NEUROLOGICAL DRUGS Flashcards
what is levodopa?
dopamine precursor
how can levodopa act centrally on the brain?
crosses blood brain barrier
where in the brain does levodopa replaces the deficit in dopamine?
basal ganglia
give an ophthalmological contraindication of levodopa
closed angle glaucoma as levodopa can cause further increase in intraocular pressure
what kind of parkinsonism contraindicates use of levodopa
drug induced
give a circulatory side effect of levodopa
Postural Hypotension, syncope and drowsiness
what can occur to the urine of a patient taking levodopa?
discolouration
why shouldn’t levodopa be used with anaesthetics?
increases the risk of dysrhythmias
why shouldn’t levodopa be used with MAOI antidepressants?
increase the risk of hypertension
what type of drug is phenytoin?
anti-convulsant
how does phenytoin work?
block voltage gated sodium channels which prevents influx of sodium and prevents action potential formation for a seizure. Prevent the spread of neuronal excitability and therefore inhibits seizure activity spread
which seizures is phenytoin not active against?
absent
apart from epilepsy, give a condition that phenytoin is used to treat
trigeminal neuralgia
what is the metabolism of phenytoin?
cytochrome p450
also induces p450
what type of drug is carbamazepine?
anti-convulsant
how does carbamazepine work?
increases release of GABA which inhibits the CNS by blocking sodium channels - stops action potential
What is carbamazepine 1st line treatment for?
Generalised tonic clonic seizure
Focal seizures
Trigeminal neuralgia= Controls the pain, reduces the frequency and severity of the attacks
carbamazepine is contraindicated in what abnormality that causes immune depression?
bone marrow depression
carbamazepine is contraindicated in what heart abnormality?
AV node conduction abnormality
carbamazepine and sodium valproate are contraindicated in which disease?
acute porphyria ( metabolic disorders)
use of carbamazepine can lead to which organ insufficiencies?
renal
hepatic
give 2 blood disorders that can be caused by carbamazepine
agranulocytosis
thrombocytopenia
how does carbamazepine interact with cytochrome p450?
Metabolised and induced by it
what type of drug is sodium valproate?
anti-convulsant
how does sodium valproate work? (3 things)
increase GABA by preventing re-uptake
Blocks sodium channels
Decreases plasma conc of aspartate (excitatory neurotransmitter)
If a patient is taking sodium valproate and has
a) renal impairment
b) hepatic impariment
what should be the recommendation?
a) reduce the dose
b) stop taking sodium valproate
give 3 other side effects of sodium valproate
weight gain
sedation
hair loss
why shouldn’t sodium valproate be given with neuroleptics?
decrease effect
why shouldn’t sodium valproate be given with TCAs?
reduce effect
what type of drug is lamotrigine?
anti-convulsant
Except for epilepsy and seizures, give 2 instances when lamotrigine can be used
lennox-gastaut syndrome
Depression in Bipolar disorder
what type of drug is levitaracetam?
anti-convulsant
how does levitaracetam work?
selectively prevents epileptic burst firing and propagation of seizures without affecting normal neuronal activity
aside from a tablet, how can levitaracetam be given?
injection
why should caution be taken when stopping a patient on levitaracetam?
withdrawal seizures
give 4 side effects of levitaracetam
Abdo pain
Anorexia
co-ordination difficulties
sedation/fatigue
why should levitaracetam be given with caution in pregnancy
can be difficult to maintain seizure control when pregnant
Why should the use of L-dopa be used with caution in patients with cardiovascular disease?
Due to the risk of hypotension
What is the risk of using L-dopa in elderly patients or patients with existing cognitive or psychiatric disease?
This is due to the further risk of confusion and hallucinations
What physiological affect does L-dopa have?
Can cause confusion and hallucinations
What is a long term complication of using L-dopa?
Increase wearing off effect which causes the notion off the on-off symptoms of parkinsons
What common GI symptoms do you get with L-dopa
Nausea and vomiting
What affect can L-dopa have on a person weight?
Can cause anorexia
What is the side effect of giving L-dopa to frequently or to high of a dose?
Dyskinesia –> involuntary movement
What drug is given in conjunction with L-dopa and why?
Carbidopa = Peripheral dopa-decarboxylase inhibitor to prevent the conversion to dopamine outside of the brain
Why should you not give L-dopa with antihypertensives?
Due to the risk of further hypotension
When is phenytoin used for status epilepticus?
When BZDP does not work
Is phenytoin the first line treatment for generalised and focal seizures?
No it’s not as other anticonvulsants have less side effects and interactions
What is the consequence of phenytoin having a low therapeutic index?
The chance of phenytoin toxicity is high as missing a dose or taking to much can have severe effects
Why shouldn’t pregnant ladies take phenytoin?
Fetal Hyuntain syndrome = abnormal cranialfacial features and lower IQ
What should patients take before conception when on phenytoin or Carbamazepine?
High dose of folic acid
What does long term use of phentyoin do to the skin?
Cause coarse skin, acne and gum hypertrophy
What are the dose related neurological effects of phentyoin?
Cerebellar toxicity ( ataxia, nystagmus and discoordination) and impaired cognition and consciousness
How does phentyoin cause osteomalacia and haematological disorders
It induces vitamin d and folic acid metabolism
What happens in hypersensitivity reaction of phentyoin or Carbamazepine?
From mild rash to life threatening rare antiepileptic hypersensitivity syndrome
Phenytoin toxicity caused by overdose can cause death by what mechanism?
Respiratory depression and cardiovascular collapse
What drugs effect the efficacy of phenytoin, carbamazepine, levetiracetam and sodium valproate?
Drugs that reduce the seizure threshold such as SSRI's TCA antidepressants Tramadol Antipsychotics
What happens in life threatening antiepileptic hypersensitivity syndrome?
Clinical features include severe skin reactions , fever and lymphadenopathy with systemic (e.g.
haematological, hepatic, renal) involvement and mortality of about 10%.
Carbamazepine is used as a alternative treatment of what two conditions?
Prophylaxis of Bipolar disorder ( lithium uneffective)
Chronic neurogenic pain
What are the potential consequence of carbamazepine exposure in utero?
Neural tube defect, cardiac and urinary abnormalities and cleft palate
What are common side effects of carbamazepine?
Nausea and vomiting
Ataxia and dizziness
What type of seizures is sodium valproate first line choice for?
Generalised seizures and absence seizures
Except for seizures what else is sodium valproate used for?
Migraine
Bipolar disorder for acute treatment of manic episodes or prevention of relapse
Which anti epileptic drug has the greatest risk of fetal abnormality?
Sodium valproate
At what points in pregnancy should sodium valproate definitely be avoided?
Contraception and first trimester
What is the potential fetal abnormalities caused by sodium valproate?
Neural tube defect
Craniofacial, cardiac and limb abnormalities
Developmental delay
What affect does sodium valproate have on cytochrome p450?
inhibitor
What is Lennox-Gastaut Syndrome ?
It is type of epilepsy with many different types of seizures
What are the two main types of seizures in which lamotrigine is used for?
Monotherapy and adjuvant therapy for generalised seizure and focal seizure
What condition can be exacerbated by lamotrigine?
Parkinsons
What two drugs decrease plasma conc of lamotrigine?
Oestrogen and rifmapicin
What drug increases plasma conc of lamotrigine?
Sodium Valproate
What is the interaction between levetiracetam and methotrexate?
Increases the plasma conc of methotrexate
What fibres does phentyoin have affect on that causess the antiarrhythmic and cardiotoxic effects?
cardiac Purkinje fibres
