Methicillin Sodium
Methicillin Sodium is a penicillinase-resistant penicillin antibiotic that was developed to treat infections caused by penicillin-resistant Staphylococcus aureus bacteria. It works by inhibiting bacterial cell wall synthesis, making it effective against certain gram-positive organisms. Due to significant safety concerns including nephrotoxicity, this medication is no longer used clinically and has been largely replaced by safer alternatives.
A historical narrow-spectrum penicillin antibiotic formerly used for penicillin-resistant staphylococcal infections, now discontinued due to safety concerns.
Key facts at a glance
- RxNorm
- 267073
- Generic
- Methicillin Sodium
- Class
- pin-variant
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Originally used to treat infections caused by penicillin-resistant Staphylococcus aureus, including skin and soft tissue infections, pneumonia, and other staphylococcal infections. Note: This medication is no longer marketed or used clinically due to safety concerns.
As a beta-lactam antibiotic, methicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), preventing the cross-linking of peptidoglycan chains necessary for bacterial cell wall strength and rigidity.
Methicillin has been discontinued from clinical use due to significant nephrotoxicity, particularly interstitial nephritis. MRSA strains are named after methicillin resistance. This drug is primarily of historical significance and has been replaced by safer alternatives such as nafcillin, oxacillin, and vancomycin for treating resistant staphylococcal infections.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 28, 2026. · Read our editorial policy