Cephalosporins Flashcards
What adverse event occurs if cephalosporin dosage isn’t adjusted in the presence renal impairment?
Induction of seizure activity
What are some clinical uses for cephalosporins?
Respiratory pathogens that cause acute otitis media, sinusitis, group A streptococcal pharyngitis, pneumonia, chronic bronchitis.
Also for UTI’s
Describe how 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
Aside from renal toxicity, Cephalosporins can also cause:
Hematological/Coagulation abnormalities
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
What is the MOA of Cephalosporins?
Inhibit mucopeptide synthesis in the bacterial cell wall
What are the first generation cephalosporins?
Cephalexin & Cefazolin
Can oral cephalosporins be taken with food?
Yes. Food or milk is okay
Staphylococcal skin infections often respond to which generation of cephalosporins?
First-generation (Cephalexin)
Cephalosporin Monitoring
Renal function
Signs of allergic reaction
Liver function
Coagulation abnormalities
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
Describe the use of cephalosporins in pregnancy:
Generally safe in pregnancy
Cross the placenta & are excreted in breast milk
Shorter half lives
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
What are unique considerations for Cefuroxime?
Interacts with H-2 blockers
Increased activity against H.Influenza
What is unique about Cefuroxime PO:
Oral prodrug (cefuroxime axetil): absorbed well in GI tract, hydrolyzed to active form.
What are the third generation cephalosporins?
Cefdinir
Cefpodoxime
Ceftriaxone (IM/IV)
Ceftriaxone should be avoided in this population?
Neonates at risk for hyperbilirubenemia
Ceftriaxone (IM) is the recommended treatment for which STI?
Gonorrhea
What instructions should you give to the patient when taking PO Cefdinir?
Take 2 hours before or 2 hours after antacids that contain magnesium or aluminum. Same for iron supplements
What are the major drug interactions with Cephalosporins?
Probenecid
Loop diuretics
Warfarin
Do 3rd generation cephalosporins cross the BBB?
Yes, parenteral form is used to treat meningitis.
What type of dosing is required when using cephalosporins?
Renal dosing
Are cephalosporins bactericidal or bacteriostatic?
Bactericidal
Which cephalosporin has good tissue penetration & is the drug of choice for surgical prophylaxis?
Cefazolin (1st generation)
Describe this relationship:
1st generation are more effective against gram + coverage, less against gram -, & they have poor CSF penetration. As the generations increase, there is less gram + coverage, more gram -, & more CSF penetration
What instruction should be given to patient when taking PO Cefpodoxime?
Should be taken with food to enhance absorption
What is similar about Cepodoxime and Cefuroxoime?
Both prodrugs
Cefpodoxime is the most active oral agent against:
N. Gonorrhea
How is Ceftriaxone distributed?
Highly bound to protein
Monitoring for Ceftriaxone includes:
hepatic dysfunction as it can extend half-life & excretion
Ceftriaxone is contraindicated in:
Neonates younger than 28 days
