Pediatric Drug Interactions with Penicillin VK

• Probenecid: inhibits renal tubular secretion, increasing penicillin levels
• Methotrexate: penicillins may reduce clearance—monitor for toxicity
• Warfarin/anticoagulants: potential INR increase—monitor closely
• Oral contraceptives: clinically significant reductions are unlikely; advise standard caution