Itchy, itchy, itchy: Antifungals and the treatment of yeast infections

Being a dude, I thank my lucky stars on a daily basis that I am not prone to fungus-type infestations of my nether regions. Let's hear it for external genitalia! A woman's special area, like many other parts of the human body, is inhabited by both bacteria and fungi. These microbes are usually just chilling out, growing slowly and not bringing any attention to themselves. A yeast infection occurs when Candida albicans, a yeast (which is a type of fungus), is given the opportunity to take over downstairs due to a change in the local environment, which can be caused by a number of things including antibiotics, pregnancy, and a weakened immune system. Candida sets up shop in the most holy of holies, and before you know it, you've got vaginal candidiasis (a yeast infection)! And just so you know, I plan to see how long I can go in this post without mentioning the actual anatomical terms for 'womanly bits'. I consider this to be an exercise in puritan restraint. And euphemisms are fun!

Similar infections can be caused by bacteria, so it's important to establish that a prospective yeast infection is indeed due to yeast, otherwise antifungal drugs aren't gonna work and actually can increase the development of antifungal-resistant strains of yeast. It's akin to the contribution that extensive unnecessary antibiotic use has made to the evolution of antibiotic-resistant bacteria. On the other hand, it's a lot easier to just hit up the drug store than to book and drop by for an appointment with a doctor. I make no recommendations. IANAD. Anyway, since we're talking about a localized fungal infection, yeast infections generally don't cause systemic effects like fever, chills, nausea, or vomiting. Instead there is lots of itching. And soreness. And discharge.

Common antifungals on the market include butoconazole (Mycelex), clotrimazole (Canesten), miconazole (Monistat 3 or 7), and tioconazole (Vagistat, Monistat 1). If these don't work, they bring out the big guns: fluconazole (Diflucan), terconazole (Terazol), and ketoconazole. The more astute of you will have noted that all of the drugs that I mentioned have similar names, as they share the suffix -azole. Indeed, they all belong to the class of topical azole antifungals, so named for the presence a particular nitrogen-containing ring in their chemical structure. Any of the antifungals available OTC (i.e. you can buy them without a prescription) will effectively treat the majority of yeast infections, it's just that drug companies have a tendency to keep on modifying a drug in order to optimize it and/or try and sell you an ever-so-slightly 'improved' version that will make them more money. Friggin' big pharma.

Anyway, azole antifungals inhibit the fungal cytochrome P450 enzyme lanosterol 14-α-demethylase, which is responsible for the production of ergosterol, a steroid needed by Candida and certain other fungi to make their cell walls. The lack of this steroid causes changes in the fungal cell wall that modify the fluidity of the fungal cell membrane and activity of membrane bound enzymes, resulting in the inhibition of fungal growth and replication. The enzyme that is targeted by azole antifungals is similar to one that is found in humans, such that these agents can mess with steroid synthesis, potentially decreasing the levels of steroid hormones such as testosterone and cortisol. So there you go.

Kalant H, Grant D, and Mitchell J. Principles of Medical Pharmacology 7th ed. Toronto: Saunders Canada, 2006.

4 chemically inspired comments:

CDC said...

That is yucky.

And here is a Puritan Joke (direct from the seminary halls):

There once was a young Puritan man, who had a great deal of difficulty remembering the various rules of conduct in his community. He tried hard, but was constantly being ridiculed because of some breach of etiquette. In desperation, he asked an older man to teach him proper manners. The task was formidable, and the older man's patience grew thin, as he had to repeatedly chastise the younger man for his awkward ways. Finally, on the way into church one Sunday, the younger man started into the building ahead of the older man. He was firmly collared by his elder, who then allowed a lady to go in ahead of both of them.

The young man expressed his regret and the older, losing his temper, screamed, "Canst thou remember nothing? How much easier can it become?"

Pointing out the woman who had just entered, he said, "It is I before Thee, except after She!"

CND said...

Ah, the seminary halls. A venerable goldmine of puritan puns, they do appear to be.

Ursa said...

You know, i've used ketoconazole (Nizoral™) for years now - as a shampoo. (Hi, my name is Ursa and i have dandruff.) It used to be prescription, but now it's sold OTC. (Interestingly enough, it used to be a clear reddish pink; now it's a thick Selsun-ish blue.)

Anyway, ever since i learned my drugs and figured out it was an -azole, i've always wondered if there are folks out there who self-medicate. Frankly, i've never really been the mad scientist guinea pig type, but i'm sure there are people out there with internal genitalia and all of the issues that go along with such who've picked up the shampoo bottle and gone "hmmm..."

(Seriously, though, it's not me. I take my ladyparts very seriously, and i'm not about to go slapping home remedies on my virignia.)

Anonymous said...

Just having danglies won't protect you from fungus...ever hear of jock itch? Same cure, just tougher product packaging.