Matthew Spinelli, MD, is an associate professor in the Division of HIV, Infectious Diseases, and Global Medicine at the University of California, San Francisco.
Cabotegravir (Vocabria) is part of a short-term treatment plan for HIV, the virus that can cause AIDS. Vocabria is a daily pill that's approved for some people ages 12 and older who have a very low amount of the virus in their blood. It's taken along with another daily tablet called rilpivirine (Edurant) to help prevent the virus from multiplying.
You can take Vocabria with Edurant for a month to find out if you'd likely respond well to a long-acting treatment, Cabenuva, that pairs injectable forms of cabotegravir and rilpivirine. Or, if you're already taking Cabenuva and you know you will miss a planned injection, you can take Vocabria with Edurant as a replacement for the shot (for up to two months, or two missed monthly injections).
We spoke with HIV and infectious-diseases doctor Matthew Spinelli about who might benefit from taking Vocabria, why it needs to be taken along with Edurant, and how pills compare with injections.
This interview has been edited for length and clarity.
Q: What's the goal of taking a short-term, daily HIV treatment like Vocabria with Edurant before switching to a long-term treatment like the Cabenuva injection?
Spinelli: It's sort of a tolerability check. Assuming that a patient doesn't have a side effect from the oral tablets, then they progress to the injection. Most people don't elect to take the tablets though. Most people go directly to injection; there are very few side effects. So patients may think, 'I want to be on long-acting, so why are you making me jump through a hoop first?' I cannot remember the last time someone has requested the oral tablets. Everyone in our clinic goes directly to the injection.
Q: Why do some people try the daily pills as a tolerability check?
Spinelli: That was the original paradigm. Cabenuva is a long-acting medication, so once you inject it, it's there for a while. So if you were to have some unpleasant side effect, particularly an allergic reaction, it's a pain if it's going to be on board for the next month or two. But thankfully, that doesn't happen very frequently.
The main side effects people get from Cabenuva are injection site reactions. And you're not going to see those with a pill, right? That's a consequence of the drug being injected into your muscle. So if the main side effect is one that you can't assess anyway, what's the point?
Editor's note: Some possible side effects of Vocabria are tiredness, headache, diarrhea, nausea, dizziness, unusual dreams, anxiety, insomnia, discomfort or distension in your belly area, and less physical strength. Ask your doctor about Edurant's possible side effects, too.
Q: Why does Vocabria need to be taken with Edurant?
Spinelli: All HIV regimens are at least two medications, and they have to work through different mechanisms; they have to attack the virus in a different way. Otherwise, resistance forms. So cabotegravir, the drug that's Vocabria in tablet form, is called an integrase inhibitor. And that's really the stalwart of most HIV regimens these days. That mechanism is it prevents the virus from integrating into your DNA.
The second medication, rilpivirine, called Edurant in that pill form, is also used in other HIV regimens as well. It is called a non-nucleoside reverse transcriptase inhibitor. That's a group of medications that block HIV's really central enzyme: the reverse transcriptase enzyme. They stop that enzyme from working — and HIV needs that enzyme to convert its RNA genetic material into DNA, so that that DNA can be integrated into your cells.
So, there are various mechanisms for how HIV drugs work, but it's always two different mechanisms together. Traditionally it was three, but we're in the era of two: two medications with at least two mechanisms.
Q: What are some advantages of taking long-acting injections rather than daily pills for HIV treatment?
Spinelli: I really like these injections for people who struggle with taking a pill every day. I treat all kinds of patients: people who are couch-surfing, who are homeless, who use drugs (things like opioids and methamphetamine). So I see a very underserved patient population where we're doing this for a reason: People really can't take their oral meds. Someone who's a little bit more cautious may like the idea of trying oral tablets first. But I would say that my patients don't see the value as much.
Also, the people who really are motivated by the injectables — other than those who have trouble remembering to take pills — are people who have lived with HIV stigma their entire lives. And not seeing that pill bottle every day really has a huge impact on their life and on their mood and their sense of well-being. That's a relatively large proportion of people.
Q: Do HIV treatments that contain cabotegravir, like Vocabria, interact with (affect) any other medicines or health conditions?
Spinelli: There are a few drug interactions. They're not numerous, but they do exist. One group that it is less ideal for are people with hepatitis B infection (which shares the main risk factors for HIV). That's because cabotegravir does not treat hepatitis B. Any HIV regimen that contains the medication tenofovir treats hepatitis B.
Editor's note: You can't take Vocabria if you take the anticonvulsants carbamazepine, oxcarbazepine, phenobarbital, or phenytoin, or the antibiotics rifampin or rifapentine. Vocabria can cause liver problems such as elevated levels of liver enzymes called transaminases. Ask your doctor about Edurant's interactions, too — you can't take it with drugs like proton pump inhibitors.
Q: Do most major insurance plans tend to cover HIV treatments?
Spinelli: Generally, the access is pretty good for HIV treatments. There are programs, including the AIDS Drug Assistance Program (ADAP), which helps people get coverage for their meds.
