Neurology Flashcards
Anticonvulsants work by
- Reduce nerve’s ability to be stimulated
- Suppress transmission of impulses from one nerve to the next
- Decrease speed of nerve impulse conduction within a neuron
Hydantoins
- Ethotoin (Peganone)
- Fosphenytoin (Cerebyx) NOT for primary care
Available only in intramuscular (IM) or intravenous (IV) dosing
Given only for about 5 days (loading dose), then will start PO drug (Dilantin) - Phenytoin (Dilantin)
Fosphenytoin (Cerebyx)
Hydantoin
NOT for primary care
Available only in intramuscular (IM) or intravenous (IV) dosing
Given only for about 5 days (loading dose), then will start PO drug (Dilantin)
Phenytoin (Dilantin)
Hydantoin
Note that phenytoin is not interchangeable with Dilantin
Hydantoins
Uses: Tonic-clonic (aka grand mal), partial complex seizures
90% plasma bound (be careful with drug-drug interactions; hypoalbuminemia -> seizures or toxicity)
Metabolism in liver
Hydantoins drug interaction
Effect of drug is increased: ETOH (short-term)
Effect of drug is reduced: ETOH (chronic use)
Reduce effectiveness of oral contraception pills, thyroid hormone
Hydantoin ADRs
Nystagmus, diplopia, dizziness, sedation, ataxia
Gingival hyperplasia, hirsutism
SJS, toxic epidermal necrolysis
Lymphadenopathy, hepatitis
Hypotension
Reddish-brown urine
Megaloblastic anemia - treat with folic acid
Signs of Hydantoin Toxicity
20-30 Nystagmus = Early sign
30-40 Ataxia = Early sign
> 40 decreased LOC
Hydantoins contraindicated in:
Pregnancy
Iminostilbenes
Carbamazepine (Tegretol)
Oxcarbazepine (Trileptal)
Valproic acid (Depakote)
Uses: tonic clonic seizure, complex partial seizure, mood stabilizer (treat mania in bipolar), trigeminal neuralgia
Highly protein bound
Metabolized in the liver
Carbamazepine (Tegretol)
Iminostilbene
May experience autoinduction
Warning for Fetal Carbamazepine Syndrome
Oxcarbazepine (Trileptal)
Iminostilbene
Valproic acid (Depakote)
Iminostilbene
Carboxylic acid derivative
Thought increase GABA, an inhibitory neurotransmitter, as well as having a direct membrane-stabilizing effect
Iminostilbene ADRs
Decrease bone marrow, aplastic anemia (monitor CBC)
Impaired liver function, impaired thyroid function
Dizziness, nystagmus, ataxia, N/V, dry mouth, diplopia, HA
Blood dycrasias
Black Box: SJS, toxic epidermal necrolysis
Black Box Warning for Iminostilbenes
Skin rash
SJS
Toxic epidermal necrolysis
Blood dyscrasias
S/S of Blood Dyscrasias
Fever, sore throat, Easy bruising
Succinimides
DOC for absence seizures Ethosuximide (Zarontin) Methsuximide (Celontin) ADRs GI, somnolence, fatigue, ataxia Long 1/2-life
Ehosuximide (Zarontin)
Succinimide
Methsuximide (Celontin)
Succinimide
Lamotrigine (Lamictal)
Adjunctive therapy for tonic-clonic, partial, absence
Used with phenytoin or valproic acid
BBW: rash, SJS
Black Box Warning for Lamotrigine (Lamictal)
Rash
SJS
Leviteracetam (Keppra)
Uses: tonic-clonic, myoclonic seizures Adjunctive therapy to treat partial seizures ADRs: dizziness, weakness, sedation Generally well tolerated NOT metabolized by CYP enzymes
1-(aminomethyl) cyclohexane acetic acid
Gabapentin (Neurontin)
Topiramate (Topamax)
Thought to elevate GABA in the brain
Uses: Adjuvantive therapy for partial seizures
Gabapentin (Neurontin)
1-(aminomethyl) cyclohexane acetic acid
Adjuvantive therapy for partial seizures
Used widely for neuropathic pain; approved for post-herpetic neuralgia
Topiramate (Topamax)
1-(aminomethyl) cyclohexane acetic acid
Adjuvantive therapy for partial seizures
Treats migraines
ADRs: confusion/cognitive problems, difficulty in concentration and speech; may decrease sweating; may increase body temp
Benzodiazepines
clonazepam (Klonopin)
lorazepam (Ativan)
diazepam (Valium)
Clonazepam (Klonopin)
Only drug approved for long term use of seizure control
ADR: drowsiness, lethargy (37%)
Status epilepticus
Treat with IV lorazepam (Ativan) or diazepam (Valium)
Parkinson’s Symptoms
TRAP T: Tremor (resting and pill-rolling) R: Rigidity (cogwheel movement) A: Akinesia/bradykinesia P: Postural instabilit (shuffling gait)
Goals of drug therapy for Parkinson’s
Correct the imbalance of neurotransmitters by increasing Dopamine and decreasing Acetylcholine (Ach)
Two major categories:
Dopaminergic agents
Anticholinergic agents
Levodopa
Most effective for symptomatic treatment of PD
DOC for bradykinesia
Increases dopamine concentration, enhances the neurotransmission of dopamine
Full therapeutic effect can take months
Highly effective, but benefits diminish over time
Food delays absorption – take on empty stomach
High fat/ high protein meals compete with levodopa for absorption
Levadopa ADRs
Large doses of levodopa = High peripheral levels of dopamine = Increased adverse effects GI distress (N/V), postural hypotension, CV dysrhythmias, dyskinesias, psychosis, confusion Thus, levodopa is given with carbidopa, a peripheral decarboxylase inhibitor (“car that drops off levodopa in the brain”)
Sinemet
Levodopa/Carbidopa
Available in immediate or sustained release
Most effective drug for Parkinson’s, and good choice for elderly
Parcopa
Levodopa/Carbidopa
Dissolves on tongue
Most effective drug for Parkinson’s, and good choice for elderly
Two types of Dopamine agonists
Derivatives of ergot – less selective; more s/e
Nonergot derivatives – highly selective for Dopamine
pramipexole (Mirapex)
Nonergot derivative; Dopa agonist
ropinirole (Requip)
Nonergot derivative; Dopa agonist
Nonergot derivatives
First-line drug for younger patients with mild-moderate PD
Used alone in early PD (< 60 yo) and with levodopa in advancing PD
Maximal benefits take several weeks to develop.
Adverse effects
Monotherapy –daytime somnolence (“sleep attacks” esp older pts), nausea, dizziness, insomnia, constipation, weakness, and hallucinations
Combined w/ levodopa – increases effect of levodopa (orthostatic hypotension, dyskinesias, etc.)
Causing rare instances of worse behavioral impulse patterns: pathologic gambling and other compulsive self-rewarding behaviors; alcoholism
ADRs of nonergot derivatives
“Sleep Attacks” = daytime sleepiness; esp. older patients
May increase ADRs of levodopa when combined therapy (orthostatic hypotension, dyskinesias)
Causes rare instances of worse behavioral impulse patterns: pathologic gambling and other compulsive self-rewarding behaviors; alcoholism
COMT inhibitors
Inhibit metabolism of levodopa in the periphery
Prolongs time that levodopa is available to the brain
No direct therapeutic effects of their own
Entacapone
Tolcapone
Entacapone
COMT inhibitor
Tolcapone
COMT inhibitor
Warning about COMT Inhibitors
Rapid withdrawal of COMT inhibitors may lead to Parkinsonian crisis: syndrome of muscle rigidity, high fevers, tachycardia, confusion, elevated CK levels = similar to neuroleptic malignant syndrome
Black Box Warning for Tolcapone
Hepatotoxicity
MAO-B Inhibitors
Inhibit MAO-B in the brain
Increases dopaminergic activity
Can reduce wearing off of levodopa
Selegiline (Eldepryl, Zelapar)
Rasagiline (Azilect)
Selegiline (Eldepryl, Zelapar)
MAO-B Inhibitor
Older; converted to amphetamine or methamphetamine
Rasagiline (Azilect)
MAO-B Inhibitor
Dopamine Modulator
Treats early mild/moderate PD in younger pts
Amantadine (Symmetrel)
Amantadine (Symmetrel)
Dopamine Modulator
Anticholinergic Drugs
Inhibits cholinergic effects
Treats: tremors, rigidity (cogwheeling), drooling; used in younger pts
Benztropine (Cogentin)
Biperiden (Akineton)
procyclidine
trihexyphenidyl
ADRs of Anticholinergic Drugs
Dry mouth, confusion, drowsiness, tachycardia, constipation
Central anticholinergic syndrome if taking multiple anticholinergics
Benztropine (Cogentin)
Anticholinergic Drug
Biperiden (Akineton)
Anticholinergic Drug
procyclidine
Anticholinergic Drug
trihexyphenidyl
Anticholinergic Drug
