Anti - Convulsive's

Question 1

When we look at seizure medication, they can be classed as narrow or broad. What does this relate to?

1 - if the drug works on all age groups of not
2 - the drug can work on a variety of seizures or a specific type of seizure
3 - drugs that have lots of interactions or not
4 - all of the above

Answer 1

2 - the drug can work on a variety of seizures or a specific type of seizure
- this will often determine which medication to give

Question 2

There are some drugs that can inhibit and induce cytochrome P450 (CYP450) in the liver, which affects the drugs efficacy or adverse events. All of the following are inducers of CYP450, which aligns with the mnemonic CRAP GPS, but which 2 are anti-epileptic that induce CYP450?

1 - carbamazepine
2 - rifampicin
3 - alcohol
4 - phenytoin
5 - griseofulvin
6 - phenobarbitone
7 - sulfonylureas

Answer 2

1 - carbamazepine
4 - phenytoin

• inducers effectively mean drugs are metabolised quicker and cleared from the body quicker, meaning the drug is less effective

Question 3

There are some drugs that can inhibit and induce cytochrome P450 (CYP450) in the liver, which affects the drugs efficacy or adverse events. All of the following are inhibitors of CYP450, which aligns with the mnemonic SICKFACES.COM, but which 1 of these is an are anti-epileptic that inhibits CYP450?

1 - sodium valproate
2 - isoniazid, cimetidine
3 - ketoconazole
4 - fluconazole
5 - alcohol and grapefruit juice
6 - chloramphenicol
7 - erythromycin
8 - sulfonamides
9 - ciprofloxacin
10 - omeprazole
11 - metronidazole

Answer 3

1 - sodium valproate

• inhibitors mean the drugs are metabolised slower, meaning the drug stays in the system for longer
• dosages may need to be reduced to reduce the risk of toxicity and adverse events

Question 4

If a patient is having a seizure that is continuing and we need to give them some form of medication quickly, which class of the following drugs should be given?

1 - SSRI
2 - benzodiazepines
3 - anti-epileptic
4 - atypical antipsychotic

Answer 4

2 - benzodiazepines
- lorazepam given IV
- diazepam given rectally

Question 5

If a patient is unstable and seizure activity is ongoing we need to prescribe the patient an anti-epileptic medication. All of the following can be given via IV for a quick response in this instance, EXCEPT which one?

1 - Carbamazepine
2 - Phenytoin
3 - Levetiracetam
4 - Sodium Valproate

Answer 5

1 - Carbamazepine

Question 6

What is steady state in relation to medication?

1 - the loading dosage required to get into the therapeutic index
2 - when volume of drug exceeds drug being excreted
3 - when concentration of blood in systemic circulation = level being excreted
4 - all of the above

Answer 6

3 - when concentration of blood in systemic circulation = level being excreted

Question 7

Steady state is when the concentration of drug in then systemic circulation is equal to the level being excreted. Typically how many half lives does it take to reach steady state?

• half life = time taken for a drug concentration to reduce by 50% in circulation

1 - 2 half lives
2 - 5 half lives
3 - 10 half lives
4 - 20 half lives

Answer 7

2 - 5 half lives

Question 8

Steady state is when the concentration of drug in then systemic circulation is equal to the level being excreted. Typically this occurs in 5 half lives. Which of the following anti-epileptics is the one exception to this rule?

1 - Carbamazepine
2 - Phenytoin
3 - Gabapentin
4 - Pregabalin

Answer 8

1 - Carbamazepine
- initially metabolised at similar rates to other drugs
- BUT it induces cytochrome P450, meaning after a while it is metabolised quicker so the half lives are shorter
- steady state only reached after aprox 20-30 days

Question 9

Rather than slowly building up the concentration of a drug in the circulation we can give a loading dose, which can come with an increased risk of adverse events. Would a loading dose be more appropriate in an acute or outpatient setting?

Answer 9

• acute
• if patient is still seizing or is high risk of re-seizure

Question 10

When giving a patient a drug dose, how do we determine when to give the next dose of the drug?

1 - when patient shows symptoms
2 - when level of drug in circulation is at its lowest level in therapeutic window
3 - when level of drug has reduced by 50% in circulation
4 - combination of all of these

Answer 10

2 - when level of drug in circulation is at its lowest level in therapeutic window
- this is called trough level
- the peak and troughs are none for each drugs typically
- next dose of medication is given at this point

Question 11

What is first order kinetics?

1 - relates to 1st pass metabolism in the liver
2 - dosage of a drug required to get into therapeutic window
3 - constant proportion of the drug is eliminated per unit time
4 - time point at which drug levels begin to drop below 50% of systemic circulation

Answer 11

3 - constant proportion of the drug is eliminated per unit time

• relationship between metabolism and excretion of a drug

Question 12

Which of the following anti-epileptic medications requires close monitoring as it does not behave in line with first order kinetics?

1 - Carbamazepine
2 - Phenytoin
3 - Gabapentin
4 - Pregabalin

Answer 12

2 - Phenytoin
- once metabolism is saturated the levels in systemic circulation increase

Question 13

Some anti-epileptic medication can influence the levels of hormones in the body. Do Carbamazepine, Phenytoin and Sodium Valproate increase or decrease levels of testosterone?

Answer 13

• been shown to reduce testosterone levels
• important in transgender men who is undergoing masculinisation therapy
• these drugs enhance serum levels of sex hormone-binding globulin (SHBG), hence decreasing the testosterone bioactivity (its there but no active as bound to SHBG)

Question 14

Some anti-epileptic medication can influence the levels of hormones in the body. Do Carbamazepine and Phenytoin increase or decrease levels of oestrogen?

Answer 14

• decrease levels of oestrogen
• these drugs induce CYP450 isoenzyme that accelerates the conversion of estrogen and progesterone to inactive metabolites
• these metabolites are then excreted

Question 15

Anti-epileptics can affect the efficacy of oral contraception. Which 2 of the following are CYP450 inducers, metabolising oral contraceptives quicker and reducing their effectiveness?

1 - Carbamazepine
2 - Phenytoin
3 - Gabapentin
4 - Pregabalin

Answer 15

1 - Carbamazepine
2 - Phenytoin

Question 16

Anti-epileptics can be affected by oestrogen birth control. Which of the following anti-epileptic medications are less affective when taking with oestrogen contraception?

1 - Carbamazepine
2 - Phenytoin
3 - Gabapentin
4 - Valprolate

Answer 16

4 - Valprolate

Question 17

Which of the following can occur in pregnancy and post partum, and can therefore affect

1 - increased renal blood flow and GFR by up to to 50% by 14 weeks gestation
2 - Sodium and water retention causing reduced protein binding [aldosterone]
3 - Alteration in CYP 450 enzyme activity (influenced by sex hormones)
4 - all of the above

Answer 17

4 - all of the above
- drugs cleared by kidneys quicker and become less effective and may need larger doses
- drugs may be more biologically active

Question 18

Which is the safest anti-epileptic medication during pregnancy from the list below?

1 - Carbamazepine
2 - Phenytoin
3 - Valprolate
4 - Levetiracetam

Answer 18

4 - Levetiracetam
- still needs to be monitored though

• Carbamazepine and Phenytoin are teratogens and can cause malformations in babies
• Valprolate is the worst drug through

Question 19

Anti-epileptic medications Carbamazepine, Phenytoin and Valprolate are all teratogens and can cause deformities in babies. What is one of the key vitamins that is affected by these drugs that leads to things such as spina bifida and Anencephaly?

1 - vitamin D
2 - B12
3 - iron
4 - folate

Answer 19

4 - folate

Question 20

What % of patients remain having some form of seizures despite medications?

1 - 3-4%
2 - 13-14%
3 - 30-40%
4 - >65%

Answer 20

3 - 30-40%