Neomycin toxic

These dm are contraindicated in patients with known hypersensitivity to the drug or any components of the drug. Because neomycin toxicity can cause nephrotoxicity and ototoxicity, neomycin is used cautiously in patients with extensive bums or trophic ulceration when extensive absorption can occur. 

Masur H, Whelton PK, Whelton A (1976) Neomycin toxicity revisited. Arch Surg 111 822-825... 

Although tyrothricia is too toxic for parenteral therapy, it was formerly sold in the United States as oral lo2enges. Modem tyrothricin formulations are composed of 70—80% tyrocidines and 30—20% linear gramicidins. Tyrocidines are not as active as linear gramicidins and are too toxic for any therapeutic use by themselves. The bactericidal linear gramicidins are used in the United States solely as an ophthalmic solution in combination with polymyxin B sulfate and neomycin sulfate. The linear gramicidin is used in this aqueous product as a substitute for bacitracin, which lacks stabiUty under such conditions. 

The answer is a. (Hardman, pp 1105-1108.) The activity of streptomycin is bactericidal for the tubercle bacillus organism. Other aminoglycosides (e.g., gentamicin, tobramycin, neomycin, amikacin, and kanamycin) have activity against this organism but are seldom used clinically because of toxicity or development of resistance. 

A salt formed by reacting neomycin with p-amino benzene sulphoacetamide was described by two groups of workers 2,73t The salt combined the chemotherapeutic properties of the components. Another unusual salt of neomycin described in the literature is that with m-sulphonylbenzaldehyde isonicotinoylhydrazone . The compound is reputed to be less toxic than neomycin and to be more active against tubercule bacilli than the individual constituents. 

Not all neomycin salts, however, possess advantages such as a reduced toxicity. In fact, the orotic acid(1,2,3,6-tetrahydro-2,6-dioxo-4-pyrimidine carboxylic acid) salt was reported to have a greater toxicity than neomycin itself74f75. some uncertainty of this fact is apparent as other authors have reported the two compounds to be of a similar toxicity 6. The salt of neomycin with usnic acid(an antibacterial substance found in lichens) has been reported to have less antibacterial activity than the neomycin used in the preparation of the salt. 

The neomycin molecule contains both free amino and free hydroxy groups. Many workers have exploited the possibility of chemical de-rivatisation at these positions in attempts to reduce the toxicity of the parent antibiotic. Substitution of methane sulphonate groups at the amino nitrogen has been reported by Umezawa et al83,84 and by Boissier et al . Both groups of workers described the derivative to be less toxic... 

The formation of a zinc-neomycin complex has been reported by Chornock95 and by Keller and Cosar96. Electrophoresis was used to demonstrate the formation of a complex which was described as possessing a similar biological activity to neomycin but a decreased toxicity. 

Certain antibiotics such as the tetracyclines, streptomycin, neomycin and kanamycin can cripple the tubules if taken in excessive amounts. Toxic damage to the kidneys can affect not only their filtration functions, but can alter the organs control over blood levels of certain critical molecules. A complex biochemical-hormonal system controlling blood pressure and volume, for example, is regulated by the kidneys, so that chronic kidney damage can inflict damage on the... 

Neomycin is too toxic for parenteral use. Its only use is via the oral route for pre-operative sterilization of the bowel or for selective decontamination in hematologic patients. However absorption may be increased significantly if there is inflammation of the bowel wall and such absorption can pose problems for the patient. 

Bacitracin is highly nephrotoxic when administered systemically and is only used topically (Chapter 62). Bacitracin is poorly absorbed. Topical application results in local antibacterial activity without systemic toxicity. Bacitracin, 500 units/g in an ointment base (often combined with polymyxin or neomycin), is indicated for the suppression of mixed bacterial flora in surface lesions of the skin, in wounds, or on mucous membranes. Solutions of bacitracin containing 100-200 units/mL in saline can be used for irrigation of joints, wounds, or the pleural cavity. 

Neomycin and kanamycin are now limited to topical and oral use. Neomycin is too toxic for parenteral use. With the advent of more potent and less toxic aminoglycosides, parenteral administration of kanamycin has also been largely abandoned. Paromomycin has recently been shown to be effective against visceral leishmaniasis when given parenterally (see Chapter 52), and this serious infection may represent an important new use for this drug. 

Gramicidin is available only for topical use, in combination with other antibiotics such as neomycin, polymyxin, bacitracin, and nystatin. Systemic toxicity limits this drug to topical use. The incidence of sensitization following topical application is exceedingly low in therapeutic concentrations. 

Gene transfer of mouse and human CD34+ HSCs, which were genetically modified by a retroviral virus encoding ADA cDNA and the neomycin-resistance marker gene, have been extensively characterized in mouse models without reports of toxicity. Furthermore, none of the preclinical studies for ADA-SCID have demonstrated evidence of cancer in animals treated with this same gene transfer approach [515137], [666652], [666655]. 

Most aminoglycosides are complexes of several almost identical components differing either in the degree of methylation of one amino sugar unit, as in the case of gentamicin, or in the stereochemistry of the disaccharide unit, as in the case of neomycin. Differences in the substitutions on the basic ring structures between the various aminoglycosides account for the relatively minor differences in antimicrobial spectra, patterns of resistance, and toxicity. 

Neomycin is particularly ototoxic and nephrotoxic when given parenterally. As with gentamicin and kanamycin, the nephrotoxicity may be reversible but the ototoxicity is usually irreversible and deafness may occur following oral administration, instillation into cavities, or topical use. It may block neuromuscular action and respiratory depression has been reported. Local treatments may cause hypersensitivity, rashes, pruritus, and anaphylaxis. Neomycin is not geno-toxic. 

Mora and coworkers201 studied the in vivo interaction, in mice, of toxic levels of cationic macromolecules with the carboxyl and sulfate derivatives of polyglucose. Toxic levels of polymyxin, protamine, streptomycin, and neomycin could be counteracted, if the synthetic macroanions were injected five to ten minutes after administration of the proteins. Subcutaneous administration of the anionic polyglucoses prior to intra-peri toneal injection of toxic levels of basic proteins afforded protection to the mice, and also demonstrated that the animals could survive, even when the two injections were by different routes. 

Peptide antibiotics are not often the drags of first choice for systemic therapy of important human disease. However, the World Health Organization, which chooses drags especially for Third World use based on efficacy, safety, quality, price, and availability, includes as essential such peptide antibiotics as bleomycin, dactinomycin, and bacitracin (as an ointment containing neomycin), plus several /8-lactams. See also Antibiotics, Antibiotics -Lactams. Systemic use of peptide antibiotics is many times limited by nephroloxicity and other toxicities. Semisynthesis or complete chemical synthesis of analogues of peptide antibiotics has most often not resulted in improved drags. 

Keller, H., W Kripe, H. Sous, and H. Mickter. 1956b. The pantothenates of streptomycin, viomycin, and neomycin New and less toxic salts. Antibiotics Annual, 1955-1956, edited by H. Welch and F. Marti-lban ez, 35-38. New York Medical Encyclopedia. 

Aminoglycosides are a group of bactericidal antibiotics originally obtained from various streptomyces species and sharing chemical, antimicrobial, pharmacologic, and toxic characteristics. The group includes streptomycin, neomycin, kanamycin, amikacin, gentamicin, tobramycin, sisomicin, netilmicin, and others. 

Owing to their significant toxicity with systemic administration, polymyxins are now restricted to topical use. Ointments containing polymyxin B, 0.5 mg/g, in mixtures with bacitracin or neomycin... 

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