IDENTIFICATION AND USE: Neomycin is an aminoglycoside antibiotic. It is used in veterinary medicine as a bactericidal drug. HUMAN EXPOSURE AND TOXICITY: Prolonged administration could result in sufficient systemic drug levels to produce neurotoxicity, ototoxicity and/or nephrotoxicity. Dermatitis is usually caused by ointment with 0.5% neomycin. However, penetration of neomycin through normal skin is so slow that only half of those who are clinically sensitive will develop a positive patch test reaction to 0.5% neomycin. Characteristic lesions of the corneal epithelium in the form of tiny snowflakes, usually associated with sensation of irritation, may develop and may persist for weeks after application of neomycin to the eye is discontinued. Delayed-onset irreversible deafness, renal failure and death due to neuromuscular blockade (regardless of the status of renal function) have been reported following irrigation of both small and large surgical fields with minute quantities of neomycin. If renal insufficiency develops during oral therapy, consideration should be given to reducing the drug dosage or discontinuing therapy. Serious sensitivity reactions, such as anaphylaxis and dermatologic reactions including exfoliative dermatitis, toxic epidermal necrolysis, erythema multiforme, angioedema, and Stevens-Johnson syndrome, have been reported rarely in patients receiving aminoglycosides; fatalities have occurred rarely. Cross-sensitivity occurs among the aminoglycosides. In human lymphocytes neomycin tested negative for sister chromatid exchanges, but it was positive in chromosome aberration assay. ANIMAL STUDIES: No significant irritation was observed 24 hours after the intrapleural administration of single doses of solutions of 1 mL neomycin sulfate (0-100 mg/mL) to guinea pigs. Twelve dogs were injected intramuscularly with 24, 48, or 96 mg/kg bw/day neomycin. At the highest dose all dogs died within 1-3 weeks. Blood urea nitrogen was increased and renal function impaired as shown by decreased phenolsulfonphthalein excretion. There was no evidence of carcinogenicity in rats. In a 3-generation reproductive toxicity study groups of rats (40-20/sex/group) were administered neomycin sulfate via the diet at 0, 6.25, 12.5 or 25 mg/kg bw/day. Through all generations no treatment-related effects were observed in any of the parameters evaluated. Neomycin was positive in cytogenetic assay in mice bone marrow.
◉ Summary of Use during Lactation:Although no information exists on the excretion of neomycin into milk, other aminoglycoside antibiotics are poorly excreted into breastmilk. Newborn infants apparently absorb small amounts of aminoglycosides, but serum levels are far below those attained when treating newborn infections and systemic effects of neomycin are unlikely. Older infants would be expected to absorb even less neomycin. Monitor the infant for possible effects on the gastrointestinal flora, such as diarrhea, candidiasis (e.g., thrush, diaper rash) or rarely, blood in the stool indicating possible antibiotic-associated colitis.
Oral, topical, ophthalmic or otic neomycin should result in very low levels in breastmilk and present negligible risk to the infant,[1][2] although topical application to the nipple may increase the risk of diarrhea in the infant. Only water-miscible cream or gel products should be applied to the breast because ointments may expose the infant to high levels of mineral paraffins via licking.[3]
◉ Effects in Breastfed Infants:Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk:Relevant published information was not found as of the revision date.
来源:Drugs and Lactation Database (LactMed)
毒理性
副作用
皮肤致敏剂 - 一种可以诱导皮肤产生过敏反应的制剂。
Skin Sensitizer - An agent that can induce an allergic reaction in the skin.
来源:Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
The effect of the hexacationic aminoglycoside antibiotic, neomycin, on platelet physiological responses, such as aggregation and secretion, as well as changes in phosphoinositide metabolism was studied. Neomycin strongly inhibited thrombin-induced aggregation and secretion whereas the antibiotic had no effect on ionomycin- or TPA-induced platelet functions. The thrombin-induced enhancement of inositol phospholipid metabolism was strongly inhibited by the presence of neomycin whereas the TPA- or ionomycin-induced increase in inositol (32)P-polyphospholipids remained unaffected. The inhibitory effect of some other aminoglycoside antibiotics was compared to that of neomycin and the data demonstrate that the inhibition of platelet secretion and phosphatidic acid production was dependent on the cationic charge of the antibiotic.
Oral neomycin may potentiate the effects of oral anticoagulants, possibly by interfering with GI absorption or synthesis of vitamin K. Prothrombin times should be monitored in patients receiving concomitant oral aminoglycoside and oral anticoagulant therapy, and dosage of the anticoagulant should be adjusted as required.
Neomycin sulfate is poorly absorbed from the normal gastrointestinal tract. The small absorbed fraction is rapidly distributed in the tissues and is excreted by the kidney in keeping with the degree of kidney function. The unabsorbed portion of the drug (approximately 97%) is eliminated unchanged in the feces.
As with other aminoglycosides, the amount of systemically absorbed neomycin transferred to the tissues increases cumulatively with each repeated dose administered until a steady state is achieved. The kidney functions as the primary excretory path as well as the tissue binding site, with the highest concentration found in the renal cortex. With repeated dosings, progressive accumulation also occurs in the inner ear. Release of tissue-bound neomycin occurs slowly over a period of several weeks after dosing has been discontinued.
In one study in adults with normal renal function, a single 4-g oral dose of neomycin sulfate produced peak plasma neomycin concentrations of 2.5-6.1 ug/mL 1-4 hours after the dose in most patients; low plasma concentrations of the drug were detectable at 8 hours but the drug was undetectable at 24 hours.
In adults who received 1-g doses of oral neomycin sulfate and 1-g doses of oral erythromycin at 19, 18, and 9 hours before colorectal surgery, mean peak serum concentrations of neomycin were 0.59 ug/mL and were attained 12 hours after the first dose (i.e., 2 hours after the third dose).
新霉素生物合成的最后一步是在新霉素 C 的 C-5‴ 处差向异构化以产生新霉素 B。负责差向异构化的候选酶是假定的自由基 S-腺苷-L-甲硫氨酸 (SAM) 酶 NeoN,它是独一无二的在新霉素生物合成基因簇中编码,并且在新霉素生物合成中仍然是未指定的蛋白质。重构和还原的 NeoN 在 SAM 存在下显示出预期的差向异构化活性。在差向异构化过程中,消耗 1 当量的 SAM 将新霉素 C 转化为新霉素 B。通过检测来自基于氧化氘的缓冲液中氘原子的掺入,新霉素 C 对差向异构化具有反应性的位点被清楚地证实为 C-5‴解决方案。更多,NeoN 半胱氨酸残基的丙氨酸扫描显示 C249 是一个关键的氨基酸残基,它提供一个氢原子来完成差向异构化。此外,在 SAM 和新霉素 C 存在下对 C249A 变体的电子顺磁共振分析表明,在新霉素 C 的 C-5‴ 处生成了自由基中间体。 因此,本研究清楚地说明了新霉素
Compounds having antibacterial activity are disclosed. The compounds have the following structure (I):
including stereoisomers, pharmaceutically acceptable salts and prodrugs thereof, wherein Q
1
, Q
2
, Z
1
, Z
2
, Z
3
, Z
4
, R
1
, R
2
and R
3
are as defined herein. Methods associated with preparation and use of such compounds, as well as pharmaceutical compositions comprising such compounds, are also disclosed.