Colistin (Colistimethate)

Indications

Colistin (Colistimethate) is used for: Bowel sterilization, gastrointestinal tract infections, respiratory tract infections

Adult Dose

Oral Bowel sterilisation; Gastrointestinal infections Adult: As colistin sulfate: 1.5-3 MIU tid. Child: As colistin sulfate: <15 kg: Not suitable; 15-30 kg: 0.75-1.5 MIU tid. Parenteral Severe Gram-negative infections Adult: As colistimethate Na (strength expressed in terms of colistin base): 2.5-5 mg/kg/day in 2-4 divided doses. Max: 5 mg/kg/day. Inhalation Adjunct to antimicrobial therapy in resp infections As colistimethate Na: 1-2 million units twice daily. Max: 2 million units 3 times/day for up to 3 mth in frequent recurrent infections.

Child Dose

Oral Bowel sterilisation; Gastrointestinal infections Child: As colistin sulfate: <15 kg: Not suitable; 15-30 kg: 0.75-1.5 MIU tid. Parenteral Severe Gram-negative infections Child: IV, IM 2.5–5 mg base/kg/day based on IBW q8h Up to 5–7 mg base/kg/day

Renal Dose

Renal impairment: CrCl (ml/min) 20-50 1-2 million units every 8 hr. 10-20 1 million units every 12-18 hr. <10 1 million units every 18-24 hr

Administration

Reconstitution: Reconstitute 150 mg vial w/ 2 mL sterile water for inj. Reconstituted soln provides colistimethate Na at a concentration equivalent to 75 mg/mL colistin base. IV/IM Administration IM or IV push: half of daily dose injected over 3-5 min q12 hr IV infusion: half of daily dose injected over 3-5 min; other half mixed with compatible IV solution and administered 1-2 hr later at 5-6 mg/hr

Contra Indications

Hypersensitivity. Anuria; porphyria; myasthenia gravis. Pregnancy and lactation.

Precautions

Preexisting renal impairment; disorders of neuromuscular transmission. Monitor serum creatinine and BUN regularly while on treatment. Lactation: unknown; use caution

Pregnancy-Lactation

Interactions

Potentiates chloramphenicol and trimethoprim. Potentially Fatal: Potentiates action of curariform muscle relaxants. Potentiates nephrotoxicity of aminoglycosides and cephalothin.

Adverse Effects

Side effects of Colistin (Colistimethate) : 1-10% Dizziness,Paresthesia, tingling sensation <1% Neurotoxicity,Nephrotoxicity,Acute respiratory failure (inhalation route),Respiratory tract paralysis Potentially Fatal: Acute tubular necrosis, neurotoxicity; nephrotoxicity. The neuromuscular blockade is potentially fatal, when associated with use of curariform muscle relaxants.

Mechanism of Action

Colistin sulfate is a polymyxin antibiotic which is active against aerobic gram-negative bacteria including most enterobacteria except Proteus, Providentia and Serratia. Susceptible organisms include P. aeruginosa, Legionella spp, H. influenzae, Acinetobacter, V. cholera, Salmonella, Shigella and Pasteurella. Colistin sulfate is used orally while colistimethate sodium is used parenterally or via inhalational route.