New Ways to Prevent and Treat AIDS
Preventing and treating AIDS is one of the Food and Drug Administration's top priorities. A new class of drugs, a home blood test collection kit, an oral diagnostic test, an HIV antigen test, an HIV-1 antigen test for blood supply, and an HIV viral load test are among the most recent in a long line of products FDA has approved to prevent, diagnose and treat infection with HIV, the virus that causes AIDS.
The 1992 National Health Interview Survey by the Centers for Disease Control and Prevention found that only 20 percent of people at increased risk for HIV infection -- such as intravenous drug users, male homosexuals, and prostitutes -- agreed to be tested for HIV. More than twice that many people in the same risk group said they might use a home testing and counseling service if one were available. At the time, however, testing could only be done by a professional.
The situation changed when, on May 14, 1996, FDA approved Confide, the first HIV test system with a home-use blood collection kit. A second test kit was approved last July. It is hoped that home testing will make diagnosis easier and more accessible, especially in populations among whom the recent rise in cases of HIV is greatest, such as women, African Americans, and Hispanics. The tests are highly reliable and are designed to protect the user's anonymity.
FDA's approval on June 3, 1996, of Orasure Western blot, a laboratory test that does not require a blood sample, is also expected to increase participation in testing for HIV. Instead of pricking a finger -- a procedure shunned by many individuals -- Orasure uses a treated cotton pad to collect a tissue sample from between the gum and cheek.
The sample is tested for antibodies to HIV by a procedure that has been shown to be highly accurate. An earlier version of Orasure used a less reliable method to screen for HIV antibodies, and people who tested positive had to undergo a standard blood test to confirm the presence of the virus.
In March 1996, FDA approved the Coulter HIV-1 p24 Antigen Assay, the first blood test to detect antigens rather than antibodies. In screening routinely carried out since the mid-1980s, technicians check donated blood for HIV-1 antibodies by using enzyme-linked immunosorbent assay (ELISA) test kits. Since a small number of ELISA test results are nonspecific or falsely positive, the standard procedure uses a second, more specific test -- the Western blot test -- to validate the positive results from ELISA testing.
The Coulter test, which is used in addition to ELISA, screens blood for antigens -- proteins found on the surface of the virus -- that are detectable about one week earlier than HIV antibodies. The new test reduces the so-called "window" period, typically up to three months long, during which standard blood tests show no HIV antibodies, even though the donor may be infected.
The Amplicor HIV-1 Monitor Test, another new blood test approved last year, enables physicians to predict the risk of HIV disease progression by precisely measuring virus levels in blood. The test, which amplifies copies of genetic material from the virus by using polymerase chain reaction technology, is based on clinical studies showing that higher virus levels can be correlated with increased risk that the disease will progress to AIDS, and AIDS-related infection or death.
Other than abstinence, latex-rubber condoms are the best protection against sexual transmission of HIV. Latex condoms should always be used for oral, anal and vaginal sex in any relationship that isn't mutually monogamous, and if there is any other chance that either partner may be infected. Condom manufacturers in the United States electronically test all condoms for holes and weak spots. In addition, FDA requires manufacturers to use a water test to examine samples from each batch of condoms for leakage. If the test detects a defect rate of more than 4 per 1,000, the entire lot is discarded.
The agency also encourages manufacturers to test samples of their products for breakage by using an air burst test in accordance with specifications of the International Standards Organization.
Under an FDA proposal, the labeling on latex condoms should state that "this product contains natural rubber latex." FDA has also requested manufacturers to state on the label that "[if] used properly, latex condoms will help reduce the risk of transmission of HIV infection (AIDS) and many other sexually-transmitted diseases."
Consumers should make sure the condom package is undamaged, and check each condom for damage as it is unrolled to be used. The condom should not be used if it is gummy or brittle, discolored, or has a hole. Condoms also should not be used after their expiration date or, if they don't have an expiration date, more than five years after the date of manufacture. Only water-based lubricants (for instance, glycerine or K-Y jelly) should be used with latex condoms, because oil-based lubricants such as petroleum jelly weaken natural rubber.
For people allergic to latex, FDA has approved several polyurethane condoms, which have been shown in laboratory tests to be comparable to latex condoms as a barrier to sperm and HIV virus. Each package of polyurethane condoms is labeled "For Latex Sensitive Condom Users." Natural membrane (lambskin) condoms, which are useful in preventing pregnancy, are not effective protection against HIV or other sexually transmitted diseases. Although sperm cannot pass through the lambskin material, small microorganisms, including HIV, can penetrate these condoms.
One product available for women -- the polyurethane Reality Female Condom -- provides limited protection against sexually transmitted diseases. FDA requires the labeling of Reality to indicate that "highly effective protection" against STDs is provided if the male partner uses a latex condom for men. Male and female condoms, however, should not be used at the same time because they won't stay in place.
Medical and Dental Equipment
To protect patients and health-care providers against exposure to potentially contaminated blood and other body liquids, FDA established quality standards for latex and synthetic rubber gloves used during surgery and patient examination. U.S. manufacturers of these products are requested to test samples from each lot to make sure they show no sign of leakage when filled for two minutes with 1,000 milliliters of water, and that they meet the standards of the American Society for Testing and Materials for stress resistance, tensile strength, materials, and dimensions. FDA also tests samples of domestic and imported surgical and patient examination gloves, using the same criteria.
FDA has joined CDC and the American Dental Association in urging dentists to autoclave -- sterilize by steam under pressure -- dental hand pieces and accessories between patients to remove possible contaminants. In addition, FDA requires that all such equipment must be designed to withstand autoclaving, and the labeling must include instructions for the sterilization process.
While most dentists are believed to comply with the recommendations for autoclaving, it's a good idea to ask what preventive measures the dentist follows before making an appointment.
Each year, about 3.6 million Americans receive transfusions of blood products. FDA inspects the more than 3,000 donor centers where blood and blood components are collected and processed, and continuously updates requirements and standards designed to prevent disease transmission through transfusion.
Blood collection centers and manufacturers and distributors of blood products are responsible for maintaining five layers of overlapping safeguards.
First, potential donors must answer questions about their health and risk factors. Those whose blood may pose a health hazard are encouraged to exclude themselves. A trained and competent health professional then interviews potential donors about their medical histories.
Donors can be temporarily excluded from donating blood for such reasons as having a temperature, cold, cough, or sore throat on the day of the donation. Potential donors are permanently excluded from donating blood for reasons including evidence of HIV infection, male homosexual activity since 1977, and a history of intravenous drug abuse or viral hepatitis.
Second, blood establishments must keep current a list of deferred donors and check donor names against that list.
Third, after donation, the blood is tested for such blood-borne agents as HIV, hepatitis and syphilis.
The fourth layer of protection prevents general use of any blood products that have not been thoroughly tested.
The fifth layer of protection is FDA's requirement that blood establishments must investigate any breaches of safeguards and correct deficiencies. An error or accident can result from improper testing, incorrectly labeled components, improper interpretation of test results, improper use of equipment or failure to follow the manufacturers' directions for its use, or accepting units from donors who should have been deferred.
The system has helped reduce the risk of transfused HIV infection from 1 in 2,500 units of blood in 1985 to 1 in 440,000 to 640,000 units by the end of 1995. Since then, the Coulter test has shortened the typical window period when the HIV virus cannot be detected to less than three months. Health experts expect the use of this test to reduce the risk of transfused HIV infection even further.
Human Tissue Transplants
In December 1993, FDA issued an interim requirement that potential donors of all human tissues for transplantation -- including tendons, bone, skin, and corneas -- be tested for HIV-1, HIV-2, and hepatitis B and C viruses, and screened for symptoms of AIDS, hepatitis, and high-risk behaviors such as sex between males and intravenous drug abuse. Imported tissues must be accompanied by records showing that the tissues were similarly screened and tested. If such records are not available, the tissues must be shipped under quarantine.
The agency is preparing a final rule and a guideline to ensure uniformity in tissue testing and screening.
In December 1995, a new class of drugs called protease inhibitors was added to the earlier approved class of nucleoside analogs, which included Retrovir (zidovudine, also known as AZT), Videx (didanosine, or ddI), Hivid (zalcitabine, or ddC), Zerit (stavudine, or d4t), and Epivir (lamibudine, or 3TC).
The protease inhibitors -- Invirase (saquinavir), Norvir (ritonavir), and Crixivan (indinavir) -- inhibit replication of HIV in a similar way as nucleoside analogs, but are active at different points in the replication process. Tested alone or in combination with the nucleoside analogs, the three protease inhibitors markedly reduced the viral load and increased the number of CD4 cells, which sharply declines in HIV infection and AIDS.
In June 1996, FDA approved Viramune (nevirapine), the first in a new class of drugs called non-nucleoside reverse transcriptase inhibitors. Viramune was approved for use in combination with nucleoside analogs to treat adults with HIV infection who have experienced clinical and/or immunological deterioration.
By the end of June, FDA also had approved 22 drugs for HIV- and AIDS-related conditions. Among them are NebuPent (aerosolized pentamidine isethionate) to prevent Pneumocystis carinii pneumonia, the most common life-threatening infection of people with AIDS, and Roferon-A (interferon alfa-2a) and Intron-A (interferon alfa-2b) for Kaposi's sarcoma, an aggressive cancer that affects primarily male homosexuals with AIDS.
Some patients with HIV have wasting syndrome, with symptoms that include major weight loss, chronic diarrhea or weakness, and constant or intermittent fever for at least 30 days. The syndrome is classified as an AIDS-defining illness. All people with HIV should carefully follow food safety practices, because their weakened immunity leaves them particularly vulnerable to food-borne illness. Diarrhea caused by such illness can lead to or worsen wasting syndrome.
To prevent food-borne illnesses, people with HIV should avoid nonpasteurized dairy products, wash hands and utensils with soap and hot water when preparing meals, and cook food thoroughly to kill harmful bacteria. Raw eggs and raw seafood such as oysters, clams, sushi, and sashimi should not be eaten. Additional information about food safety and HIV can be obtained from FDA.
Loss of appetite (anorexia) can be treated with two FDA-approved prescription medicines for HIV and AIDS patients. Marinol (dronabinol), a synthetic extract of marijuana, is indicated for anorexia associated with weight loss. Megace (megestrol acetate) can be used for anorexia, cachexia (emaciation), or any unexplained significant weight loss.
Recognizing the special needs of people with HIV infection and AIDS, FDA uses its discretion to allow them to import for their personal use unapproved but promising drugs for HIV and HIV-related life-threatening diseases. At the same time, the agency vigorously campaigns against AIDS health scams that have bilked their victims of as much as $ 10 billion a year.
As a result of FDA investigations, federal and state authorities have taken legal actions against individuals involved in hundreds of fraudulent cures for AIDS such as "energized" water, "ozone therapy," and hydrogen peroxide "treatment."
Because most of the scams are local enterprises, FDA initiated in 1989 an AIDS Health Fraud Task Force Network to monitor and counter the promotion of suspected fraudulent AIDS products. The task forces, so far established in 10 states, have built broadly based coalitions of federal, state and local authorities with the medical community and AIDS activists. They cooperate in explaining to individuals and organizations how to identify fraudulent health products and distribute general information about HIV infection.
Mike Kubic is a member of FDA's public affairs staff.