COLIMEX® Oral Suspension Monograph
Colistin Sulfate 50,000 IU/mL
1. DISCLAIMER
IMPORTANT NOTICE: This monograph is intended exclusively for healthcare professionals and is provided for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations, and does not replace clinical judgment or official prescribing information.
Oral colistin formulations are not recommended in current international guidelines for routine management of acute infectious diarrhea, due to limited contemporary randomized clinical trial evidence and the availability of safer, better-studied alternatives. Any use should be restricted to exceptional cases, under specialist supervision, with documented microbiological susceptibility and strict adherence to antimicrobial stewardship principles.
No guarantee is made regarding the accuracy, completeness, or currency of the information provided. Official product labeling, regulatory approvals, and national or institutional guidelines must always be consulted before prescribing or dispensing this medication. The reader assumes full responsibility for any clinical decisions based on this content.
2. SUMMARY
COLIMEX® is an oral polymyxin-class antibacterial preparation containing colistin sulfate (polymyxin E), intended to exert a local antibacterial effect within the gastrointestinal tract. Due to its high molecular weight and cationic structure, systemic absorption following oral administration is minimal in individuals with intact intestinal mucosa.
Historically, oral colistin has been used in selected enteric infections, particularly in pediatric populations. However, the emergence of global colistin resistance—especially plasmid-mediated mcr genes—has significantly narrowed its clinical role, necessitating cautious and highly selective use.
3. BRAND NAME
COLIMEX®
4. CATEGORY
- Pharmacological Class: Polymyxin antibiotic (Polymyxin E)
- Therapeutic Class: Intestinal antibacterial agent
- ATC Code: A07AA – Antibiotics for intestinal use
5. ACTIVE INGREDIENT
Colistin Sulfate (Polymyxin E sulfate) is a cyclic polypeptide antibiotic originally isolated from Paenibacillus polymyxa. Its antibacterial activity is expressed in International Units (IU) due to its heterogeneous composition.
Important distinction: Colistin sulfate (oral use) is pharmacologically and clinically distinct from colistimethate sodium, a parenteral prodrug used for systemic infections.
6. PHARMACEUTICAL FORM & STRENGTH
- Dosage Form: Powder for oral suspension (reconstitutable)
- Final Concentration: 50,000 IU/mL after reconstitution
- Final Volume: 60 mL
- Appearance: White to off-white powder; reconstituted suspension is white to pale yellow
- Packaging: Amber bottle to protect from light and moisture
7. MANUFACTURER & MARKETING AUTHORIZATION HOLDER
- Manufacturer (Egypt): MinaPharm
- Under License of: Alpharma – Denmark
Note: Manufacturing and licensing arrangements may vary by market and batch. Verification with local regulatory authorities and official product labeling is recommended.
8. MECHANISM OF ACTION
Colistin sulfate is a cationic amphipathic molecule that binds to the anionic lipid A component of lipopolysaccharide in the outer membrane of susceptible Gram-negative bacteria. This interaction displaces stabilizing divalent cations (calcium and magnesium), leading to increased membrane permeability and rapid leakage of intracellular contents, resulting in bactericidal activity.
Secondary intracellular effects, including interference with bacterial respiratory enzymes and induction of oxidative stress, have been demonstrated primarily in vitro. The clinical relevance of these additional mechanisms remains incompletely defined.
9. SPECTRUM OF ACTIVITY & RESISTANCE
Usually susceptible organisms:
- Escherichia coli
- Klebsiella pneumoniae
- Enterobacter spp.
- Shigella spp.
Limited or controversial role:
- Salmonella spp. – Routine antimicrobial treatment of uncomplicated gastroenteritis is generally discouraged due to potential prolongation of fecal carriage.
Intrinsically resistant organisms:
- Proteus, Serratia, Morganella, Providencia
- Burkholderia cepacia complex
- All Gram-positive organisms, anaerobes, fungi, and viruses
Resistance mechanisms include chromosomal lipid A modification and plasmid-mediated mcr genes (mcr-1 to mcr-9). Cross-resistance with polymyxin B is complete.
10. PHARMACOKINETICS (ORAL ADMINISTRATION)
Systemic absorption of orally administered colistin sulfate is negligible in individuals with intact gastrointestinal mucosa. The drug remains largely confined to the intestinal lumen, achieving high local concentrations. It is minimally metabolized and excreted predominantly unchanged in feces.
Increased systemic absorption has been reported in neonates, premature infants, and in conditions associated with severe intestinal inflammation or mucosal disruption.
11. INDICATIONS
- Treatment of documented enteric infections caused by colistin-susceptible Gram-negative bacteria when targeted antimicrobial therapy is justified
Not indicated for: systemic infections, invasive disease, or non-bacterial diarrhea.
12. METHOD OF PREPARATION & HANDLING
The powder should be reconstituted with water to the indicated mark to obtain a final volume of 60 mL. The bottle should be shaken vigorously until a homogeneous suspension is formed and shaken before each dose.
Stability after reconstitution:
- Up to 7 days after reconstitution, according to local product information
13. CONTRAINDICATIONS & PRECAUTIONS
Contraindications:
- Known hypersensitivity to colistin or other polymyxins
- Myasthenia gravis
Precautions:
- Neonates and premature infants
- Severe intestinal mucosal damage or inflammatory bowel conditions
14. WARNINGS & CLINICAL CONSIDERATIONS
Oral colistin should not be used empirically or for prolonged durations. Monitoring for neurological or renal adverse effects is advised if increased systemic exposure is suspected.
15. DRUG INTERACTIONS
Clinically significant interactions are unlikely due to minimal systemic absorption. Caution is advised if used concurrently with other nephrotoxic or neurotoxic agents in situations of increased absorption.
16. ADVERSE EFFECTS
Most adverse effects are mild and gastrointestinal in nature. Rare systemic toxicities, including neurotoxicity and nephrotoxicity, have been reported primarily in association with increased absorption or prolonged use.
17. USE IN SPECIAL POPULATIONS
- Pregnancy: Use only if clearly necessary
- Lactation: Generally considered compatible
- Pediatrics: Use under medical supervision
- Cystic Fibrosis: Use with extreme caution
18. STORAGE CONDITIONS
Unreconstituted powder should be stored at 15–25°C, protected from moisture and light. Reconstituted suspension should not be frozen and should be discarded if discoloration or particulate matter appears.
19. FREQUENTLY ASKED QUESTIONS (FAQ)
Q: Is oral colistin absorbed systemically?
A: Systemic absorption is minimal in individuals with intact intestinal mucosa but may increase in neonates or severe intestinal inflammation.
Q: Can COLIMEX® be used for routine diarrhea?
A: No. Routine use is not recommended and should be restricted to documented susceptible infections.
Q: Is this the same as injectable colistin?
A: No. Oral colistin sulfate differs from injectable colistimethate sodium in formulation, pharmacokinetics, and indications.
20. REFERENCES
WHO Essential Medicines List, EMA product assessments, Lexicomp, UpToDate, CLSI and EUCAST guidance, and official product information (updated to December 2024).
