Parenteral Dosage: Usual dosage: 2.5 to 5 mg/kg/day IM or IV or IV infusion in 2 to 4 divided doses, depending upon the severity of the infection. Maximum dose: 5 mg/kg/day.
Dosage in renal impairment: Reduce the daily dose in the presence of any renal impairment.
Recommended dose for adults with impaired renal function is provided in Table. (See Table.)
Oral Inhalation Dosage: For treatment of Pseudomonas aeruginosa respiratory tract infection in cystic fibrosis patients, colistimethate sodium has been given by oral inhalation via nebulization in a dosage of 33.33-66.66 mg of colistin 2 or 3 times daily. This corresponds to a dosage of 1-2 million international units 2 or 3 times daily.
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Mode of Administration: Colistimethate sodium is administered by IM injection, IV injection, or continuous IV infusion. The drug also has been administered by oral inhalation via nebulization.
IV Injection: The appropriate dose should be injected directly into a vein over 3- to 5-minute period.
IV Infusion: For continuous IV infusion, one-half of the total daily dose should be injected directly into a vein over 3- to 5-minute period; the remaining one-half of the total daily dose should be added to compatible IV solution and administered 1-2 hours later (over the next 22-23 hours) by slow IV infusion. The infusion rate should be 5-6 mg/hour in patients with normal renal function. For patients with impaired renal function, the infusion rate should be reduced depending on the degree of renal impairment.
Preparation for IM or IV administration: The 150 mg vial should be reconstituted with 2 ml of sterile water for injection. During reconstitution swirl gently to avoid frothing. The reconstituted solution provides; colistimethate sodium at a concentration equivalent to 75 mg/ml colistin base activity and should be used promptly after preparation.
Preparation for continuous IV infusion: The reconstituted solution should be added to a compatible IV solution (e.g., NSS, D5W, D5S, D5S/2·, D5S/4, Ringer's lactated or invert sugar 10%). The specific IV solution and volume of the solution used should be based on the patient's fluid and electrolyte requirements. Freshly prepare any infusion containing colistimethate sodium.
Preparation for Oral Inhalation: For oral inhalation via nebulization, an isotonic solution of colistimethate sodium has been prepared by diluting the appropriate dose in 2-4 ml of preservative-free 0.9% sodium chloride injection, sterile water, or a mixture of 0.9% sodium chloride injection and sterile water. Administer solution promptly following preparation to decrease possibility of high concentrations of colistin from forming which may lead to potentially life-threatening lung toxicity.