Pharmacology Chapter on Drug Distribution

Questions and Answers

What is the primary organ responsible for the detoxification and metabolism of drugs?

Liver (correct)

Kidneys

Lungs

Heart

Drug excretion can occur through saliva and breast milk.

True

What is the term for the phenomenon whereby a drug is greatly reduced in concentration before it reaches systemic circulation following oral administration?

First pass effect

The time required for the body to eliminate 50% of the drug is known as __________.

half-life Signup and view all the answers

Match the following terms with their definitions:

Protein Binding = The attachment of drug molecules to plasma proteins in the blood Blood-Brain Barrier = A selective barrier that controls the passage of substances into the brain Excretion = The removal of drugs and metabolites from the body Biotransformation = The chemical modification made by an organism on a chemical compound Signup and view all the answers

Which route of administration typically has the fastest absorption rate?

Intravenous Signup and view all the answers

Drugs that are highly lipid-soluble are slower to be absorbed than those with low lipid solubility.

False Signup and view all the answers

What is the primary determinant for the rate of drug absorption in the body?

Surface area Signup and view all the answers

The __________ of a drug is influenced by its physical and chemical properties, such as pH and lipid solubility.

absorption Signup and view all the answers

Match the drug absorption factors with their descriptions:

Lipid Solubility = Ability of a drug to dissolve in fats and oils Blood Flow = Rate of absorption is faster in well-perfused areas pH Partitioning = Influences the movement of drugs across membranes Rate of Dissolution = Time taken for a drug to dissolve before absorption Signup and view all the answers

Study Notes

Distribution of Drug Molecules

Involves transporting drugs to target sites in the body.
Blood circulation is essential for delivering drugs to organs like the heart, liver, and kidneys.
Drug distribution occurs via movement to tissues and intracellular spaces.
Key factors in distribution include:
- Protein Binding: Influences drug availability.
- Blood-Brain Barrier: Restricts certain drugs from entering the brain.
- Placental Transfer: Drugs can cross the placenta and enter breast milk.

Metabolism (Biotransformation)

Refers to the chemical alteration of drug structures in the body.
Primarily occurs in the liver, where detoxification takes place.
Cytochrome P450 enzymes play a significant role in metabolizing most drugs into less active forms.
First Pass Effect: Oral drugs may undergo significant metabolism before reaching systemic circulation, reducing drug concentration.
Six therapeutic consequences of metabolism include:
- Accelerated renal drug excretion
- Drug inactivation or increased therapeutic action
- Activation of prodrugs
- Changes in toxicity levels

Excretion

Defined as the removal of drugs and their metabolites from the body.
Primary organ for excretion is the kidneys; drugs can also exit via urine, bile, sweat, saliva, breast milk, and expired air.
Half-Life: Time it takes for drug concentration to decrease by half; varies between drugs.
Important for determining dosing frequency:
- Short half-life requires more frequent dosing.
- Long half-life may require less frequent dosing.

Absorption Factors

Routes of Administration: Affects drug absorption rate; oral drugs generally absorbed slower than parenteral routes.
Intravenous (IV): Provides immediate effect, avoiding initial breakdown.
Intramuscular (IM): Absorbed into circulation from muscle capillaries.
Factors influencing absorption:
- Physical/Chemical Properties: Determine drug solubility and absorption rate.
- Physiological Factors: Blood flow and surface area at the absorption site enhance absorption rates.
- Lipid Solubility: Highly lipid-soluble drugs cross membranes easily, promoting faster absorption.
- pH Partitioning: Affects the ionization and absorption of drugs.

Pharmacokinetic Considerations

Onset of action can vary between drugs.
Half-life is critical for planning dosing schedules.
Effects may manifest within minutes or take hours, influenced by sites of excretion and metabolism.

Influencing Factors on Drug Response

Factors include weight, gender, environmental conditions, individual health, and tolerance levels.

Ethical-legal Considerations in Nursing

Nurses must follow Nurse Practice Acts, cannot prescribe or administer drugs without a healthcare provider's order.
Ethical values and principles guide nurse conduct and decision-making.
American Nurses Association Code of Ethics emphasizes:
- Compassion and respect for each patient’s dignity.
- Primary commitment to patients and their rights.
- Authority and accountability in nursing practice for optimal patient care.

Description

Explore the intricate process of drug distribution within the body in this quiz. Learn how drugs are transported to their sites of action and understand the roles of protein binding, the blood-brain barrier, and placental drug transfer. Gain insights into the importance of circulation in delivering medication to vital organs.