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Review of Pharmacology - 9E (2015)

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Chemotherapy A: General Consideration and Non-specific Antimicrobial Agents<br />

Toxicity<br />

• Main toxicity is hypersensitivity including serum sickness. Anaphylaxis is most<br />

commonly associated with these drugs; therefore intra-dermal sensitivity testing is<br />

must before administration <strong>of</strong> penicillins. If a patient develops severe hypersensitivity<br />

reaction to a penicillin, all other beta lactam antibiotic are contra-indicated except<br />

aztreonam (cross sensitivity is not present).<br />

• Ampicillin is involved in causing maculopapular skin rash in the patients with viral<br />

diseases like infectious mononucleosis.<br />

• Methicillin is the most common antibiotic implicated in causing interstitial nephritis.<br />

• Nausea and diarrhea may be caused by oral drugs like amoxicillin and ampicillin.<br />

Ampicillin causes diarrhea more frequently, because it is incompletely absorbed<br />

and causes more suppression <strong>of</strong> normal microbial flora. It can also cause<br />

pseudomembranous colitis.<br />

• Procaine penicillin in high doses can result in seizures and CNS abnormalities (due to<br />

procaine).<br />

• Oxacillin can cause hepatitis and nafcillin is involved in causing neutropenia.<br />

• Carbenicillin in high dose can result in bleeding.<br />

Cephalosporins<br />

These are β-lactam antibiotics having 7-aminocephalosporanic acid nucleus. These are<br />

classified into four generations.<br />

First Generation Second Generation Third Generatin<br />

Fourth<br />

Generation<br />

Fifth<br />

Generation<br />

Oral Parenteral Oral Parenteral Oral Parenteral Parenteral Parenteral<br />

Cephalexin<br />

Cefadroxil<br />

Cepharadine<br />

Pharmacokinetics<br />

Cefazolin<br />

Cefaclor<br />

Cefuroxime<br />

axetil<br />

Loracarbef<br />

Cefprozil<br />

Cefuroxime<br />

Cefotetan<br />

Cefoxitin<br />

Cefmetazole<br />

Cefixime<br />

Cefpodoxime<br />

Ceftibuten<br />

Cefditoren<br />

Cefdinir<br />

• Most cephalosporins are excreted via kidney through tubular secretion.<br />

• Ceftriaxone and cefoperazone are secreted in the bile.<br />

• Nephrotoxicity <strong>of</strong> these drugs is increased with loop diuretics.<br />

Antibacterial Spctrum<br />

Useful spectrum <strong>of</strong> cephalosporins<br />

Generation Organism Remarks<br />

First<br />

Second<br />

Gram +ve Cocci<br />

• Streptococci<br />

• Staphylococci<br />

Gram –ve bacilli<br />

• E. coli<br />

• Klebsiella<br />

• Proteus<br />

• H. influenza<br />

• M. catarrhalis<br />

• Bacteroides<br />

Cefotaxime<br />

Ceftizoxime<br />

Ceftriaxone<br />

Ceftazidime<br />

Cefoperazone<br />

Moxalactam<br />

Not active against penicillin resistant<br />

strains<br />

Only cefoxitin, cefmetazole and cefotetan<br />

are effective against Bacteroides<br />

Contd...<br />

Nafcillin can cause neutropenia<br />

Ampicillin should be avoided<br />

in patients with viral illness<br />

particularly EBV because it can<br />

cause rash in these patients.<br />

Cefepime<br />

Cefpirome<br />

Ceftaroline<br />

Ceftobiprole<br />

1. All cephalosporins having A<br />

after cef are 1st generation<br />

(except cefaclor)<br />

2. Cephalosporins containing<br />

PI are 4th gen. (cefePIme,<br />

cefPIrome)<br />

3. Cephalosporins ending with<br />

ME are 3rd gen. except.<br />

cefuroxiME.<br />

Chemotherapy A: General Considerations <strong>Pharmacology</strong> and Non-specific...<br />

519<br />

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