KEFLET
Clinical safety rating: caution
Comprehensive clinical and safety monograph for KEFLET (KEFLET).
Keflet (warfarin) inhibits vitamin K epoxide reductase, preventing the recycling of vitamin K and thereby reducing the synthesis of clotting factors II, VII, IX, and X in the liver.
| Metabolism | Hepatic metabolism via CYP450 enzymes, primarily CYP2C9 (major), CYP3A4, CYP1A2, CYP2C19, and CYP2C8. |
| Excretion | Renal (80-90% unchanged via glomerular filtration and tubular secretion); biliary/fecal < 5%. |
| Half-life | 0.5-1 hour; prolonged in renal impairment (up to 20-30 hours in ESRD). |
| Protein binding | 5-15%, primarily to albumin. |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution primarily in extracellular fluid. |
| Bioavailability | Oral: 50-70% (decreased by food). |
| Onset of Action | Oral: 0.5-1 hour; IV: immediate. |
| Duration of Action | 6-8 hours; shorter in hypermetabolic states. |
| Molecular Weight | 347.39 |
500 mg orally every 12 hours for 10-14 days; for uncomplicated UTI: 250 mg orally every 12 hours for 7 days.
| Dosage form | TABLET |
| Renal impairment | CrCl 30-49 mL/min: 500 mg every 24 hours; CrCl 15-29 mL/min: 250 mg every 24 hours; CrCl <15 mL/min (not on dialysis): 250 mg every 48 hours. |
| Liver impairment | No adjustment required for mild to moderate hepatic impairment; use with caution in severe impairment (Child-Pugh C) as data limited. |
| Pediatric use | For children ≥6 months: 30 mg/kg/day divided every 12 hours for 10 days; not to exceed 1000 mg/day. |
| Geriatric use | Initiate at 250 mg orally every 12 hours; monitor renal function and adjust based on CrCl. |
| 1st trimester | Use only if clearly needed; no evidence of harm in animal studies, but human data limited. Consider alternative antibiotics if possible. |
| 2nd trimester | Generally considered safe; no known teratogenicity. Use if indicated. |
| 3rd trimester | Safe in late pregnancy; no risk of kernicterus noted with cephalosporins. |
Clinical note
Comprehensive clinical and safety monograph for KEFLET (KEFLET).
| Placental transfer | Cephalexin crosses the placenta; achieves fetal serum concentrations 5-20% of maternal levels. |
| Breastfeeding | Excreted into breast milk in low concentrations; compatible with breastfeeding. Monitor infant for diarrhea, rash, or thrush. |
| Lactation Rating |
■ FDA Black Box Warning
Warfarin can cause major or fatal bleeding. Risk factors include high dose, advanced age, poor nutritional status, renal insufficiency, and certain genetic factors. Patients should be monitored regularly for INR. Concomitant use with NSAIDs, aspirin, or anticoagulants increases bleeding risk.
| Serious Effects |
Hypersensitivity to cephalexin or any cephalosporin antibioticHistory of immediate-type hypersensitivity reaction (e.g., anaphylaxis) to penicillins or other beta-lactams
| Precautions | Hemorrhage risk; necrosis or gangrene of skin or other tissues (calciphyaxis) on rare occasions; systemic atheroemboli and cholesterol microemboli; caution in patients with hepatic or renal impairment; caution in elderly; pregnancy: may cause fetal harm. |
| Food/Dietary | Food may delay absorption but does not significantly reduce total absorption; if gastrointestinal upset occurs, take with food. Avoid alcohol during therapy and for 48 hours after the last dose to minimize risk of disulfiram-like reaction. No specific food restrictions. |
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| L2 (Safer) |
| Teratogenic Risk | KEFLET (cephalexin) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and there are no adequate well-controlled studies in pregnant women. First trimester: Limited data show no increased risk of major malformations. Second and third trimesters: No known fetal risks; used for maternal infections. Avoid use only if clearly needed. |
| Fetal Monitoring | No specific monitoring required beyond standard prenatal care. Monitor maternal renal function if high-dose or prolonged therapy. For fetal monitoring, assess for any signs of infection (e.g., maternal fever). |
| Fertility Effects | No known effects on human fertility. Animal studies have not demonstrated impaired fertility at therapeutic doses. |
| Clinical Pearls | Keflet is a cephalosporin antibiotic (cephalexin). Use with caution in penicillin-allergic patients due to cross-sensitivity (~5-10%). Adjust dose in renal impairment (CrCl <50 mL/min). Monitor for Clostridium difficile-associated diarrhea. Take on empty stomach for better absorption; food may delay absorption but not decrease total amount. Common side effects include nausea, diarrhea, and rash. |
| Patient Advice | Take this medication exactly as prescribed, even if you feel better. · Complete the full course of therapy to prevent bacterial resistance. · Take on an empty stomach (1 hour before or 2 hours after meals) unless stomach upset occurs, then may take with food. · Avoid alcohol during treatment and for 48 hours after last dose to reduce risk of disulfiram-like reaction (though rare with cephalexin). · Notify your doctor if you develop diarrhea, rash, or signs of allergic reaction (hives, difficulty breathing). · Store at room temperature away from moisture and heat. |