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Exam Prep MCQs > Drugs used in the treatment of epilepsy > Flashcards

Drugs used in the treatment of epilepsy Flashcards

1
Q

At what age can sodium valproate be given?

A

Valproate can be safely used in children down to 1 month of age.

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2
Q

What kind of seizures can sodium valproate be used for?

A

Generalised, mixed and partial seizures

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3
Q

When is sodium valproate contraindicated?

A

Severe hepatic or renal failure

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4
Q

How does sodium valproate work?

A

Sodium valproate acts by weakly blocking sodium ion channels. It inhibits GABA transaminase, which would deactivate gamma-Aminobutyric Acid (GABA) and may also stimulate GABA synthesis.

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5
Q

Where is valproic acid metabolised?

A

The liver

75% by the CYP450 system

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6
Q

What is valproic acid at room temperature?

A

Liquid fatty acid but it can be reacted with a base to form a solid salt.

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7
Q

How does valproic acid affect platelets?

A

Interferes with platelet aggregation and can cause blood disorders

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8
Q

How many days until valproic acid treatment is effective?

A

14 days

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9
Q

Can valproic acid be used to treat migraines?

A

Yes

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10
Q

What effect does phenytoin have on the enzyme intestinal conjugase?

A

It inhibits intestinal conjugase and this causes folate deficiency.

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11
Q

What is phenytoins half life?

A

6 - 24hrs

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12
Q

Is phenytoin a CYP450 enzyme inducer or inhibitor?

A

Inducer

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13
Q

What are the CVS effects of phenytoin?

A

Hypotension and arrhythmias so should be administered with cardiac monitoring if giving IV.

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14
Q

What effect does phenytoin have on blood glucose?

A

Phenytoin can cause hyperglycaemia & glycosuria due to insulin inhibition

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15
Q

How protein bound is phenytoin?

A

Highly protein bound, mainly to albumin

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16
Q

What kind of kinetics does phenytoin undergo?

A

Phenytoin follows saturatable first order kinetics which converts to zero order kinetics when the enzyme system is overwhelmed.

It has a narrow therapeutic index and blood levels are therefore monitored.

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17
Q

What does SEs does phenytoin toxicity cause?

A

Toxicity causes blurred vision, mydriasis and brisk tendon reflexes.

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18
Q

What is the oral bioavailability of phenytoin?

A

Bioavailability is good, but oral absorption is slow, variable & can be only partial.

Volume of distribution is approx 70% of body weight.

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19
Q

What kind of effect does phenytoin cause on FBC?

A

Phenytoin causes macrocytic, megaloblastic anaemia due to folate deficiency.

20
Q

Is phenytoin antiarrhythmic?

A

It is a class Ib antiarrhythmic agent, like Lidocaine.

21
Q

What effect does phenytoin have on thyroid function?

A

No effect.

But will cause falsely low TFTs after long term treatment.

22
Q

What routes can phenytoin be given effectively?

A

Not effective IM

PO (slow)

IV

23
Q

Is phenytoin carcinogenic?

A

No

24
Q

What drug can be given to treat digoxin induced dysrhythmias?

A

Phenytoin

25
Q

What enzyme metabolises phenytoin?

A

Hepatic microsomal enzymes

26
Q

What SEs can phenytoin cause?

A

It can cause rash, horizontal gaze nystagmus, gum overgrowth, acne as well as blood disorders.

27
Q

Is phenytoin still effective if given with the OCP?

A

Phenytoin is effective in the presence of the OCP but the contraceptive effect may not be effective due to enzyme induction

28
Q

What effect does phenytoin have on excitable membranes?

A

Stabilises them

29
Q

What is the half life of phenobarbital?

A

Phenobarbital is extremely long acting, with a half life of 50 - 100 hours or more.

30
Q

What can phenobarbital be used to treat?

A

All seizures except absence

31
Q

What is the protein binding of phenobarbital?

A

20-45% protein bound

32
Q

What problems can phenytoin and carbamazepine cause in pregnancy?

A

Phenytoin is teratogenic and can cause Fetal Hydantoin Syndrome (like Carbamazepine).

33
Q

What is fetal hydantoin syndrome?

A

FHS causes intra-uterine groth retardation, microcephaly, craniofacial abnormalities and limb defects

34
Q

Is phenobarbital sedating?

A

Yes, but use has largely been superceded by benzodiazepines.

35
Q

What does phenytoin do to sodium channels?

A

Phenytoin stabilises sodium channels in their inactive state

36
Q

Where is phenytoin excreted?

A

In bile, but some is excreted renally

37
Q

CAn phenytoin be used to treat trigeminal neuralgia?

A

Yes

38
Q

Can sodium valproate cause tremors?

A

Yes

39
Q

Does sodium valproate cause hair loss?

A

Yes, in 10% of people

40
Q

Does phenytoin only rarely cause allergic reactions?

A

No, phenytoin can cause severe allergic reactions and must be given with vigilance.

41
Q

Is carbamazepine safe in pregnancy?

A

No.

Carbamazepine can cause spina bifida & other neurodevelopmental problems after intrauterine exposure

42
Q

What is the half life of carbamazepine?

A

25-65hrs

43
Q

What effect does carbamazepine have on blood tests?

A

Carbamazepine can reduce serum sodium & WBC levels at normal drug levels, but also cause life-threatening loss of platelets.

44
Q

Does carbamazepine increase the risk of lupus?

A

Lupus risk increases by nearly 90% (probably only in women)!

45
Q
A

Exam Prep MCQs (19 decks)

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