INFECTIONS: PENICILLIN, PENICILLASE-RESISTANT Flashcards
1
Q
PENICILLINS, PR: INDICATIONS
A
- Staphylococcal infection, including:
1) Skin and soft tissue infections such as cellulitis (in combination with benzylpenicillin for more severe infection)
2) Osteomyelitis and septic arthritis
3) Other infections, including endocarditis.
2
Q
PENICILLINS, PR: MOA
A
- Penicillins inhibit the enzymes responsible for cross-linking peptidoglycans in bacterial cell walls
- This weakens cell walls, preventing them from maintaining an osmotic gradient
- Uncontrolled entry of water into bacteria causes cell swelling, lysis and death
- Penicillins contain a β-lactam ring, which is responsible for their antimicrobial activity
- Side chains attached to the β-lactam ring can be modified to make semi-synthetic penicillins
- The nature of the side chain determines the antimicrobial spectrum and other properties of the drug
- For flucloxacillin, an acyl side chain protects the β-lactam ring from β-lactamases, which are enzymes made by bacteria to deactivate penicillin
- This makes flucloxacillin effective against β-lactamase producing staphylococci.
- Meticillin-resistant Staphylococcus aureus (MRSA) resists the actions of flucloxacillin by reducing penicillin binding affinity.
3
Q
PENICILLINS, PR: ADVERSE EFFECTS
A
- Minor GI upset
- Penicillin Allergy (acute/delayed)
- Liver Toxicity - cholestasis and hepatitis
- CNS toxicity can occur in high doses of penicillin or where severe renal impairment delays excretion
4
Q
PENICILLINS, PR: WARNINGS
A
- Generally safe in most situations
- Dose reduction in renal failure
- Main CI to Flucloxacillin use is a Hx of Penicillin allergy
- Prior Flucloxacillin-related hepatotoxicity
5
Q
PENICILLINS, PR: INTERACTIONS
A
- MTX
6
Q
PENICILLINS, PR: EXAMPLES
A
- Flucloxacillin