Brush Letter Pharm: Fosfomycin, Oritavancin, and Linezolid!
Hi everyone! It has been quite some time since I've done a brush letter pharm, so today I decided to do 3 of them! I've seen these agents sporadically in my emergency med rotation and thought they were pretty interesting drugs to cover. Each of them has interesting quirks so I hope you appreciate the science behind them!
Fosfomycin
Mechanism of action: inhibits bacterial cell wall synthesis by inactivating pyruvyl transferase, an important enzyme in the creation of bacterial cell walls
Spectrum of coverage: Gram positive agents (staph, strep) and gram negative (E.coli, H.influenzae, Neisseria spp., Salmonella and Shigella)
ADR: headache, dizziness, diarrhea, nausea
Fun facts!
- This drug remains concentrated in the urine for up to 48 hours which makes it a really useful one dose agent for women with UTIs
- The FDA approved indication is for women with uncomplicated cystitis, but I've seen it increasingly used in the ED for men (complicated UTI) due to case studies that support its use
Oritavancin
Mechanism of action: A lipoglycopeptide that inhibits bacterial cell wall synthesis by binding peptidoglycan precursors and inhibiting crosslinking. Ultimately ruins cell wall integrity and causes bacterial cell death.
Spectrum of coverage: gram positive infections caused by staph (MSSA and MRSA), strep species, and enterococcus faecalis
ADR: hypersensitivity and infusion related reactions, C.diff infection, osteomyelitis
Fun facts!
- This drug is used for skin and skin structure infections as a one time dose (the half life is 245 hours!)
- This agent has a similar mechanism to Vancomycin!
Linezolid
Mechanism of action: inhibits bacterial protein synthesis by binding to the 50s subunit, preventing the 70s initiation complex needed for translation
Spectrum of coverage: gram positive infections caused by VRE, strep species and MRSA
ADR: GI upset, rash, myelosuppression
Fun facts!
- This drug causes an increase in serotonin due to inhibition of monoamine oxidase and therefore we have to be cautious with other serotonin increasing drugs and foods to avoid serotonin syndrome
Hope you enjoyed this edition of brush letter pharm! More to antibiotics to come soon!
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