Pharmacokinetics

Question 1

P-Glycoprotein (Multidrug Resistance Protein 1) [MDR1]

Answer 1

Multidrug transmembrane transporter protein responsible for transporting several molecules, including drugs, across cell membranes. It reduces drug absorption and is associated with multi-drug resistance. Its function includes:

In the liver: transporting drugs into bile for elimination
In kidneys: into urine for excretion
In the intestines: into the intestinal lumen
In the brain capillaries: transporting drugs back into the blood, thus limiting drug access to the brain.

Question 2

Bioavailability

Answer 2

The fraction of administered dose of a drug that reaches the systemic circulation.

Question 3

Pharmaceutical Equivalence

Answer 3

When drugs contain the same active ingredients and are identical in concentration, dosage form, and route of administration.

Question 4

Bioequivalent

Answer 4

Two pharmaceutically equivalent drug products are said to be bioequivalent when their concentration-time plots are nearly superimposable. This allows for one to safely replace the other (Generic Brands for example).

Question 5

Albumin and Alpha1 - Acid Glycoprotein

Answer 5

Many drugs circulate in the bloodstream bound to plasma proteins, mostly to plasma ALBUMIN for acidic drugs and to ALPHA1 - ACID GLYCOPROTEIN for basic drugs.

Sulfonamides may compete for binding with albumin leading to encephalopathy in newborns due to bilirubin, or increased bleeding when administered alongside Warfarin.

Question 6

Cyclophosphamide

Answer 6

It is a prodrug. It is bio-activated by metabolism to an active anticancer metabolite.

Question 7

N-acetylcysteine

Answer 7

Antidote for acetaminophen poisoning. This compound provides cysteine as a precursor for increased glutathione production, and also reacts directly with (and thereby detoxifies) NAPQI.