Thu7October1249PM 1

True / False

Is a first line treatment for status epilepticus Incorrect answer selected

Reduces the effectiveness of warfarin Correct

Is a class II anti-arrhythmic agent Correct

Exhibits zero order kinetics Incorrect answer selected

Is a hepatic cytochrome enzyme inducer Correct

Explanation

Phenytoin influences sodium and calcium influx in excitable cells, given it has both anticonvulsant and class I anti-arrhythmic properties.

Phenytoin is an inducer of hepatic CYP3A4 and CYP2C9 families of the P450 enzymes reducing the effectiveness of many drugs including warfarin.

Its side effects include gingival hyperplasia, megaloblastic anaemia and hirsutism.

It has a narrow therapeutic index partly due to its propensity to exhibit zero order kinetics close to the therapeutic range.

It is a second line treatment for status epilepticus.

Reference:

NICE. Epilepsy (CG137).

Answer Statistics

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Average score: 78.60%

Times answered: 271