Table 3.9 Anticonvulsants DRUG
MECHANISM/ACTIONS
Barbiturate and benzOdlsz'(!/nes Phenobarbital Enhances l\SA-rrediated
---
chloride Influx through inhibitory neurotransmitter channels (Fig 3.6).
INDICATIONS
UNDESIRABLE EFFECTS
Generalized seizures In pedlstrrc---tNS depression, drowsiness. patients. Less ollen In adults. Associated with decreased IQ in children that have been treated chronically.
Prlmidone
Metabolized to phenobarbital and phenylelhylmaJonarride.
Alternative therapy lor partial or tonic-clonic seizures.
DIazepam
Enhances GABA mediated chloride In!lux (Fig. 3.6).
Status epileptic US. Rapid onset useful for slopping active seizures. Not used for chronic seizure control.
Drowsiness, clouding of consciousness, ataxia. other signs of CNS depression.
Clonazepam
""
Alternative to ethosuximide or valproic acid lor absence seizure.
""
Clorazepate
""
Alternative for partial seizures. Alcohol withdrawal. anxiety.
""
Tiagablne (Ga itril)
Blocks presynaptic GABA路 uptake.
Partial seizures.
Dizziness, nervousness, tremor.
Phenytoin (Dilanlln) Mephenytoln Ethotoln Fosphenytoin (Cerebyx)
Reduces sodium, calcium and potassium currents across neuronal membranes. Unclear which effects are responsible tor seizure prophylaxIs.
All types 01 seizures except absence.
f':lystagroos, ataxia, other CNS disturbances, bone marrow suppression. gingival hyperglasia, hepatotoxicity, GI dlstur ances. IV administration may cause CNS depression, severe hy~tension, arrhythmias, and hype inesis.
Carbamazepine (Tegretol)
Similar to phenytoin. Also has antidiuretic effect. Chemical structure similar to tricyclic antidepressants.
All types of seizures except absence. Trigeminal neuralgia. manic depression, schizophrenia that fails to respond to antipsychotics.
Agranulocytosis or aplastic anema (monitor blood counts), vertigo, nausea. vomiting.
Vaiproic Acid (Depakote)
MeChanism unkno'Nll. Enhancement of GABA neurotransmssion postulated.
All seizure ?:pe~articuiarlY disorders 0 co ned seizure ~pes. Manic episodes in bipotar Isorder.
Severe/fatal hepatotoxicity, particularly in small children, rTk.lch less in adults. ThrorTbocytopenia, hyperanYl1Onema.
Felbamate (Felbatol)
Mechantsm unknown. Ma~r recorrmended beCause related to actions at the GABA of aplastic anema and liver failure or NMOA (glutamate) receptor risk. channels.
Ethosuximide Methsuxlmlde Phensuximlde
Mechanism unkno'Nll.
Absenceseizures.
Headache, nausea, dizziness, vomting, fatigue, ataxia. blurred vision, confusion. rashes. hepatotoxicity, blood dyscrasias, 'LP-us-like syndrome (rare).
Gabapentln (Neurontin)
Mechanism unknown. Related to GABA, bullikely acts at distinct receptor.
Adjunctive treatment of partial seizures.
Somnolence, ataxia, dizziness, other CNS effects.
Lamotrlglne (Lamictal)
Mechanism unclear. Ma~ stabilize neurons and af eet glutamate/aspartate release.
Adult patients with partial seizures or Lenl'lOx-Gastaut Syndrome.
Dizziness, headache. nausea, ataxia, somnolence, diplopia, blurred vision. life-threatening rash in children (1 :50) and adults (1:1000).
Toplramate
Mechanism unknown. Ma be related to actions at GAB or kainate/AMPA receptors.
Partial onset seizures.
Psychomotor slowing. Somnolence, ataxia. dizziness, speech i~irmenl.
(Valium) Lorazepam (At ivan)
Ataxia, vertigo, olherCNS
changes, nausea, anorexia.
----WsceJlaneous
(Tcpa"",,)
54 Central Nervous System
A
AfSl<Of ~'astic anenia~ ~~patlc failure. omnolence, headache, fatigue, nausea, photosensitivity.