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銀作為醫療用途
Medical Use of Silver
(Wikipedia)
Silver has medical uses as an antiseptic and a disinfectant. The silver ion (Ag+) is bioactive and in sufficient concentration readily kills bacteria in vitro. Silver also kills bacteria in external wounds in living tissue, and physicians therefore use wound dressings containing silver sulfadiazine (Ag-SD) or silver nano-materials to treat external infections.[1][2][3][4][5][6] Wound dressings containing silver are increasing in importance due to the recent increase of antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus.[7] The disinfectant properties of silver are used in medical applications, such as urinary catheters and endotracheal breathing tubes, where the silver content is effective in reducing incidences of catheter-related bacteriuria and ventilator-associated pneumonia (VAP) respectively.[8][9][10][11] Silver is also used in bone prostheses, reconstructive orthopaedic surgery and cardiac devices,[12] as well as on surfaces and fabrics to reduce the spread of infection[13][14]
Since the 1990s, "colloidal silver" has been marketed as an alternative medicine product, with unsubstantiated, and in some jurisdictions illegal, claims of effectiveness. Medical authorities advise against the use of such colloidal silver preparations, as does the published medical literature, because of their lack of proven effectiveness and the risk of toxicity.[15][2][16][17] Historically, colloidal silver, a liquid suspension of microscopic silver particles, was also used as an internal medication to treat a variety of diseases. In the 1940s they were discontinued due to both the development of safe and effective modern antibiotics and concern about argyria and other side effects of silver products.[18][19]
Argyria consists of silver deposition in normal tissue, and occurs through chronic exposure to, or indiscriminate use of, silver products, most typically colloidal silver. The most extreme, and common, manifestation is that the skin turns irreversibly blue or grey, which can be cosmetically and socially debilitating, but which is not life-threatening.[20][13]
銀化合物作為醫療用途
Silver compounds in medical appliances
(Wikipedia)
The disinfectant properties of silver are used in some other medical applications, such as catheters and endotracheal breathing tubes.[54][55] The use of these devices is contraindicated for persons who are allergic to silver,[13] and no thorough testing and standardization of these products has yet been undertaken.[38] According to Lansdown (2006), the risk expected due to clinical exposure to silver is "minimal".[13]
Only chronic ingestion or inhalation of silver preparations leads to an accumulation of silver in the human body and can cause argyria, argyrosis (accumulation of silver in the eye) and other conditions.[13]A study on the use of silver-alloy catheters by the University of Michigan School of Medicine concluded that “The data supporting the use of silver alloy urinary catheters to reduce urinary catheter-related bacteriuria is reasonably strong.”[56] The study also concluded that silver alloy catheters are more effective than standard catheters for reducing bacteriuria in adults in hospital having short term catheterization, and that although they cost about $6 more than standard urinary catheters, they may be worth the extra cost since catheter-related infection is a common cause of nosocomial infection and bacteremia. Related meta-analysis also clarified discrepant results among earlier trials of silver-coated urinary catheters by revealing that silver alloy catheters are significantly more effective in preventing urinary tract infections than are silver oxide catheters.[57] These conclusions are supported by, among others, studies by the University Hospitals Leuven, Belgium[13] and the University Hospital for Anesthesiology and Surgical Intensive Care, Halle, Germany.[58][59]
In 2007, AGC Flat Glass Europe introduced the first antibacterial glass to fight hospital-caught infection: it is covered with a thin layer of silver.[60] Ionizable silver is also incorporated into fabrics to reduce the spread of bacteria.[13]
Ventilator-associated pneumonia (VAP) causes substantial morbidity. A 2008 study by Kollef et al concluded that “Patients receiving a silver-coated endotracheal tube had a statistically significant reduction in the incidence of VAP and delayed time to VAP occurrence compared with those receiving a similar, uncoated tube.” [61] In addition, the U.S. Food and Drug Administration (FDA) has recently approved an endotracheal breathing tube with a fine coat of silver for use in mechanical ventilation, after studies found it reduced the risk of ventilator-associated pneumonia.[11]
其他醫療用途
歷史性的應用
Other medical uses
Historical applications
Silver has had some medicinal uses going back for centuries. Physicians used it as an eyedrop for ophthalmic problems,[62] for various infections,[63][64] and sometimes internally for diseases such as tropical sprue, epilepsy, gonorrhea, and the common cold.[2][16][65] In the 1940s, however, the medical use of silver diminished, due to both the development of safe and effective modern antibiotics and concern about argyria and other side effects of silver products.[18][19] The total number of people who developed argyria as a result of colloidal silver preparations described by physicians is unknown. Fung & Bowden point out there were 365 cases of argyria from 1802 to 1951 reported in the medical literature by 1971 in total,[66] but this number would also include cases of argyria due to other kinds of exposure to silver.
The use of colloidal silver preparations (CSP) to treat or prevent "gonorrhea and gonorrheal conjunctivitis due to purported bacteriocidal properties" has largely been replaced "by less toxic antimicrobials with substantiated effectiveness."[19] Considering "direct application to mucous membranes in the nose, throat, urethra, and colon", there is "no evidence that CSP [colloidal silver preparations] are effective at these other sites and toxicity has been reported."[19] Although "silver products were infrequently promoted for oral use, benefits have been even more questionable."[19]
目前作為副藥物的使用
Current alternative medicine use
(Wikipedia)
From approximately 1990 there has been a resurgence of the promotion of colloidal silver as an alternative medicine treatment, marketed with claims of it being an essential mineral supplements or that it can prevent or treat numerous diseases like cancer, diabetes, HIV/AIDS, and herpes, [67] as well as tuberculosis.[2] Although colloidal silver products are legally available at health food stores in the United States and Australia and are marketed over the Internet as a dietary supplement, it is illegal in the U.S. and Australia for marketers to make such claims of medical effectiveness for colloidal silver. There is no medical evidence that colloidal silver is effective for any of these claimed indications.[68][69] Silver is not an essential mineral in humans; there is no dietary requirement for silver, and no such thing as a silver "deficiency".[2]
The commercial product referred to as "colloidal silver", includes solutions that contain various concentrations of ionic silver compounds, silver colloids or silver compounds bound to proteins in water. Such products with concentrations of 30 parts per million (ppm) or less are typically manufactured using an electrolysis process, whereas those with higher concentrations of 50 ppm or more are usually silver compounds that have been bound with a protein. These solutions are currently marketed for internal and external use as an alternative medical remedy though there is no scientific evidence to support its effectiveness in vivo.[2]Currently, there are no evidence-based medical uses for ingested colloidal silver. There are no clinical studies in humans demonstrating effectiveness, and a few reports of toxicity.[16]
The U.S. National Center for Complementary and Alternative Medicine has issued an advisory indicating that the marketing claims made about colloidal silver are scientifically unsupported, and that the silver content of marketed supplements varies widely and that colloidal silver products can have serious side effects to the consumer, including "argyria,... neurologic problems (such as seizures), kidney damage, stomach distress, headaches, fatigue, and skin irritation. Colloidal silver may interfere with the body's absorption of some drugs, such as penacillamine, quinolones, tetracyclines, and thyroxine."[2]
A number of case reports describe argyria after ingestion of colloidal silver marketed as an alternative-medicine treatment.[24][23][18][70] Colloidal silver may theoretically reduce the absorption of some medications, including tetracycline and quinolone antibiotics and penicillamine, thereby reducing the effectiveness of those medications.[16]
政府監管
Government regulation
In August 1999, the U.S. Food and Drug Administration (FDA) banned colloidal silver sellers from claiming any therapeutic or preventive value for the product, noting that colloidal silver was being marketed for numerous diseases without evidence of safety or effectiveness.[69] Before issuing its decision, the FDA requested comments and evidence from the public and from marketers of colloidal silver. In response, the FDA received isolated case reports and testimonials from marketers and consumers, but did not receive any scientific evidence. The FDA concluded: "None of the comments presented any evidence of safety or effectiveness beyond personal experience."[69] As a result, the product now has the status of a dietary supplement in the US; it can be promoted with general "structure-function" claims, but cannot be marketed as preventing or treating any illness.[69] Following this ruling, the FDA has issued numerous warnings to Internet sites which have continued to promote colloidal silver as an antibiotic or for other medical purposes.[71][72]
In 2002, the Australian Therapeutic Goods Administration (TGA) found that there were no legitimate medical uses for colloidal silver and no evidence to support its marketing claims. Given the associated safety risks, the TGA concluded that "efforts should be made to curb the illegal availability of colloidal silver products, which is a significant public health issue.[73]
http://en.wikipedia.org/wiki/Colloidal_silver
偽科學法典關於膠狀銀是錯的
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