* Stroke & Epilepsy Pharm Flashcards
What is tissue plasminogen activators (tPA)?
- Clot busters
- Binds to fibrin to convert plasminogen to plasmin -> stimulates fibrinolysis of atherosclerotic lesion
- eg ALTEPLASE
What is the inclusion criteria for tPA?
- > 18yo
- Last known well time is <4.5 hrs
- Ischemic stroke
~ with NIHSS >4
What is the exclusion criteria for tPA?
- Evidence of hemorrhagic stroke (ICH/SAH)
- Active internal bleeding
- Stroke or head injury within past 3 months
- Intracranial or intraspinal surgery within the last 3 months
- While on warfarin, INR is >1.5, or PT > 15
- Received heparin within 48 hours + aPTT elevated
- Persistent blood pressure elevation
~ SBP > 185 or DBP > 100 - CBG <2.7 or >22.2 mmol/l
What are the complications of tPA?
- Intracranial hemorrhage
- Other bleeding complications
- Angioedema
- Transient hypotension
Note: Tf need to monitor BP every 15 mins during tPA infusion
Nursing PEARLs for tPA administration?
- Actual weight of px (for accurate dosing)
- 18-gauge IV access for perfusion imaging
~ + 2nd IV if px is receiving thrombolytics / receiving radiology for thrombectomy - IV Alteplase must be swirled, NO shaking
- IV alteplase double-checked with 2nd clinician
- Check BP and neurological status 15 min before administration
~ BP prior: <185/110
~ BP after: <180/105 for 24 hrs
~ BP after (for px wo thrombolytics): <220/110 (permissive BP)
What does antiplatelet and anticoagulant therapy include?
- Anti-PLT: Aspirin, Clopidogrel
- Anti-coag: Warfarin
~ INR 2-3
~ Used short term (3 mths) + followed by an anti-PLT - Heparin anticoagulation
What drug is used as a vasodilator to prevent vasospasms post-op for hemorrhagic stroke?
NIMODIPINE
IMPT
What characteristics put a px at lower risk of recurrent seizures?
- Single seizure
- Normal EEG
- Normal brain scan
IMPT
What puts a px at higher risk of recurrent seizures?
- Previous undiagnosed seizures
- Epileptiform seizures (whack EEGs)
- Abnormal brain scans
What are the main anti-epileptic drugs?
- Phenytoin
- Carbamazepin
- Valproate
- Benzodiazepine (drug class)
Pls Control Bellowing Voices
IMPT:
What are the 2 main actions of anti-epileptics?
1) Decrease membrane excitability
- By altering Na and Ca2 conductance during action potentials
2) Enhance effects of inhibitory GABA transmitters
IMPT:
How does phenytoin work and what is it used for?
- Blocks voltage-dependent Na+ channels
~ Decreases excitability of neurons
Suitable for all types of seizures
- Except absence seizures
IMPT:
What precautions are there when using phenytoin?
1) Narrow therapeutic range
- 40-100 microM
- Careful titration needed
2) Non-linear r/s b/w dose and plasma concentration
- Requires titration and monitoring
3) Teratogenic
- Leads to birth defects
- Contraindicated in pregnancy
IMPT:
- How does carbamazepine work and what is it used for?
- Similar to phenytoin (blockage of Na channels)
Suitable for all types of seizures
- Except absence seizures
IMPT:
What precautions are there when using carbamazepine?
1) Repeated doses of carbamazepine induces increased production of CYP450 (hepatic enzyme)
- Accelerates elimination of drugs
- Half life of cbmzp + other drugs half-life shortens -> Drug dose needs to increase
2) May cause aplastic anemia
- Inability of bone marrow to produce all types of blood cells
IMPT:
How does valproate work and what is it used for?
1) Blocks Na+ and Ca2+ channels
2) Inhibits GABA transaminase (which breaks down GABA) -> inc GABA in synaptic space
- Increases inhibition of excitatory action
Suitable for all types of seizures + absence seizures
Note: GABA maintains inhibitory tone that counterbalances neuronal excitation
IMPT:
What are the precautions before using valproate?
1) Strongly binds to plasma proteins
- Displaces other antiepileptics -> needs to increase dose of those drugs
- Difficult for px on multi-therapy
IMPT:
How do benzodiazepines work and what are they used for?
1) Enhances binding of GABA neurotransmitters on Cl- channels
- Increases inhibitory effect on excitatory neuron action
- Done by potentiating influx of Cl- ions leading to hyperpolarisation (opp of depolarisation)
Used when other antiepileptics are not effective
IMPT
What are the more common benzodiazepines used to treat epilepsy?
Short-acting BZP not often used as multiple doses are required
- Unsafe due to addictive nature, w epilepsy being a chronic condition
- Effective duration only 3-8 hours
Intermediate-acting:
- CLONAZEPAM
- LORAZEPAM
- Used in refractory seizures (not effectively treated by first-line meds)
- Lorazepam also can be used for Status Epilepticus
- 10-20 hours
Long-acting:
- DIAZEPAM
- Used in refractory seizures and Status epilepticus
- 1-3 days effective duration
IMPT:
When are anti-epileptic drug levels tested?
- When assessing COMPLIANCE of drug treatment of px w refractory epilepsy
- When suspecting possible anti-epileptic drug toxicity
- Titration of phenytoin dose due to therapeutic dose
Not required without clear clinical indication
What are the 3 drugs used for insomnia?
- Triazolam
- Temazepam
- Flurazepam
