Question 1

What is the Meaning of P-Glycoprotein?

Accepted Answer

P-Glycoprotein (P-gp), also known as ABCB1, is an ATP-dependent efflux pump located in cell membranes. It actively transports a wide array of structurally diverse substrates, including many drugs and xenobiotics, out of cells, thereby protecting them.

Question 2

What is the Context of P-Glycoprotein?

Accepted Answer

P-Glycoprotein is widely expressed throughout the body, notably in tissues forming protective barriers like the intestinal epithelium, the blood-brain barrier, renal tubules, liver canalicular membrane, and adrenal cortex. Its presence regulates the absorption, distribution, metabolism, and excretion of various substances, influencing systemic exposure.

Question 3

What is the Significance of P-Glycoprotein?

Accepted Answer

Understanding P-Glycoprotein's activity is clinically important due to its impact on drug pharmacokinetics and therapeutic efficacy, particularly in oncology, neurology, and endocrinology. Variations in P-gp expression or function can lead to altered drug responses, contributing to drug resistance in cancers or insufficient drug levels at target sites, directly affecting patient outcomes.

Question 4

What is the Mechanism of P-Glycoprotein?

Accepted Answer

P-Glycoprotein functions as an active transporter, utilizing energy from ATP hydrolysis to pump substrates from the intracellular to the extracellular space. This efflux mechanism involves conformational changes within the protein, allowing it to bind substrates from the inner leaflet of the cell membrane or the cytoplasm and translocate them across the membrane against a concentration gradient.

Question 5

What is the Application of P-Glycoprotein?

Accepted Answer

Clinically, P-Glycoprotein modulation is a strategy explored to enhance drug delivery or overcome resistance. Inhibiting P-gp can increase the bioavailability of certain oral medications or improve drug penetration into the brain. Conversely, inducing P-gp activity might accelerate drug elimination in specific toxicological scenarios, guiding medication selection and dosage adjustments.

Question 6

What is the Metric of P-Glycoprotein?

Accepted Answer

P-Glycoprotein activity or expression can be assessed indirectly through pharmacokinetic studies, measuring plasma concentrations of P-gp substrate drugs. Direct assessment involves molecular techniques such as Western blotting or immunohistochemistry to quantify protein levels in tissue biopsies, or functional assays using specific fluorescent P-gp substrates in cellular models.

Question 7

What is the Risk of P-Glycoprotein?

Accepted Answer

Aberrant P-Glycoprotein function can lead to significant clinical risks. Reduced P-gp activity, often due to genetic polymorphisms or drug interactions, results in increased systemic drug exposure and potential toxicity. Conversely, P-gp overexpression, common in certain cancers, contributes to multidrug resistance, making chemotherapy less effective and necessitating alternative treatment strategies.

P-Glycoprotein

Meaning

Context

Significance

Mechanism

Application

Metric

Risk

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