Therapy of Epilepsy Flashcards
What happens in epilepsy?
Disrupted regulation of electrical activity in the brain = Synchronized and excessive neuronal discharge
What is critical to selection of appropriate pharmacotherapy for epilepsy?
Accurate classification and diagnosis of seizure type, including mode of seizure onset.
Aims of Drug therapy in Epilepsy?
1) Reducing the frequency of seizures
2) Minimizing adverse effects of anti-seizure drugs
3) Addressing coexisting health and social conditions
4) Enhancing quality of life (QOL)
Seizures that do NOT constitute epilepsy are those provoked by:
1) Infections
2) Fever (febrile seizures)
3) Drug overdose
4) Alcohol
5) Barbiturate or benzodiazepine withdrawal
6) Brain hemorrhage
7) Hypocalcemia
8) Hypoglycemia
9) Uremia
10) Eclampsia
What is the mainstay of epilepsy treatment?
Anti-seizure drug (ASD) therapy
Are Anti-seizure drugs (ASD) curative?
No, symptomatic and preventative only
How long are ASDs taken for?
Life-long
What do you do if the therapeutic goal for epilepsy is NOT achieved with monotherapy?
1) Add a second antiseizure drug (ASD), with a different mechanism of action
2) Switch to an alternative single ASD
What should you emphasize in epilepsy treatment?
Treat with a single drug!
What does the epilepsy drug treatment of first-choice depend on?
1) Type of epilepsy
2) Patient characteristics
What should you do once the proper ASD is selected?
Patient education and understanding of the treatment plan
What is the single most common reason for ASD treatment failure?
Medication non-adherence
Up to __% of patients with epilepsy are nonadherent to therapy.
60%
Reasons for ASD non-adherence:
1) Financial constraints
2) Complexity of the drug regimen
3) Frequent uncontrolled seizures
How should you stop ASD treatment?
Gradually, in order to avoid recurrence of seizures.
Sudden ASD withdrawal can be associated with:
Status Epilepticus
Withdrawal seizures are more common with which drugs?
1) Benzodiazepines
2) Barbiturates
Which patient characteristics must be considered before starting ASD treatment?
1) Age
2) Gender
3) Medical conditions
What should we keep in mind when giving ASDs to children?
They are more susceptible to neuropsychiatric adverse effects
What should we keep in mind when giving ASDs to Women of child-bearing potential?
They should not receive teratogenic ASDs
What should we keep in mind when giving ASDs to the elderly?
They are more susceptible to adverse effects on cognition
What if a patient has co-morbid conditions (migraine, tremor, or neuropathy)?
They may benefit from the use of an ASD that can also treat the
other condition
What should you pay EXTREME attention to when giving ASDs?
1) Drug-drug interactions with other drugs
2) Drug-drug interactions among ASDs themselves
What are the steps when giving ASDs?
1) Select one ASD, start with a low dose, and gradually titrate to a moderate dose goal, taking into account the patient’s response to treatment.
2) If there is NO adequate response at that dose, attempt increasing the dose.
3) If the first ASD monotherapy is still ineffective, or if the patient experiences intolerable adverse effects, adding a second ASD with a different mechanism of action and then tapering and discontinuing the first ASD is appropriate.
4) If the second ASD is ineffective, combination therapy may be indicated (although NOT
desirable).
A patient takes 1 ASD at a moderate dose, yet there is no therapeutic response. What is the next step?
Increase the dose
A patient takes 1 ASD at a moderate dose, yet has extreme side effects. What is the next step?
Add a second ASD with a different mechanism of action, then slowly taper off the first ASD.
A patient takes 1 ASD at a high dose and has previously tried 2 other ASDs, yet there is still no response. What is the next step?
ASD combination therapy
You have an elderly patient who is sensitive to falls, sedation, and neuro-cognitive adverse effects. How do you start ASD therapy?
Start at much lower initial dose and then titrate slowly (weeks –months), with a lower maximum dose goal.
You have a patient with multiple recent seizures (higher frequency). How do you start ASD therapy?
A therapeutic dose needs to be reached much more quickly, and a more rapid titration over days instead of weeks is appropriate.
Which ASDs have strong enough evidence to be labeled as effective, or as probably effective as initial monotherapy in certain seizure types?
1) Carbamazepine
2) Ethosuximide
3) Gabapentin
4) Levetiracetam
5) Oxcarbazepine
6) Phenytoin
7) Valproic acid
8) Zonisamide
ASD resistance is defined as:
Failure of two tolerated and appropriately chosen ASD (as monotherapy or in combination) to achieve sustained seizure freedom.”
Approximately 65% of patients can be maintained on one ASD and considered well controlled, although NOT necessarily ____.
Seizure free
The percentage of patients who are seizure-free on one drug after 12 months of treatment for only generalized tonic-clonic seizures is:
50%
The percentage of patients who are seizure-free on one drug after 12 months of treatment for only focal seizures is:
25%
The percentage of patients who are seizure-free on one drug after 12 months of treatment for those with mixed seizure types is:
25%
Of the 35% of patients with unsatisfactory control on monotherapy, __% will be well
controlled with a two-drug combination.
10%
____ are common and serious complicating factor in ASD selection.
Pharmacokinetic interactions
Which ASD drugs are considered enzyme inducers?
1) Carbamazepine
2) Lamotrigine
3) Phenytoin
4) Phenobarbital
5) Vigabatrin
Which ASD drugs are considered enzyme inhibitors?
1) Valproic acid
2) Topiramate
Knowledge of the presence of ____ of ASDs is important as they affect duration of action of the drug.
Active metabolites
Why is knowledge of the presence of active metabolites of ASDs important?
They affect duration of action of the drug
Which ASDs have active metabolites?
1) Carbamazepine
2) Primidone
Which ASDs have toxic metabolites?
Valproic acid
What are some common adverse effects shared by ASDs?
1) CNS adverse effects:
a) Sedation
b) Dizziness
c) Blurred or double vision
d) Difficulty in concentration
e) Ataxia
2) Impairment of cognition
3) Osteomalacia and osteoporosis
Which ASD causes more cognitive impairment than any other ASDs?
Barbiturates
What do barbiturates do in children?
Paradoxically cause hyperactivity
Which newer ASD causes substantial cognitive impairment?
Topiramate
How can ASD adverse effects be avoided?
By titrating the dose upward very slowly
How can ASD adverse effects be improved?
1) By decreasing the dose
2) By switching from polytherapy to monotherapy
Which ASDs interfere with vitamin D metabolism and/or absorption?
1) Phenytoin
2) Phenobarbital
3) Carbamazepine
4) Oxcarbazepine
5) Valproic acid
Patients receiving ASDs that interfere with Vitamin D metabolism/absorption should also receive:
1) Supplemental vitamin D and calcium
2) Bone mineral density testing
Why do we monitor the older ASDs?
To optimize therapy for an individual patient !NOT!! as a therapeutic end point in itself!!!
The serum concentration of ASDs should be always interpreted in association with:
Clinical response
Which seizure type needs higher concentrations of ASDs?
Focal dyscognitive seizures
Serum levels can also be useful:
1) To document lack or loss of efficacy
2) To document non-adherence
3) To determine how much room there is to increase a dose based on expected toxicity
4) In patients with significant renal or hepatic dysfunction
5) In those taking multiple drugs
6) In women who are pregnant or taking OCPs
When should ASD monitoring be performed?
ONLY at steady-state
What is Carbamazepine’s active metabolite?
10,11-epoxide
What is Clobazam’s active metabolite?
N-desmethylclobazam
What is Eslicarbazepine’s active metabolite?
Oxcarbazepine
What is Ezogabine’s active metabolite?
N-acetyl metabolite
What is Oxcarbazepine’s active metabolite?
10-hydroxycarbazepine
What is Primidone’s active metabolite?
Phenobarbital
Which 4 ASDs are highly protein bound?
1) Perampanel
2) Phenytoin
3) Tiagabine
4) Valproic acid
Clinical response is more important than the serum drug concentrations and involves:
1) Identifying the type and number of seizures
2) Identifying drug adverse effects
Evaluation of therapeutic outcomes includes:
1) Clinical response
2) Severity and frequency of seizures
3) Ascertain if the patient is truly seizure free
4) Monitor patient long-term for co-morbid conditions, social adjustment (including Quality-Of-Life assessments), drug interactions, and adherence.
5) Screen periodically for co-morbid neuropsychiatric disorders (depression and
anxiety).
The most important aspect of ASD use is:
Individualization of therapy
The following should be considered together in personalized pharmacotherapy:
1) Seizure type
2) Concomitant medical problems (hepatic function, renal function, psychiatric diseases, other neurologic problems, …).
3) Concurrent medications
4) Patient specific characteristics (age, gender, child-bearing ability, and ethnicity)
The elderly are often on polytherapy which may contribute to:
1) Increased sensitivity to neuro-cognitive effects
2) Increased possibility of drug-drug interactions with ASDs that affect CYP450
Which ASDs affect CYP450?
1) Carbamazepine
2) Phenytoin
3) Valproic acid
What should we consider when giving drugs to the elderly?
1) They are often on polytherapy
2) Hypoalbuminemia
3) Body mass changes
4) Compromised renal or hepatic function
Why is hypoalbuminemia an issue when giving ASDs?
Because it may cause problems with highly protein bound ASDs
Why are body mass changes (increase in fat to lean body mass or decrease in body water) an issue when giving ASDs?
They can affect the drug volume of distribution and elimination half-life.