Should lithium be held for a patient who is NPO, and when can it be safely restarted?

Lithium Management in NPO Patients

Lithium should be held when a patient is NPO, and oral medications should not be administered until swallowing has been assessed with a validated screening tool 1, 2. Alternative routes such as intravenous or rectal administration should be considered while the patient remains NPO 1, 2.

When to Hold Lithium

The Canadian Stroke Best Practice Recommendations provide the clearest guidance on NPO medication management. Patients must remain NPO until swallowing screening is completed for patient safety, and oral medications—including lithium—should not be given until this screening is normal 1, 2. This is a Level B evidence recommendation that prioritizes aspiration prevention and patient safety.

The rationale is straightforward: aspiration risk supersedes the need for immediate oral medication administration. While swallowing screening ideally occurs within 24 hours of hospital arrival, medications must be held until this assessment confirms safe oral intake 2.

Managing the NPO Period

During the NPO period, consider these key factors:

• Duration matters: Lithium has a relatively long half-life (18-36 hours), so brief NPO periods (12-24 hours) for procedures are generally well-tolerated without immediate risk of relapse
• Hydration status is critical: NPO status combined with dehydration significantly increases lithium toxicity risk, as lithium is renally cleared and sensitive to volume status 3
• Monitor for toxicity risk: The FDA label explicitly warns that lithium should generally not be given to patients with dehydration or sodium depletion, as toxicity risk is very high 3

When to Restart Lithium

Restart lithium as soon as swallowing screening confirms safe oral intake 1, 2. The specific algorithm is:

1. Complete validated swallowing screening tool
2. If screening is normal → resume oral medications including lithium
3. If screening is abnormal → refer to swallowing specialist for in-depth assessment; continue holding oral medications 1, 2
4. Monitor clinical status closely, as swallowing ability can change in the acute period 2

Special Considerations for Restarting

When resuming lithium after a brief discontinuation:

• Check lithium level before restarting if NPO period exceeded 24-48 hours, particularly in older adults or those with renal impairment
• Ensure adequate hydration before resuming, as dehydration dramatically increases toxicity risk 3
• Consider dose adjustment in older adults (≥60 years), who may require lower therapeutic targets (0.4-0.6 mmol/L) 4, 5
• Avoid rapid reinitiation: Gradual resumption at the previous maintenance dose is appropriate for brief interruptions; do not "load" the patient

Common Pitfalls to Avoid

1. Do not give lithium via alternative routes while NPO: Unlike some medications, lithium should simply be held rather than converted to IV/rectal routes, as these formulations are not standard practice
2. Do not restart without confirming hydration status: Volume depletion is a major risk factor for lithium toxicity 3
3. Do not assume brief discontinuation causes refractoriness: Evidence shows that 82.7% of patients respond when lithium is restarted after discontinuation 6, 7. The concern about "lithium-discontinuation-induced refractoriness" is not well-supported for brief interruptions
4. Monitor for drug interactions: If the patient is on diuretics, ACE inhibitors, or NSAIDs, toxicity risk increases substantially and closer monitoring is required 4, 8

Risk-Benefit Context

While brief lithium discontinuation (24-48 hours) carries minimal relapse risk given lithium's pharmacokinetics, the risk of aspiration from administering oral medications to an NPO patient with unassessed swallowing is immediate and potentially fatal. The guideline evidence clearly prioritizes aspiration prevention over maintaining uninterrupted lithium therapy 1, 2.

For planned procedures, some sources suggest discontinuing lithium 12-24 hours before scheduled events and restarting 6-12 hours post-procedure once oral intake is safe 9, 10, though this is primarily from obstetric literature and should be adapted to the specific clinical context.