Medications and Substances That Cannot Be Given with Lactated Ringer's Solution
Lactated Ringer's (LR) solution is incompatible with 8 specific medications and should be avoided in patients with severe traumatic brain injury or head trauma.
Physical Incompatibilities: Medications That Precipitate or Separate
The following medications are physically incompatible with LR and will precipitate, separate, or form particles when mixed, making concurrent Y-site administration unsafe 1:
- Ciprofloxacin - forms visible precipitate 1
- Cyclosporine - incompatible on mixing 1
- Diazepam - precipitates immediately 1
- Ketamine - physically incompatible 1
- Lorazepam - forms precipitate 1
- Nitroglycerin - incompatible with LR 1
- Phenytoin - precipitates on contact 1
- Propofol - separates and forms visible particles 1
These medications must use alternative IV fluids (typically normal saline) and cannot share the same IV line with LR even with adequate flushing between medications 1.
Clinical Contraindication: Severe Head Trauma and Traumatic Brain Injury
LR is absolutely contraindicated in patients with severe traumatic brain injury (TBI) or head trauma because it is hypotonic (osmolarity 273-277 mOsm/L compared to plasma 275-295 mOsm/L), which worsens cerebral edema and increases intracranial pressure 2, 3, 4, 5.
Specific Guidelines for Brain-Injured Patients:
- Use 0.9% normal saline instead (osmolarity 308 mOsm/L, truly isotonic) as the crystalloid of choice for patients with severe head trauma 2, 4, 5
- Maintain mean arterial pressure ≥80 mmHg in patients with combined hemorrhagic shock and severe TBI 2, 3
- When real osmolality (not theoretical) is measured, LR is definitively hypotonic and should be avoided in all brain-injured patients 4, 5
Relative Contraindication: Rhabdomyolysis and Crush Syndrome
Avoid LR in suspected or proven rhabdomyolysis or crush syndrome due to its potassium content (4 mmol/L), which poses additional risk when potassium levels increase markedly following reperfusion of crushed limbs 4.
Bile Acid Sequestrant Timing Considerations
When patients are receiving bile acid sequestrant therapy (BAST) such as cholestyramine or colestipol, these agents may bind medications given concurrently 2. While this primarily affects oral medications rather than IV fluids, administer other drugs at least 1 hour before or 4-6 hours after BAST to avoid potential interactions 2.
Common Pitfalls to Avoid
- Do not assume potassium content is a contraindication: The 4 mmol/L potassium in LR is not a contraindication for patients with mild-to-moderate hyperkalemia or renal dysfunction, except in rhabdomyolysis/crush syndrome 4
- Do not use LR for neurosurgical patients: Even without overt TBI, neurosurgical patients should receive isotonic saline to maintain plasma osmolarity and prevent increases in brain water content 5
- 86 medications ARE compatible: The vast majority of IV medications (86 out of 94 tested) are compatible with LR during Y-site administration 1
Recommended Uses Where LR Is Preferred
For context, LR remains the preferred crystalloid for most other clinical scenarios including general trauma resuscitation (without severe TBI), burns management, perioperative fluid management, and sepsis, as it reduces major adverse kidney events and mortality compared to normal saline 3, 4.