Difference between revisions of "Anticonvulsant levels and reloading"

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== Background ==
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==Background==
*IV load can be performed with phenobarbital, phenytoin, valproate, levetiracetam
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*IV load can be performed with phenobarbital, [[phenytoin]], valproate, levetiracetam
 
*Oral loading can be spread over day or more to avoid GI upset
 
*Oral loading can be spread over day or more to avoid GI upset
 
*May use IV vs PO reload at physican discretion<ref name="ACEP">Seizures ACEP Policy committee . Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Seizures. Ann Emerg Med. 2014;63(4):437–447.e15. doi:10.1016/j.annemergmed.2014.01.018.</ref>
 
*May use IV vs PO reload at physican discretion<ref name="ACEP">Seizures ACEP Policy committee . Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Seizures. Ann Emerg Med. 2014;63(4):437–447.e15. doi:10.1016/j.annemergmed.2014.01.018.</ref>
  
==Loading<ref name="ACEP"></ref>==
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==Initial Loading<ref name="ACEP"></ref>==
 
{|class="wikitable"
 
{|class="wikitable"
|'''Drug (with brand name)'''
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|'''[[Anticonvulsant]] (brand name)'''
|'''Loading Dose and Route of Administration'''
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|'''PO Loading Dose'''
 +
|'''IV Loading Dose'''
 
|-
 
|-
| [[Carbamazepine]] (Tegretol)||8 mg/kg oral suspension;
+
| [[Carbamazepine]] (Tegretol)
single oral load;
+
|8mg/kg suspension in single oral load  
IV not available
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|NA
 
|-
 
|-
| [[Gabapentin]] (Neurontin) ||900 mg/day oral (300 mg tid) for 3 days;
+
| [[Gabapentin]] (Neurontin)  
IV not available
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|900mg/day oral (300mg tid) for 3 days
 +
|NA
 
|-
 
|-
| [[Lacosamide]] (Vimpat) ||Oral and IV formulations available and safe;
+
| [[Lamotrigine]] (Lamictal)  
loading dosages not studied
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|6.5mg/kg single oral load if on lamotrigine for >6 mo without a history of rash or intolerance in the past and only off lamotrigine for <5 days
 +
|NA
 
|-
 
|-
| [[Lamotrigine]] (Lamictal) ||6.5 mg/kg single oral load if on lamotrigine;
+
| [[Levetiracetam]] (Keppra)  
for >6 mo without a history of rash or intolerance in the past and only off lamotrigine for <5 days;
+
|1,500mg oral load
IV not available
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|1,000-1,500 mg IV
 
|-
 
|-
| [[Levetiracetam]] (Keppra) ||1,500 mg oral load;
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| [[Phenytoin]] (Dilantin)  
rapid IV loading safe and well tolerated in doses up to 60 mg/kg  
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|20mg/kg divided in maximum doses of 400mg every 2 hours
 +
|18mg/kg (max rate of 50mg/min)
 
|-
 
|-
| [[Phenytoin]] (Dilantin) ||20 mg/kg divided in maximum doses of 400 mg every 2 h orally;
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|[[Fosphenytoin]] (Cerebyx)  
or 18 mg/kg IV at maximum rate of 50 mg/min  
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|NA
 +
|18 PE/kg IV (max rate of 150 PE/min)
 
|-
 
|-
| [[Fosphenytoin]] (Cerebyx) ||18 PE/kg IV at maximum rate of 150 PE/min;
+
| [[Valproate]] (Depacon)  
IM administration possible
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|NA
|-
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|Up to 30mg/kg IV (max rate of 10mg/kg/min)
| [[Valproate]] (Depacon) ||Up to 30 mg/kg IV at max rate of 10 mg/kg/min IV
 
 
|}
 
|}
  
 
==Reloading==
 
==Reloading==
=== Dose ===
+
*'''Dose (mg) = [[ideal body weight estimation|ideal body weight]] (kg) X Vd X [desired level - current level (mcg/mL)]'''
'''Dose (mg) = ideal body weight (kg) X Vd X [desired level - current level (mcg/mL)]'''
 
  
=== Volume of Distribution ===
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===Volume of Distribution===
  
{| style="width: 500px" border="1" cellpadding="1" cellspacing="1"
+
{| class="wikitable"
 
|-
 
|-
| '''Agent<br/>'''
+
| '''Agent'''
| '''Volume of Distribution<br/>'''
+
| '''Volume of Distribution'''
 +
| '''Desired Level'''
 
|-
 
|-
 
| Phenytoin (dilantin)  
 
| Phenytoin (dilantin)  
 
| 0.8
 
| 0.8
 +
| 20 mcg/mL
 
|-
 
|-
 
| Carbamazepine (tegretol)
 
| Carbamazepine (tegretol)
 
| 0.8
 
| 0.8
 +
| 12 mcg/mL
 
|-
 
|-
 
| Phenobarbital
 
| Phenobarbital
 
| 0.6
 
| 0.6
 +
| 40 mcg/mL
 
|-
 
|-
 
| Valproate (depakote)
 
| Valproate (depakote)
 
| 0.2
 
| 0.2
 +
| 100 mcg/mL
 
|}
 
|}
 
=== Desired Level ===
 
*Pt's optimal level = desired level
 
**If optimal level unknown target upper end of therapeutic range:
 
***Phenytoin = 20 mcg/mL
 
***Valproate = 100 mcg/mL
 
***Phenobarbital = 40 mcg/mL
 
  
 
==See Also==
 
==See Also==
 
*[[Seizure]]
 
*[[Seizure]]
*[[Seizure (Peds)]]
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*[[Seizure (peds)]]
*[[Febrile Seizure]]
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*[[Seizure with known seizure disorder]]
 +
*[[Anticonvulsants]]
  
==Source==
+
==References==
 
<references/>
 
<references/>
  
[[Category:Drugs]]
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[[Category:Pharmacology]]
[[Category:Neuro]]
+
[[Category:Neurology]]

Latest revision as of 15:25, 27 September 2019

Background

  • IV load can be performed with phenobarbital, phenytoin, valproate, levetiracetam
  • Oral loading can be spread over day or more to avoid GI upset
  • May use IV vs PO reload at physican discretion[1]

Initial Loading[1]

Anticonvulsant (brand name) PO Loading Dose IV Loading Dose
Carbamazepine (Tegretol) 8mg/kg suspension in single oral load NA
Gabapentin (Neurontin) 900mg/day oral (300mg tid) for 3 days NA
Lamotrigine (Lamictal) 6.5mg/kg single oral load if on lamotrigine for >6 mo without a history of rash or intolerance in the past and only off lamotrigine for <5 days NA
Levetiracetam (Keppra) 1,500mg oral load 1,000-1,500 mg IV
Phenytoin (Dilantin) 20mg/kg divided in maximum doses of 400mg every 2 hours 18mg/kg (max rate of 50mg/min)
Fosphenytoin (Cerebyx) NA 18 PE/kg IV (max rate of 150 PE/min)
Valproate (Depacon) NA Up to 30mg/kg IV (max rate of 10mg/kg/min)

Reloading

Volume of Distribution

Agent Volume of Distribution Desired Level
Phenytoin (dilantin) 0.8 20 mcg/mL
Carbamazepine (tegretol) 0.8 12 mcg/mL
Phenobarbital 0.6 40 mcg/mL
Valproate (depakote) 0.2 100 mcg/mL

See Also

References

  1. 1.0 1.1 Seizures ACEP Policy committee . Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Seizures. Ann Emerg Med. 2014;63(4):437–447.e15. doi:10.1016/j.annemergmed.2014.01.018.