ANTIBIOTICS

ANTI-INFECTIVE DRUGS

drugs that are designed to act selectively on foreign organisms that have invaded and infected the body

GENERAL MECHANISM OF ACTION OF ANTI-INFECTIVE AGENTS

• Inhibition of the biosynthesis of bacterial cell WALL

  • preventing the bacteria from multiplying and ultimately leading to their death.

• Inhibition of protein synthesis

• Some change the cell membrane permeability

  • leading to cell death and preventing the bacteria from multiplying.

• Some inhibit DNA synthesis

CELL WALL INHIBITORS

penicillin, cephalosporin, vancomycin

PROTEIN SYNTHESIS INHIBITORS

macrolides, aminoglycosides

CELL WALL PERMEABILITY

ketoconazole

DNA SYNTHESIS INHIBITORS

quinolones

Narrow spectrum

anti-infectives affect only a few bacterial types. The early penicillin (G&V) drugs are examples

Broad-spectrum

anti-infectives affect many bacteria. Meropenem is an example. Because narrow spectrum antibiotics are selective, they are more active against single organisms than the broad spectrum antibiotics.

BACTRIOSTATIC

Anti-infectives that interfere with the ability of the cell to reproduce/replicate without killing them

• Tetracycline is an example.

  • Stopping the growth only

  • Low concentration

BACTRICIDAL

• Antibiotics that can aggressively cause bacterial death

  • High concentration 

NEPHROTOXICITY

Antibiotics that are metabolized and excreted in the kidney most frequently cause kidney damage.

GASTRO-INTESTINAL TOXICITY

Direct toxic effects to the cells of the GI tract can cause nausea, vomiting, stomach pain and diarrhea. Some drugs are toxic to liver cells and can cause hepatitis or liver failure.

CNS TOXICITY

• When drugs can pass through the brain barrier and accumulate in the nervous tissues, they can interfere with neuronal function.

  • Dizziness

  • Headache

  • Confusion

  • Paresthesia - numbness tingling sensation can cause seizure.

HYPERSENSITIVITY

Most protein antibiotics can induce the body’s immune system to produce allergic responses. Drugs are considered foreign substances and when taken by the individual, it encounters the body’s immune cells.

SUPER-INFECTIONS

• Opportunistic infections that develop during the course of antibiotic therapy

  • Disrupts normal microbial flora

  • Antibiotic associated diarrhea

  • Vaginal yeast infection

Narrow spectrum penicillins

• Penicillin G

• Penicillin V

Broad Spectrum Penicillins (aminopenicillin)

• Amoxicillin

• Ampicillin

• Bacampicillin

Penicillinase-resistant Penicillin (anti-staphylococcal penicillins)

• Cloxacillin

• Nafcillin

• Methicillin

• Dicloxacillin

• Oxacillin

Extended-Spectrum penicillins (Anti-pseudomonal penicillins)

• Carbenicillin

• Mezlocillin

• Piperacillin

• Ticacillin

Beta-lactamase inhibitors

• Clavulanic acid

• Sulbactam

• Tazobactam

Penicillin

is a beta-lactam drug, with a beta-lactam ring.

FIRST GENERATION CEPHALOSPORINS

• are largely effective against the same gram-positive organisms affected by penicillin.

  • Cefadroxil

  • Cefazolin

  • Cephalexin

  • Cephalotin

  • Cephapirin

  • Cephadrine

SECOND GENERATION CEPHALOSPORINS

• are effective against those strains as well as Haemophilus influenza, Enterobacter aerogenes and Neisseria sp. These drugs are less effective against gram positive bacteria.

  • Cefaclor

  • Cefamandole 

  • Cefonizind

  • Cefotetan

  • Cefoxitin

  • Cefmetazole

  • Cefprozil

  • Cefuroxime 

THIRD GENERATION CEPHALOSPORINS

• are relatively weak against gram-positive bacteria but more potent against gram- negative bacteria, to include Serratia marcescens.

  • Cefnidir

  • Cefixime

  • Cefoperazone

  • Cefotaxime

  • Cefpodoxime

  • Ceftazidime

  • Ceftibuten

  • Moxalactam

FOURTH GENERATION CEPHALOSPORINS

• are developed to fight against the resistant gram-negative bacteria. The first drug is cefepime.

  • Cefepime

BACTERICIDAL

The cephalosporins are primarily

CEPHALOSPORINS

They interfere with the cell-wall building ability of bacteria when they divide.

CEPHALOSPORINS

• They prevent the bacteria from biosynthesizing the framework of their cell wall.  

• The weakened cell wall will swell and burst causing cell death.

AMINOGLYCOSIDES

• Gentamycin

• Tobramycin

• Amikacin

• Netilmicin

• Kanamycin

AMINOGLYCOSIDES

These are BACTERICIDAL.

AMINOGLYCOSIDES

These drugs are used to treat serious infections caused by gram-NEGATIVE bacteria.

MACROLIDES

• Azithromycin

• Clarithromycin

• Dirithromycin

• Erythromycin

LINCOSAMIDES

These agents are similar to the Macrolides but are more toxic.

LINCOSAMIDES

• Clindamycin  

• Lincomycin

TETRACYCLINES

These agents were first isolated from Streptomyces aureofaciens

Short-acting tetracycline

tetracycline

oxytetracycline

Intermediate acting tetracyclines

Demeclocycline

methacycline

Long acting tetracyclines

doxycycline

Minocycline

TETRACYCLINES

it is not recommended for use in pregnancy and lactation because the drug can affect the bones and teeth, causing permanent discoloration and sometimes arrest of growth.

FLUOROQUINOLONES

are broad-spectrum antibiotics. They are usually manufactured synthetically and are associated with mild adverse reactions.

FLUOROQUINOLONES

• Nalidixic acid

• ciprofloxacin

• ofloxacin

• norfloxacin

• Levofloxacin

• Sparfloxacin

SULFONAMIDES

• Sulfazalazine

• Sulfamethoxazole

• Sulfadiazine

• Sulfixoxazole

SULFONAMIDES

competitively block the para-amino benzoic acid to prevent the synthesis of folic acid in susceptible bacteria that synthesize their own folates for the production of RNA and DNA.

TETRACYCLINES

inhibit protein synthesis in susceptible bacteria leading to the inability of the bacteria to multiply.

SULFONAMIDES

It is not recommended for use in pregnancy because it can cross the placenta and cause birth defects and kernicterus.

LINCOSAMIDES

These agents penetrate the cell membrane and bind to the ribosome in the bacterial cytoplasm to prevent the protein production

MACROLIDES

They exert their effect by binding to the bacterial cell ribosomes and changing or altering protein production/function. This will lead to impaired cell metabolism and division.

AMINOGLYCOSIDES

They inhibit protein synthesis in susceptible strains of gram-negative bacteria, leading to loss of functional integrity of the bacterial cell membrane, which causes cell death.

CEPHALOSPORINS

They interfere with the cell-wall building ability of bacteria when they divide. They prevent the bacteria from biosynthesizing the framework of their cell wall. The weakened cell wall will swell and burst causing cell death.

PENICILLINS

produce BACTERICIDAL effects by interfering with the ability of susceptible bacteria from biosynthesizing the framework of the cell wall.