MSG Judged Safe For Most People

The food ingredient monosodium glutamate (MSG) is safe at normally consumed levels for the general population, according to results of a scientific review sponsored by FDA.

A panel of experts, convened by the Federation of American Societies for Experimental Biology (FASEB) under contract with FDA, found no evidence linking MSG to any serious, long-term medical problems in the general population.

But FASEB's report on the findings did state that evidence suggests certain people may develop short-term reactions when they consume large doses--approximately 3 grams or more per meal--of MSG or related "free glutamates." These reactions, dubbed "MSG Symptom Complex" in the report, were not linked to low levels of glutamate consumption.

The report also expressed concern that glutamate may affect a small group of people with severe asthma. Limited clinical studies show some of these people experienced bronchospasm up to six to 12 hours after being exposed to MSG.

MSG is one of several types of glutamates--substances derived from glutamic acid, a major building block for proteins. When glutamate that has been bound within a protein is released during breakdown of the protein molecule, "free glutamate" is formed. These substances can be added to food to enhance its flavor and are the focus of much of the concern about glutamates. Some foods, such as ripe tomatoes and parmesan cheese, contain high levels of naturally occurring free glutamates.

Based on a preliminary review of the FASEB report, FDA plans to propose that foods containing significant amounts of free glutamate declare glutamate as an ingredient on the label. This would allow consumers to distinguish between foods with insignificant free glutamate levels and those that might contribute to a reaction.

Currently, foods containing added MSG must declare it as an ingredient on their labels. Processed foods containing other ingredients with significant levels of free glutamate (such as autolyzed yeast, soy sauce, and some flavorings) must declare these ingredients, like any other ingredient, on their labels.

FDA sponsored extensive reviews of MSG and related substances in 1978 and 1980, both of which concluded MSG is safe for the general public at common-use levels. But the 1980 review noted that additional data were needed to judge whether a significant increase in glutamate consumption can cause adverse effects. FASEB's report, contracted by FDA in 1992, is the most comprehensive review of existing information on glutamate safety.

New Osteoporosis Therapy

Two clinical trials demonstrated that daily use of calcitonin salmon nasal spray increases bone mass in the spine, although no bone-building effects were shown on bone mass of the forearm or hip. The manufacturer, Sandoz Pharmaceuticals Corp. of East Hanover, N.J., agreed to conduct additional studies to evaluate the product's long-term effectiveness in preventing fractures.

The most common side effects during the trials included inflammation of the membranes in the nose, nosebleeds, and sinusitis. Patients using the nasal spray should have periodic nasal examinations for ulceration or irritation.

Osteoporosis, the thinning of bones in postmenopausal women and elderly men, is a major cause of bone fractures that affect as many as 20 million Americans. Women over 45 commonly suffer fractures of the hip, wrist or spine due to loss of bone mass from osteoporosis.

Women on drug therapy for osteoporosis should take daily supplements of calcium and vitamin D. This regimen--along with exercise--helps prevent the loss of bone mass.

(For more information about osteoporosis, see "Osteoporosis Treatment Advances" in the April 1991 FDA Consumer.)

Information on Norplant Available

Women who choose Norplant--a contraceptive device surgically inserted into the upper arm--will now be given a form to sign, acknowledging that they received information on the risks and benefits of the device before insertion.

Norplant, which was approved in 1990, consists of six silicone rubber capsules containing the hormone levonorgestrel. The capsules are surgically inserted under the skin of a woman's upper arm and provide contraceptive protection for up to five years. The capsules are surgically removed at the end of that time or earlier if desired. Both procedures are done in the doctor's office.

To help ensure that women are appropriately informed of the product's risks and benefits before implantation, FDA and Norplant's manufacturer, Wyeth-Ayerst Laboratories of St. David's, Pa., developed new education materials for patients and providers. Included is the acknowledgment form and revisions of the product package insert for doctors and patients that include a discussion of reported adverse reactions.

Side effects commonly associated with Norplant include vaginal bleeding, headaches, nausea, dizziness, and nervousness.

FDA's postmarketing surveillance of Norplant and its ongoing analysis of adverse reaction reports have found no basis for questioning the product's safety and effectiveness when used as directed in the labeling.

For more information on Norplant and the names of providers experienced in inserting and removing the device, call Wyeth-Ayerst's toll-free telephone line (1-800) 934-5556.

(See also "Norplant, Birth Control at Arm's Length," in the May 1991 FDA Consumer.)

Treatment IND for Drug to Treat CMV

CMV retinitis is an eye infection that can lead to blindness in people with impaired immune systems, such as AIDS patients.

FDA established the Treatment IND (investigational new drug) process for patients suffering from serious or life-threatening conditions who have exhausted existing treatments or have no satisfactory treatments. Under the process, patients can obtain promising experimental drugs that have undergone sufficient clinical testing to show they may be safe and effective. The agency based its decision to expand access to intravenous Vistide on a controlled clinical study that showed the drug may slow CMV retinitis progression.

Drugs already approved to treat CMV retinitis are Foscavir (foscarnet sodium) and Cytovene (ganciclovir sodium). Neither can cure CMV retinitis, but both can significantly delay disease progression.

Vistide is made by Gilead Sciences Inc., Foster City, Calif. The company started offering the drug free under this Treatment IND program on Sept. 5. For more information, call (1-800) GILEAD-5. For more about other AIDS clinical trials, call (1-800) TRIALS-A.

Pertussis Vaccine Trials

The trials, sponsored by NIAID and conducted in Italy and Sweden, also reported that the experimental vaccines caused fewer side effects than a vaccine currently used in the United States.

FDA's scientists in its Center for Biologics Evaluation and Research have been instrumental in developing and evaluating acellular vaccines and have collaborated with NIAID and the vaccine manufacturers to design the European trials.

The experimental vaccines are called acellular vaccines because they contain only the parts of the pertussis bacterium thought to be important for immunity. U.S. vaccines licensed for use in infants are called whole-cell vaccines, because they contain the whole, inactivated pertussis organism.

The trials, which began in 1992, involved about 25,000 infants. Groups of infants received either an acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTaP), a whole-cell (DTP) vaccine, or, in the control group, a diphtheria-tetanus vaccine.

Three DTaP vaccines were found to be approximately 85 percent effective, while the DTP vaccine was 36 percent effective in the Italian trial and 48 percent effective in the Swedish trial. A fourth DTaP vaccine was 58 percent effective.

Whole-cell pertussis vaccines currently marketed in the United States are reported to be 70 to 90 percent effective.

Only three doses were given in the trials, compared to five doses normally given in the United States. It is not known whether this difference in dosage accounts for some of the disparity in the effectiveness of the whole-cell vaccine. In addition, the epidemic conditions in Sweden and Italy, where pertussis vaccines are not as widely used as in the United States, differed from the United States, where pertussis is much less common.

Seizures were reported rarely in the trials, but occurred no more frequently in any of the pertussis vaccine groups than in the control group. Side effects, such as redness, pain and swelling at the site of the injection, fever, and protracted crying, were reported to be less common with the acellular vaccines than with the whole-cell one.

FDA has made special efforts to encourage submission of applications for the use of acellular pertussis vaccines in infants. The agency will target such applications for complete review within six months of receiving them. However, actual times to any licensing can vary, depending on the quality and completeness of the data submitted.

FDA recommends that parents continue to get their children vaccinated against pertussis with available vaccines. The agency has licensed four whole-cell pertussis vaccines and, for the fourth and fifth doses, two acellular vaccines.

All vaccines pose risks of side effects, but for both whole-cell and acellular pertussis vaccines, serious, long-lasting problems are extremely rare. The disease itself can be fatal. In 1993, 11 pertussis deaths were reported to the national Centers for Disease Control and Prevention.

(For more information about pertussis vaccination, see "New Pertussis Vaccine Offers Prevention Alternative," in the September 1992 FDA Consumer.)

Saraflox Approved to Control Poultry Illnesses

Fluoroquinolones are the newest class of antibiotics developed for treating infections in people and animals. Another fluoroquinolone drug, enrofloxacin, was approved in 1989 to treat certain pet infections.

"Sarafloxacin provides veterinarians a way of preventing disease in poultry flocks as long as it is used appropriately," said FDA Commissioner David A. Kessler, M.D. "It is important that antibiotics for food animals be used correctly to minimize the potential for development of drug-resistant microbes."

During a public hearing in May 1994, FDA's veterinary medicine and anti-infective drugs advisory committees recommended approval of fluoroquinolones found to be safe and effective for animal use, but also recommended that the agency establish conditions for approval to minimize any potential for development of resistant bacteria.

FDA is cooperating with the U.S. Department of Agriculture and the national Centers for Disease Control and Prevention in a program to detect and prevent drug-resistant microbes. In addition, the manufacturer will test samples of animal E. coli to measure emergence of any drug resistance.

Saraflox, available only by prescription, is manufactured by Abbott Laboratories, North Chicago, Ill. It was approved last Aug. 18.

Free Info from FDA

Also available are three free FDA Consumer reprints. The titles and publication numbers are:

• If You Eat Raw Oysters, You Need to Know ... (FDA) 95-2293
• Public Affairs Specialists: FDA's Walking Encyclopedias (FDA) 95-1222
• An FDA Guide to Choosing Medical Treatments (FDA) 95-1223
• Keeping Medical Devices Safe from Electromagnetic Interference (FDA) 95-4261.

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.