About Dexamethasone A potent synthetic glucocorticoid, Antiasthmatic, anti-inflammatory and immunosuppressant. About Neomycin An aminoglycoside, Antibiotic, Ammonium Detoxicant. Mechanism of Action of Neomycin This aminoglycoside cause protein synthesis inhibition by "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. Interactions for Dexamethasone ENDOCRINE SYSTEM: Barbiturates: Decreases efficacy of dexamethasone. Carbamazepine, Primidone: Decreases efficacy.