Cephalosporins Exam 1 Drug list Flashcards
Need to know Cephalosporins
First gen (Cephalexin and Cefazolin(IV/IM)
Second gen (Cefuroxime)
Third gen (Cefdinir, Cefpodoxime, Ceftriaxone (IM/IV))
Cephalosporins are similar to
Penicillin’s chemically and structurally
What adverse event occurs if cephalosporin dosage isn’t adjusted in the presence renal impairment?
Induction of seizure activity
Cephalosporins most effective against
Rapidly growing organisms forming cell walls when antibiotic concentrations exceed the pathogen’s MIC for at least 50% of the dosing interval
What are some clinical uses for cephalosporins
Active against respiratory pathogens
Acute otitis media, sinusitis, group A streptococcal pharyngitis, pneumonia, chronic bronchitis, and UTIs
how well are cephalosporins absorbed through the GI?
Oral formulations are well-absorbed
Is hepatic metabolism significant in cephalosporins?
No
How are cephalosporins excreted?
Via the kidneys as unchanged drug
Renal impairment significantly extends half-life
What species are intrinsically resistant to cephalosproins?
Enterococcus species
Are cephalosporin’s stable in the presence of penicillinase produced by S. aureus?
Yes
What lab values signifies a renal dosing adjustment is needed for cephalosporins?
Recommended when GFR is less than 30mL/min
Cephalosporins MOA
Inhibit mucopeptide synthesis in the bacterial cell wall
Make bacterium osmotically unstable
Cephalexin and Cefazolin are active against
Gram-positive cocci, S. aureus, s. epidermidis, and most streptococci
ex. E.coli, proteus mirabilis, klebsiella pneumoniae
Cephalexin and Cefazolin Common Side Effects
Gastrointestinal upset (nausea, vomiting, diarrhea)
Rash
Allergic reactions, including anaphylaxis (rare)
Staphylococcal skin infections often respond to which generation of cephalosporins?
First-generation (Cephalexin)
Cephalosporin Monitoring
Renal function especially in patients with renal impairment (BUN and CrCl)
Signs of allergic reaction, such as rash, itching, swelling, and respiratory difficulties
Periodic liver function tests during prolonged therapy (tiredness, weakness, and jaundice)
Cephalosporin ADRs
Severe allergic reactions, including anaphylaxis
Clostridium difficile-associated diarrhea
Coagulation abnormalities
Seizure activity
Who are at risk for coagulation abnormalities from cephalosporin admin?
those with impaired renal function, cancer, Vit K synthesis, Low Vit K stores, or malnutrition
Are cephalosporins Bacteriostatic or Bactericidal?
Bactericidal
Do 1st and 2nd generations cross the BBB, placenta, and breast milk?
Don’t enter CSF
Generally safe in pregnancy
Cross the placenta
Small amounts in milk
What are the most common mechanisms of resistance to cephalosporins?
Beta-lactamase production and altered target sites.
Cefazolin Adsorption
Not absorbed in GI tract
Cefazolin Distribution
Various tissues and body fluids, including skin, bones, joints, gallbladder, and bile
Protein binding 80%
Cephalexin Distribution
Widely throughout body, bone, bile, synovial fluid, pleural fluid
10-15% bound to plasma proteins
Second Generation Cephalosporin
Cefuroxime
Cefuroxime Indications
Same as first gens, but increased activity against H. influenzae, limited activity against anaerobes (Bacteroides fragilis)
Second generation require?
susceptibility tests do to different spectrum of activity.
Cefuroxime common side effects
GI upset
Rash
Hypersensitivity reactions
superinfections (ex candida overgrowth)
Cefuroxime ADRs
Severe hypersensitivity reactions (e.g., anaphylaxis)
Clostridioides difficile-associated diarrhea
Hemolytic anemia
Nephrotoxicity
Is cefuroxime bacteriostatic or bactericidal?
Bactericidal
Cefuroxime adsorption
Oral prodrug (cefuroxime axetil) absorbed well in GI tract, hydrolyzed to active form.
Cefuroxime distribution
Widely in the body, tissues and fluids (lungs, pleural fluid, and bile)
Third Generation Cephalosporins
Cefdinir
Cefpodoxime
Ceftriaxone (IM/IV)
Third Generation cephalosporins are active against?
Streptococcal species, streptococcus pneumoniae, MSSA, H. Influenzae, Moraxella, N gonorrheae, N meningitis, E. coli, klebsiella, proteus, salmonella
No 3rd gen cephalosporins are reliable against?
Anaerobes other than peptostreptococcus
Ceftriaxone elimination is mainly?
Extrarenal, via biliary, making its half-life stable to changes in renal function.
Ceftriaxone binds highly to what, and leads to what?
Highly bound to albumin
Avoid in neonates at risk for hyperbilirubinemia (especially preterm infants)
Ceftriaxone (IM) is recommended treatment for?
Gonorrhea
Cefdinir and Cefpodoxime activity
Best against gram-positive
Cefdinir and cefpodoxime drug interations
Antacids (take 2 hours before or after)
Cefdinir (iron supplements)
All cephalosporin drug interactions
Probenecid
Loop diuretics
Warfarin
Do 3rd generation cephalosporins cross the BBB?
Yes, parenteral form is used to treat meningitis.