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types of seizures?
- 1) nonconvulsive seizure: staring; stop whatever they are doing
- 2) convulsive seizure: loss of consciousness
- 1) simple: consciousness unaltered
- 2) complex: consciousness impaired or lost
general mechanism of action of anticonvulsant
- 1) limit the sustained repetitive firing of neuron, by promoting the inactivated state of the sodium channel when Na are inactivated, no transport of Na, no depolarization --> neurons wont fire; seizure prevented
- 2) enhance GABA mediated synaptic inhibition. some agents block T-type calcium channel
- anything that enhance GABA - prevent seizures!
- ex. barbiturates**phenobarbitol
enhance GABA binding, delaying closure of chloride channels
increase the frequency of opening chloride channel of GABA
phenytonin (dilantin) hydantoins
- Generalized tonic-clonic seizures and partial seizures with complex symptoms. Oldest nonsedative antiseizure drug.
adverse effect: gingival hyperplasia!!!!!
- slow rate of recovery of Na channel from inactivation. reducing Na current and neuronal firing
absorption is slow but complete and occure mainly in duodenum
- can displace thyroxin, salicylic acid, valproic acid from albumin
- zero-order kinetics - high dose required for control seizure
what is the adverse effect of phenytoin?
- gingival hyperplasia 20% of pt
- most common menifestation of phenytoin toxicity
but only where the teeth are present! not in toothless area
drug interaction of phenytoin
with oral contraceptive - unplanned pregnancy
because phenytoin induce p450 which degrades oral contraceptives
also used to treat trigeminal neuralgia and bipolar disorders
not gonna be on this exam but maybe for NB
- blocks T type calcium current in thalamic neuron
valproic acid (depakene) divalproex
fatty carboxylic acids with antiseizure properties
used to terat all types of epilepsy and cause fatal hepatitis
inhibit GABA transporter GAT-1
- inhibit carbonic anhydrase and may cause renal calculi
- mechanism of action
- blockade of Na+ and voltage gated Ca++ channels
Anticonvulsants (partial seizure)
to tx status epilepticus
4 main clinical features of parkinsons
- 1) bradykinesia (slowness of and poor movement)
- 2) muscular rigidity
- 3) resting tremor (abates during voluntary movement)
- 4) postural instability leading to disturbance of gait and falling
sometimes they ust freeze and someone has to come and help them
hallmark of parkinsons dz
they pathologic hallmark of PD is a loss of pigmented dopaminergic neurons of the substantia nigra pars compacta, with the appearance of intercellular inclusions called lewy bodies
inhibit formation of cAMP
Levodopa is given with what?
what is the antiparkinson agent?
levodopa and carbidopa TOGETHER!
combination of levodopa and carbidopa
peripherally acting inhibitor of aromatic L-amino acid decarboxylase that do not penetrate well into CNS
major side effect of levodopa?
- orthostatic hypotension
- (bc dopamine can act as a vasodilator)
what agents cause hypertensive crisis with levodopa?
nonspecific MAO inhibitor (phenelzine and tranylcypromine)
wine and cheese are not good for people on MAO bc of high content of tyromine which can cause release of these catecholamines
some fact: duration of beneficial effects of levodopa may exceed the plasma lifetime of the drug, suggesting that the nigrostriatal dopamine system retains some capacity to store and release dopamine
- buffereing capacity - capacity to store levodopa
- sometimes on someitmes off you dont know
dopamine receptor agonists
Catechol-O-methyltransferase (COMT) inhibitors
- responsible for most oxidative metabolism of dopamine in the brain
- present in periphery
- selegline is selective for MAO-B
selective inhibitor of MAO-B