A.32.Antiepileptics used in partial seizures and generalized tonic-clonic seizures except for "broad spectrum" agents. Flashcards
what agent is more sedative- phenytoin or phenobarbital?
phenobarbital
what are Phenytoin and Carbamazepine?
narrow-spectrum antiepileptics
what does phenytoin and Carbamzepine do?
inhibition of axonal Na⁺ channels–> prevent seizure propagation
but no intiation
How is Phenytoin given?
Oral or IV
important pharmacokinetic properties of Phenytoin
- extensive binding to plasma proteins 97%
- non-linear kinetics–> shift from 1st order (low dose) to zero-order (high dose)
- inducer of CYP450
what are the indications of phenytoin
1.tonic-clonic seizures
NOT EFFECTIVE IN ABSENCE SEIZURES
2. status epilepticus (IV)
3. Antiarrhythmic activity in digoxin toxicity
side effects of phenytoin (8)
- CNS depression
- Diplopia
- Gingival hyperplasia
- hirsutism
- osteomalacia
- megaloblastic anemia
- aplastic anemia
- teratogenicity
what does Phenytoin do if given in pregnancy?
‘Fetal hydantoin syndrome’
craniofacial anomalies, cleft lip and palate
what are the indications for Carbamazepine?
- tonic-clonic (generalized) seizures
- partial seizures
- trigeminal neuralgia (1st- line)
- bipolar disorders
side effects of carbamazepine (8)
- CNS depression
- diplopia
- stevens-johnson syndrome (exfoliative dermatitis)
- ADH secretion ↑ (SIADH)
- osteomalacia
- megaloblastic anemia
- aplastic anemia
- teratogenicity
what teratogenicity does carbamazepine do?
neural tube defects (spina bifida), craniofacial anomalies
what does Vigabatrin do?
inhibits GABA transaminase–> ↑ GABA in the synaptic cleft
when do we give Vigabatrin?
partial seizures
infantile spasm
adjunct therapy for generalized tonic-clonic seizures
what are the side effects of Vigabatrin
vision loss!
sedation, dizziness
mnemonic for Phenytoin
"PPHENYTOIN" cytochrome P-450 Pseudo-lymphoma Hirsutism Enlarged gums Nystagmus Yellow-brown skin Teratogenicity Osteopenia Inhibited folate absorption Neuropathy
