Myacine - General Information
A component of neomycin that is produced by Streptomyces fradiae. On hydrolysis it yields neamine and neobiosamine B. (From Merck Index, 11th ed)
Pharmacology of Myacine
Myacine is an aminoglycoside antibiotic. Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth. Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis. Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses.
Myacine for patients
Before administering the drug, patients or members of their families should be informed of possible toxic effects on the eighth nerve. The possibility of acute toxicity increases in premature infants and neonates.
Caution should be taken in concurrent or serial use of other neurotoxic and/ or nephrotoxic drugs because of possible enhancement of the nephrotoxicity and/or ototoxicity of neomycin.
Caution should also be taken in concurrent or serial use of other aminoglycosides and polymyxins because they may enhance neomycinís nephrotoxicity and/or ototoxicity and potentiate neomycin sulfateís neuromuscular blocking effects.
Oral neomycin inhibits the gastrointestinal absorption of penicillin V, oral vitamin B-12, methotrexate and 5-fluorouracil. The gastrointestinal absorption of digoxin also appears to be inhibited. Therefore, digoxin serum levels should be monitored.
Oral neomycin sulfate may enhance the effect of coumarin in anticoagulants by decreasing vitamin K availability.
Neomycin sulfate oral preparations are contraindicated in the presence of intestinal obstruction and in individuals with a history of hypersensitivity to the drug.
Patients with a history of hypersensitivity or serious toxic reaction to other aminoglycosides may have a cross-sensitivity to neomycin.
Neomycin sulfate oral preparations are contraindicated in patients with inflammatory or ulcerative gastrointestinal disease because of the potential for enhanced gastrointestinal absorption of neomycin.
Additional information about Myacine
Myacine Indication: For the adjunctive treatment of acute hepatic failure, alcoholic cirrhosis of the liver, and suppression of intestinal bacteria.
Mechanism Of Action: Aminoglycosides like neomycin "irreversibly" bind to specific 30S-subunit proteins and 16S rRNA. Specifically neomycin binds to four nucleotides of 16S rRNA and a single amino acid of protein S12. This interferes with decoding site in the vicinity of nucleotide 1400 in 16S rRNA of 30S subunit. This region interacts with the wobble base in the anticodon of tRNA. This leads to interference with the initiation complex, misreading of mRNA so incorrect amino acids are inserted into the polypeptide leading to nonfunctional or toxic peptides and the breakup of polysomes into nonfunctional monosomes.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Neomycin
Synonyms: Caswell No. 595; Neomycin B Sulfate; Neomycin Sulfate; Neomycin Sulphate; Neomycin trisulfate salt hydrate; USAF CB-19
Drug Category: Anti-Bacterial Agents; Antibiotics
Drug Type: Small Molecule; Approved; Withdrawn
Absorption: Poorly absorbed from the normal gastrointestinal tract. Although only approximately 3% of neomycin is absorbed through intact intestinal mucosa, significant amounts may be absorbed through ulcerated or denuded mucosa or if inflammation is present.
Toxicity (Overdose): LD50 = 200 mg/kg (rat). Because of low absorption, it is unlikely that acute overdosage would occur with oral neomycin. However, prolonged administration could result in sufficient systemic drug levels to produce neurotoxicity, ototoxicity and/or nephrotoxicity.
Protein Binding: Protein binding studies have shown that the degree of aminoglycoside protein binding is low and, depending upon the methods used for testing, may be between 0% and 30%.
Biotransformation: Neomycin undergoes negligible biotransformation after parenteral administration.
Half Life: 2 to 3 hours
Dosage Forms of Myacine: Solution / drops Ophthalmic
Chemical IUPAC Name: (2R,3S,4R,5R,6R)-5-amino-2-(aminomethyl)-6-[(1R,2R,3S,4R,6S)-4,6-diamino-2-[(2S,3R,4S,5R)-4-[(2R,3R,4R,5S,6S)-3-amino-6-(aminomethyl)-4,5-dihydroxyoxan-2-yl]oxy-3-hydroxy-5-(hydroxymethyl)oxolan-2-yl]oxy-3-hydroxycyclohexyl]oxyoxane-3,4-diol
Chemical Formula: C23H46N6O13
Neomycin on Wikipedia: https://en.wikipedia.org/wiki/Neomycin
Organisms Affected: Enteric bacteria and other eubacteria