When may oral feeding be restarted in a patient after ingesting eight tablets of olanzapine (Zyprexa) overdose?

When to Resume Feeding After Olanzapine Overdose (8 Tablets)

Oral feeding can be safely resumed once the patient is fully awake, alert, and able to protect their airway—typically within 24-48 hours after an 8-tablet olanzapine overdose, though consciousness disturbances may rarely persist up to 6 days in severe cases. 1, 2

Clinical Course and Monitoring

Expected Timeline of Symptoms

• Mean duration of consciousness disturbances after olanzapine overdose is approximately 45 hours, with endotracheal intubation averaging 22 hours when required 2
• Eight tablets (typically 80-160 mg depending on tablet strength) represents a moderate to high overdose, as moderate symptoms occur at doses above 120 mg 1
• Unpredictable fluctuations between somnolence/coma and agitation are characteristic of moderate to high olanzapine overdoses, requiring careful clinical monitoring 1, 2
• Serum olanzapine concentrations can remain elevated for several days, with coma potentially persisting for up to 6 days in massive overdoses 3, 2

Key Clinical Indicators Before Resuming Feeding

The patient must demonstrate ALL of the following before oral feeding:

• Glasgow Coma Scale score indicating full alertness (not just arousal from coma) 2
• Stable vital signs without ongoing tachycardia, hypertension, or hypotension 2
• Absence of psychomotor agitation (present in 81% of olanzapine overdoses) 2
• Intact gag reflex and ability to protect airway 1
• No ongoing fluctuations between somnolence and agitation 1

Feeding Resumption Protocol

Step 1: Airway Protection Assessment (Priority)

• Verify patient can follow commands consistently without fluctuating mental status 1, 2
• Confirm intact swallowing mechanism and absence of aspiration risk 4
• Document stable neurological examination for at least 4-6 hours without deterioration 1

Step 2: Initial Feeding Trial

• Begin with clear liquids only after confirming stable mental status 5
• Observe for 4-6 hours to ensure tolerance and continued alertness 5
• Monitor for any recurrence of somnolence during this observation period 1

Step 3: Diet Advancement

• If clear liquids tolerated, advance to full liquids within 6-12 hours 5
• Progress to soft diet as tolerated based on continued clinical stability 5
• Avoid rushing advancement given the potential for prolonged drug effects 3, 2

Critical Contraindications to Feeding

Do NOT resume oral feeding if:

• Patient remains somnolent or demonstrates fluctuating consciousness 1, 2
• Gag reflex is absent or diminished 4
• Patient requires mechanical ventilation 2
• Ongoing psychomotor agitation prevents safe oral intake 2
• Any evidence of aspiration or compromised airway protection 4

Common Pitfalls to Avoid

• Do not assume early arousal means sustained alertness—olanzapine overdose characteristically causes unpredictable fluctuations between somnolence and agitation that can recur 1
• Do not resume feeding based solely on time elapsed—clinical status is more important than hours since ingestion, as consciousness disturbances can persist up to 6 days 3, 2
• Do not overlook miosis as a sign of ongoing toxicity—present in 65% of cases and associated with moderate poisoning 1, 2
• Do not rush diet advancement—the prolonged half-life and elevated serum concentrations warrant cautious progression 3

Special Monitoring Considerations

• Hospitalization typically lasts 5-6 days for olanzapine overdose, reflecting the prolonged clinical course 2
• Half of olanzapine overdose patients experience severe poisoning (PSS 3), warranting intensive monitoring 2
• Tachycardia (85%), psychomotor agitation (81%), and hypertension (73%) are the most common symptoms requiring ongoing assessment 2
• Extubation does not automatically indicate readiness for oral feeding—additional observation for sustained alertness is required 2