FDA regulation of dietary supplements and requirements regarding adverse event reporting.

In 1994, the Dietary Supplement Health and Education Act (DSHEA) amended the Federal Food, Drug, and Cosmetic Act (FDC Act) to set up a distinct regulatory framework for what we now call dietary supplements. The DSHEA was passed with the intent of striking a balance between providing consumers access to safe dietary supplements to help maintain or improve their health and giving the US Food and Drug Administration (FDA) authority to regulate and take action against manufacturers of supplements or supplement ingredients that present safety problems, are presented with false or misleading claims, or are adulterated or misbranded. This article will present FDA's recent experience in collecting and evaluating dietary supplement adverse event data for the purpose of assuring the public that the dietary supplements they purchase are safe.

Two-generation reproductive toxicity study of plant stanol esters in rats.

Plant stanol esters are intended for use as an ingredient in food to reduce the absorption of cholesterol from the gastrointestinal tract. Consumption of plant stanol esters has a demonstrated diet-derived public health benefit, as shown by numerous clinical studies. Plant stanol esters are ring-saturated analogs of common dietary sterols that are transesterified with fatty acids from vegetable oils such as canola oil. The reproductive and developmental toxicity of plant stanol esters was investigated in male and female Wistar rats during F0 and F1 generations using dietary concentrations of 1.75, 4.38, and 8.76% stanol esters (equivalent to 1, 2.5, and 5% total stanols). No adverse treatment-related effects were noted on reproductive performance of male or female rats in any dose group. Increased food consumption was observed in high-dose F0 generation males throughout the entire premating period and in F1 males at specific time periods during the premating period. This increase in food consumption was also observed in F0 generation females (mid- and high-dose groups) and F1 generation females (low-, mid-, and high-dose groups) at specific time periods throughout the 10-week premating period. At different intervals throughout the gestation and lactation periods, increased food consumption was observed in F0 generation females of the mid- and high-dose groups, while increased food consumption was noted in F1 generation females of the mid- and high-dose groups during gestation, but not during lactation. Such increases in food consumption are expected as a result of the animals' attempt to compensate for the reduced caloric value of the test diet compared to controls. No adverse developmental effects were noted in F1 or F2 pups of the low- and mid-dose groups based on evaluation of the following parameters: litter size, pup mortality, pups weights, and sex ratio. However, a treatment-related effect on body weight and body weight change was observed in both F1 and F2 male and female pups of the high-dose group, particularly during the latter stages of lactation (postnatal days 14 and 21) in F1 pups, and during the majority of the lactation period (postnatal days 4-21). Lower body weight in the high-dose pups is attributed to a reduction in the caloric value of the test diet compared to control. The pups, unlike adult animals, are particularly sensitive to reductions in caloric value of feed since they are in a rapid growth phase of their development. It is likely that they could not increase their food consumption enough to adequately meet their caloric and nutritional needs. In conclusion, dietary concentrations of up to 4.38% plant stanol esters (equivalent to 2.5% total stanols in the diet) are not associated with adverse effects on reproduction, pup mortality, pup body weight, or pup body weight change.

Genotoxicity evaluation of wood-derived and vegetable oil-derived stanol esters.

Plant stanol esters from wood and vegetable oil sources were tested for genotoxicity in bacterial (Salmonella typhimurium) and mammalian cell (L5178Y) gene mutation assays and in a mammalian cell chromosome aberration assay (CHO cells). The two stanol ester formulations were tested separately at doses up to the limit of solubility, with and without the addition of an Aroclor-induced rat liver microsome metabolic activation system (S9 mix). All tests were performed in duplicate and gave negative results for both wood and vegetable oil stanol ester formulations. Thus, plant stanol esters are not genotoxic under the conditions of exposure tested.

Short-term tests of estrogenic potential of plant stanols and plant stanol esters.

To test for potential estrogenic activity of plant stanols and plant stanol esters, two short-term tests were performed. These were the E-screen test, which measures a substance's ability to induce proliferation of estrogen-responsive human breast adenocarcinoma (MCF-7) cells in culture, and an in vivo test, which measures uterotrophic activity in immature female rats fed the test substance. Four samples of vegetable oil-derived stanols (containing 88-99% stanols) were tested in the E-screen test, and one sample of wood-derived and one of vegetable oil-derived stanol fatty acid esters were tested in the in vivo test. In the E-screen test, the positive control substance, 17beta-estradiol, at 100 pM, produced a statistically significant, 11.6-fold increase in cell proliferation, as measured by sulforhodamine B staining. None of the stanol preparations produced any increase in cell proliferation when tested at 1, 10, and 100 microM. The highest dose of each stanol sample was associated with microscopic evidence of cytotoxicity and crystalline precipitation in the culture dishes. In the in vivo test, the positive control compound, diethylstilbestrol, produced a significant, dose-related increase in absolute and relative uterus weight in young female rats (17 days old at the start of treatment) fed the compound at 5, 10, and 20 ppb in the diet for 4 days. Neither of the two stanol ester preparations caused any significant change in absolute or relative uterus weight when fed at a concentration of 8.3% in the diet for 4 days. Thus, under the conditions of testing used, neither the free stanols nor the stanol fatty acid ester preparations showed evidence of estrogenic or uterotrophic activity.

13-week oral toxicity study with stanol esters in rats.

Plant sterols and their saturated derivatives, known as stanols, reduce serum cholesterol when consumed in amounts of approximately 2 g per day. Stanol fatty acid esters have been developed as a highly fat-soluble form that may lower cholesterol more effectively than stanols. Stanol esters occur naturally in human diets, but at levels far below those known to lower cholesterol. The present study was conducted to assess the safety of stanol esters upon subchronic ingestion at levels comparable to or exceeding those recommended for lowering cholesterol. Two stanol fatty acid ester preparations, wood-derived stanol esters and vegetable oil-derived stanol esters, were fed to groups of 20 male and 20 female Wistar rats for 13 weeks, at dietary concentrations of 0, 0.2, 1, and 5% total stanols (equivalent to 0, 0.34, 1.68, and 8.39% wood-derived stanol esters and 0, 0.36, 1.78, and 8.91% vegetable oil-derived stanol esters). Both preparations were well tolerated as evidenced by the absence of clinical changes or major abnormalities in growth, food and water consumption, ophthalmoscopic findings, routine hematological and clinical chemistry values, renal concentrating ability, composition of the urine, appearance of the feces, estrus cycle length, organ weights, gross necropsy findings, and histopathological findings. Plasma cholesterol and phospholipids were slightly decreased in males fed the stanol esters. In both sexes, plasma levels of plant sterols were decreased whereas those of stanols tended to increase. Fecal excretion of sterols, including cholesterol, and stanols was markedly increased in the stanol ester groups. Compared to controls, male rats fed stanol esters showed somewhat lower liver weights and more pronounced glycogen depletion. These hepatic changes were considered to reflect an altered nutritional condition and not a pathological condition. Plasma levels of vitamin E, vitamin K1, and, to a lesser extent, vitamin D were decreased in males and females fed the high-dose diets. Hepatic levels of vitamins E and D showed similar changes (vitamin K1 in the liver was not determined). For both preparations, the mid-dose level (1% total stanols in the diet) was a no-observed-adverse-effect level. This dietary level provided approximately 0.5 g total stanols/kg body wt/day.

Developmental toxicity study of vegetable oil-derived stanol fatty acid esters.

In a standard developmental toxicity study, a mixture of vegetable oil-derived stanol fatty acid esters was administered in the diet to groups of 28 mated female HsdCpb:WU Wistar rats at concentrations that provided 0, 1, 2.5, and 5% total stanols (equivalent to 0, 1.75, 4.38, and 8.76% plant stanol esters). Test diets were adjusted with rapeseed oil to maintain an equivalent caloric content of fatty acids at each of the treatment levels. The treatment period extended from day 0 to 21 of gestation. No compound-related toxicity or clinical effects were seen in any of the treated groups. No statistically significant differences were seen in body weights or body weight gain in the low- or mid-dose groups, although slight but statistically significant decreases in mean body weight relative to controls were seen at gestation days 7 and 14 in the high-dose group. The decreases in body weight in the high-dose group may be attributable to the virtual lack of absorption of the dietary stanols. Body weight gains were equivalent to controls throughout the study except for a statistically significant decrease seen only in the 0- to 7-day gestation period in the high-dose group. No significant effects were seen on food consumption in terms of g/rat/day, but a slight, statistically significant increase was seen in the mid-dose group during gestation days 7-14. A significant increase was seen in the high-dose group during the 7- to 21-day period of gestation. Reproductive performance was not affected by the treatment. There were no statistically significant differences in uterine weight, placental weight, fetal weight, number of fetuses, number of implantation sites, number of corpora lutea, and early/late resorptions between the treated and control groups. In addition, there was no biologically meaningful effect on fetal sex ratio. Visceral and skeletal examinations did not show any significant increases in the incidence of malformations, anomalies, or variations that were considered to be treatment related. Dietary plant (8.76% plant stanol esters) stanol esters at concentrations up to 5% total stanols were concluded to have no adverse effects on reproduction or development.

90-Day oral toxicity study of D-tagatose in rats.

D-tagatose is a ketohexose, tastes like sugar and is useful as a low-calorie sweetener. To assess D-tagatose's safety, an oral 90-day toxicity study was conducted on male and female Crl:CDBR rats at dietary doses of 5, 10, 15, and 20% D-tagatose. One control group (dietary control) received only lab chow; a second control group received 20% cellulose/fructose in the diet. There were no treatment-related effects at 5% D-tagatose in the diet. At higher doses, treatment-related effects included transient soft stools in male and female animals from the 15 and 20% dose groups. This was anticipated as a result of the osmotic effect of a large dose of relatively undigested sugar and was not considered a toxic effect. All treatment groups gained weight over the study period; however, mean body weights were statistically significantly decreased in the 15 and 20% dose-group males and the 20% dose-group females at selected intervals compared to dietary control animals. No significant reduction in mean food consumption was noted in the treatment groups compared to the dietary control. Statistically significantly increased relative liver weights were noted in male and female animals from the 10, 15, and 20% dose groups compared to the dietary control. No gross pathological findings correlated with these increased liver weights. Minimal hepatocellular hypertrophy was observed in male and female animals from the 15 and 20% dose groups. An independent review of the liver slides concluded that histomorphologic changes associated with D-tagatose were restricted hepatocyte hypertrophy and hepatocyte glycogen accumulation. Therefore, it was concluded that increased liver weights and minimal hypertrophy were the result of adaptation to the high dietary levels (greater than 5% in the diet) of D-tagatose. No adverse effects were seen at 5% D-tagatose in the diet.

Developmental toxicity study of D-tagatose in rats.

D-tagatose is a low-calorie sweetener that tastes like sucrose. The developmental toxicity of D-tagatose was investigated in Crl:CD(SD)BR rats administered D-tagatose at three dose levels (4000, 12,000, and 20,000 mg/kg body wt/day) via gastric intubation on days 6-15 of gestation. No compound-related toxicity was seen among any of the maternal groups. No treatment-related clinical effects were seen in the maternal animals at the 4000 mg/kg/day dose level. At the mid- and high-dose levels, most maternal animals had unformed or watery stools; this effect was most prominent early in the treatment period (Gestation Days 6-8). This effect was attributed to the osmotic effect of the large amount of D-tagatose given to the animals at these doses. Since D-tagatose is not digested or absorbed to a large extent, most of the sugar passes into the colon where it absorbs water and is fermented by colonic bacteria. Mean weight gain for the low- and mid-dose animals was comparable to the control; however, the high-dose group experienced a mean weight loss over the Gestation Day 6-9 interval. Over the entire treatment interval, however, mean weight gain for the high-dose animals was comparable to control. The decreased weight gain in the high-dose animals during the Gestation Day 6-9 interval was considered to be a direct result of laxation. In addition to the effect of laxation on body weight, reduced food consumption also contributed to the decreased weight gain. In the low-dose animals, no effect on food consumption was seen; however, both mid- and high-dose animals had food consumption values that were statistically significantly lower than the control. Food consumption was lowest during the Gestation Day 6-9 interval, the period when laxation was most prominent. Food consumption rebounded and was statistically significantly higher than the control for the mid- and high-dose animals during the posttreatment interval. Maternal liver weight for the low-dose animals was comparable to the control. However, a statistically significant increase in mean maternal liver weight was noted for the mid-and high-dose animals. Based on a lack of any corresponding histopathology, the increased liver weights were not considered toxicologically significant. There were no adverse effects on reproductive performance noted in any treatment group. No adverse treatment-related fetal effects on fetal weight, sex distribution, liver weight, or external, skeletal, or visceral malformations were noted at any dose level.

Genotoxicity tests on D-tagatose.

D-tagatose is a low-calorie sweetener that tastes like sucrose. Its genotoxic potential was examined in five standard assays: the Ames Salmonella typhimurium reverse mutation assay, the Escherichia coli/mammalian microsome assay, a chromosomal aberration assay in Chinese hamster ovary cells, a mouse lymphoma forward mutation assay, and an in vivo mouse micronucleus assay. D-tagatose was not found to increase the number of revertants per plate relative to vehicle controls in either the S. typhimurium tester strains or the WP2uvrA- tester strain with or without metabolic activation at doses up to 5000 microg/plate. No significant increase in Chinese hamster ovary cells with chromosomal aberrations was observed at concentrations up to 5000 microg/ml with or without metabolic activation. D-tagatose was not found to increase the mutant frequency in mouse lymphoma L5178Y cells with or without metabolic activation up to concentrations of 5000 microg/ml. D-tagatose caused no significant increase in micronuclei in bone marrow polychromatic erythrocytes at doses up to 5000 mg/kg. D-tagatose was not found to be genotoxic under the conditions of any of the assays described above.

Measurement of 2,4-toluenediamine in urine and serum samples from women with Même or Replicon breast implants.

The objective of this matched case-control study was to determine whether women with Même or Replicon polyurethane-covered silicone breast implants are exposed to clinically significant levels of free 2,4-TDA from biodegradation of the polyurethane foam. Urine and serum samples were obtained from 61 patients with Même or Replicon breast implants and 61 controls on two separate occasions separated by 10 +/- 3 days. Free TDA was analyzed by gas chromatography combined with negative chemical ionization mass spectrometry with lower limit of quantitation in both urine and serum of 10 pg/ml. The results were correlated with the length of time since implantation. No patients or controls had detectable free 2,4-TDA in their sera. Thirty patients had quantifiable levels of free 2,4-TDA, and 18 had detectable levels in their urine. Controls had no quantifiable levels, but 7 subjects had detectable levels. The biodegradative half-life of the polyurethane foam was estimated to be 2 years. A risk assessment using the cancer potency estimate calculated by the FDA from rat data and the National Academy of Sciences methodology provided a theoretical lifetime risk of approximately one in one million. It was concluded that the polyurethane foam cover on the Même and Replicon breast implants biodegrades. The risk assessment of approximately one in one million derived from this study strengthens earlier conclusions by the Health Protection Branch (Canada) that there is no significant risk of cancer from exposure to the 2,4-TDA formed from this biodegradation.

Assessing the role of the biomaterial Aquavene in patient reactions to Landmark midline catheters.

Landmark midline catheters (Menlo Care, Inc., Palo Alto, CA) provide peripheral venous access for the infusion of medications or fluids. They are constructed of an inner layer of polyurethane and an outer layer of the biomaterial Aquavene, a blend of polyurethane and polyethylene oxide to which butylated hyroxyanisole (BHA), butylated hydroxytoluene (BHT), and triallyl-s-triazine trione (TTT) are added. Once inside the vein, the Aquavene material becomes hydrated and the catheter swells resulting in minimal trauma to the vein. It is well recognized that some patients experience reactions to catheterization. Recent reports of hypersensitivity-like reactions in some patients catheterized with Landmark catheters have prompted the manufacturer to reexamine biocompatibility data and clinical data to assess whether Aquavene was the source of the patient responses. None of the biocompatibility studies provided by Menlo Care in support of U.S. registration and marketing of Aquavene-based catheters demonstrated any tendency for Aquavene or material extracted from Aquavene to invoke an immunological or toxicological response. Examination of potential catheter residuals revealed that significant amounts of BHA and BHT were unlikely to be released from the catheters during expected use. The amounts of polyethylene oxide and TTT expected to be released during the first few minutes after catheter insertion (when most of the patient reactions were reported) are almost 92,500 and 270,000 times lower, respectively, than nontoxic animal exposures. These analyses do not support chemically mediated toxicity as an explanation for the adverse events experienced by some patients. A review of the postmarket surveillance data on Aquavene-based catheters revealed that the reported events were not consistent with a hypersensitivity (immunogenic) response to the biomaterial. The rare reported adverse events tend to occur quickly, most often after flushing of the catheter, and resolve quickly, even when the catheter remains in place. Determining the frequency and severity of adverse events reported in association with the use of Landmark catheters will ultimately require a controlled prospective study, preferably one with a concurrent control group using alternative products.

Generally recognized as safe (GRAS) evaluation of 4-hexylresorcinol for use as a processing aid for prevention of melanosis in shrimp.

4-Hexylresorcinol (C12H18O2) is proposed for use as a processing aid for prevention of melanosis ("black spot") in shrimp and as an alternative to the currently approved sulfites. A safety evaluation was conducted to affirm, based upon scientific procedures, the generally recognized as safe ("GRAS") status of 4-hexylresorcinol for proposed use. The GRAS safety evaluation compiled, reviewed, and analyzed data on the following areas: chemical identity, analytical methodology, historical and proposed uses, functionality, and safety. The publicly available safety data on 4-hexylresorcinol cover a broad range of potential toxicity concerns including acute and subacute toxicity, subchronic toxicity, carcinogenicity, mutagenicity, and allergenicity. These studies, along with the aforementioned data, demonstrate that 4-hexylresorcinol presents no risk of toxicity at the levels proposed for treatment of shrimp, and the use of 4-hexylresorcinol as a processing aid to prevent melanosis in shrimp is GRAS.

Safety of Sanguinaria extract as used in commercial toothpaste and oral rinse products.

This report represents the findings of an Expert Panel on the safety of Sanguinaria extract used in Viadent oral rinse and toothpaste products and represents an independent review of the Sanguinaria extract toxicologic data base. It is based on reviews and discussions of the data base by all members of the Expert Panel on Sanguinaria extract. The Panel concluded that the data base on Sanguinaria extract is substantial and indicates that Sanguinaria extract is safe in its present use in Viadent products based on a large margin of safety between levels of human exposure and levels found to produce minimum effect or to be without adverse effect in animals. The panel further concluded that published literature suggesting an association between human exposure to Sanguinaria extract and potential reproductive, cardiovascular, or ocular toxicity, or carcinogenicity is largely anecdotal, unfounded, and not corroborated by or consistent with the substantial data base that was subjected to peer review.

Bioavailability of oxalic acid from spinach, sugar beet fibre and a solution of sodium oxalate consumed by female volunteers.

Oxalate bioavailability from sugar beet fibre (40 g), spinach (25 g) and a solution of sodium oxalate (182 mg) was tested in nine women using a triplicated 3 x 3 Latin square arrangement. Each test substance provided 120 mg oxalic acid. Throughout the study the volunteers consumed a control diet and the test substances were administered at breakfast on specified days. After an initial 2-day control period, oxalate was administered in three test periods that consisted of one test day followed by one control day. Urine collected during 24-hr periods was analysed daily for oxalate. Oxalate excretion did not differ among the five control days and was not increased significantly following the ingestion of sugar beet fibre by the volunteers. Oxalate excretion was greater (P less than 0.0001) for the mean of the spinach and sodium oxalate solution diets than for the mean of the sugar beet fibre and control diets. Oxalate bioavailability from sugar beet fibre was 0.7% compared with bioavailabilities of 4.5 and 6.2% for spinach and oxalate solutions, respectively. The low bioavailability of oxalate from sugar beet fibre may be attributable to its high ratio of minerals (calcium and magnesium) to oxalate, its complex fibre matrix or the loss of the soluble oxalate during processing of sugar beets.

Formaldehyde risk assessment for occupationally exposed workers.

Formaldehyde has been shown to be carcinogenic in animals and should be considered potentially carcinogenic in humans. The mechanism of action is unknown but formaldehyde is weakly genotoxic and also may act as a late stage carcinogen or promoter. An estimated 1.3 million workers are potentially exposed to formaldehyde through their occupation. Of those exposed workers, about 3.5% were found to be exposed to formaldehyde air concentrations greater than the 3 ppm set by OSHA as a permissible exposure level. Fewer than 12% were exposed to concentrations greater than 1 ppm, but over 88% were exposed to concentrations of 0.5 ppm or more. A quantitative risk assessment, using the multistage low-dose extrapolation model, found the (maximum likelihood) estimate of lifetime risk for excess cancers to be 620 per 100,000 at the OSHA permissible exposure level. The estimated risk is 23 per 100,000 at 1 ppm and 2.8 per 100,000 at 0.5 ppm. Reduction of the OSHA permissible exposure level to 1 ppm would significantly decrease risk with minor economic disruption for most industries involved. However, reduction of risk to levels which have been generally regarded by other regulatory agencies as acceptable, i.e., 10(-5) to 10(-6), would require increased control by all the industries reviewed.