Neurology Drugs Flashcards
What is Levetricatem also known as?
Keppra
How does Leventricatem / Keppra work?
What is its half life?
What are its side effects?
Works by SV2A protein binding
HL = 7hr
AE = Neuropsychiatric
How does Valproate work?
What is its half life?
What are its side effects?
Na channel inhibition, GABA enhancement
HL = 12-15h
AE - Alopecia, tremor, thrombocytopenia, pancreatitis, fetal abnormalities
How does diazepam work?
What is its half life?
AEs?
Allosteric binding to GABA-A Receptor - increasing frequency in which Cl- channels open
HL = 30-40 hours
AE = respiratory depression, respiratory arrest, drowsiness, confusion, headache, syncope, nausea and vomiting, diarrhoea, and tremors.
How does carbamazepine work?
What is its half life?
What are its AEs?
Inhibits Na channels
HL= 12-18h
AEs = hyponatremia, leucopenia, aplastic anaemia, can have hypersensitivity
How does Phenytoin work?
What is its half life?
What are its AEs?
Inhibits Na channels
HL = 24h
AEs = gum hypertrophy, hirsutism, megaloblastic anaemia, cerebellar ataxia, atrophy and peripheral neuropathy
How many half lives does it take to reach steady state?
Approximately 5
What is steady state?
Where the rate of absorption = rate of elimination
What is a trough level with medications?
It is the lowest blood concentration of the drug - taken just before the next dose is given
Why is phenytoin a complex drug to give?
Is 90% protein bound - therefore alterations in proteins impact on the free (active) drug. Means there is a difference between individuals in terms of the level of saturation.
What things affect the available proteins for drug binding in the blood?
Liver failure
Kidney failure
Pregnancy
What metabolism considerations are there about Valproate?
Highly protein bound = will compete with phenytoin
Metabolised by liver, excreted in urine
Dose-dependant teratogenicity
What metabolism considerations are there about Carbamazepine?
Potent inducer of CYP450
Steady state not reached until 20 days due to auto induction. Is sub thereapeutic for 20 days because it incs liver metabolism = auto-induction.
When is a P considered to have drug-resistant epilepsy?
What are their tx options?
Considered drug-resistant if they have failed to respond to 2 different appropriate antiseizure meds
Options = surgery, neurostimulator devices, ketogenic diet
How does LT treatment of a seizure differ depending on if it is provoked or unprovoked?
If provoked - provided we correct the provoking factor - the likelihood of having a recurrent seizure in the future is low, so dont have to give Rx for further seizures.
If we dont know why (unprovoked) - is always a risk of harm - therefore will need treatment.
What are common SEs of anti-seizure meds?
Sedation
Poor coordination
Imbalance
Fatigue
Osteopenia (long-term)
Suicidal ideation
Respiratory depression
What type of anti-seizure meds are best for focal seizures?
Sodium channel blockers
Which are the first generation anti-seizure meds we need to know?
Phenytoin
What generation are the following anti-seizure meds?
Clonazepam
Valproate
Carbamazepine
Diazepam
Second generation drugs
What generation are the following anti seizure meds?
Pregabalin
Levetiracetam
Gabapentin
Lamotrigine
Third generation drugs
Which antiseizure meds work on Na channels?
Phenytoin
Carbamazepine
Valproate
Apart from seizures, what is diazepam used for?
Anxiety
Alcohol withdrawal
Short term insomnia
Muscle spasms
Which anti seizure meds are also used for mood disorders?
Carbamazepine
Sodium valproate
Gabapentin and pregabalin - are used for anxiety disorders
Which anti seizure meds are broad spectrum for seizures?
Levetriacetam
Valproate
Lamotrigine
Which antiseizure meds do not have hepatic metabolism?
Where are they instead cleared from?
Levetiracetam
Gabapentin
Pregabalin
What are the side effects of pregabalin and gabapentin?
Weight gain
Cough
Worsens mycoclonic and absence epilepsy
Which antiseizure meds do have hepatic metabolisation?
Carbamazepine
Phenytoin
Diazepam
Sodium Valproate
Which antiseizure meds can cause Stevens Johnsons syndrome?
Carbamazepine
Phenytoin
Lamotrigine
Which antiseizure meds are teratogenic?
Sodium valproate
Carbamazepine
Phenytoin
?Pregabalin
Which antiseizure medications induce CP450?
Carbamazepine
Phenytoin
Which antiseizure medications inhibit CP450?
Sodium valproate
What is the management of acute seizures?
(1) Benzos - IV Lorazepam in hospital / Midazolam or diazepam outside hospital
(2). IV antiseizre medication - Levetiracetam, Phenytoin, Valproate
(3). Escalate to ITU if needed
How many half lives does it take to reach steady state?
What is steady state?
5
When rate of absorption = rate of elimination
What is special about Carbamazepine’s steady state?
Carbamazepine speeds up its own breakdown (autoinduction) - so getting a trough level doesn’t occur for 20-30 days - may need to up the drug initially and tweak it after the first month.
What is the trough level?
The level of drug in the blood immediately before the next dose is due.
How do Phenytoin and Sodium Valproate interact?
Phenytoin is 90% protein bound - but is displaced by valproate. Can mean that this increases the serum levels of phenytoin.
What is the IV version of Phenytoin called?
Fosphenytoin
Which antiseizure meds have interactions with sex hormones?
Phenytoin
Valproate
Carbamazepine
Levetiracetam
How do antiseizure meds affect birth control?
Carbamazepine and phenytoin can inc metabolism of oestrogen birth control
Valproate and Lamotrigine are made less effective by oestrogen birth control
What is the MOA of Lamotrigine?
Na channel blocker but also affects Ca channels and serotonin receptors
When should you not use lamotrigine?
If P has cardiac issues
If P is taking oestrogen birth control
Which antiseizure meds are safest for pregnancy?
Levetiracetam
Lamotrigine
What is the first line Rx for Parkinsons?
Levodopa
Is a dopamine precursor
Which drug for PD is a dopamine precursor + decarboxylase inhibitor?
Co-careldopa (Sinemet)
Which dopamine agonist is given for Parkinsons disease?
Ropinirole
What COMT Inhibitor is given for Parkinsons?
Entacapone
Which MAO-B Inhibitor is given for Parkinsons?
Rasagiline
What drug under “others” is given for Parkinsons?
Amantadine
What are possible complications of dopaminergic Rx?
Which Rx are given as an adjunctive Rx for Parkinsons?
Ropinirole
Rasagiline
Entacapone
What drugs are given for the following non-motor Sx of Parkinsons?
- Postural hypotension
- Excessive daytime sleepiness
- REM Sleep Disorder
- Constipation
- Urinary frequency / incontinence
- Depression
- Hallucination or psychotic Sx
- Dementia
Which drugs are given for acute vertigo?
Anti-histamines (cyclizine)
Neuroepileptics (prochlorperazine)
Anti-emetics (metoclopramide, ondansetron)
Anti migraine drugs
How does amitriptyline work?
Reduces uptake of 5HT and NOR
Is a tricyclic AD.
What are the SEs of amitriptyline?
Systemic side effects - anti muscarinic effects - affect bowel, bladder, cognition, secretions and QTc prolongation
What are gabapentin and pregabalin used for in MS?
Central and neuropathic pain
What are the side effects of gabapentin and pregabalin?
Weight gain
Fatigue
Sleepiness
Brain fog
? Suicide
What are the side effects of Pyridostigmine?
Diarrhoea, abdo pain, PSS effets inc bradycardia
What daily Rx is given for MG?
Pyridostigmine (Acetylcholinestease inhibitor)
What Rx is given for acute relapse in MG?
Prednisolone
What do you need to monitor with predinisolone (or any steroids?)
If P has diabetes - monitor sugars as can inc risk of hyperglycaemia
MG is one of the few situations where long term steroids may be used. Which is most commonly used?
Azathioprine
How does Azathioprine work?
Inhibits purine synthesis
What are the potential SE of Azathioprine?
Bone marrow suppression
Hepatotoxicity
How does Mycophenolate work?
What are its SEs?
T & B cell inhibition.
GI side effects are common. Monitor for skin cancer.
How does methotrexate work?
What are its SEs?
Inhibits DNA synthesis & T cell mediated inflammation
Can cause interstitial lung disease, bone marrow suppression and hepatotoxicity (but quickest to work)
What drugs should be avoided in MG?
Anything that causes neuromuscular blockade
- Cardiac drugs
- Abx
- APs
- β blockers
- Aminoglycosides
