Cephalosporins, a class of beta-lactam antibiotics first discovered in 1945, are derived from 7-aminocephalosporanic acid and are effective against a variety of gram-positive and gram-negative bacteria. They act by inhibiting cell wall synthesis and can be categorized into four generations based on their spectrum of activity, with the first generation highly active against gram-positive cocci. Resistance to cephalosporins may arise from alterations in target proteins, reduced permeability, or production of beta-lactamases by bacteria.

2.  First discovered in 1945
 A class of Beta Lactam Antibiotics
 Are derivatives of 7-aminocephalospranic
acid
 They were first isolated from
Cephalosporium acremonium (fungus)

3.  Are Beta-lactam compounds
 In which the beta-lactam ring is fused
to a 6-membered dihydrothiazine ring,
thus forming the cephem nucleus.

5. They are Bactericidal agents by cell
lysis.
Bind to the Penicillin-binding
proteins (PBPs) on the bacterial cell
membrane and inhibit cell wall
synthesis.
Inhibit Peptidoglycan synthesis by
inhibiting the transpeptidation
reaction – failure of cross-linking of
peptidoglycan.

6.  Acquired resitance to cephalosporins could be
due to:
1. Alternation of the PBPs (target protiens)
2. Impermeability to the antibiotic thus
preventing it to reach it’s site of action.
3. Production of Beta lactamases by many
bacteria that inactivate the drug.
4. Resistance developed by penicilinase
produced by staphylococci (less than
penicillin)

7.  Based on their spectrum of activity,
Cephalosporins can be broadly categorized
into four generations.
› 1st Generation (Cefazolin, Cephalexin)
› 2nd Generation (Cefotetan, Cefoxitin)
› 3rd Generation (Cefoperazone, Cefixime)
› 4th Genertaion (Cefepime)

8.  Also called Narrow spectrum Cephalosporins
 Include
ORAL
 CEPHALEXIN
 CEFADROXIL
 CEPHRADINE
PARENTERAL
 CEFAZOLIN (prototype)
 CEPHAPIRIN

9.  First generation cephalosporins are very active
against gram positive cocci which include:
› Pneumococci
› Streptococci
› staphylococci.
 Against gram negative bacilli
› E. coli
› Klebsiella
› Proteus
 Active against most penicillin-susceptible anaerobes
found in the oral cavity,
› except those belonging to the Bacteroides fragilis (that are
Gram-negative bacillus bacterium species, and an obligate
anaerobe of the gut ) group.

10.  Pharmacokinetics:
› Route of administration: Parentral
› PPB  70 – 86%
› Volume of distribution  9.2/1.73
sg.meter
› Half life  1.6 – 2.2 hours
› Renal Excretion  87%

11.  Dosage:
› In mild disease: 250mg – 500mg after every 8
hours
› In Moderate to sever disease : 500mg – 1g after
every 6 hours
› In most severe cases (e.g Endocarditis,
Septicemia) : 1g – 1.5g every 6 hours

12.  Pharmacokinetics:
› Route of administration: Oral
› Partially bound to plasma protiens.
› Half life : 60 mins
› It attains high concentration in the bile
› Excretion through the urine
 Dosage:
› In Adults  250mg – 1g every 6 – 8 hours
› In Children  25 – 1000mg/kg/day

13.  Pharmacokinetics:
› Route of administration  Oral
› Half life  1.5 hours
› Metabolism  Unknown
› Absorption in GIT
› PPB  20% of drug binds to plasma protien.
› Can cross the placental barrier and also appear in
the breast milk
› Excretion  90% through urine
 Dosage: 500mg – 1g after every 12 hours.

14.  Pharmacokinetics:
› Route of administration  Oral and I/M
› Volume of distribution  0.29 +- 0.03l/kg
› PPB  Less than 10%
› Half life  0.7 hours (oral) and 2-3hrs (I/M)
 Dosage:
› In Adults  250mg – 4g/day (orally)
› In Children  25 -100mg/kg/day (I/M)

15.  Pharmacokinetics:
› Route  I/V
› Half life  0.36hrs
› Can cross the placental barrierand appear in the
breast milk
 Dosage:
› 2 grams every 6 hours

16.  For dental surgical prophylaxis (Cephalexin
and Cefazolin)
 Skin and bone infections (Cefazolin)
 Pharyngitis
 Tonsilitis
 Otitis
 Pneumonia
 UTI
 Skin infections

17.  Diarrhea
 Nausea
 Vomiting
 Abdominal discomfort
 Headache
 Fever
 Rashes
 Pruritis

18.  Urticaria
 Serum sickness like reaction
 Disturbance in liver enzymes
 Transient Hepatitis
 Cholestatic jaundice
 Eosinaphilia
 Blood disorders
 Antibiotic associated colitis (rare)