PrEP stands for Pre-Exposure Prophylaxis, and refers to the medications used for preventing HIV infection. HIV PrEP medication comes in the form of pills, which can be taken daily or per need, or injections, which can be taken once every two months.
While HIV PrEP pills are the same ones used for HIV treatment, taking them in a different dosage and interval allows for almost total protection from HIV infection, making PrEP a vital asset in combating the HIV epidemic.
In this article, we take a look at the different types and features of PrEP HIV medication, and discuss their effectiveness, target populations, and potential side effects. Let’s start off with who this medication is meant for.
PrEP HIV medication can be taken by any adult who considers themselves to be at an elevated risk of HIV infection. It is especially recommended for:
First off, PrEP is only effective as protection in those who are HIV negative. Anyone wanting to take PrEP for HIV prevention must get their negative status definitively confirmed before starting a PrEP regimen.
When used exactly as prescribed, PrEP has been found to reduce the risk of HIV transmission through sexual intercourse by 99%, and through sharing needles by 74-84%.
According to a recent Global PrEP Tracker report, out of 930,000+ individuals worldwide whose adherence to PrEP treatment has been confirmed, only a handful have contracted HIV.
So, can PrEP prevent HIV? Yes, it can, if properly taken.
Aside from sticking to the dosage and regimen, ideally, HIV PrEP pills need to be taken for a corresponding interval depending on mode of transmission:
No research data is available for HIV PrEP pill effectiveness timeframes for insertive anal/vaginal sex, nor for PrEP shots.
The most battle-tested HIV-combatting pharmaceutical combination currently available is that of emtricitabine and tenofovir. These two medications come bundled together in a single PrEP HIV pill.
Two FDA approved variants of this pill are available, with a slight variation in the chemical structure of the medications and slightly different harm profiles: Truvada and Descovy.
Additionally, an effective pill with a different composition, Cimduo, is recommended as PrEP by the WHO but has not yet been approved by the FDA, and the first-ever non-daily PrEP option, the injectable suspension Apretude, just recently joined the list of FDA-approved PrEP medications.
No research is available on the safety and effecacy of these HIV PrEP drugs in children under 12 years of age or 17 kgs (37 lbs) of weight.
Truvada was first approved by the FDA in 2012. Its effects and side effects have been studied at great length, and, reportedly, for healthy individuals, it’s safe to consume daily for at least up to 10 years.
Truvada contains tenofovir disoproxil and emtricitabine, and is taken once daily as long as there is a risk of contracting HIV. It is recommended for people at risk of HIV infection through sex or injection drug use, making it the most versatile form of PrEP for HIV prevention.
An alternative regimen, for those who are only under occasional elevated risk of infection through sex, is the ‘on-demand’ 2+1+1 Truvada regimen (two pills taken 2h to, ideally, 24h before sex and then one pill daily for the next 2 days). This course of medication intake has been backed up by trial studies as sufficiently effective against HIV in men who have sex with men (MSM). However, this on-demand HIV PrEP pill regimen is not approved by major health organizations.
Although it rarely happens, Truvada use has been implicated in mild to moderate declines in kidney function, mostly in people over 50, those with conditions which make them more susceptible to this kind of damage (such as diabetes), or those with glomerular filtration rates less than 90. Typically, these declines have been reported to stabilize after several weeks on the drug, and reverse once the regimen was stopped.
Osteopenia, or bone loss, has also been recorded as a side effect of Truvada. However, it is deemed modest as it does not reportedly lead to osteoporosis, so it is not viewed as a serious enough concern for treatment termination.
Descovy was approved for use by the FDA in 2019, so the shorter timespan of its availability means that less longitudinal research of its effects and side effects is available.
Descovy contains tenofovir alafenamide and emtricitabine, and, as PrEP, it’s taken in the same way as Truvada — once daily as long as there is a risk of contracting HIV. It is recommended for those at risk of HIV infection only through sex, and is not recommended for people assigned female at birth who are at risk for HIV through receptive vaginal sex.
It is also not advised to use Descovy as on-demand PrEP.
Although not much research is available, a phase 3 comparison trial conducted in 2019 indicated that Descovy may have a safer effect profile in terms of renal and bone damage than Truvada. For this reason, many healthcare providers have been switching their HIV-positive patients from Truvada to Descovy since its approval.
However, similarly to Truvada, Descovy may cause slight increases in LDL cholesterol and triglycerides.
Cimduo was approved for use for HIV treatment by the FDA in 2018. It contains tenofovir disoproxil and lamivudine, and is also meant to be taken once daily as long as there is a risk of contracting HIV. Like Descovy, it is not advised to use Cimduo as on-demand PrEP.
While this medication is recommended by the WHO for use as PrEP, it is not approved by the FDA for this purpose — no comparison studies have been conducted as Descovy is already considered a better performing version of Truvada, which, in and of itself, works well enough as PrEP.
The advantage of Cimduo is that its cost is significantly lower than the other two HIV PrEP pills, making it a more viable alternative for many who are at risk, want to take PrEP without insurance, and cannot afford Truvada or Descovy.
The most recent addition to the PrEP drug lineup is Apretude. This extended-release injectable suspension of cabotegravir was approved for use by the FDA in December 2021, and it’s widely hailed as a revolution in the world of PrEP HIV medication.
With adherence to daily regimens being the single major cause of breakthrough infections in those taking PrEP HIV pills, Apretude, which only needs to be taken once every two months, is expected to be the next step in stopping the HIV epidemic. Apretude is recommended for those at risk of HIV infection only through sex.
While PrEP has been confirmed to be mostly safe for healthy individuals, a “start-up syndrome” characterized by nausea, headache, and/or stomach issues is common in those who start taking any of the HIV PrEP drugs. Typically, these symptoms resolve themselves within a few weeks; however, if they persist and start adversely impacting livelihood, a physician must be consulted.
Other common side effects of PrEP HIV medication include:
Although much rarer, more serious side effects have also been reported. These include:
The medication Truvada, which is used both as PrEP for HIV prevention and as part of an HIV treatment regimen, is also used as post-exposure prophylaxis or PEP.
In essence, the difference between PrEP and PEP is the difference between prevention and treatment. The former is given before HIV is contracted, and the latter is given after suspected infection.
Naturally, the dosage for prevention is more moderate — a single PrEP HIV pill per day — while the dosage for stopping HIV from gaining foothold in the body once it’s already entered it will be more aggressive — three to five PEP pills per day.
Previously, Truvada alone was prescribed PEP, but WHO currently recommends that it be taken with Isentress or Tivicay (additional medications to ensure that PEP is more effective).
Like PrEP, PEP can be prescribed only when the person tests negative for HIV (both antigens and antibodies). In order to be effective, a PEP regimen must be started within the first 72h after suspected exposure. PEP treatment typically lasts for four weeks, and the common side effects include malaise, fatigue, diarrhea, headache, nausea, and vomiting.
Those who are at high risk of re-exposure to HIV due to unprotected intercourse or other behavioral variables should be started on a PrEP regimen promptly after the PEP treatment is completed. In contrast, PEP therapy is not required for those who are adherent to a PrEP regimen.
The main pharmaceuticals in PrEP HIV medication, as well as in HIV treatment, are emtricitabine and tenofovir. Taken in a specific regimen, this combination stops HIV from developing in the body.
However, if those who are already infected with HIV (typically those in an undiagnosed acute stage) take this combination in the dosage and intervals meant for PrEP, they can develop a resistance to either emtricitabine or tenofovir (or, potentially, both) drugs, meaning that the drugs’ ability to treat the infection decreases due to inadequate dosing.
If this happens, HIV therapy drug alternatives can become more limited for the carrier as the virus mutates and becomes less susceptible to treatment.
This is why anyone who wishes to take PrEP HIV medication needs to be tested for HIV before a regimen is prescribed, why anyone on PrEP is advised to be screened regularly (quarterly), and why HIV positive individuals must be prescribed a different therapy for managing their infection.
There is also an ongoing concern that PrEP regimens themselves may lead to HIV drug resistance. However, as a recent review of studies concluded, “the benefit of a decreased HIV incidence with wider PrEP use is likely to outweigh the risk of harms from possible increases in the prevalence of HIV drug resistance.”
But, there is another inadvertent consequence of taking these medications — in breakthrough infections (infections despite adherence to the PrEP prescription), the HIV viral load is reportedly significantly lower than in those who hadn’t taken PrEP. This ‘blunted’ infection is also characterized by a reduced number of antibodies, meaning that it becomes much more difficult to detect. Luckily, breakthrough infections appear to be incredibly rare at this time.
While PrEP is undoubtedly a revolutionary product of modern-day medicine, it’s still not widespread enough to single handedly stop the HIV epidemic.
The prospect of taking a (costly) daily pill, adhering to the regimen as strictly as possible, and enduring the potential adverse effects is, understandably, not appealing to enough people, and the biweekly injection alternative is a very recent emergence, one yet to become an established measure. Finally, education on the existence of PrEP as a viable protection measure against HIV is mostly only revealed to those who make the effort to seek it out.
As such, regular preventative HIV testing still remains the most important weapon for curbing the spread of HIV. Anyone who is at an elevated risk of infection — the same group of people to whom PrEP is recommended — is strongly advised to carry out quarterly or biannual HIV testing, depending on the level of risk involved.
Fortunately, effective PrEP HIV medication is not the only product of recent medical advancements — nowadays, inexpensive and highly reliable rapid HIV self-testing kits have become available for purchase online. These at-home tests take away the stigma that HIV testing sadly still carries and allow anyone to learn their status at any time from the comfort and privacy of their home.
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