Beta Lactams Flashcards
What is the target of beta-lactams?
Transpeptidase enzyme
It alters the action of transpeptidase, resulting in defective cell wall synthesis. Cell wall is unosmotically active and cell dies.
Microbial resistance to beta-lactams
- Beta-lactamase enzyme
- Hydrolyzes beta-lactam ring - Permeability of cell wall
- Gram neg are impermeable to beta-lactams - Reduced sensitivity of penicillin binding protein
What are penicillin binding proteins
Proteins that link to transpeptidase enzyme
Beta lactams bind to PDPs, interfering with transpeptidase reaction
When are beta lactams effective
Only during rapid growth stage
because cell-wall synthesis occurs in rapidly growing period
What is natural penicillin derived from
Penicillin mold
What spectrum is natural penicillin
Narrow
What improves solubility of penicillin G
Na/K salts
What improves the half-life of penicillin G
Benzathine and Procaine salts
Which natural penicillin is highly inactivated by acidic mediums and thus should only be taken parenteral route
Penicillin G
Which natural penicillin is highly stable in a gastric acid medium
Penicillin V
Which natural penicillin can be taken orally
Penicillin V (acid resistant)
T/F - natural penicillins are good for anerobic infections
TRUE
T/F - natural penicillins are good for gram positive aerobic infection
True
T/F - natural penicillins are effective against gram negative aerobic and anaerobic infections
False! They are only effective against gram + aerobic infections
They are effective against both gram pos/neg anerobes
3 dosage forms of natural penicillin
- Sodium/potassium salt (Crystalline penicillin)
- Procaine penicillin
- Benzathine penicillin