Repeated USMLE Questions Step 1- Review- 93- Pharmacology

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Q- A 30-year-old female with a history of epilepsy is prescribed a new antiepileptic drug. The medication primarily enhances the activity of gamma-aminobutyric acid (GABA) by binding to a specific site on the GABA-A receptor, leading to increased chloride influx into neurons.

Which of the following drugs is she most likely prescribed?

A- Diazepam

B- Lamotrigine

C- Levetiracetam

D- Phenytoin

E- Topiramate

A- Diazepam- It is a benzodiazepine that acts as an antiepileptic drug by enhancing the inhibitory effects of gamma-aminobutyric acid (GABA) in the central nervous system.

Q- Which of the following is the primary mechanism of action of fluoxetine in treating a case of major depression?

A- Blockade of serotonin receptors

B- Inhibition of monoamine oxidase

C- Inhibition of serotonin reuptake

D- Inhibition of serotonin synthesis

C- Inhibition of serotonin reuptake- Fluoxetine is a selective serotonin reuptake inhibitor (SSRI), and its primary mechanism of action in treating major depression is to inhibit the reuptake of serotonin.

By inhibiting the reuptake of serotonin, fluoxetine increases the concentration of serotonin in the synaptic cleft, leading to enhanced neurotransmission. This prolonged presence of serotonin allows for improved communication between neurons and is believed to contribute to the therapeutic effects of fluoxetine in alleviating symptoms of depression.

Q- A patient taking warfarin is prescribed a new medication that inhibits CYP2C9.

Which of the following is most likely effect on this patient’s INR?

A- Decreased INR

B- Increased INR

C- No change in INR

D- Variable change in INR

B- Increased INR- Warfarin is processed in the liver, and CYP2C9 is an enzyme that helps break it down. Inhibition of this enzyme leads to higher levels of warfarin.

 

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