What Are the Potential Benefits of a Single-Tablet Regimen for HIV?

HIV treatment can be complicated. Effective treatment requires a combination of antiretroviral therapies. This is known as either cART (combined antiretroviral therapy), or HAART (highly active antiretroviral therapy). Combination HIV therapy generally uses drugs from at least two different treatment classes. This helps to keep the virus from developing resistance to therapy.

Drug classes used in HIV treatment include:

• protease inhibitors (PIs) - which block an enzyme needed to assemble HIV virions
• nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) - which keep HIV from transcribing its RNA into DNA so that it can be copied by cells
• non-nucleoside reverse transcriptase inhibitors (NNRTIs)- which serve a similar function as NRTIs, but bind in a different place
• integrase inhibitors - which keep HIV from integrating its genome into cells
• entry inhibitors - which prevent HIV from getting into cells. One subset of entry inhibitors are ccR5 co-receptor antagonists. These block a protein that HIV binds to when entering cells

Each drug class has potential advantages and disadvantages. For example, some doctors prefer to use nuc-sparing treatment regimens to avoid side effects, such as premature aging, that are associated with NRTIs. However, HIV specialists know that no single regimen is right for every patient with HIV. When prescribing treatment, they have to take into consideration a number of factors. This includes side effects, viral resistance, and how likely patients are to take all of their pills on time and as directed.

It can be hard to manage the timing of certain cART regimens. For many regimens, pills have to be taken at different times of the day. Some have to be taken with, and some without, food. There's therefore been growing interest in single-tablet regimens for HIV treatment. These regimens contain drugs from multiple classes in a single pill. It's basically a once a day med for HIV, although some might need to be taken twice a day. Currently, several single-tablet regimens have been approved by the FDA:

• Atripla - which contains tenofovir, emtricitabine, and efavirenz (Approved 7/2006)
• Complera - which contains tenofovir, emtricitabine, and rilpivirine (Approved 8/2011)
• Stribild ("Quad") - which contains tenofovir, emtricitabine, elvitegravir, and cobicistat (Approved 8/2012)
• Genvoya - which contains elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide) (Approved 11/5/15) 

Single-pill regimens are also known as fixed-dose combinations. However, not all fixed-dose combinations are single-pill regimens. Some need to be used in combination with other drugs. 

There are a number of potential benefits to single-tablet regimens for HIV treatment. The single biggest advantage, for both patients and providers, is how easy these regimens are to take. One pill, once a day, is far easier for most patients to keep track of than multiple pills. That's true even if they can all be taken at the same time. This means that HIV-positive patients are more likely to take their pills consistently. Correspondingly, those drugs are going to be much more effective.

Another related advantage is that patients are more likely to take their prescriptions correctly with a single-pill regimen. Patients taking multiple pills may not worry as much if they run out of one of their prescriptions, or if they can't afford to refill another. They may think they're "covered" as long as they're still taking something. However, cART regimens are prescribed as combinations for a reason. Taking these regimens incorrectly increases the risk of treatment failures and viral resistance.

In contrast, the biggest disadvantage of single-pill regimens is the limited number of options. There are currently only a couple of drugs available on the market, and each is based on the combination of tenofovir and emtricitabine that is often sold as Truvada. So patients who have difficulty tolerating either of these drugs won't be able to switch to single-tablet treatment. There's also no way for doctors to adjust the doses of individual drugs within the regimen. These pills are known as fixed-dose combinations for a reason. While they may work well for many patients, some doctors may find the lack of flexibility limiting. This may be particularly true for doctors trying to manage toxicity and other side effects.

If you are HIV positive and have trouble complying with your current treatment regimen, then yes. You should definitely consider talking to your doctor about whether a once-a-day, fixed-dose pill might be a good option for you. Anything that makes it easier for you to take your medication is likely to improve its effectiveness.

However, these drugs are not appropriate for everyone. They can cause side effects that may be problematic for certain patients. They're also expensive: currently, only brand-name options are available, and generic versions won't be hitting the market for several years. In addition, people who have a history of heavy treatment, or who are treatment-resistant, are unlikely to be eligible for single-pill regimens.

For people who are currently happy with their HIV treatment, hang tight. These drugs aren't enough of an improvement over other regimens that you should feel the need to jump ship. If your current regimen is working well, has low toxicity, and you're comfortable taking it, that's great. It's never a bad idea to talk to your doctor about whether you're staying on your treatment because of inertia or because it's the best option. However, having a discussion doesn't mean you have to switch.