Cephalosporins are a slightly modified chemical “twin” to penicillins due to their beta lactam chemical structure. (See Figure 3.8 for a comparison of the beta-lactam ring structure, spectrum of activity, and route of administration across different classes of medications.) Because of these similarities, some patients who have allergies to penicillins may experience cross-sensitivity to cephalosporins.
Indications: Cephalosporins are used to treat skin and skin-structure infections, bone infections, genitourinary infections, otitis media, and community-acquired respiratory tract infections.
Mechanism of Action: Cephalosporins are typically bactericidal and are similar to penicillin in their action within the cell wall. Cephalosporins are sometimes grouped into “generations” by their antimicrobial properties. The 1st-generation drugs are effective mainly against gram-positive organisms. Higher generations generally have expanded spectra against aerobic gram-negative bacilli. The 5th-generation cephalosporins are active against methicillin-resistant Staphylococcus aureus (MRSA) or other complicated infections. [1]
Specific Administration Considerations: Patients who are allergic to pencillins may also be allergic to cephalosporins. Patients who consume cephalosporins while drinking alcoholic beverages may experience disulfiram-like reactions including severe headache, flushing, nausea, vomiting, etc.[2]Additionally, like penicillins, cephalosporins may interfere with coagulability and increase a patient’s risk of bleeding. Cephalosporin dosing may require adjustment for patients experiencing renal impairment. Blood urea nitrogen (BUN) and creatinine should be monitored carefully to identify signs of nephrotoxicity.
Patient Teaching & Education: Patients who are prescribed cephalosporins should be specifically cautioned about a disulfiram reaction, which can occur when alcohol is ingested while taking the medication. Additionally, individuals should be instructed to monitor for rash and signs of superinfection (such as black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stool) and report to the prescribing provider.
It is also important to note that cephalosporin can enter breastmilk and may alter bowel flora of the infant. Thus, use during breastfeeding is often discouraged.[3] Now let’s take a closer look at the cephalosporin medication grid in Table 3.6.[4]
Table 3:6 Cephalosporin Medication Grid
Class/Subclass
Prototype/Generics
Administration Considerations
Therapeutic Effects
Side/Adverse Effects
Cephalosporins
1st generation:
cephalexin
Cefazolin
2nd generation:
cefprozil
3rd generation:
ceftriaxone
4th generation:
cefepime
5th generation:
ceftolozane
Check for allergies, including if allergic to penicillin
Dosage adjustment if renal impairment
Use with caution with seizure disorder
PO: Administer without regard to food; if GI distress, give with food
IV: Reconstitute drug with sterile water or normal saline; shake well until dissolved. Inject into large vein or free-flowing IV solution over 3-5 minutes
Drug interaction: anticoagulants
Monitor for systemic signs of infection:
-WBCs
– Fever
Monitor actual site of infection
Monitor culture results, if obtained
Common side effects:
-Nausea
-Vomiting
-Epigastric distress
-Diarrhea
Monitor for:
-Rash
-C-diff
Nephrotoxicity if pre-existing renal disease
Elevated INR and bleeding risk
Development of hemolytic anemia
Critical Thinking Activity 3.6a
Using the above grid information, consider the following clinical scenario question:
Mrs. Jenkins is an 89-year-old patient admitted to the medical surgical floor for treatment of a skin infection. The admitting provider prescribes Cefazolin 1 gram every 8 hours IV.
Mrs. Jenkins’ admission laboratory tests include renal laboratory studies reflecting: