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
Drug inhibits phenobarbital and phenytoin metabolism?
Valproic Acid
غالب الادويه كانت تسوي induction
هذا لا , inhibition
وممكن يسبب neutropenia
Adverse effect of Valproic Acid?
Teratogenicity Spina bifida cleft palate ( اكثر واحد ممنوع بالحمل )
fulminant hepatitis..
Heart burn
weight gain
Inc appetite
Hair loss ( alopecia )
Inhibitors of Calcium Channels in thalamus?
Ethosuximide
Drug of choice only used for Absence
seizure?
Ethosuximide
(Not effective in other seizure types )
The only barbiturate with selective anticonvulsant effect?
Phenobarbital ( enhance GABA transmission )
Used in status epilepticus?
Phenobarbital
فيه غيره مب هو فقط
لكنه نوع من barbiturate لو حدد السؤال
+more effective in children
ممكن يستعمل بانواع ثانيه من الصرع بس نادر
Pharmacokinetics of Phenobarbital
orally, IM & IV.
easily cross blood brain barrier
Excretion is ↑ in alkaline urine
induce liver microsomal enzymes,
Phenobarbital Toxicity
• ((Sedation)) ataxia, respiratory depression, stupor, coma
• ((Tolerance))dependence & abuse
Converted to phenobarbitone in body?
Primidone
Mostly used in status epilepticus?
benzodiazepine (Diazepam) and Lorazepam longer acting
Adverse effects of Benzodiazepines?
Amnesia
tolerance فيه اشياء بالمحاضره زياده
Wide margin of safety as compared to
barbiturates & phenytoin?
Benzodiazepines
Benzodiazepines used in absence
seizures ?
Clonazepam
Benzodiazepines Used for infantile spasms & myoclonic seizures?
Nitrazepam
Infantile = febrile
-associated with visual field loss - irreversible
Vigabatrin
(ranging from mild to severe in 30% or more of patients)
V -> vision
effective in a wide variety of seizure types, including focal, generalized, absence seizures, It is also used to treat bipolar disorder.
Lamotrigine
MOA of Lamotrigine
-blocks sodium channels, as well as high voltage-
dependent calcium channels.
اول واحد جديد له علاقه بexcitatory transmitters وكويس بالحمل
effective for use in partial and primary generalized epilepsy. It is also approved for prevention of migraine?
Topiramate
حتى valproic acid بس واحد جديد وواحد كلاسيك
Adverse effects of Topiramate
weight loss
Renal stones
Hyperthermia
—————-
oligohidrosis
Somnolence
glaucoma
Epilepsy in pregnancy.
Planning is the most important component. All women should be provided with folic acid. Divalporex & barbiturates should be avoided.
MOA of Benzodiazepines (diazepam, clonazepam)
Enhance GABA Transmission
