Difference between revisions of "Anticonvulsant levels and reloading"

(Volume of Distribution)
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== Background ==
+
==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>
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==Initial Loading<ref name="ACEP"></ref>==
 
==Initial Loading<ref name="ACEP"></ref>==
 
{|class="wikitable"
 
{|class="wikitable"
|'''Anticonvulsant (brand name)'''
+
|'''[[Anticonvulsant]] (brand name)'''
|'''Loading Dose and Route of Administration'''
+
|'''PO Loading Dose'''
 +
|'''IV Loading Dose'''
 
|-
 
|-
| [[Carbamazepine]] (Tegretol)||PO: 8 mg/kg suspension in single oral load  
+
| [[Carbamazepine]] (Tegretol)
IV: not available
+
|8mg/kg suspension in single oral load  
 +
|NA
 
|-
 
|-
| [[Gabapentin]] (Neurontin) ||PO: 900 mg/day oral (300 mg tid) for 3 days
+
| [[Gabapentin]] (Neurontin)  
IV: not available
+
|900mg/day oral (300mg tid) for 3 days
 +
|NA
 
|-
 
|-
| [[Lacosamide]] (Vimpat) ||PO: dosages not studied
+
| [[Lamotrigine]] (Lamictal)  
IV: not studied
+
|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) ||PO: 6.5 mg/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
+
| [[Levetiracetam]] (Keppra)  
IV: not available
+
|1,500mg oral load
 +
|1,000-1,500 mg IV
 
|-
 
|-
| [[Levetiracetam]] (Keppra) ||PO: 1,500 mg oral load
+
| [[Phenytoin]] (Dilantin)  
IV: rapid IV loading safe and well tolerated in doses up to 60 mg/kg  
+
|20mg/kg divided in maximum doses of 400mg every 2 hours
 +
|18mg/kg (max rate of 50mg/min)
 
|-
 
|-
| [[Phenytoin]] (Dilantin) ||PO: 20 mg/kg divided in maximum doses of 400 mg every 2 hours
+
|[[Fosphenytoin]] (Cerebyx)  
IV: 18 mg/kg at maximum rate of 50 mg/min  
+
|NA
 +
|18 PE/kg IV (max rate of 150 PE/min)
 
|-
 
|-
| [[Fosphenytoin]] (Cerebyx) ||PO:
+
| [[Valproate]] (Depacon)  
IV: 18 PE/kg IV at maximum rate of 150 PE/min
+
|NA
IM: administration possible
+
|Up to 30mg/kg IV (max rate of 10mg/kg/min)
|-
 
| [[Valproate]] (Depacon) ||PO:
 
IV: Up to 30 mg/kg IV at max rate of 10 mg/kg/min
 
 
|}
 
|}
 
==Levels==
 
Medications with verifiable levels include:
 
#[[Phenytoin]]
 
#[[Carbamazepine]]
 
#[[Phenobarbital]]
 
#[[Valproate]]
 
 
=== Desired Levels ===
 
*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
 
***Carbamazepine = 12 mcg/mL
 
  
 
==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 ===
+
===Volume of Distribution===
  
 
{| class="wikitable"
 
{| 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
 
|}
 
|}
  
 
==See Also==
 
==See Also==
 
*[[Seizure]]
 
*[[Seizure]]
*[[Seizure (Peds)]]
+
*[[Seizure (peds)]]
 
*[[Seizure with known seizure disorder]]
 
*[[Seizure with known seizure disorder]]
 
*[[Anticonvulsants]]
 
*[[Anticonvulsants]]
  
==Source==
+
==References==
 
<references/>
 
<references/>
  
[[Category:Drugs]]
+
[[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.