Title: Simplifying Phenytoin in the ED<br/>Author: Wesley Oliver<br/><a href='mailto:1911'>[Click to email author]</a><hr/><p>
<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;">Phenytoin can be a complex medication. There are different levels than can be ordered, adjustments based on albumin, various pharmacokinetic equations, and multiple formulations. Below are the simplified answers to some of the most common questions (see in-depth section for explanations):</span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><u><strong><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">Which phenytoin level (free or total) do I order?</span></span></strong></u></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">Total Phenytoin Level.</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><u><strong><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">What do I do after the level results?</span></span></strong></u></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><strong>Undetectable Level:</strong> Load patient with 20 mg/kg of total body weight (max dose 1,500 mg).</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><strong>Subtherapeutic Level (<10 mcg/mL): </strong>Calculate an approximate loading dose using this equation….Phenytoin Dose (mg)=(15-measured total level)/(0.7*patient weight).</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><strong>Therapeutic Level (10-20 mcg/mL):</strong> Add an additional agent.</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;"><strong>Supratherapetutic/Toxic Level (>20 mcg/mL):</strong> Contact Poison Center (1-800-222-1222).</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><u><strong><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">What formulation do I order for loading?</span></span></strong></u></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">IV: Use fosphenytoin.</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span id="docs-internal-guid-02f21cfa-7fff-9346-f591-d82b1a0cbc20"><span style="font-variant-numeric: normal; font-variant-east-asian: normal; vertical-align: baseline; white-space: pre-wrap;">PO: Any formulation will work. Give as a single loading dose or, if concerned for GI upset, give in 2-3 divided doses separated by 2 hours.</span></span></span></span></p>
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<span style="font-size:12px;"><span style="font-family:arial,helvetica,sans-serif;"><span style="white-space: pre-wrap;">***Disclaimer: These answers are simplified for the initial management of most patients in the ED. More complex answers may be required in some situations.***</span></span></span></p>
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<fieldset><legend>References</legend>
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