Thimerosal mercury containing

Pharmaceuticals. A variety of mercury compounds have had pharmaceutical appHcations over the years, eg, mercury-containing diuretics and antiseptics. Whereas some mercury compounds remain available for use as antiseptics such as merbromin [129-16-8] mercuric oxide, and ammoniated mercury [10124-48-8] or as preservatives such as thimerosal [54-64-8] in dmgs and cosmetics, most have been supplanted by more effective substances. A detailed discussion of mercury-containing antiseptics is available (37). Many hospitals use mercury metal to serve as weight for keeping nasogastric tubes in place within the stomach. 

The mercury containing compound, thimerosal, has found use as an antimicrobial agent and is employed in biological vaccines and contact lens solutions. The decomposition products, methy lmercury chloride, dimethy lmercury, and mercury (III) chloride, have been separated by using RPLC with a C18 column and a 3% acetonitrile mobile phase [27,31]. Long-term degradation of thimerosal was demonstrated with complete recovery for all species. 

The LC/AAS has been employed for many years and Holak [43] used it to monitor the separation of a number of mercury containing drugs, mersalyl, thimerosal and phenyl mercuric borate. Suzuli et al. [44] used the technique to identify the heavy metals bound to isoproteins extracted from liver tissue. Robinson and Boothe [45] used the selectivity of the LC/AA system to monitor the alkyl lead compounds in sea water and Messman and Rains [46] separated four alkyl leads. 

A 2004 report by the Institute of Medicine s Immunization Safety Review Committee concluded that available evidence favored rejection of a causal relation between thimerosal-containing vaccines and autism. In like manner, a recent retrospective cohort study conducted by the CDC did not support a causal association between early prenatal or postnatal exposure to mercury from thimerosal-containing vaccines and neuropsychological functioning later in childhood. 

The use of mercury in fhe treafment of diseases such as syphihs, psoriasis, and congestive heart failure began more fhan fwo cenfuries ago. Although mercury s medicinal use has tapered off in recent years, mercury compounds such as thimerosal and phenylmercuric nitrate still have a limited use in human and veterinary medicines to prevent bacterial growth in injection solutions (e.g. vaccines), antiseptics, and skin ointments. The United States Food and Drug Administration [1] estimates that approximately 200 human and veterinary drug products marketed in the U.S. contain mercury as an active or inactive ingredient. 

Included in the FDA Inactive Ingredients Guide (IM, IV, and SC injections ophthalmic, otic, and topical preparations). Included in nonparenteral and parenteral medicines licensed in the UK. In the UK, the use of thimerosal in cosmetics is limited to 0.003% w/w (calculated as mercury) as a preservative in shampoos and hair-creams, which contain nonionic emulsifiers that would render other preservatives ineffective. The total permitted concentration (calculated as mercury) when mixed with other mercury compounds is 0.007% w/w. Included in the Canadian List of Acceptable Non-medicinal Ingredients. 

In the past, mercurous chloride was widely used in medicinal products such as laxatives, worming medications, and teething powders. These older medicines should be properly disposed of and replaced with safer and more effective medicines. Other chemicals containing mercury, such as mercurochrome and thimerosal (sold as Merthiolate and other brands), are still used as antiseptics or as preservatives in eye drops, eye ointments, nasal sprays, and vaccines. Some... 

Geier DA, Geier MR. A comparative evaluation of the effects of MMR immunization and mercury doses from thimerosal-containing chEdhood vaccines on... 

Each 0.5 mL of the vaccine consists of 10 meg of hepatitis B surface antigen adsorbed on 0.25 mg of aluminum as aluminum hydroxide with a trace amount of thimerosal (<0.5 meg of mercury) from the manufacturing process, sodium chloride (9 mg/mL), and phosphate buffers (disodium phosphate dihydrate, 0.98 mg/mL sodium dihydrogen phosphate dihydrate, 0.71 mg/mL). Each 1-mL adult dose consists of 20 meg of hepatitis B surface antigen adsorbed on 0.5 mg of aluminum as aluminum hydroxide. The adult vaccine is formulated without preservatives. The adult formulation contains a trace amount of thimerosal (<1.0 meg of mercury) from the manufacturing process, sodium chloride (9 mg/mL), and phosphate buffers (disodium phosphate dihydrate, 0.98 mg/mL sodium dihydrogen phosphate dihydrate, 0.71 mg/mL). 

The vaccine-mercury linkage, recently under heavy suspicion as a cause of postnatal autism, is no longer considered significant. The reason given is that the cessation of the use of postnatal vaccines containing mercury (in the compound thimerosal) as a preservative has produced no decrease in the prevalence of autism.73 But there might be other reasons for the absence of a decrease in prevalence other than an absence of linkage. 

The possible health risks of thimerosal (CH CH —Hg—S—C H —COOH), an antibacterial preservative used in vaccines, have been debated. The FDA has determined that that there is a significant safety margin incorporated into all the acceptable mercury exposure limits, and there are no data or evidence of any harm caused by the level of exposure that some children may have encountered in following the existing immunization schedule. Nevertheless, the availability of vaccines with alternate preservatives led to the removal of all vaccines containing thimerosal. 

The test identifies the substance to be examined as either a salt of mercury, Hg2 + or Hg + or a substance containing covalently bound mercury. At the present, reference to mercury is made in only two monographs. One is an inorganic salt mercuric chloride, HgCl2, which has antibacterial action through precipitation proteins and thimerosal (Figure 3.24.1), which likewise is an antiseptic but also a preservative in pharmaceutical product. The use... 

Reproductive system In 278624 subjects in birth cohorts from 1990 to 1996 exposure to mercury in thimerosal-containing vaccines was associated with premature puberty [82 ]. 

The debate about the relation between autism and mercury (as thimerosal) in vaccines continues, without useful conclusions [37 ]. In a population-based study of the pharmacokinetics of mercury after immunization of 72 premature infants weighing 2000-3000 g at birth, the mean maximal blood mercury concentration was 3.6 fig/l, and it occurred at 1 day after immunization the maximal mean stool mercury concentration was 35 ng/g, and it occurred on day 5 urine mercury was almost undetectable [38 ]. The blood mercury half-life was 6.3 (95% Cl = 3.9S.8) days, and mercury concentrations returned to prevaccination values by day 30. The blood half-life of intramuscular ethyl mercury from thimerosal in vaccines given to premature infants is substantially shorter than that of oral methyl mercury in adults. Because of the differing pharmacokinetics, exposure guidelines based on oral methyl mercury in adults may not be accurate for children who receive thimerosal-containing vaccines. 

---