An ongoing dialogue on HIV/AIDS, infectious diseases,
November 3rd, 2019
Learning the Names of HIV Drugs Is Horribly Difficult — Here’s Why
Happens every time. We start teaching about HIV, and at first, everything is going great.
Epidemiology, pathogenesis, diagnosis, clinical presentation. The students are right there with us.
However, then we start covering treatment — and things immediately get tricky.
Because no matter how engaged and brilliant they are, and no matter how scintillating we are, when the long list of antiretroviral agents appears, their eyes glaze over with fatigue.
Instant somnolence. Like someone turned up the temperature in the room, dimmed the lights, and passed out soft blankets and pillows.
And it’s no wonder! There are lots of drugs, with a dizzying array of names, abbreviations, combination tablets, and mechanisms of action.
We haven’t helped matters by following these RULES OF HIV MEDICINE, all of which were designed by evil creatures (with advanced degrees in medicinal chemistry and marketing) to make learning HIV medications terrifying. Here are these baleful rules:
- All drugs must have at least three names. Generic, brand, and 3-character abbreviation. To make matters worse, some have more than three names, starting with the very first drug way back in 1987, zidovudine. It was also called AZT (that’s what most people called it), ZDV, and Retrovir (that’s 4, including zidovudine). It also showed up in Combivir and Trizivir, for good measure. Now that’s just mean.
- HIV specialists must refer to them by different names at different times, for no apparent reason. Do we do this to maintain our special status? To be whimsical? To deliberately confuse others, just for sport? Whatever the motivation, it’s working wonderfully to keep this knowledge the very definition of arcane.
- Names of combination tablets should have nothing in common with their parent drugs. Some recent examples: Combine Tivicay and Epzicom — what do you get? Triumeq, of course. Descovy plus Edurant? Odefsey! See, isn’t this fun?
- Some of the abbreviations must bear no resemblance to either the generic or the brand name. Example — what does “3TC” have to do with the word “lamivudine,” for which it is the widely accepted abbreviation? Hint: nothing. Unless you check its chemical structure. And who, we might ask, will be doing that? And since emtricitabine is very similar to lamivudine (you knew that, right?), emtricitabine is abbreviated “FTC,” which makes all kinds of sense since emtricitabine starts with an “F.” (Oh wait. No it doesn’t.) The first time this disconnect between the true and abbreviated name came up was with the abbreviation for the drug zalcitabine, which was abbreviated “ddC”, for a chemical name that no one used. That’s right, two small “d”s followed by a capital “C.” Careful readers will note that zalcitabine has neither a single “d” nor a capital “C.” Fortunately, few prescribed this lousy drug anyway, which made its suitably horrific brand name (“Hivid”) just a faint stain on the history of HIV drug development.
- Names of different drugs might sound alike, but will have nothing whatsoever to do with each other. Nelfinavir (Viracept) and nevirapine (Viramune) give us an example where both the generic and the brand names sound kind of similar. But they are completely different drugs — different dose, mechanisms of action, side effects. About the only thing they have in common was that they are both HIV treatments. You think people have confused them? You bet.
- Drugs should change their names when they come out in different formulations. Take a look at the various name changes when tenofovir disoproxil fumarate (TDF) spawned tenofovir alafenamide (TAF) — this generated a whole new crop of confusing drug names, as both are extensively coformulated. But the trickiest (and saddest) story is saquinavir, the very first protease inhibitor. First it was Invirase, taken as three 200 mg capsules three times a day. Due to poor bioavailability, Invirase was later changed to the humongous soft-gel capsules called Fortovase, taken as six capsules three times a day. (Yes, that was the dose — it was practically a patient’s whole diet.) Then, with the realization that humans could not subsist on a drug that was six large capsules three times a day, saquinavir went back to being Invirase, but now had a new size (500 mg), and was taken as two tablets twice daily with ritonavir twice daily. Got that? Of course not.
- The order in which drugs are listed in combination pills will be different in different sources. After years of litereally everyone writing TDF/FTC as the abbreviation for the pill that contains tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC), along comes the first PrEP study, which reversed them. Not only that, they used a dash rather than a slash — “FTC-TDF.” Because why? And with three- and four-drug combinations, which drugs goes first? What’s the order? Alphabetical? By mechanism? Your guess is as good as mine.
- If people are getting used to the three-letter abbreviations, go ahead and abbreviate the drugs in combination tablets with one letter, not three. This is a relatively recent trend, but one that people eager to make HIV drugs harder to learn surely must support. Example: When darunavir is given with ritonavir, it’s often written “DRV/r.” Ritonavir is changed to a lower case “r” (and not abbreviated RTV) to denote that it is not being used as an antiviral, but as a pharmacokinetic booster. Makes sense, sort of, except that nobody shared the code. However, the slash implies that it’s a combination tablet, which it most certainly isn’t. When we write or say “DRV/c,” or Prezcobix, however, this is a combination tablet, with the “c” standing for “cobicistat.” So cobicistat is also abbreviated as one letter, unless you are fans of the cute-sounding “COBI,” which is four letters, and for the record is pronounced like the former Los Angeles basketball star and the famous Japanese beef, but definitely has nothing to do with either one of them. But why stop there and let darunavir have all the fun? Let’s move right on to “ECF-TAF,” which stands for elvitegravir, cobicistat, emtricitabine (FTC, remember?), and tenofovir alafenamide (TAF). Certainly it makes all kinds of sense to use single letters for three of the four drugs in this combination tablet, then three letters for one of them — following a dash. Right? I mean come on, it’s so obvious.
So what’s a poor clinician to do? Some great responses here, I especially liked this one:
I’ve had folks threaten to get an interpreter when we were discussing HIV meds in our hospital formulary meeting.
— Adam C Lake MD (@ACLakeMD) November 3, 2019
My solution (ha) to this mess will come in Part 2 of this topic. In the meantime, I welcome your input about how we should go about teaching (or learning) this material.
And it’s obviously time to reprise this classic. Take it away, Trip!