cephalexin

Binds to bacterial cell wall membrane, causing cell death.

Therapeutic effects:

Bactericidal action against susceptible bacteria.

Spectrum:

Active against many gram-positive cocci including:
- Streptococcus pneumoniae,
- Group A beta-hemolytic streptococci,
- Staphylococci (including penicillinase-producing strains).
Active against the following gram-negative organisms:
- Escherichia coli,
- Haemophilus influenzae,
- Klebsiella pneumoniae,
- Moraxella catarrhalis,
- Proteus.
Not active against methicillin-resistant staphylococci or enterococci:
- Enterococcus.
Not active against anaerobes.

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed after oral administration.

Distribution: Widely distributed. Crosses the placenta and enters breast milk in low concentrations. Poor CSF penetration.

Metabolism/Excretion: Excreted almost entirely unchanged in the urine.

Half-Life: Neonates: 5 hr; Children: 2.5 hr; Adults: 50–80 min (↑ in renal impairment).

Time/Action Profile ⬆ ⬇

(blood levels)

ROUTE	ONSET	PEAK	DURATION
PO	rapid	1 hr	6–12 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to cephalosporins;
Serious hypersensitivity to penicillins.

Use Cautiously in:

Renal impairment;
History of GI disease, especially colitis;
Lactation: Use during breastfeeding only if potential maternal benefit outweighs potential risk to infant.

Adv. Reactions/Side Effects ⬆ ⬇

Derm: rash, urticaria

GI: diarrhea, CLOSTRIDIOIDES DIFFICILE-ASSOCIATED DIARRHEA (CDAD), abdominal pain, nausea, vomiting

Hemat: eosinophilia, hemolytic anemia, neutropenia, thrombocytopenia

Neuro: SEIZURES (HIGH DOSES)

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS), superinfection

Interactions ⬆ ⬇

Drug-drug:

Probenecid↓ excretion and ↑ blood levels of renally excreted cephalosporins.
Concurrent use of loop diuretics or aminoglycosides may ↑ risk of renal toxicity.

Route/Dosage ⬆ ⬇

PO (Adults ): Most infections: 250–500 mg every 6 hr. Uncomplicated cystitis, skin and soft tissue infections, streptococcal pharyngitis: 500 mg every 12 hr. Maximum dose: 4 g/day.
PO (Children ): Most infections: 25–50 mg/kg/day divided every 6–8 hr (can be administered every 12 hr in skin/skin structure infections or streptococcal pharyngitis). Otitis media: 75–100 mg/kg/day divided every 6 hr. Maximum dose: 4 g/day.

Availability ⬆ ⬇

(Generic available)

Capsules: 250 mg; 500 mg; 750 mg
Oral suspension: 125 mg/5 mL; 250 mg/5 mL
Tablets: 250 mg; 500 mg

Assessment ⬆ ⬇

Assess patient for infection (vital signs; appearance of wound, sputum, urine, and stool; WBC) at beginning of and throughout therapy.
Before initiating therapy, obtain a history to determine previous use of and reactions to penicillins or cephalosporins. Persons with a negative history of penicillin sensitivity may still have an allergic response.
Obtain specimens for culture and sensitivity before initiating therapy. First dose may be given before receiving results.
Observe patient for signs and symptoms of anaphylaxis (rash, pruritus, laryngeal edema, wheezing). Discontinue drug and notify physician or other health care professional immediately if these problems occur. Keep epinephrine, an antihistamine, and resuscitation equipment close by in case of an anaphylactic reaction.
Monitor bowel function. Diarrhea, abdominal cramping, fever, and bloody stools should be reported to health care professional promptly as a sign of
Clostridioides difficile
-associated diarrhea (CDAD). May begin up to several wk following cessation of therapy.

Lab Test Considerations:

May cause positive results for Coombs' test.
- May cause ↑ AST, ALT, alkaline phosphatase, bilirubin, LDH, BUN, serum creatinine.
- May rarely cause neutropenia, thrombocytopenia, and eosinophilia.

Implementation ⬆ ⬇

PO: Administer around the clock. May be administered on full or empty stomach. Administration with food may minimize GI irritation. Shake oral suspension well before administering. Refrigerate oral suspension.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take medication around the clock at evenly spaced times and to finish the medication completely as directed, even if feeling better. Take missed doses as soon as possible unless almost time for next dose; do not double doses. Advise patient that sharing this medication may be dangerous. Pedi: Tell parents or caregivers to use calibrated measuring device with liquid preparations.
Advise patient to report signs of superinfection (furry overgrowth on the tongue, vaginal itching or discharge, loose or foul-smelling stools) and allergy.
Instruct patient to notify health care professional if fever and diarrhea develop, especially if diarrhea contains blood, mucus, or pus. Advise patient not to treat diarrhea without consulting health care professional.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇