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Colistimethate
- indication:For the treatment of acute or chronic infections due to sensitive strains of certain gram-negative bacilli, particularly <i>Pseudomonas aeruginosa</i>.
- pharmacologypharmacology:
- mechanism: Colistimethate is a surface active agent which penetrates into and disrupts the bacterial cell membrane. Colistimethate is polycationic and has both hydrophobic and lipophilic moieties. It interacts with the bacterial cytoplasmic membrane, changing its permeability. This effect is bactericidal. There is also evidence that polymyxins enter the cell and precipitate cytoplasmic components, primarily ribosomes.
- toxicity: Oral LD<sub>50</sub> in rats is 5450 mg/kg. Overdosage with colistimethate can cause neuromuscular blockade characterized by paresthesia, lethargy, confusion, dizziness, ataxia, nystagmus, disorders of speech and apnea. Respiratory muscle paralysis may lead to apnea, respiratory arrest and death.
- absorprion: Very poor absorption from gastrointestinal tract.
- halflife: 2-3 hours following either intravenous or intramuscular administration in adults and in the pediatric population, including premature infants.
- roouteelimination:
- volumedistribution:
- clearance: