NUR-641E Mid-Term Exam Study Guide

Note: Read the questions: the questions only have one answer unless the question specifically

states there is more than one correct answer.

ANSWERED SO FAR

Understand what a prodrug is, and activation/inactivation by liver enzymes, and

how it differs from active drugs.

The liver is the principal site of drug metabolism. Although metabolism typically inactivates

drugs, some drug metabolites are pharmacologically active—sometimes even more so than the

parent compound. An inactive or weakly active substance that has an active metabolite is called a

prodrug, especially if designed to deliver the active moiety more effectively.

Know what Bioavailability (BA)

a term used in pharmacology and nutritional and environmental sciences. In

pharmacology, it refers to the degree and rate at which an administered drug is

absorbed by the body's circulatory system, the systemic circulation. Bioavailability is

an essential measurement tool since it determines the correct dosage for nonintravenous administration of a drug availability means

Bioavailability. In pharmacology, bioavailability (BA or F ) is a subcategory of

absorption and is the fraction of an administered dose of unchanged drug that reaches

the systemic circulation

Bioavailability is affected by chemical instability, solubility and first-pass

metabolism

The first pass effect- is a phenomenon of drug metabolism whereby the concentration

of a drug is greatly reduced before it reaches the systemic circulation. It is the fraction

of drug lost during the process of absorption which is generally related to the liver and

gut wall.

Bioequivalence does not affect bioavailability

Bioequivalence is the similarity of two drugs that share the same desired outcome for

patients. Pharmaceutical equivalence means two drugs release the active ingredient into

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the bloodstream at the same amount and same rate. When assessing how well a generic

drug works, scientists evaluate its bioequivalence to the name-brand version.

Understand what the Cytochrome P450 system is in the liver

Cytochrome P450 enzymes are primarily found in liver cells but are also located in

cells throughout the body. ... Cytochrome P450 enzymes account for 70 percent to 80

percent of enzymes involved in drug metabolism. Cytochrome P450 enzymes also

function to metabolize potentially toxic compounds, including drugs and products of

endogenous metabolism such as bilirubin, principally in the liver.

Clopidogrel (Plavix) is a prodrug and must be activated by hepatic CYP2C19 metabolism;

individuals who are poor metabolizers may not form the active metabolite and have reduced

antiplatelet response.

A drug’s half-life determines how often the drug is administered?

The elimination half-life of a drug is a pharmacokinetic parameter that is defined

as the time it takes for the concentration of the drug in the plasma or the total

amount in the body to be reduced by 50%. In other words, after one half-life, the

concentration of the drug in the body will be half of the starting dose.

Steady state of a drug is reached in approximately 5 to 6 times the half-life

Inhalation, oral and parenteral drug action and onset of effects?

Inhalational administration can be used. The lungs serve as an effective route of

administration of drugs. The pulmonary alveoli represent a large surface and a minimal

barrier to diffusion. The lungs also receive the total cardiac output as blood flow. Thus,

absorption from the lungs can be very rapid and complete.

Bioavailability of drugs administered orally varies greatly.

Parenteral administration refers to any routes of administration that do not involve

drug absorption via the GI tract (par = around, enteral = gastrointestinal), including the

IV, intramuscular (IM), subcutaneous (SC or SQ), and transdermal routes

Know the mechanism of action of anticoagulants (e.g., warfarin, apixaban, heparin).

Warfarin competitively inhibits the vitamin K epoxide reductase complex 1 (VKORC1), which

is an essential enzyme for activating the vitamin K available in the body. Through this

mechanism, warfarin can deplete functional vitamin K reserves and therefore reduce the

synthesis of active clotting factors

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