Comparative Pharmacology
Head-to-head clinical analysis: BETHKIS versus NEOMYCIN AND POLYMYXIN B SULFATES AND DEXAMETHASONE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: BETHKIS versus NEOMYCIN AND POLYMYXIN B SULFATES AND DEXAMETHASONE.
BETHKIS vs NEOMYCIN AND POLYMYXIN B SULFATES AND DEXAMETHASONE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Tobramycin, an aminoglycoside antibiotic, binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibiting protein synthesis, leading to bacterial cell death.
Neomycin and polymyxin B sulfates are aminoglycoside and polypeptide antibiotics, respectively, that inhibit bacterial protein synthesis and disrupt bacterial cell membrane integrity. Dexamethasone is a corticosteroid that suppresses inflammation by inhibiting phospholipase A2, reducing prostaglandin and leukotriene synthesis.
4 IU/kg (1 mg/kg) intramuscularly or subcutaneously once weekly for 4 weeks, then a maintenance dose of 2 IU/kg (0.5 mg/kg) once weekly.
Ophthalmic: 1-2 drops in affected eye(s) every 3-4 hours; severe infections: 1-2 drops every 1-2 hours, then taper. Otic: 3-4 drops in affected ear(s) 3-4 times daily.
None Documented
None Documented
Terminal elimination half-life 2-3 hours in patients with normal renal function; prolonged to 20-40 hours in severe renal impairment (CrCl <30 mL/min).
Neomycin: 2-3 hours (IM/IV, if absorbed); Polymyxin B: 6-7 hours; Dexamethasone: 3-4.5 hours. Clinically, neomycin's half-life is not relevant due to minimal absorption; polymyxin B prolonged in renal impairment; dexamethasone CNS effect lasts > half-life.
Primarily renal excretion of unchanged drug via glomerular filtration; ~90% of absorbed dose excreted in urine within 24 hours; biliary/fecal elimination <5%.
Neomycin: ~99% of oral dose eliminated unchanged in feces; <1% absorbed renally excreted. Polymyxin B: ~60% renal elimination of absorbed fraction; remainder non-renal via biliary/fecal. Dexamethasone: ~65% renal as metabolites, <10% unchanged; ~35% fecal.
Category C
Category A/B
Aminoglycoside Antibiotic
Aminoglycoside Antibiotic