Drugs for infections

Question 1

Name the 2 types of reverse transcriptase inhibitors. (2)

Describe their mechanisms and name an example for each. (4)

Answer 1

Nucleoside/nucleotide reverse transcriptase inhibitors eg zidovudine. Inihibit synthesis of DNA by reverse transcription and act as chain terminators.

Non-nucleoside reverse transcriptase inhibitors eg nevirapine bind directly to an inhibit reverse transcriptase.

Question 2

Name a protease inhibitor used against HIV and describe the mechanism of action. (2)

Answer 2

Ritonavir, acts competitively on HIV aspartyl protease enzyme, which is involved in the production of functional viral proteins and enzyme.

Question 3

Name the 5 types of drugs see in HAART. (5)

Answer 3

NRTI
NNRTI
Protease inhibitors
Fusion inhibitors
Integrase inhibitors

Question 4

What is in tazocin? (2)

Answer 4

Piperacillin (extended spectrum) and tazobactam (beta lactamase inhibitor)
It has good activity against gram positive, negative and anaerobes such as psuedomonas.

Question 5

What is the mechanism of penicillins and cephalosporins? (2)

Answer 5

Inhibit production of peptidoglycan cell walls, thus being bactericidal.

Question 6

What is the differences between the generations of cephalosporins? (2)

Answer 6

Increasing gram negative effect, and also tend to cross the BBB better.

Question 7

How do aminoglycosides work? (2)

What organisms are they active against? (2)

Answer 7

Bacteriocidal, they inhibit protein synthesis by irreversibly binding to the ribosomal unit.

Active against gram negatives (e.g. psuedomonas), some gram positive but not anaerobes.

Question 8

What is the mechanism of macrolides. (2)

Answer 8

Bacteriostatic, interfering with bacterial protein synthesis by binding irreversible to 50s unit of ribosomes.

Question 9

What antibiotics are a good alternative to penicillins in allergic patients? (1)

Answer 9

Macrolides e.g. erythromycin, clarithromycin, azithromycin because they have a similar antibacterial spectrum.

Question 10

What is the mechanism of action of sulphonamides and trimethoprim? (2)

Answer 10

Inhibit dihydrofolate reductase in synthetic pathway to folic acid.

Question 11

What is the mechanism of metronidazole? 91)

Answer 11

Bacteriocidal by a toxic metabolite that inhibits DNA synthesis and breaks down existing DNA.
But only some anaerobes and some protozoa contain the enzyme to create the toxic metabolite.

Question 12

Name a quinolone. (1)
How does it work? (1)
When is it contraindicated? (1)

Answer 12

Ciprofloxacin
Bacteriocidal, inhibits the replication of bacterial DNA.
History of tendon disorders related to quinolone use. The risk is further enhanced by steroid use. Stop if suspecting tendonitis.