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Zinc gluconate |
| Zinc gluconate | |
|---|---|
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| Identifiers | |
| CAS number | 4468-02-4 |
| Properties | |
| Molecular formula | C12H22O14Zn |
| Molar mass | 455.685 g/mol |
| Melting point |
172-175 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Zinc gluconate is the zinc salt of gluconic acid. It is an ionic compound consisting of two moles of gluconate for each mole of zinc. Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement.
Gluconic acid is found naturally, and is industrially manufactured by the fermentation of glucose, typically by Aspergillus niger, but also by other fungi, e.g. Penicillium, or by bacteria, e.g. Acetobacter, Pseudomonas and Gluconobacter.1 In its pure form, it is a white to off-white powder. It can also be manufactured by electrolytic oxidation2, although this is a more expensive process. The advantages are a lower microbiological profile, and a more complete reaction, yielding a product with a longer shelf life.
Zinc gluconate may interfere with the absorption of antibiotics, so combinations may be unsafe.
Contents |
Zinc gluconate glycine is a formulation containing zinc gluconate and the amino acid glycine. It is available as an over-the-counter remedy for the common cold.
Zinc gluconate, when made into a lozenge by itself, has a mildly acidic taste, which will turn into a bitter taste over a period of time. The addition of large amounts of glycine to the lozenge produces a much milder and more stable taste. The resulting commercial products have a nearly unlimited shelf life.
This compound was patented in 1985 by John C. Godfrey of Godfrey Science & Design. The Quigley Corporation has trademarked the name ZIGG for the compound. The company is also the only major supplier of zinc gluconate glycine, distributed under the brand name Cold-Eeze. All clinical trials of the compound to date have involved the lozenges in this product family.
Like zinc gluconate, zinc gluconate glycine has been shown in clinical trials to shorten the mean and median duration of symptoms of the common cold.3 The amount of glycine added can range anywhere from two to twenty moles of glycine for each mole of zinc gluconate (US Patent 4,684,528, Claim 1).
The manufacturer claims that its product reduces the duration of common cold symptoms by 42%, compared to the natural duration. However, this benefit depends on regular usage (every few hours of being awake) beginning with the first appearance of symptoms. Repeated clinical trials of the compound have generally shown a measurable, but varied, benefit relative to a placebo, typically on the order of a one- to four-day reduction in symptom duration.456
A 2001 study seemed to show that zinc gluconate only works with certain types of colds, and its effect is most measurable after the 2nd or 3rd day.7 One review of the research found that out of nine controlled experiments using zinc lozenges, the results were positive in four studies, and no better than placebo in five.8 This review also suggested that the research is characterized by methodological problems, including differences in the dosage amount used, and the use of self-report data.
In September 2003, zicam faced lawsuits from users who claimed that the product negatively affected their sense of smell, and sometimes taste. However, Zicam advocates assert that instructions on the container clearly indicate proper use, which will allow users to avoid these problems. In January 2006, 340 lawsuits were settled for $12 million.9 In early 2004, at the height of the controversy, Matrixx Initiatives, Inc., the maker of Zicam, claimed that only a small number of people had experienced problems and that anosmia (loss of smell) can, amongst others, also be caused by the common cold itself. Matrixx also claimed that zinc gluconate dissolves into zinc ions and gluconate, and that both are naturally occurring compounds which are found in all human tissues. They also claim that Zicam is a buffered gel which is formulated to have a neutral pH. The plaintiffs countered Matrixx, claiming that many of the patients had experienced a strong and very painful burning sensation when they used the product, indicating damage to the nasal tissue. No part of the settlement targeted the product's removal from sale, and the nasal gel continues to be available at drug stores throughout the USA. The two creators of Zicam have come under scrutiny. Robert Steven Davidson received his PhD from an unaccredited university which has since closed while Charles B. Hensley has been cited by the US Food and Drug Administration for selling unapproved drugs over the Internet.10
The U.S. Food and Drug Administration (FDA) considers zinc gluconate to be generally recognized as safe (GRAS) when used in accordance with good manufacturing practice, although this does not constitute a finding by the FDA that the substance is a useful dietary supplement.11
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