CPTP 3.20 - Pharmacology of Antimicrobials 1 Flashcards
Define chemotherapy?
Use of synthetic chemicals to destroy infective agents
Describe the two ways in which antibacterials work?
Bacteriostatic - inhibit multiplication
Bacteriocidal - kill bacteria directly
How do Beta-lactems work?
Inhibit the transpeptidation reaction during synthesis of peptoglycan cell wall (cross-link prevention) - bbind to active site of penicillin binding protein
They are all bactericidal
Give an example of a B-lactamase resistant form of penicillin?
Flucoxicillin
Effective against staphylococi
Give an example of a broad spectrum form of penicillin?
Amoxicillin
Effective against gram negative
Give an example of a extended-spectrum form of penicillin?
Pipercillin with tazobactam
In terms pharmacokinetics - what percentage of penicillins are plasma protein bound?
60%
In terms pharmacokinetics - how are the majority of penicillins excreted?
90% Tubular secretion
How may some bacteria confer resistance against penicillins?
B-lactamase enzyme cleave the B-lactam ring in penicillins leading to the loss of their activity - Often encoded for on plasmids
Name two drugs which are B-lactamase inhibitors?
Co-amoxiclav
Pipercillin with Tazobatam (extended spectrum)
Describe cephalosporins?
Beta lactamase sensitive
Good transfer across BBB
Broad specificity against gram negative bacteria
Give two examples of cephalosporins?
Cefalexin
Cefotaxime
What adverse drug reactions may occur with the use of cephalosporins?
Nephrotoxicity
Diarrhoea
What are carbapenems and give an example?
Developed to deal with B-lactamase bacteria = maropenem
How does the antibiotic Vancomysin work and how and under what circumstances is it administered?
Targets bacterial wall - binding to D-ala at the end of the peptoglycan side chain
Reserved for treatment of severe gram negative infections (MRSA/C.diff)
IV infusion
Describe folate biosynthesis?
pABA is converted into folate (via dihydrofolate sythetase ONLY found in bacteria)
Folate is converted into tetrahydrofolate (via dihydrofolate reductase found in ALL organisms)
Tetrahydrofolate is converted into DNA
How do sulphinamides work?
Bacteriostatic agents - work as competative inhibitors for dihydrofolate synthetase ONLY found in bacteria
Allergies are very common
How does Trimethoprim work?
Bacteriostatic agent - Inhibitor for dyhydrofolate reductase
