NURS 1060: Drug Absorption Concepts Exam 1

Questions and Answers

What is the process that occurs before a drug can be absorbed in the GI tract?

Distribution

Disintegration (correct)

Metabolism

Excretion

Which route of drug administration is considered parenteral?

Sublingual

Rectal

Oral

IV (correct)

What is the primary mechanism by which most drugs are absorbed into the bloodstream?

Passive Diffusion (correct)

Active Transport

Endocytosis

Facilitated Diffusion

What type of molecules can generally cross a lipid membrane?

Lipid-soluble Signup and view all the answers

How does ionization affect a drug's solubility in relation to the environment's pH?

It causes acids to become charged particles. Signup and view all the answers

What are the four basic pharmacokinetic processes in sequence?

Absorption, Distribution, Metabolism, Excretion Signup and view all the answers

How does the blood-brain barrier affect drug absorption?

It selectively allows certain drugs to cross into the brain. Signup and view all the answers

What is the role of P-Glycoprotein in drug absorption?

It serves as a transporter that can limit drug absorption. Signup and view all the answers

What is the primary difference between enteral and parenteral routes of administration?

Parenteral bypasses the digestive system. Signup and view all the answers

What is meant by the term 'metabolism' in pharmacokinetics?

The enzymatic breakdown of drugs into metabolites. Signup and view all the answers

Which process follows drug absorption in pharmacokinetics?

Distribution Signup and view all the answers

What is the primary characteristic of an acid in relation to protons?

It acts as a proton donor. Signup and view all the answers

Why is understanding acid-base balance important in pharmacokinetics?

It affects the solubility of drugs in the body. Signup and view all the answers

How does a basic drug behave in an acidic environment?

It becomes ionized and water soluble. Signup and view all the answers

What factor significantly contributes to drug absorption in the intestine compared to the stomach?

More surface area due to villi. Signup and view all the answers

Which route of drug administration is typically absorbed the fastest?

Intravenous route. Signup and view all the answers

Which method is most commonly used by drug developers to ensure a drug crosses cell membranes effectively?

Direct diffusion across the membrane. Signup and view all the answers

What type of drugs can most easily cross cell membranes?

Non-ionized drugs Signup and view all the answers

In which organ does P-glycoprotein transport drugs out of blood into the urine?

Kidney Signup and view all the answers

What is the principle of ion trapping based on?

The pH difference across membranes Signup and view all the answers

What happens to aspirin when it is in the acidic environment of the stomach?

It remains non-ionized and easily crosses membranes Signup and view all the answers

Which of the following accurately describes P-glycoprotein's role?

It prevents drug absorption Signup and view all the answers

What type of environment would basic drugs accumulate in during ion trapping?

Acidic environments Signup and view all the answers

Which ionized state would aspirin be in a basic environment?

Fully ionized Signup and view all the answers

What role do transport systems play in drug movement across cell membranes?

They actively move drugs against concentration gradients Signup and view all the answers

How does an acidic pill taken orally dissolve in the stomach?

It dissolves as non-ionized due to the acidic pH and is lipid soluble. Signup and view all the answers

What is the pH range of the small intestine where basic pills are absorbed?

6-7 Signup and view all the answers

Why do basic pills remain in the stomach when taken orally?

They remain ionized due to the acidic pH of the stomach. Signup and view all the answers

What characterizes drugs that can cross the blood-brain barrier (BBB)?

They must be able to pass through cell walls and are mostly lipid-soluble. Signup and view all the answers

What happens to the drug after it is absorbed from the GI tract?

It travels to the liver before entering general circulation. Signup and view all the answers

What impact does the rate of absorption have on the effects of a drug?

It determines both how soon and how intense the effects will be. Signup and view all the answers

What is the primary method by which drugs cross membranes during absorption?

Passive Diffusion Signup and view all the answers

What property of lipid-soluble drugs enhances their ability to penetrate the blood-brain barrier?

Increased lipophilicity Signup and view all the answers

What is the primary mechanism by which lipid-soluble drugs enter the brain through the blood-brain barrier?

Passive diffusion Signup and view all the answers

Which of the following factors does NOT affect the permeability of drugs across the blood-brain barrier?

Blood pressure Signup and view all the answers

Which type of drug is least likely to penetrate the blood-brain barrier effectively?

Aminoglycosides Signup and view all the answers

Which transport mechanism allows the uptake of larger lipid-soluble compounds into cells?

Endocytosis Signup and view all the answers

What type of lipid-soluble drugs are more likely to have increased bioavailability in the central nervous system?

Drugs that are non-ionized Signup and view all the answers

Which pathological condition is known to alter the permeability of the blood-brain barrier?

Inflammation Signup and view all the answers

What characteristic do lipophilic drugs generally possess?

Lower polarity Signup and view all the answers

Study Notes

Absorption of Drugs

Critical thinking and clinical reasoning are essential for accurate and safe medication administration.
Clinical Decision Making involves analyzing patient problems to prioritize responses, minimizing adverse changes in patient conditions.

Pharmacokinetics Overview

Pharmacokinetics studies drug movement through four main processes:
- Absorption: Drug moves from administration site into the bloodstream.
- Distribution: Drug travels from blood to action or storage sites.
- Metabolism: Drug undergoes enzymatic breakdown into metabolites.
- Excretion: Removal of drug or metabolites from the body.

Drug Administration Routes

Enteral: Absorption occurs in the gastrointestinal (GI) tract (e.g., oral, sublingual, rectal).
Parenteral: More direct methods bypassing the GI tract (e.g., intravenous (IV), intramuscular (IM), subcutaneous (SubQ)).

Drug Absorption Process

Oral drug absorption requires disintegration (tablet breaking apart) and dissolution (mixing with stomach fluids).
Most drugs utilize passive diffusion for absorption, moving from high to low concentration areas.

Factors Influencing Drug Absorption

Rate of dissolution varies by drug.
Surface area: Larger surface area in the intestine facilitates faster absorption compared to the stomach.
Blood flow: Higher blood flow areas enable more rapid absorption.

Drug Passage Mechanisms

Drugs can cross membranes via:
- Direct diffusion: Requires lipid solubility.
- Channels and pores: Very few drugs can use this method.
- Transport systems: Includes P-glycoprotein, which transports drugs out of cells, limiting absorption.

Role of P-Glycoprotein

Acts as an anti-absorption transporter in organs such as:
- Liver: Transports drugs into bile for elimination.
- Kidney: Moves drugs into urine.
- Intestine: Transfers drugs from blood into intestinal lumen.
- Brain: Limits drug access to the brain.

Ionization and Drug Solubility

The ionization state of drugs affects their solubility:
- Acidic drugs tend to ionize in basic (alkaline) environments while basic drugs ionize in acidic environments.
- Non-ionized forms are lipid-soluble and can diffuse across membranes.

Ion Trapping (pH Partitioning)

Accumulation of drugs occurs based on pH differing across membranes:
- Acid drugs accumulate in basic environments and vice versa.
Example:
- Aspirin (acid) in the stomach (pH 1) is non-ionized and lipid-soluble, allowing absorption into the bloodstream.

Blood-Brain Barrier Considerations

Tight junctions in CNS capillaries restrict drug passage; only lipid-soluble drugs can penetrate.

Summary of Absorption Mechanism

Oral absorption involves drug movement from the GI tract into the bloodstream, passing through the liver before entering systemic circulation.
Overall absorption rate affects drug onset and intensity of effects.

Lipid-solubility in Pharmacology

Lipid-solubility signifies a drug's capability to dissolve in fats, influencing its ability to traverse cell membranes.
Drugs with high lipid-solubility are more proficient at penetrating the Blood Brain Barrier (BBB), which safeguards the brain from harmful substances.
Increased lipid solubility generally leads to enhanced bioavailability within the central nervous system (CNS).
Lipophilic drugs usually possess lower molecular weight and exhibit non-polar characteristics.
Notable examples of lipid-soluble drugs include anesthetics, certain antidepressants, and antipsychotics.

Drug Permeability Mechanisms

Diffusion: Lipid-soluble drugs primarily enter the brain through passive diffusion, thanks to their affinity for lipid bilayers.
Transport Mechanisms:
- Carrier-mediated transport: Certain lipid-soluble substances utilize specific transport proteins for crossing the BBB, often through facilitated diffusion.
- Endocytosis: This process involves cell membrane engulfment, allowing larger lipid-soluble compounds to be taken up.
Factors Affecting Permeability:
- Molecular Size: Smaller molecules find it easier to traverse the BBB.
- Ionization: Non-ionized (neutral) drug forms have a higher likelihood of penetrating the BBB.
- Physicochemical Properties: Factors such as lipophilicity, solubility, and charge significantly affect a drug's BBB crossing ability.
Pathological Conditions: Conditions like inflammation or injury can modify BBB permeability, permitting more drugs and potentially harmful elements to reach the CNS.
Examples:
- Lipid-soluble drugs such as diazepam, morphine, and propranolol demonstrate effective penetration into the CNS.
- Conversely, water-soluble drugs like aminoglycosides and penicillin generally struggle to access the brain.
Recognizing the relationship between lipid solubility and drug permeability mechanisms is vital in drug design aimed at CNS therapeutic applications.

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Description

Test your understanding of drug absorption and the critical thinking necessary for safe medication administration in nursing. This quiz focuses on clinical decision-making processes essential for providing quality patient care and clinical judgment.