L1,2 Flashcards
Definition of Epilipsy
neurological disorder, characterized by repeated seizures. there is
1- sudden, excessive & synchronous discharge of cerebral neurons.
2- loss of consciousness, abnormal movements & a typical behavior.
Etiology of epilepsy
excessive firing of the neurons.
Due to genetic and unknown causes
Drugs reduce seizures through such mechanisms as:
–1. Blocking voltage-gated channels (Na+ or Ca2+)
– 2. Enhancing inhibitory γ-aminobutyric acid (GABA)-ergic impulse
– 3. Interfering with excitatory glutamate transmission.
Classical Anticonvulsants
1- phenytoin
2- carbamazepine
3- valporic Acid
4- Etho-suximide ( Absence seizer only )
5- phenbarbital
6- primidone
benzodiazepines
Newer Anticonvulsants
Lamotrigine
Felbamate
Topiramate
Tiagabine
Vigabatrin
Gabapentin
It is effective for treatment of
• partial seizures
• generalized tonic –clonic seizures
• in treatment of status epilepticus.
• Used in cardiac arrhythmia.
Phenytoin
Mechanism of action of Phenytoin
Blocks Na- channels
معاه ca وسالفة GABA بس الصوديوم اهم
Pharmacokinetics of phenytoin
-orally or IV
-Metabolites are excreted in urine
-Induces liver microsomal enzymes & can cause drug interactions
-Fosphenytoin is more water soluble, given by injection & rapidly converted to phenytoin in plasma ( for status )
-zero order kinetics (elimination )
Phenytoin – Toxicity
-Chronic oral Toxicity
-Gingival Hyperplasia
-Hyperglycemia
-Hirsutism
– Osteomalacia due to inc metabolism of VIT D
Carbamazepine MOA?
-Sodium channel blocker in brain only
-Potentiates post-synaptic action of GABA?مشمهم
Therapeutic Uses of Carbamazepine
• Epilepsy (Partial) focal ((1st line for treatment this type))
• Generalized (tonic-clonic)
• Trigeminal neuralgia
• Bipolar depression
AE of Carbamazepine
- aplastic anemia
-Antidiuretic effect (anti ADH) ( increase it secretion )
-Hyponatremia + edema
(بسبب ADH الزايد)
Contraindication of Carbamazepine?
-Absence seizures يزودهم
-myo-clonic
has an auto induction?
Carbamazepine يكسر نفسه
+ مثل phenytoin انديوسر
drug Effective in multiple seizure types
And its MOA
1. Blocks Na channels
2. Blocks Ca channels.
3. Inhibits GABA transamin
Valproic Acid الباشا
Ep يعالج كل انواع