Post-Exposure Prophylaxis

Basic Information

Post-exposure prophylaxis (or PEP) refers to HIV-negative persons taking antiretroviral medications in order to prevent disease transmission after contact with a person who is HIV-positive. It is basically a method of disease prevention. In order to necessitate a person taking antiretroviral medication, the contact has to be serious enough. Basic touch between a person with HIV and a person without HIV is not considered cause for PEP. There needs to be an exchange of HIV-containing bodily fluids, such as blood or saliva. Conditions that require PEP often involve exposure to HIV through either sex or drug use. In some instances, a person may be stuck with a needle that is infected with HIV in a non-drug use situation. This latter situation is an occupational concern for all healthcare workers. Since the 1990s, PEP has been a common procedure for healthcare workers who have been exposed to HIV. PEP is also used to prevent mother-to-infant HIV transmission. The risk that a mother will pass the infection to her child is around 25 percent. Studies have shown that PEP is very effective in preventing disease transmission from infected mothers to their infants.

Studies have shown that PEP greatly reduces the chance of disease transmission after exposure to infected body fluids. In one study, over 80 percent of healthcare workers exposed to HIV through accidental needle jabs did not become infected.

Although PEP is effective as a means of disease prevention, it has been a controversial topic since its first use in the 1990s. There are several issues involved in the debate regarding PEP. One concern is that some of the antiretroviral medications used for PEP have extremely harmful (and potentially fatal) side effects. Many people are not able to complete a full cycle of treatment due to the severity of these side effects.

Another concern is that the availability of PEP to people exposed to HIV during non-occupational circumstances might encourage practices such as unsafe sex and drug abuse. In this case, the difference between the two types of exposure is whereas occupational exposure is typically a nonrecurring accident, people who practice unsafe behavior continually put themselves at risk of infection. This issue has been a subject of great debate since the introduction of PEP. At first, PEP was only available for situations at the workplace. Recently, certain cities have been including PEP for non-workplace exposure in their HIV-prevention programs. Critics of these programs argue that there is no reason to believe that PEP will prevent disease transmission unless the treatment immediately follows exposure. They claim such immediate action is typically only possible at the workplace. Currently, no research has been done into how soon after contact a person needs to begin PEP in order to prevent transmission. Another argument against city-run PEP programs is the great cost of such treatment. A single PEP treatment can cost as much as a thousand dollars. Some critics of non-occupational PEP fear that certain people, thinking that PEP is a cheap and easy method of avoiding HIV infection, will continue unsafe activities and ultimately take unfair advantage of municipal healthcare budgets. Many gay community leaders counter that HIV transmission is not always the result of unprotected sex. Oftentimes, people are exposed to the infection when a condom breaks during safe sex.

Regardless, PEP has been proven to be effective as a means of reducing the risk of infection after sexual exposure. In one study over 400 people who underwent PEP following sexual exposure to HIV did not become infected.

Even at the workplace where healthcare is provided, it is crucial to not rely on PEP for disease prevention. Primary preventative measures can be taken to eliminate the risk of exposure. These measures include protective gear, self-sheathing needles, devices with rounded edges, and workplace safety training. At the same time, cities that offer PEP in their healthcare programs can both educate about the costs of PEP and continue to encourage safe practices such as protected sex and non-needle sharing drug use (or, for that matter, the complete avoidance of drug use).

Description

When a person is exposed to HIV, they should immediately begin taking antiviral medication. Doctors suggest that a potentially infected person must contact medical experts within 24 and 48 hours after exposure. Research has led experts to believe that exposure to HIV does not result in an instantaneous systematic infection. When the virus enters the body, it attaches itself to the lymph cells before penetrating the nucleus of the cell. If the medications can reach the virus during the period of time before the virus works its way into the cell, then viral reproduction will be cancelled, and the PEP treatment will prove a success.

There are several different types of antiretroviral medications. These drugs are not available over-the-counter. The kind that the person takes depends on the severity of the exposure. Severe exposures typically involve a large quantity of blood, contact between open sores or cuts, the sharing of a needle on which blood is visible, and unprotected sexual intercourse.

PEP is not contained in a single pill. Rather, it requires taking a drug (or a combination of drugs) a few times a day for up to a month. It is crucial that a person takes every dose. If a person misses a dosage, they greatly increase the risk of HIV infection. A missed dose allows the virus an opportunity to build up an immunity to the medication, which weakens the medication's effect.

The two approved classes of drugs used to prevent HIV infection include nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitors. ZDV is a NRTI that is commonly used to treat HIV infection after severe exposure. For less serious contact situations, AZT or 3TC are recommended. The potentially infected person typically takes the drugs for a month.

In some serious cases, because these two classes of drugs are effective at different times during the cycle of viral replication, an NRTI and a protease inhibitor are used together. In other instances, multiple NRTIs will be used at the same time. This kind of combination treatment is called a "cocktail". Cocktails are necessary when the person is known to be resistant to certain drugs that are normally used during PEP. The disadvantage of an antiviral cocktail is the toxic effect these potent drugs can have on the body.

Side Effects and Considerations

In one study the side effects of antiviral medications were so negative that over 40 percent of healthcare workers exposed to HIV could not complete PEP. At one point, a person has to weigh the slight possibility of infection through workplace exposure against the heavy toxicity that comes with the use of antiretroviral medication. For this reason, a doctor must evaluate the severity of the exposure and then determine a dosage that is not any stronger than what is required to eliminate infection. This is important because a person needs to be able to tolerate the drugs for the entire four weeks in order for the treatment to be effective.

All antiretroviral medications have negative side effects. The most common side effects include:

• Nausea
• Diarrhea
• Vomiting
• Fatigue
• Headaches
• Kidney stones
• Hepatitis
• Suppressed blood cell production

Oftentimes, these side effects become worse when a person is prescribed more than one drug at a time.

Because the use of antiretroviral medications can have such adverse side effects, counseling needs to be given to a person about to receive PEP. Doctors should thoroughly inform persons exposed HIV about the risk of infection and the potential side effects. If there is not much of an infection risk, doctors will often advise patients to avoid PEP.

As aforementioned, if a person proves to be resistant to a certain drug, then doctors may seek other combinations of drugs. In severe circumstances, a drug that is usually considered too strong may be included in the treatment.

The Use of Nevirapine

Certain drugs that have been used for PEP have not been approved by the Center for Disease Control (CDC). One of these drugs is nevirapine. Nevirapine is an extremely strong antiretroviral drug that can result in permanent liver damage or even death. This drug can also cause bad skin reactions. While it is not recommended for an extended PEP regimen, some doctors still use it to prevent mother-to-child HIV transmission. A child can become infected with HIV either during pregnancy or through nursing. Because only a single dose is needed to prevent mother-to-child transmission (and not a month-long regimen), many doctors feel comfortable prescribing nevirapine. Rarely, a doctor might prescribe nevirapine for PEP if the potentially infected person has a built-up resistance to other "softer" antiretroviral medications. In such cases, the doctor must inform the patient about the possible side effects, and the patient must be closely monitored during the treatment.

Follow-Up

Following PEP, a person should regularly test for HIV. Most doctors suggest that testing should be done at least for half a year after the PEP treatment is completed. If a potentially infected person notices any symptoms during this time, they should immediately notify a doctor. Sometimes a person is advised to seek counseling to deal with the emotional stress that accompanies an HIV scare. Until it is certain that they are HIV-negative, a potentially infected person should practice safe sex and avoid donating blood or plasma.

Outcome

Most occupational exposures to HIV do not result in HIV infection. In fact, there is less than a one percent chance that a person will become infected with HIV through percutaneous exposure. Percutaneous exposure refers to any intrusion of the skin caused by a sharp object or a needle jab. Because of the low risk, oftentimes the toxicity caused by preventative drugs offsets the need to undergo PEP. At the same time, PEP is not 100% effective. In situations where healthcare workers are exposed to HIV and then are treated through PEP, approximately 20% still become infected.

Always Your Choice Updated August 2001