Antifungal Agents

00:00 And finally when we talk about individual fungal diseases, we're going to be talking about ways to cure them. And we don't have vaccines against most of these fungal diseases, but we do have drugs that can be used to treat them, and some of them work very well, some of them are somewhat toxic, but it's all that we have.

00:20 So here's a table that lists all of the available antifungal agents, let's zoom in on the top part of this table so that we can discuss them in a little detail. We have a number of different classes of antifungal agents, the first here is the polyenes. These are rather large molecules whose mechanism of action is to bind a component of the cell membrane called ergosterol, and they disrupt the membrane, and examples include amphotericin B, nystatin which can be either given intravenously or topical. Nystatin is a very common topical antifungal which can be used to treat lots of surface infections and you can see in the last column labeled pathogen the various fungal infections that are treated. You've got some specific names like candida and Cryptococcus, and then the endemic mycoses, which refers to this category of infections that we acquire from specific environments. We also have another category called the allylamines, which block synthesis of the same membrane component, ergosterol, and an example of that is terbinafine which is either topically or orally given for dermatophytes. We have the azoles which block ergosterol synthesis as well, so you can see this is a common target. Ketoconazole which is given orally for various infections.

01:38 and then let's zoom in on the bottom, we're continuing with some of these azoles that block ergosterol synthesis, itraconazole, fluconazole and voriconazole, all IV or oral administered for various infections and we will refer to these specifically when we talk about the diseases. The echinocandins inhibit cell wall synthesis, caspofungin is an example of a drug given intravenously for Candida and Aspergillus infections. And finally there's a pyrimidine inhibitor. This inhibits DNA and protein synthesis called flucytosine,.

02:11 This is given all orally for Cryptococcal and candida infections. And not all of these are specific, so the ergosterol inhibition is rather specific, but pyrimidine inhibitors are not, so they often have side effects.