3 drugs - MOA & selective toxicity

Question 1

Rifamycin (Rifampin)

Answer 1

Antibiotic

MOA - Targets the enzyme, RNA polymerase, involved in transcription, RNA synthesis.

Selective toxicity - Prokaryotic RNA polymerase differs from eukaryotic RNA polymerase (actually 3 kinds)

Question 2

Miconazole (Monistat)

Answer 2

Antifungal to treat vaginal yeast infections

MOA - Inhibits ergosterol synthesis which creates pores in the plasma membrane & cause leakage and cell death.

Selective toxicity - Miconazole targets the sterol in the fungi, which is ergosterol. The sterol in animal plasma membranes is cholesterol, so they are unaffected by the drug.

Question 3

Azidothymidine (AZT)

Answer 3

Antiviral - treats HIV infections

MOA - HIV is an RNA virus, so much first undergo reverse transcription and make DNA before it can duplicate. AZT inhibits the enzyme (reverse transcriptase) that HIV uses to synthesize DNA, and so prevents viral DNA from forming

Selective toxicity - Our cells go through transcription, not reverse transcription, so we don’t have the reverse transcriptase enzyme.