Antiepileptics Flashcards
Sodium valproate:
Is contraindicated in children
False. Valproate can be safely used in children down to 1 month of age.
Sodium valproate:
Is used to treat petit mal seizures
True. It is used to treat generalised, mixed and partial seizures.
Sodium valproate:
Is used to treat grand mal seizures
True
Sodium valproate:
Can be used safely in liver disease patients
False. It is contraindicated in severe hepatic or renal failure.
Sodium valproate:
Acts by enhancing concentrations of the neurotransmitter GABA
True. 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.
Valproic acid:
Is metabolised in the liver
True. 75% is metabolised by the CYP450 system.
Valproic acid:
Is a liquid fatty acid at room temperature
True. Valproate is a liquid at room temperature but can be reacted with a base to form a solid salt.
Valproic acid:
Enhances platelet aggregation
False. Valproate interferes with platelet aggregation and can cause blood dyscrasias.
Valproic acid:
Takes at least 3 weeks to have it’s effect
False. It is effective 14 days after treatment commences.
Valproic acid:
Has been used to treat migraines
True. Though mainly in the US.
Phenytoin:
Inhibits the enzyme intestinal conjugase
True. Phenytoin does inhibit intestinal conjugase, which causes folate deficiency, not vitamin B2 deficiency.
Phenytoin:
Has a half life of about 4hrs
False. Phenytoin’s half life is 6 to 24 hours.
Phenytoin:
Is an CYP450 enzyme inhibitor
False. It is an enzyme inducer.
Phenytoin:
Can cause Vitamin B2 deficiency
False
Phenytoin:
Causes hypotension
True. When administered IV, Phenytoin can cause hypotension and arrhythmias and should be administered with cardiac monitoring.
Phenytoin:
Does not cause glycosuria
False. Phenytoin can cause hyperglycaemia & glycosuria due to insulin inhibition.
Phenytoin:
Is highly protein bound
True. It is mainly bound to Albumin.
Phenytoin:
Undergoes zero order kinetics with a wide therapeutic index
False. 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.
Phenytoin:
Toxicity can cause diminished tendon reflexes
False. Toxicity causes blurred vision, mydriasis and brisk tendon reflexes.
Phenytoin:
Oral bioavailability is high and absorption is rapid
False. Bioavailability is good, but oral absorption is slow, variable & can be only partial. Volume of distribution is approx 70% of body weight.
Phenytoin:
Causes megaloblastic anaemia due to Vitamin B12 deficiency
False. Phenytoin causes macrocytic, megaloblastic anaemia due to folate deficiency.
Phenytoin: Is a class Ia antiarrhythmic
False. It is a class Ib antiarrhythmic agent, like Lidocaine.
Phenytoin:
Has no effect on Thyroid function
True. Causes falsely low TFTs after long term treatment.
Phenytoin:
Is absorbed rapidly via IM or IV routes
False. Not effective IM, only PO (slowly) and IV.
Phenytoin:
Phenyotin is carcinogenic
False. There is no good evidence that Phenytoin is carcinogenic.
Phenytoin:
Can be used to treat Digoxin induced dysrhythmias
True
Phenytoin:
Is metabolised in the liver by the enzyme rhodanase
False. Phenytoin is metabolised by hepatic microsomal enzymes.
Phenytoin:
Can cause significant side effects including nystagmus
True. It can cause horizontal gaze nystagmus, gum overgrowth, acne as well as blood disorders.
Phenytoin:
Is effective with the oral contraceptive pill
True. Phenytoin is effective in the presence of the OCP but the contraceptive effect may not be effective due to enzyme induction.
Phenytoin:
Stabilises excitable membranes
True
Phenobarbitone/Phenobarbital:
Is the most widely used anticonvulsant
False.
Phenobarbitone/Phenobarbital:
Lasts longer than Phenytoin
True. Phenobarbital is extremely long acting, with a half life of 50 - 100 hours or more.
Phenobarbitone/Phenobarbital:
Is used in the treatment of generalised seizures
True. It is effective in all seizure activity except absence seizures.
Phenobarbitone/Phenobarbital:
Is ineffective in absence seizures
True.
Phenobarbitone/Phenobarbital:
Is highly protein bound
False. Protein binding is in the order of 20 - 45%.
Phenytoin is safe in pregnancy
False. Phenytoin is teratogenic and can cause Fetal Hydantoin Syndrome (like Carbamazepine).
Fetal Hydantoin syndrome is associated with Carbamazepine treatment only
False. FHS causes intra-uterine groth retardation, microcephaly, craniofacial abnormalities and limb defects.
Phenobarbital is also a sedative agent
True. Use of Phenobarbital as a sedative has largely been superceded by benzodiazepines.
Phenytoin act to stabilise active voltage gated sodium channels in the CNS
False. Phenytoin stabilises sodium channels in their inactive state
Phenytoin can cause skin rashes
True.
Phenytoin only very rarely provokes an allergic reaction
False. Phenytoin can cause severe allergic reactions and must be given with vigilance.
Phenytoin is mainly excreted unchanged in the urine
False. Primarily, Phenytoin is initially excreted in the bile as inactive metabolites and reabsorbed before being excreted in the urine. Only a small amount is excreted unchanged renally.
Phenytoin can be used to treat trigeminal neuralgia
True
Sodium valproate can cause tremors
True
10% of people treated with Sodium valproate experience hair loss
True
Carbamazepine:
Is safe in pregnancy
False. Carbamazepine can cause spina bifida & other neurodevelopmental problems after intrauterine exposure.
Carbamazepine:
Can be used in chronic pain
True
Carbamazepine:
Has a short half life
False. Half life is in the order of 25 - 65 hours
Carbamazepine:
Can cause severe thrombocytopenia
True. Carbamazepine can reduce serum sodium & WBC levels at normal drug levels, but also cause life-threatening loss of platelets.
Carbamazepine:
Increases the risk of developing Lupus in women
True. Lupus risk increases by nearly 90% (probably only in women).
