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The Guidant implantable defibrillator was originally approved by FDA in 1988 for patients who have had at least one cardiac arrest or have recurrent and sustained rapid heartbeat despite treatment with the best available drugs. These people are at high risk of sudden death.
FDA gave the additional approval last May 15 for a large new group of patients--about 10 percent of heart attack patients--who also are at high risk of sudden death from abnormal rapid heartbeat (ventricular arrhythmia) but who have had no obvious symptoms. These patients' arrhythmias can be detected by electrocardiograph, and usually they are treated with drugs. However, 30 percent of these patients die from ventricular arrhythmia within two years.
In a five-year clinical study, such patients implanted with the Guidant defibrillator had 54 percent fewer deaths than those treated with drugs. The significant results prompted the sponsor to stop the study early so that all patients would be eligible to receive the device.
The Guidant defibrillator is about the size of a cassette tape and is implanted in the abdomen or chest and linked to the heart with wire leads. It can be programmed to deliver small, swift pacing signals to fit patients' needs.
It is made by CPI Guidant Corp., of St. Paul, Minn.
(For more about defibrillators, see "A Gentler Jolt and Tickle for Trembling Hearts," in the April 1994 FDA Consumer.)
Activase (alteplase), previously licensed to dissolve clots in heart attacks and in the artery leading to the lungs, received approval last June 18 for the additional use of dissolving blood clots that block blood flow to the brain in ischemic strokes. Activase is a genetically engineered version of tissue plasminogen activator (t-PA).
Because therapy with Activase must start within three hours of stroke onset, it is important that people with stroke symptoms seek medical attention as soon as possible. Bleeding in the brain must be ruled out by cranial computerized tomography (CT) scan before Activase treatment can begin. The treatment is not approved to treat hemorrhagic strokes, caused by bleeding into and around the brain.
Yearly, about 500,000 Americans have strokes, with about 150,000 dying as a result. Of these strokes, about 400,000 are ischemic and the rest are hemorrhagic.
The licensing of Activase for ischemic stroke follows a unanimous recommendation for approval by FDA's Peripheral and Central Nervous System Drugs Advisory Committee last June 6.
Activase is manufactured with recombinant DNA technology by Genentech, Inc., of South San Francisco.
The Amplicor HIV-1 Monitor Test measures blood levels of HIV-1--the strain of human immunodeficiency virus responsible for most HIV infections in the United States. It is the first licensed HIV-1 test using polymerase chain reaction (PCR) technology. PCR replicates millions of copies of genetic material (RNA) from HIV-1. The amplified RNA is tagged with color indicators so it can be measured. This technology enables more precise measurement than is possible with other approved technologies.
FDA licensed the test last June 3, less than seven months after receiving the manufacturer's application. Licensing was based on laboratory studies showing the test could measure HIV RNA in the blood, and on clinical data showing HIV blood levels correlated with disease progression
Laboratory studies showed the test was specific for HIV-1--that is, other unrelated viruses or organisms did not cause a false positive result (indicating the presence of HIV-1). Also, in an analysis of 495 samples known not to be infected with HIV-1, none was falsely positive.
In two small clinical studies, the test was used to measure viral levels in patients with advanced HIV disease who either had not received antiviral drugs or had received AZT (zidovudine, marketed as Retrovir) in combination with other antivirals for less than 16 weeks. Viral levels that were high before treatment or that increased fivefold after eight weeks of therapy correlated with disease progression to AIDS or AIDS-related infection or death.
In two additional clinical studies, the test was used to evaluate the effectiveness of antiviral therapy. Patients had been treated with AZT and were currently receiving the protease inhibitor saquinavir (marketed as Invirase) in combination with other drugs, such as AZT or DDC (also known as zalcitabine and marketed as Hivid). The test showed decreased levels of HIV-1 RNA in patients who received combination therapies.
The studies did not, however, show if changes in viral RNA levels are related to clinical responses to drug therapy. Last March, FDA's Blood Products Advisory Committee supported approval of the test for prognosis of HIV-infected patients, but recommended additional studies to determine how physicians could use the test to monitor the results of therapy. FDA required these studies, now under way, as a condition of licensing.
The manufacturer is Roche Diagnostic Systems Inc., Branchburg, N.J.
Hycamtin (topotecan), approved last May 29, belongs to the class of drugs called camptothecins, which inhibit an enzyme called topoisomerase-I.
Results from two multicenter clinical trials showed that the drug reduced ovarian tumor size in 17 percent of 337 patients for an average of about five months. That response was at least as good as that seen in patients treated in one of the studies with Taxol (paclitaxel), another ovarian cancer drug.
Because Hycamtin is associated with neutropenia (a temporary drop in white blood cells that makes it difficult for the body to fight infections), some patients may require hospitalization and antibiotics.
Other side effects include thrombocytopenia (a decrease in blood platelets that can lead to excessive bleeding), anemia, nausea, and vomiting.
Hycamtin is marketed by SmithKline Beecham of Philadelphia.
Taxotere (docetaxel), a semi-synthetic drug containing derivatives of the evergreen tree's needles, was approved last May 14 for women whose advanced breast cancer has progressed despite standard cancer treatment regimens. The first drug derived from the Pacific yew, Taxol (paclitaxel), is approved to treat ovarian and breast cancer.
Taxotere's approval was based on several studies, including three trials in the United States and Europe that showed the drug can shrink tumors in some breast cancer patients.
At the highest tested dose, the drug shrank tumors in 42 percent of patients for an average of six months. At this dose level, Taxotere, like many cancer drugs, is associated with serious side effects, including a decrease in white blood cell counts, fluid retention, allergic reactions, and hair loss. At a lower dose, however, the drug shrank tumors in 35 percent of patients for four months, and the side effects were negligible.
The drug's labeling warns that patients should be premedicated to prevent problems with fluid retention and allergic reactions. Certain patients with liver dysfunction should not use Taxotere.
FDA granted Taxotere an accelerated approval based on clinical improvements such as tumor shrinkage, rather than survival time or quality of life. By basing accelerated approval on these partial responses, and allowing more definitive data to be developed on clinical endpoints after approval, FDA is giving patients earlier access to more promising cancer therapies.
FDA may withdraw the approval of such products if postmarketing studies do not verify clinical benefits. More extensive trials testing Taxotere's clinical benefits are ongoing.
Taxotere is marketed by Rhône-Poulenc Rorer Inc., of Collegeville, Pa.
Camptosar (irinotecan) is for patients whose colorectal cancer has recurred or progressed despite treatment with standard chemotherapy. Approved June 17 as recommended by FDA's Oncology Drugs Advisory Committee, Camptosar is the second in a promising new class of antitumor drugs called camptothecins to be approved in three weeks. Camptothecins work by inhibiting the enzyme topoisomerase-I.
Primary treatment for colorectal cancer is surgery, with or without added chemotherapy or radiotherapy. However, the cancer recurs in about half the patients. The drug Fluorouracil (5-FU), with or without leucovorin (a compound related to the vitamin folic acid), is first-line chemotherapy for patients with colorectal cancer that has spread. However, by the time the cancer is diagnosed, it has already spread in about half of the patients. Treatment options when the cancer does not respond to first-line therapy are very limited.
In three studies of patients whose metastatic (spread) colorectal cancer recurred or progressed despite chemotherapy, the new drug reduced tumor size in about 13 percent of patients for an average of six months. Side effects included diarrhea (in some cases, prolonged or severe enough to require treatment) and leukopenia, a temporary drop in white blood cells that reduces the body's ability to fight infections.
On the oncology advisory committee's recommendation, FDA granted Camptosar accelerated approval based on clinical improvements such as tumor shrinkage, rather than survival time or quality of life. The committee also gave advice on additional studies to further evaluate the safety and effectiveness of the drug. FDA may withdraw its approval if postmarketing studies do not verify clinical benefits.
Camptosar is manufactured by Pharmacia & Upjohn Inc., Kalamazoo, Mich.
Because only about 300 Americans get either disease each year, the new treatment, Albenza (albendazole), is considered an "orphan" drug. This designation provides incentives for companies that develop products for disorders affecting fewer than 200,000 people in the United States and its territories. FDA approved the drug June 12.
NCC is caused by pork tapeworm larvae and is considered the leading infectious cause of seizures worldwide. People acquire the disease when they consume tapeworm eggs, usually through contaminated food or water. Seizures and headaches result when the disease involves brain tissue. Symptoms may not develop for five years or longer following exposure. Albendazole was shown to be effective in 40 to 70 percent of patients with active cysts.
Cystic hydatid disease causes enlarging parasitic cysts in the liver, lungs, abdominal cavity, brain, or bone. The cysts grow slowly and may go undetected for years. Symptoms may be vague complaints of abdominal fullness or may be more acute if the cyst ruptures. People contract the disease by ingesting dog tapeworm eggs through close contact with infected dogs. Albendazole was shown to eliminate hydatid cysts in approximately 30 percent of patients and reduce their size in an additional 40 percent.
Adverse effects may include diminished liver function and fewer white blood cells. NCC patients may have headache, nausea, or vomiting; hydatid disease patients may have abnormal liver function, abdominal pain, nausea, or vomiting.
SmithKline Beecham Pharmaceuticals of Philadelphia makes Albenza.
FDA based its June 5 approval of Xalatan (latanoprost) on study results indicating patients treated with the drug for six months had reduction in eye pressure equivalent to other glaucoma treatments. The approval followed a recommendation for approval by the agency's Ophthalmic Drugs Advisory Committee.
The once-a-day treatment may cause an unexplained gradual change in eye color. Based on the committee's concern about this unusual side effect, Xalatan's labeling tells patients and health-care providers about the phenomenon and recommends use only by patients that can't tolerate or don't respond to other treatments.
The manufacturer, Pharmacia & Upjohn Inc., of Kalamazoo, Mich., will study the eye color change in postmarketing studies.
(See also "Guarding Against Glaucoma" in the November 1995 FDA Consumer.)
The Miniguard is a triangle-shaped pad with adhesive coating on one side, which the woman places over her urinary opening, where it forms a seal.
Urinary stress incontinence is a condition in which urine leaks as a result of physical stress, such as coughing, laughing, or lifting heavy objects. The condition affects about 10 million people, mostly women.
Although the Miniguard does not stop leakage, it lessens its frequency. In a study of 356 women, the average participant improved from about 14 leaks a week without the device to about five leaks a week with it. Women with severe stress incontinence, who had about 34 episodes of leakage a week, had only 10 leaks a week with the device. When urine leaked in these women, the amount was smaller.
Because leaks are possible, women using the Miniguard need to wear panty liners or pads for additional protection.
The device can be worn two to five hours at a time during the day and throughout the night. When a woman needs to urinate, she peels the pad off and discards it. After urinating, she puts on a new pad. The Miniguard may be worn during exercise, although vigorous activity, such as running, may move it out of position.
The product is not for women with urinary tract or vaginal infections or local irritations. Also, it is not as effective in women who have had surgery for their incontinence.
The Miniguard is made by Advanced Surgical Intervention, of Dana Point, Calif.
Multiple sclerosis is a chronic, often disabling disease of the central nervous system that occurs when the protective covering of the nerve fibers breaks down. In relapsing MS, symptoms can diminish or disappear for months or years between flare-ups. (See "Multiple Sclerosis: New Treatment Reduces Relapses" in the June 1994 FDA Consumer.)
The new treatment, Avonex (interferon beta-1a), is a genetically engineered form of a naturally occurring protein in the body which is vital to immune functions.
In a two-year clinical trial, patients receiving a weekly injection of interferon beta-1a into the muscle were 37 percent less likely to have physical disability than patients getting a placebo. Also, those receiving interferon beta-1a had less frequent flare-ups and fewer lesions.
The most common side effect was flu-like symptoms, which diminished with continued treatment. Interferon beta-1a did not appear to increase depression, a side effect associated with some interferon products. There were no reports of tissue death at the injection site, which differentiates the product from Betaseron (interferon beta-1b), licensed in 1993 to treat relapsing MS.
The May 17 licensing of Avonex follows a recommendation for approval by FDA's Peripheral and Central Nervous System Drugs Advisory Committee.
The drug will be marketed by Biogen, Inc., of Cambridge, Mass.
In a joint letter sent May 7, 1996, the agencies said advertising or promotion should contain enough information about the risks and limitations of PRK to prevent deception, and consumers should be given enough information about the surgery to make an informed decision. Unrealistic claims such as "throw away your eye glasses" and unsubstantiated claims about success rates could be misleading to consumers.
In clinical studies, about 5 percent of patients who had PRK continued to need glasses all the time for distance, and up to 15 percent needed glasses occasionally, such as for driving. Best corrected vision (vision with glasses) was slightly worse after surgery in about 5 percent of patients.
In PRK, an excimer laser is used to reshape the cornea to improve mild to moderate nearsightedness. The surgery is not reversible. Excimer lasers have not been shown safe and effective for severe nearsightedness (more than -7 diopters), farsightedness or astigmatism. People who need reading glasses continue to need them after PRK. Also, PRK does not prevent farsightedness associated with aging, so people may require reading glasses as they age even if they have had the laser surgery. Risks of PRK to the cornea beyond three years have not been studied.
Some doctors perform PRK on both eyes without a waiting period between. Patient brochures developed by the laser manufacturers and reviewed by FDA, however, recommend a three-month wait between eye surgeries to allow vision to stabilize.
In addition, some surgeons perform a laser procedure called LASIK to improve nearsightedness. FDA has not cleared lasers for this use, however, and the devices cannot be promoted or advertised for it.
The publications and their numbers are:
To order single copies, write to FDA, Rockville, MD 20857. To order 2 to 100 copies, write to FDA, HFI-40, at the same address, or fax your order to (301) 827-5308. Include the publication number.