Free NAPLEX QBANK Pharmacology and Drug Mechanisms Questions and Answers 1

Question 1

A patient with heterozygous familial hypercholesterolemia is prescribed alirocumab. What is the primary mechanism of action of this medication?

Accepted Answer

It binds to proprotein convertase subtilisin/kexin type 9 (PCSK9), preventing its interaction with LDL receptors.

Answer

Alirocumab is a monoclonal antibody that targets and inhibits PCSK9. Normally, PCSK9 binds to LDL receptors on hepatocytes, promoting their degradation. By inhibiting PCSK9, alirocumab prevents this degradation, leading to an increased number of LDL receptors on the liver cell surface, which enhances the clearance of LDL cholesterol from the circulation.

Question 2

A 58-year-old male with newly diagnosed type 2 diabetes mellitus is started on metformin. Which of the following best describes the primary mechanism by which metformin exerts its antihyperglycemic effect?

Accepted Answer

Activation of AMP-activated protein kinase (AMPK), leading to decreased hepatic gluconeogenesis.

Answer

Metformin's principal effect is to decrease hepatic glucose production (gluconeogenesis). It achieves this primarily by activating the enzyme AMP-activated protein kinase (AMPK) in the liver. It also increases insulin sensitivity in peripheral tissues and decreases intestinal glucose absorption, but the reduction of hepatic gluconeogenesis is its main mechanism.

Question 3

A patient who was recently started on lisinopril for hypertension develops a persistent, non-productive cough. This adverse effect is primarily attributed to the accumulation of which substance in the respiratory tract?

Accepted Answer

Bradykinin

Answer

Angiotensin-converting enzyme (ACE) is responsible for both converting angiotensin I to angiotensin II and for breaking down bradykinin. By inhibiting ACE, lisinopril causes an accumulation of bradykinin. Elevated levels of bradykinin in the lungs can irritate cough receptors and stimulate the cough reflex, leading to the characteristic dry, non-productive cough associated with this drug class.

Question 4

A patient is brought to the emergency department with respiratory depression and miosis. An opioid overdose is suspected. Administration of naloxone rapidly reverses these symptoms. By what mechanism does naloxone work?

Accepted Answer

It acts as a competitive antagonist at mu, kappa, and delta opioid receptors.

Answer

Naloxone is a pure opioid antagonist that has a high affinity for opioid receptors, particularly the mu-receptor. It works by competitively binding to these receptors, thereby displacing the opioid agonist (like heroin or oxycodone) and rapidly reversing its effects, most critically respiratory depression.

Question 5

Which of the following statements most accurately describes the pharmacological mechanism of selective serotonin reuptake inhibitors (SSRIs) like sertraline?

Accepted Answer

They selectively block the presynaptic serotonin transporter (SERT), increasing serotonin concentration in the synaptic cleft.

Answer

SSRIs, as their name implies, work by specifically and selectively inhibiting the serotonin transporter (SERT) on the presynaptic neuron. This action reduces the reuptake of serotonin from the synapse, which leads to an increased concentration and prolonged availability of serotonin to bind with postsynaptic receptors.

NAPLEX QBANK Practice Test

NAPLEX QBANK Practice Test

Free NAPLEX QBANK Pharmacology and Drug Mechanisms Questions and Answers 1