Protease inhibitors are in the category of antiretroviral drugs and are currently in use to treat HIV/AIDS and hepatitis C virus (HCV) patients. By blocking protease, protease inhibitors prevent viral replication to stop new HIV or HCV from becoming mature enough to infect other cells. In other words, protease inhibitors reduce the level of the virus and the rate of growth.

First, a protease (or proteolytic enzyme) is an enzyme that is the catalyst for proteolysis. Next proteolysis is the breakdown of proteins for better digestion by the body. Interestingly, this happens during a process called hydrolysis which happens when the peptides inside the protein cleave with water to break the bonds.  

How Do the HIV & HCV Viruses Grow?

When either HIV or HCV is present in the body it grows by inserting itself into the CD4 immune system cells. Furthermore,  the purpose of CD4 cells is to fight off viruses and provide immunity for the body.

However, when the virus gets inside them, the cells lose their ability to provide immunity. At that point, the virus uses the cells to make new proteins which then targets other cells. Then, over time this makes the body more prone to infections and diseases.

What Do Protease Inhibitors Do?

In short, protease inhibitors block the action of protease which results in viruses that no longer infect other cells in the body.

Although protease inhibitors do not cure HIV, they are very effective when taken with other antiretroviral drugs. Through this process, the protease inhibitors decrease HIV to undetectable levels which makes it unable to transmit through sexual contact. Furthermore, this gives a person with HIV who adheres to a prescribed treatment plan the ability to live a healthy life and not transmit it to others.

What’s more, when used in a medication regimen for hepatitis C virus protease inhibitors actually play their part in curing hepatitis C! That’s what the amazing protease inhibitors do.

What Are Antiretroviral Drugs?

Antiretrovirals are a group of drugs specifically developed for HIV patients. Additionally, this drug group includes protease or proteolytic enzymes but also includes many others.

Interestingly, antiretrovirals don’t kill the virus. Rather, they block specific stages of the virus life cycle thereby rendering it unable to reproduce itself.

When doing your research, keep in mind that each type of drug affects distinct stages of the virus infection. Also, remember that replication which is the reason for the combinations.

To be more effective, doctors prescribe protease inhibitors in combination with other antiretroviral drugs. However, the selection of those drugs is dependent on many factors of the patient’s diagnosis including the following:

Tip o’ the Hat to VeryWellHealth.

HIV Protease Inhibitors

In today’s world of HIV medications, you will hear reference to cART which stands for combination antiretroviral therapy. That refers to the fact that most medical professionals prescribe three or more drugs for the treatment of HIV from at least two major classes.

There are currently five classes of antiretroviral drugs as follows:

The fact is the antiretroviral drugs of today are normally prescribed in combinations to treat HIV. Moreover, this is done because each drug has its own unique way of working at different stages of virus growth. Interestingly, using combinations also helps decrease the buildup of resistance to the medications. This is also an advantage for long-term therapy.

Next, these are the terms in use today for this type of combination medication therapy:

The drug combos consist of three or more active drugs from at least two different drug classes. Moreover, the reasons for using combinations of drugs are many. But primarily, they make a more effective treatment regimen. Also, as we stated before, using combinations reduces the patient’s ability to build up resistance to the medications.

For modern HIV medication therapy, there are six categories. Within those categories are more than two dozen antiretroviral drugs. Those categories and drugs include protease inhibitors and are as follows:

Nucleotide & Nucleoside Reverse Transcriptase Inhibitors (NRTIs)

Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs)

Protease Inhibitors (PIs)

Integrase Inhibitors

Fusion Inhibitors

CCR5 Antagonist

Post-Attachment Inhibitor or Monoclonal Antibody

Pharmacologic Enhancers Combinations (Drug Boosters)

Ritonavir taken in low doses increases blood levels of lopinavir and Kaletra. Additionally, cobicistat increases blood levels of lopinavir and Kaletra in combination with atazanavir, elvitegravir, and darunavir. Please note that drug boosters enhance the levels of other drugs. So, be sure to give your doctor a complete list of all medications you currently take.

Fixed-Dose Combinations

For convenience, some pills are manufactured with specific combinations. Those include the following:

Protease Inhibitor (PI) Based

Non-nucleoside Reverse Transcriptase Inhibitor (NNRTI) Based

Nucleoside/nucleotide Reverse Transcriptase Inhibitor (NRTI) Based

Tip o’ the Hat to WebMD.

Historical Treatment of HCV

In the past, HCV was treated with a two-drug combination that included pegylated interferon (PEG-INF) and ribavirin (RBV). Typically, this therapy took place over a six to twelve-month time. Unfortunately, it only worked for less than half the patients with genotype 1 (the most common type.) It also had some very unpleasant side effects.

The DAAs Class of Drugs

After a time, that therapy was followed by the introduction of a new class of drugs called direct-acting antivirals (DAAs). Protease inhibitors fall into the DAAs class of drugs.

In late 2014, two interferon-free therapies were introduced in the United States for the treatment of HCV genotype 1 patients. Those were manufactured under the brand names of Harvoni and Viekira Pak.

First, Harvoni was a combo of two drugs in one pill taken once a day for 12 to 24 weeks. Then, the Viekira Pak was a combo of three medications and consisted of four to six pills per day for 12 weeks.

The results are that 90 percent of all HCV patients with genotype 1 are virus-free who take the medication. So, in this instance, protease inhibitors in combination with other antiretroviral drugs are a cure.

Since then, other drugs have been under development as well. For instance, antivirals have replaced the first inhibitors, boceprevir, and telaprevir. Interestingly, this gives the treatment even greater effectiveness in addition to improvements to safety profiles.

Hepatitis C Virus Protease Inhibitors Drug List

Presently, there are three classes of approved DAAs. They are:

HCV Drug Combinations Currently Available

Protease Inhibitors Side Effects

One of the downsides of the use of antiretroviral medications is that they sometimes cause immune reconstitution inflammatory syndrome (IRIS). Unfortunately, this happens when protease inhibitors cause a flareup of an old infection. It can also happen if the patient didn’t know about the infection. In either instance, it indicates an improvement to the immune system.

However, you must note that protease inhibitors often interact with other drugs. This means that you must be thorough in listing every medication you’re currently taking and report it to your doctor.

Furthermore, be sure that in addition to prescription drugs, you also list all the herbs, over-the-counter medications, and supplements that you are taking. Remember, this ensures that your doctor can prescribe correctly. In addition, your doctor will advise you of issues to expect with possible drug interactions.

Statin Interactions with Protease Inhibitors

Protease inhibitors are known to interact with drugs used to lower cholesterol. Unfortunately, this causes an unhealthy increase of statin in the body. Moreover, these symptoms include kidney damage and muscle pain.

In fact, simvastatin and lovastatin must never be taken with protease inhibitors. This is because it often results in life-threatening side effects.

Other Drug Interactions with Protease Inhibitors

Again, always prepare a thorough list for your medical professional of all other drugs you take along with supplements, over-the-counter medications, and herbs.

Here is a quick list of the types of medications that are known to interact with protease inhibitors.

Over-the-Counter (OTC) Interactions with Protease Inhibitors

Stomach acid OTC drugs that interact with protease inhibitors are listed below for your convenience and information. Please note that medical professionals will tell you if you are able to take these OCT drugs.

Listed by brand name, then, followed by drug name, these OTC drugs include:

Other OTCs to avoid include the allergy medication, Flonase or fluticasone. Also, avoid taking St. John’s wort which is an herbal supplement for depression.

Side Effects of HIV Protease Inhibitors

The following list shows side effects that may occur when taking protease inhibitors for HIV.

Severe Side Effects

Side effects are sometimes severe. When this happens, call for emergency care immediately. Although these symptoms are rare, it is always best to be prepared.

Side Effects of Hepatitis C Virus Protease Inhibitors

The following list are side effects that may occur when taking protease inhibitors for hepatitis C virus (HCV.)

Severe Side Effects

Side effects are sometimes severe. When this happens, call for emergency care immediately. Although these symptoms are rare, it is always best to be prepared.

Tip o’ the Hat to Medicinenet.

Conclusion

This is a lot of medical information with a broad spectrum of details about protein inhibitors. That’s why it’s imperative that you consult with your doctor for the perfect combination of medication therapy to achieve the best health possible for you.

These statements have not been evaluated by the Food and Drug Administration. Products discussed are not intended to diagnose, treat, cure, or prevent any disease.