Colistin: Nursing Drug Guide, Nephrotoxicity & Renal Dosing
Last-line IV colistimethate for multidrug-resistant gram-negative infections — but doses are written in colistin base activity (CBA), not colistimethate milligrams. Exceeding renal excretory capacity triggers a toxic cycle of rising creatinine, neuromuscular blockade, and apnea. Verify Table 1 renal schedules, I&O, and neuro cues before every dose.
Colistimethate can cause nephrotoxicity and neuromuscular blockade with apnea when daily colistin base activity (CBA) exceeds renal excretory capacity—a toxic cycle of rising creatinine, decreased urine output, perioral numbness, and respiratory depression. FDA labeling caps normal renal function at 5 mg/kg/day CBA. Doses are expressed in CBA mg/kg/day, not colistimethate sodium milligrams alone. Before every dose, verify Table 1 renal adjustment, I&O, and neuro cues; discontinue immediately if impaired renal function or neuromuscular signs appear per labeling.
📋 Contents
⚡ Quick facts
💡 Key takeaway
Verify every colistimethate order in colistin base activity (CBA) mg/kg/day—not colistimethate milligrams alone—and confirm the MAR matches Table 1 renal schedules before each dose. New perioral numbness, slurred speech, rising creatinine, or falling urine output on colistin is a hold-and-escalate event until nephrotoxicity and neuromuscular blockade are ruled out.
Most common brand names
Colistimethate sodium is available generically and as Coly-Mycin M (polymyxin E). Each vial contains colistimethate sodium equivalent to 150 mg colistin base activity (CBA)—reconstitute with 2 mL sterile water for injection to yield 75 mg/mL CBA. Verify CBA mg/kg/day on the MAR, not colistimethate milligrams alone.
Why we give it — Indications
Colistimethate is a last-line polymyxin antibiotic for serious infections caused by susceptible gram-negative organisms—especially multidrug-resistant strains when limited alternatives exist. Nurses most often see it on critical-care and infectious-disease pathways for ventilator-associated or hospital-acquired infections after blood cultures identify resistant organisms.
| Use | Detail |
|---|---|
| Multidrug-resistant gram-negative infection | Last-line therapy for susceptible MDR organisms during sepsis or severe hospital-acquired infection when other agents fail or are contraindicated |
| Pneumonia | Hospital-acquired or ventilator-associated pneumonia due to susceptible gram-negative bacilli when colistin is ordered per susceptibility and ID protocol |
| Urinary tract infection | Complicated urinary tract infection caused by susceptible resistant organisms when IV polymyxin therapy is selected |
| Empiric / combination therapy | May appear with other agents on MDR gram-negative pathways—dose in CBA mg/kg/day per Table 1 |
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How it works
Colistimethate is a prodrug converted to colistin, which disrupts the gram-negative outer membrane. It is a last-line agent for susceptible multidrug-resistant organisms. The drug is eliminated primarily by the kidneys; when CrCl falls, colistin accumulates—triggering nephrotoxicity and neuromuscular blockade if CBA mg/kg/day exceeds Table 1 renal schedules.
Dosing overview
Adult doses are expressed as mg/kg/day of colistin base activity (CBA), divided into 2–4 doses when CrCl is normal. Maximum daily CBA is 5 mg/kg/day with normal renal function. Use ideal body weight in obesity per labeling. When CrCl falls, reduce per Table 1—exceeding renal excretory capacity causes a toxic cycle of worsening kidney function and neuromuscular blockade.
Reconstitution: Each vial = 150 mg CBA; add 2 mL sterile water for injection → 75 mg/mL CBA.
Table 1 — DailyMed adult CBA dosing by creatinine clearance
| Creatinine clearance (mL/min) | CBA dose (mg/kg/day) | Frequency |
|---|---|---|
| ≥80 | 2.5–5 | 2–4 divided doses |
| 50–79 | 2.5–3.8 | 2 divided doses |
| 30–49 | 2.5 | Once daily or BID |
| 10–29 | 1.5 | Every 36 hours |
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Estimate CrCl when only serum creatinine is available (Cockcroft-Gault per labeling). Trend eGFR and creatinine during diuretic therapy, contrast, or sepsis-related acute kidney injury.
Missed dose: Not specified in the reviewed prescribing information. Do not double doses; contact pharmacy for the next safe administration time when renal function is borderline.
Onset, peak, duration, and half-life
| Parameter | Value | Nursing relevance |
|---|---|---|
| Administration | Half daily CBA dose IV bolus over 3–5 min q12h, or continuous infusion per protocol | Bolus over 3–5 minutes—not a rapid push; continuous infusion per pharmacy protocol when ordered |
| Half-life (healthy adults) | ≈2 hours (mean) | Prolonged in renal impairment—drives interval extension |
| Elimination | ≈85% unchanged in urine | Renal Table 1 CBA adjustment mandatory when CrCl falls |
| Hemodialysis removal | Removal in overdose unknown per labeling | HD/PD removal in overdose unknown—coordinate with pharmacy/nephrology |
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Before you give it — Safety check
Pretreatment checks
- Confirm CBA mg/kg/day on MAR matches pharmacy calculation—not colistimethate mg alone
- Calculate or verify CrCl/eGFR; compare MAR dose and interval to renal adjustment table—especially when creatinine is rising or urine output is falling
- Perform medication reconciliation for concurrent nephrotoxins or IV incompatibilities
Contraindications
- Hypersensitivity to colistimethate sodium or any component of the formulation
Important interactions
| Drug / class | Effect | Nursing action |
|---|---|---|
| Furosemide / dehydration | Volume depletion and AKI raise colistin levels and nephrotoxicity/neuromuscular blockade risk | Monitor I&O, creatinine, mental status; request dose re-evaluation if renal function worsens |
| Aminoglycosides / polymyxins | Additive nephrotoxicity and neuromuscular blockade with aminoglycosides/polymyxins | Monitor renal function and neuro status; notify pharmacist before concurrent use |
| Curariform relaxants / succinylcholine | Enhanced neuromuscular blockade—respiratory arrest risk | Verify ventilator capability and reversal agents per protocol if NMB added |
| Sodium cephalothin | Additive nephrotoxicity per labeling—avoid concurrent use | Notify pharmacist if cephalothin is ordered; do not co-administer without ID/pharmacy review |
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Administration
Route: Intravenous preferred; intramuscular deep IM when IV not feasible. Labeling reports respiratory arrest after IM administration—use IV when possible.
- Reconstitute 150 mg CBA vial with 2 mL SWFI (75 mg/mL CBA); verify CBA dose with pharmacy before drawing up
- IV: Administer half the daily CBA dose as a bolus over 3–5 minutes every 12 hours, or use a continuous-infusion protocol per labeling and pharmacy
- Follow IV infusion pump setup for continuous infusions; independent double-check CBA mg/kg/day against Table 1
- Use high-alert medication administration practices—confirm units are CBA, not colistimethate sodium mg alone
- Avoid concurrent sodium cephalothin (additive nephrotoxicity per labeling); separate aminoglycoside administration when ordered
Expected therapeutic response
- Defervescence and improving clinical status for the treated infection (when paired with source control and culture-directed therapy)
- Down-trending inflammatory markers and culture clearance when susceptibilities confirm colistin activity
- Stable neurologic baseline and stable creatinine—colistin should not cause new perioral numbness, slurred speech, or falling urine output when CBA dosing matches Table 1
Red flags — Stop and act
Hold colistimethate and escalate immediately for neuromuscular blockade, nephrotoxicity, severe hypersensitivity, or fulminant CDAD.
- Perioral or extremity numbness, slurred speech, dizziness, weakness, paresthesia, seizures, respiratory distress, or apnea—especially when CBA dose exceeds Table 1
- New confusion with rising creatinine or oliguria
- Urticaria, bronchospasm, hypotension, or other signs of anaphylaxis during or after infusion
- Generalized rash, mucosal lesions, or blistering (possible severe cutaneous reaction)
- Profuse watery diarrhea with abdominal pain or fever during or after antibiotic therapy (evaluate for CDAD)
- Creatinine rise, oliguria, or missed renal dose adjustment on the MAR when neuro symptoms appear
Adverse effects
| Adverse effect | Frequency / severity | Nursing response |
|---|---|---|
| GI upset (nausea, vomiting, diarrhea) | Common | Assess hydration; evaluate for CDAD if profuse or bloody |
| Paresthesia, slurred speech, dizziness, vertigo, seizures | Serious; dose-related | Hold drug, notify prescriber/pharmacist, monitor airway and respiratory effort |
| Itching, urticaria, rash; fever, anaphylaxis | Hypersensitivity spectrum | Stop infusion, treat reaction per protocol, document allergy |
| Increased BUN/creatinine, decreased CrCl, oliguria | Nephrotoxicity | Hold per prescriber, trend renal function, verify Table 1 adjustment |
| Respiratory distress, apnea | Neuromuscular blockade | Urgent escalation, airway support, discontinue colistimethate |
| CDAD | Antibiotic-associated | Evaluate stool; do not give antimotility agents without evaluation |
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Overdose, toxicity, and antidote
No specific antidote is listed in DailyMed colistin labeling. Overdose may cause neuromuscular blockade with paresthesia, confusion, apnea, respiratory arrest, and acute renal failure—especially when CBA exceeds renal excretory capacity.
Management
- Discontinue colistin and provide supportive care with close neurologic monitoring
- Whether colistimethate can be removed by hemodialysis or peritoneal dialysis in overdose is unknown per labeling—provide supportive care
- Contact prescriber, pharmacist, and local poison control / toxicology services per facility protocol
Look-alike / sound-alike and error prevention
- CBA vs colistimethate sodium mg—150 mg vial = 150 mg CBA; pharmacy may write mg/kg/day CBA while MAR shows colistimethate units
- Colistin vs colistimethate vs polymyxin B—different polymyxins with different dosing and toxicity profiles
- mg/kg/day vs mg/dose—labeling uses daily CBA mg/kg; dividing errors cause toxic accumulation
- 150 mg CBA vial reconstitution—2 mL SWFI = 75 mg/mL; verify drawn volume matches ordered CBA
- Standard renal dose left on MAR after AKI—small CrCl change can require Table 1 schedule change from BID to q36h
Practical bedside notes
| Topic | Bedside guidance |
|---|---|
| Renal recheck triggers | New diuretics, contrast, hypotension, rising creatinine—request pharmacy re-evaluation before next dose |
| Neuro checks | Baseline and daily mental status in older adults and CKD; perioral numbness or slurred speech = stop and escalate |
| Infusion time | 3–5 minute IV bolus or continuous rate per protocol; never rapid push |
| CBA unit check | Confirm MAR shows mg/kg/day CBA and Table 1 interval before every dose |
| Commonly missed | 5 mg/kg/day CBA cap exceeded or Table 1 not applied after CrCl drop; home dialysis schedule not communicated to pharmacy |
| Ask pharmacy when | CrCl borderline, concurrent gentamicin/NMB, suspected nephro/neuro toxicity, or incompatible IV meds on same line |
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High-risk populations
| Population | Considerations |
|---|---|
| Older adults | Higher baseline renal impairment; labeling reports serious neurotoxicity in geriatric patients given unadjusted doses |
| Renal impairment / dialysis | Mandatory Table 1 CBA adjustment at all listed CrCl tiers; Renal function may change daily in critical illness—recalculate before each dose |
| Obesity (use ideal body weight for CBA) | Actual body weight overestimates CBA and raises toxicity risk per labeling |
| Critical illness with fluctuating CrCl | Sepsis, shock, and diuretics alter renal function daily—do not assume admission CrCl still applies |
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Monitoring and documentation
Monitor
- Renal function (creatinine, BUN, urine output) at baseline and during therapy when CrCl may change
- Neurologic status (perioral numbness, speech, paresthesia, muscle strength, respiratory effort) at least each shift—more often if renal impairment
- Infection markers (fever, WBC, culture results) and stool pattern for CDAD
- IV site and infusion completion times
Document
- CrCl/eGFR used to verify dose, actual dose infused, rate, and time
- Any held doses with prescriber/pharmacist notification and neuro symptom timeline
- Patient teaching on reporting diarrhea, rash, or confusion
Patient teaching
- Report numbness or tingling of lips/tongue/fingers, slurred speech, increasing weakness, or breathing difficulty immediately—even if the infection seems to be improving
- Report severe or persistent diarrhea, especially if bloody or accompanied by abdominal pain
- Report rash, itching, swelling, or trouble breathing during infusion
- IV antibiotics require full infusion time; notify the nurse if the pump alarms or the site burns
The Hold Rule
- Perioral numbness, slurred speech, dizziness, weakness, paresthesia, respiratory distress, or apnea
- Rising creatinine, falling urine output, or MAR CBA dose that exceeds Table 1 for current CrCl
- Known hypersensitivity, urticaria, or suspected anaphylaxis during infusion
- Profuse CDAD-type diarrhea pending evaluation
- Concurrent aminoglycoside or neuromuscular blocker added without pharmacy review
Hold parameters may vary by institutional protocol. Follow prescriber orders, pharmacy guidance, and facility policy.
Clinical practice integration and workflow
Colistin is often ordered on sepsis pathways where renal function changes hourly. Build CBA unit verification and Table 1 checks into antibiotic time-outs—nephrotoxicity and neuromuscular blockade are preventable when daily CBA matches renal excretory capacity.
1. Check-before-you-give protocol
- Right patient, drug, dose, route, time—and right renal-adjusted interval
- Compare today’s creatinine/CrCl to the value used when the order was written
- Independent double-check CBA mg/kg/day, vial reconstitution (150 mg CBA in 2 mL SWFI), and bolus duration (3–5 min) or infusion rate
- Confirm incompatible agents will be administered separately
2. High-alert and safety badge
Nephrotoxicity / neurotoxicity risk — treat dose/interval verification as high-stakes even when not on institutional high-alert listDailyMed labeling warns that doses above renal excretory capacity can cause nephrotoxicity, neuromuscular blockade, and apnea. Use the same rigor as high-alert IV antibiotics whenever colistimethate is ordered.
3. Clinical workflow: hold and question rules
- If neuro symptoms appear, hold the next dose and page prescriber/pharmacy before restarting—symptoms may reverse after discontinuation and/or hemodialysis
- If creatinine rises mid-course, pause until pharmacy recalculates—do not continue q8h by habit
- Escalate CDAD suspicion early; do not automatically restart colistin if alternative therapy is needed
4. Critical teach-back questions
- “What new symptoms should you report while on this IV antibiotic?” (Numbness, slurred speech, weakness, severe diarrhea, rash, breathing trouble.)
- “Why might your nurse ask about kidney function before each dose?” (Colistin is cleared by the kidneys; CBA mg/kg/day must change when kidney function falls.)
5. Care coordination
Pharmacist: Renal dose verification, HD/CAPD scheduling, Y-site compatibility, and alternative agents if neurotoxicity occurs
Prescriber / nephrology: Notify for rising creatinine, dialysis timing questions, or need to switch antibiotic class after serious reaction
🧠 Quick mental checklist
- Is the MAR written in CBA mg/kg/day and does it match Table 1 for today’s CrCl?
- Has creatinine changed since the order was written?
- Any perioral numbness, slurred speech, weakness, or falling urine output since the last dose?
- Are aminoglycosides or neuromuscular blockers concurrent without pharmacy clearance?
- If neurotoxicity suspected, is colistin held and prescriber/pharmacy notified?
Colistin NCLEX practice questions
Practice NCLEX-style clinical judgment practice for colistin using a tabbed inpatient case (MAR, labs, I&O, nursing notes), then priority action, cue recognition, trend interpretation, matrix urgency sorting, renal dosing judgment, and documentation cloze—recognise cues → analyse → prioritise → act → evaluate outcomes.
Select a tab to view MAR, labs, I&O, and nursing note details for this case.
- Colistimethate 150 mg CBA IV q12h (≈3.8 mg/kg/day CBA for 70 kg) — 0800 given; 2000 due
- Gentamicin IV per pharmacy — separate line; trough pending
- Furosemide 20 mg IV BID — 1400 given
- Pharmacy note: today’s CrCl 22 mL/min — MAR still shows q12h CBA dose for CrCl 50–79 tier
- Admission CrCl ≈ 42 mL/min; creatinine 2.1 mg/dL (was 1.4), estimated CrCl 22 mL/min
- BUN 52 mg/dL; BMP otherwise stable
- Blood cultures: carbapenem-resistant Acinetobacter (preliminary susceptibility: colistin sensitive)
- Previous 24 h: intake 2.1 L; output 480 mL (≈20 mL/h average)
- Weight up 1.2 kg; patient reports decreased urination
- 1200–2000: output 90 mL despite diuretic
- 1830: 68-year-old ICU patient with MDR gram-negative pneumonia on colistimethate
- 1845: New perioral numbness and slurred speech; denies chest pain; respirations 18/min, unlabored
- 1850: Nurse reviewing MAR, labs, and I&O before 2000 colistimethate dose
Answer key & rationale
Frequently asked questions
What units must nurses verify before giving colistimethate?
FDA labeling expresses adult doses as mg/kg per day of colistin base activity (CBA), not colistimethate sodium milligrams alone. Each vial contains colistimethate sodium equivalent to 150 mg CBA. Maximum daily CBA should not exceed 5 mg/kg/day with normal renal function. Confirm pharmacy calculations and whether the MAR reflects Table 1 renal adjustments before administration.
When should a nurse hold colistin and call the prescriber or pharmacist?
Hold and escalate when new perioral numbness, slurred speech, dizziness, muscle weakness, or respiratory distress appears; when urine output falls or creatinine and BUN rise; when the ordered dose exceeds renal Table 1 schedules; or when concurrent neuromuscular blocking drugs or aminoglycosides are added without pharmacy review. Discontinue immediately if signs of impaired renal function occur per labeling.
How is colistimethate dosed in renal impairment?
For adults with creatinine clearance 50–79 mL/min, labeling suggests 2.5–3.8 mg/kg/day CBA divided into two doses; CrCl 30–49: 2.5 mg/kg once daily or divided into two doses; CrCl 10–29: 1.5 mg/kg every 36 hours. Doses above renal excretory capacity can cause a toxic cycle of worsening kidney function and neuromuscular blockade with apnea.
What is the antidote for colistin overdose?
No specific antidote is listed in the reviewed prescribing information. Overdose management includes discontinuing colistimethate sodium and providing general supportive measures. Neuromuscular blockade may cause paresthesia, confusion, apnea, respiratory arrest, and acute renal failure. Whether colistimethate can be removed by hemodialysis or peritoneal dialysis in overdose is unknown per labeling.
Is colistin safe during pregnancy or breastfeeding?
Colistimethate sodium is Pregnancy Category C; animal studies showed fetal talipes varus at higher doses and there are no adequate controlled studies in pregnant women. It crosses the placenta and should be used in pregnancy only if potential benefit justifies risk. Colistin sulphate is excreted in human breast milk; caution is advised when colistimethate is given to nursing women per labeling.
References
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U.S. National Library of Medicine. Colistimethate sodium — Full prescribing information. DailyMed.https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8ec7dc90-825c-422e-9f4b-c8ace9d93af5
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U.S. Food and Drug Administration. Table of antimicrobial breakpoints.https://www.fda.gov/drugs/development-resources/table-antimicrobial-breakpoints
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Drugs and Lactation Database (LactMed). Colistin. Bethesda (MD): National Institute of Child Health and Human Development.https://www.ncbi.nlm.nih.gov/books/n/lactmed/LM453/
Review and transparency
This medication guide is written and reviewed using NurseOnShift editorial and clinical review standards.
Educational use only. This content does not replace clinical judgment, prescriber orders, pharmacist guidance, product labeling, or institutional protocols.