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Other strengths and forms by Square Pharmaceuticals PLC, Pabna

Indications & Uses

Colistimethate Sodium is used to treat acute or chronic infections caused by sensitive strains of certain gram-negative bacilli. It is particularly indicated for infection caused by sensitive strains of Pseudomonas aeruginosa. It is not indicated for infections due to Proteus or Neisseria. Colistimethate Sodium works very well against infections caused by these gram-negative organisms: Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa.

Pharmacology

Colistimethate is a surface active agent. It penetrates the bacterial cell membrane and disrupts it. The molecule is polycationic and has both hydrophobic and lipophilic moieties, and it interacts with the bacterial cytoplasmic membrane and changes its permeability. This action is bactericidal. There is also evidence that polymyxins enter the cell and precipitate cytoplasmic components, mainly the ribosomes.

Dosage Reference

Reference Information Only

Dosages shown are general references from official sources. Always consult your doctor or pharmacist for personalized dosing.

Adults:

The usual maintenance dose of colistimethate sodium is 9 MIU a day, given in 2 to 3 divided doses. If the patient is critically ill, a loading dose of 9 MIU should be given.

Renal impairment

Patients with renal impairment need their dose adjusted. A reduced dose is recommended when creatinine clearance is below 50 ml/min, and the daily dose should be given twice daily.

Creatinine clearance <50-30 ml/min: daily dose 5.5-7.5 MIU

Creatinine clearance <30-10 ml/min: daily dose 4.5-5.5 MIU

Creatinine clearance <10 ml/min: daily dose 3.5 MIU

Haemodialysis (HD) patients

On days without HD, the dose is 2.25 MIU/day (2.2-2.3 MIU/day). On HD days it is 3 MIU/day, and this should be given after the HD session. Twice daily dosing is recommended here too.

Pediatric population

Base the dose on lean body weight. For children up to 40 kg, the dose is 75,000-150,000 IU/kg/day, divided into 3 doses. For children over 40 kg, more than 150,000 IU/kg/day has been reported in children with cystic fibrosis.

Hepatic impairment

There are no data in patients with hepatic impairment, so take caution when giving colistimethate sodium to these patients.

Side Effects

Colistimethate Sodium has been linked with a number of side effects. These include gastrointestinal upset, tingling of the extremities and tongue, slurred speech, dizziness, vertigo and paresthesia. Some people get generalized itching, urticaria and rash, or fever. Changes in kidney function have also been reported: increased blood urea nitrogen (BUN), elevated creatinine, decreased creatinine clearance, nephrotoxicity and decreased urine output. Respiratory distress and apnea can occur as well.

Cautions & Contraindications

Warnings & Precautions

Colistimethate Sodium needs careful handling in patients with impaired renal function. If the kidneys are actually impaired, the medicine can still be used, but the greatest caution is needed and the dose should be reduced in proportion to how severe the impairment is. Take the same care when giving Colistimethate Sodium to neonates, infants and children.

Contraindications

Don't give Colistimethate Sodium Parenteral to anyone who has had a sensitivity reaction to the medicine or to any of its components.

Pregnancy & Breastfeeding

No adequate and well-controlled studies have looked at the use of Colistimethate in pregnant women. Colistimethate crosses the placental barrier in humans, so it should be used during pregnancy only if the likely benefit justifies the possible risk to the fetus. It isn't known whether Colistimethate passes into human breast milk. For that reason, take care when giving it to nursing women.

⚠️ Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.

Overdose

Too much Colistimethate Sodium can cause neuromuscular blockade. The signs are paresthesia, lethargy, confusion, dizziness, ataxia, nystagmus, disorders of speech and apnea. Paralysis of the respiratory muscles may lead to apnea, respiratory arrest and death.

An overdose can also cause acute renal failure, which shows up as decreased urine output and increases in serum concentrations of B.U.N and creatinine. As with any overdose, Colistimethate Sodium therapy should be stopped and general supportive measures should be used.

⚠️ In an emergency call 999 or go to the nearest hospital emergency department.

Storage

Keep Colistimethate Sodium below 30°C before it is reconstituted. Once reconstituted, store it at 2°C to 8°C and do not freeze it. Use it within 24 hours.

Drug Interactions

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Common questions about Gigabac 150 mg

What is Gigabac 150 mg IM/IV Injection?

Gigabac 150 mg IM/IV Injection is a medicine that contains Colistimethate Sodium. It is made by Square Pharmaceuticals PLC, Pabna. It belongs to the Other antibacterial preparation group of medicines.

What is Gigabac used for?

Colistimethate Sodium is used to treat acute or chronic infections caused by sensitive strains of certain gram-negative bacilli. It is particularly indicated for infection caused by sensitive strains of Pseudomonas aeruginosa.

What are the side effects of Gigabac?

Colistimethate Sodium has been linked with a number of side effects. These include gastrointestinal upset, tingling of the extremities and tongue, slurred speech, dizziness, vertigo and paresthesia.

Can I take Gigabac during pregnancy or while breastfeeding?

No adequate and well-controlled studies have looked at the use of Colistimethate in pregnant women. Colistimethate crosses the placental barrier in humans, so it should be used during pregnancy only if the likely benefit justifies the possible risk to the fetus. Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.

What happens if I take too much Gigabac?

Too much Colistimethate Sodium can cause neuromuscular blockade. The signs are paresthesia, lethargy, confusion, dizziness, ataxia, nystagmus, disorders of speech and apnea. In an emergency call 999 or go to the nearest hospital emergency department.

How should I store Gigabac?

Keep Colistimethate Sodium below 30°C before it is reconstituted. Once reconstituted, store it at 2°C to 8°C and do not freeze it.

Can I take other medicines with Gigabac?

Some medicines can interact with Colistimethate Sodium, for example: Sodium Citrate, Vecuronium Bromide. Tell your doctor or pharmacist about every medicine you take.

Do I need a prescription for Gigabac?

Gigabac is a prescription (Rx) medicine. Take it as your doctor advises.

Last updated: 18 Aug 2026