Additional adjuvants

In addition to the immunostimulatory substances discussed above, the adjuvanticity of a variety of other substances is also being appraised. These include saponins, liposomes and ISCOMs. 

Saponins are a family of glycosides (sugar derivatives) widely distributed in plants. Each saponin consists of a sugar moiety bound to a sapogenin (either a steroid or a triterpene). The immunostimulatory properties of the saponin fraction isolated from the bark of Quillaja (a tree) has been long recognized. Quil A (which consists of a mixture of related saponins) is used as an adjuvant in selected veterinary vaccines. However, its haemolytic potential precludes its use in human vaccines. Research efforts continue in an attempt to identify individual saponins (or derivatives thereof) that would make safe and effective adjuvants for use in human medicine. 

The adjuvanticity of liposomes depends upon their composition, number of layers and charge characteristics. They act as effective adjuvants for both protein- and carbohydrate-based antigens and help stimulate both B- and T-cell responses. Their likely mode of action includes depot formation, but they also possibly increase/enhance antigen presentation to macrophages. The exact molecular mechanism(s) by which they stimulate a T-cell response remains to be elucidated, 

ISCOMs are stable (non-covalent) complexes composed of a mixture of Quil A, cholesterol and (an amphipathic) antigen. ISCOMs stimulate both humoral and cellular immune responses and have been used in the production of some veterinary vaccines. Their use in humans, however, has not been licensed so far, mainly due to safety concerns relating to the Quil A component. 

In summary, therefore, a whole range of adjuvants have thus far been identified/developed. Problems of toxicity have precluded the use of many of these adjuvants (particularly in humans). However, research efforts continue in an attempt to develop the next generation of safe and, hopefully, even more effective vaccine adjuvants. 

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The primary course of DTP protection consists of three doses of a combined vaccine, each dose separated by at least 1 month and commencing not earlier than 2 months of age. In such combinations the pertussis component ofthe vaccine acts as an additional adjuvant for the toxoid components. Monovalent pertussis and tetanus vaccines, and combined vaccines lacking the pertussis component (DT) are available. If pertussis vaccination is contraindicated or refused then DT vaccine alone should be offered. The primary course of pertussis vaccination is considered sufficient to confer life-long protection, especially since the mortality associated with disease declines markedly after infancy. The risks associated with tetanus and diphtheria infection persist... 

To solve this problem, modern pesticide formulations use a variety of additives (adjuvants) to improve the mass efficiency. Surfactants and polymeric rheology modifiers are used to reduce spray drift, surfactants are used to modify surface tension and reduce... 

Following resection of liver metastases, infusion of chemotherapy through the portal vein provides an additional adjuvant treatment approach. Historically 5-FU and floxuri-dine have been the agents used most commonly for hepatic portal vein infusion owing to their high metabolism in the liver. Although some studies demonstrate a decrease in recurrence rates, the value of portal vein infusion of chemotherapy for colon cancer remains to be determined.25 Table 88-4 summarizes adjuvant treatment recommendations for colon cancer. 

Part 178—Indirect food additives Adjuvants, production aids, and sanitizers... 

FDA. 2001b. Indireet food additives Adjuvants, production aids, and sanitizers. Sanitizing solutions. U.S. Food and Drug Administration. Code of Federal Regulations. 21 CFR 178.1010. 

FDA, Department of Health and Human Services. 1981. Indirect food additives Adjuvants, production aids, and sanitizers hydrogen peroxide. Final Rule. Federal Register 46, 2341-2343. 

Katare, Y. K., Muthukumaran, T., and Panda, A. K. (2005), Influence of particle size, antigen load, dose and additional adjuvant on the immune response from antigen loaded PLA microparticles, Int. J. Pharm., 301,149-160. 

Portal Administration. Because the liver is the site of recurrence in about 40% of patients, infusion of chemotherapy via the portal vein provides an additional adjuvant treatment approach. The rationale for this is based on a belief that intraoperative manipulation of the tumor... 

Source Indirect Food Additives Adjuvants, Production Aids and Sanitizers. Mineral Oil, 21 CFR 178.3620. With permission. 

FDA. 1984. Indirect food additives Adjuvants production aids and sanitizers. 21 CFR Part 178 308. 

The plastics manufacturer must consider his product from the points of view of basic polymer, additives/adjuvants and migration of anything from the plastic into the packaged commodity. 

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