Pharmacology Quiz: Serum Drug Concentration

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Questions and Answers

What is primarily responsible for the release of a drug into the body?

Liberation (correct)

Distribution

Absorption

Excretion

Which of the following factors does NOT affect the absorption of a drug?

Metabolism rate (correct)

pH levels

Intestinal movement

Presence of food

In which part of the body are weak bases primarily absorbed?

Liver

Stomach

Colon

Small intestine (correct)

What term describes the relationship between tissue and blood levels of a drug?

Distribution space Signup and view all the answers

Which pharmacological parameter is primarily concerned with the removal of drugs from the body?

Excretion Signup and view all the answers

Which drug classification includes digoxin?

Cardiac glycosides Signup and view all the answers

What is a common cause of drug toxicity?

Elevated concentration of free drug Signup and view all the answers

Which class of drugs does NOT include a sodium channel blocker?

Class II Signup and view all the answers

What process involves conversion of a parent drug to its metabolites?

Metabolism Signup and view all the answers

Which electrolyte can influence the therapeutic actions of digoxin?

Potassium Signup and view all the answers

Which characteristic qualifies a drug for therapeutic drug monitoring?

High variability in patient responses Signup and view all the answers

What is the primary purpose of therapeutic drug monitoring?

To maintain drug concentrations within the therapeutic range Signup and view all the answers

What differentiates trough concentration from peak concentration?

Trough is measured before the next dose, peak is after administration. Signup and view all the answers

Which statement accurately reflects the relationship between drug dosage and circulating concentrations in TDM?

There is a poor relationship between drug dosage and circulating concentrations. Signup and view all the answers

Which route of administration is associated with 100% bioavailability?

Intravenous Signup and view all the answers

What role does the mixed function oxidase (MFO) system play in drug metabolism?

It is responsible for the majority of drug metabolism. Signup and view all the answers

Why is it important to monitor patient compliance in TDM?

To ensure patients are taking medications as prescribed. Signup and view all the answers

What happens to the half-life of a drug when the physiological state of a patient changes significantly?

It may unpredictably change, affecting drug levels. Signup and view all the answers

Which of the following is NOT an objective of therapeutic drug monitoring?

Establishing the pharmacological classification of the drug Signup and view all the answers

What is typically the result of both overdosing and underdosing a therapeutic drug?

Both can lead to severe consequences. Signup and view all the answers

Study Notes

Pharmacological Parameters Affecting Serum Drug Concentration

Liberation: Release of the drug from its formulation.
Absorption: Transport of drug from administration site to blood; primarily via passive diffusion in a non-ionized state.
Distribution: Delivery of drug to tissues, often achieving higher concentrations in tissues compared to blood.
Metabolism: Chemical modification of the drug, primarily occurring in the liver via cytochrome P450 enzymes.
Excretion: Removal of the drug and metabolites from the body, either unchanged in urine or as metabolites.

Absorption

Therapeutic doses require appropriate concentration at the site of action.
Tablets and capsules need to dissolve before absorption, while liquids are absorbed rapidly.
Weak acids are absorbed in the stomach; weak bases in the intestine.
Factors affecting absorption include intestinal movement, pH, inflammation, and presence of food or drugs.

Distribution

Effective drug locations are primarily tissue-based, not bloodstream-centered.
Distribution space reflects the extent of drug movement into tissues versus staying in circulation.

Excretion

Drug clearance from circulation depends on drug type and patient's metabolic capacity.
All drugs are ultimately excreted, either unchanged or as metabolites.
Some drugs can re-enter the enterohepatic circulation and are excreted in stool.

Causes of Drug Toxicity

High levels of free drug concentration in the bloodstream.
Abnormal drug response post-administration.
Active drug metabolites contributing to adverse effects.

Cardioactive Drugs

Used to treat cardiac conditions like arrhythmias and CHF.
Class I: Rapid sodium channel blockers (e.g., Quinidine, Procainamide, Lidocaine).
Class II: Beta receptor blockers (e.g., Propranolol).
Class III: Potassium channel blockers (e.g., Amiodarone).
Class IV: Calcium channel blockers (e.g., Verapamil).
Digoxin: Cardiac glycoside for atrial arrhythmia and CHF; serum electrolytes influence its effects and toxicity.

Therapeutic Drug Monitoring (TDM)

Aims to optimize therapeutic benefit while minimizing side effects by maintaining consistent drug serum levels.
Relevant for drugs with narrow therapeutic indices and those with poor dose-concentration correlation.
TDM involves assessing drug concentrations in serum, plasma, or whole blood.

Indications for TDM

Serious consequences from overdosing or underdosing.
Small difference between therapeutic and toxic dosages.
Changes in patient physiology affecting drug concentrations.
Potential for drug interactions.
To monitor patient adherence to treatment.

Routes of Drug Administration

Circulatory system provides effective drug delivery to target sites.
Intravenous Administration: 100% bioavailability; immediate effect.
Oral bioavailability is approximately 0.7; has larger variability.
Other routes include intramuscular, subcutaneous, inhalation, suppository, and transcutaneous.

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Description

Test your knowledge on the five pharmacological parameters that influence serum drug concentration. This quiz covers essential concepts such as liberation, absorption, distribution, metabolism, and excretion. Enhance your understanding of how these factors impact drug efficacy.