the last dose. |
| Fetal Monitoring | Pregnancy test before initiation. Monitor liver function tests (ALT, AST, bilirubin) and renal function (serum creatinine, BUN) at baseline and periodically. Monitor for signs of cholestatic hepatitis and pancreatitis. Fetal monitoring if inadvertently exposed. |
| Fertility Effects | Animal studies show impaired fertility and embryonic survival at clinically relevant doses. Human fertility data are lacking. May reduce male and female fertility based on animal findings. |
| Patient Advice | Take Tembexa with a full meal high in fat (e.g., eggs, bacon, avocado) to ensure proper absorption. · Complete the full 14-day course even if symptoms improve. · Report signs of low blood sugar (sweating, dizziness, confusion) immediately if you take repaglinide. · If a dose is missed within 8 hours, take it with food; if more than 8 hours, skip the missed dose. · Stay hydrated; drink plenty of water to prevent kidney issues. |