Pharmacology Drug Absorption Quiz

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Questions and Answers

What does it mean for two drugs to be considered bioequivalent?

Their rate and extent of bioavailability are not significantly different. (correct)

They have the same chemical composition.

They are produced by different manufacturers.

They cause the same side effects in all patients.

Why is bioequivalence particularly important for drugs with narrow therapeutic ranges?

Because they are more affordable.

Small differences in blood levels can greatly affect effectiveness. (correct)

They are less likely to produce side effects.

They have a longer half-life.

What is the primary factor that differentiates chemically bioequivalent drugs from biologically bioequivalent drugs?

The method of drug manufacturing.

The presence of different active ingredients.

The duration of drug action in the body.

The amount of drug in the bloodstream. (correct)

Which parameters must fall within 80% and 125% to establish bioequivalence?

AUC and geometric means ratios. Signup and view all the answers

What is a key clinical implication of highly plasma protein bound drugs?

They remain primarily within the vascular compartment. Signup and view all the answers

What does the term 'Tmax' refer to in the context of bioequivalence?

The time to reach peak plasma concentration. Signup and view all the answers

Which of the following statements about the bound fraction of drugs is true?

The bound fraction is not available for metabolism or excretion. Signup and view all the answers

In the context of plasma concentration of drugs, what does it include?

Both the bound fraction and free drug. Signup and view all the answers

Which of the following organs is associated with the accumulation of tetracycline?

Bone and teeth Signup and view all the answers

What does the 'E' in ADME of knowledge represent?

Elimination of outdated facts & figures. Signup and view all the answers

What is the primary difference between drug absorption and bioavailability?

Absorption is the process of entering the body, while bioavailability measures the extent to which a drug reaches systemic circulation. Signup and view all the answers

Which factor does NOT influence oral absorption and bioavailability of drugs?

Type of drug manufacturing company Signup and view all the answers

What role does first-pass metabolism play in drug absorption?

It reduces the bioavailability of drugs that are metabolized before reaching systemic circulation. Signup and view all the answers

Which of the following factors affects the distribution of a drug in various tissues?

Plasma protein binding Signup and view all the answers

How does ionization at physiological pH affect drug distribution?

Non-ionized drugs are usually more readily absorbed and distributed. Signup and view all the answers

What is one of the factors that can lead to variation in drug distribution in the body?

Selectivity of drug accumulation in tissues Signup and view all the answers

What is the significance of blood flow in drug distribution?

Increased blood flow enhances the rapidity and extent of distribution. Signup and view all the answers

Which characteristic of the blood-brain barrier impacts drug absorption into the CNS?

Its preference for lipid-soluble drugs Signup and view all the answers

What characteristic of the epithelial lining of the gastrointestinal tract mainly aids in drug absorption?

It is lipoidal. Signup and view all the answers

Why is the absorption of basic drugs delayed until they reach the duodenum?

They remain ionized in acidic environments. Signup and view all the answers

What effect does food have on drug absorption in the gastrointestinal tract?

It dilutes drugs and retards absorption. Signup and view all the answers

How does capsule or enteric-coated tablet administration affect drug absorption?

They remain intact during digestion to delay absorption. Signup and view all the answers

What is a potential adverse effect related to high peak plasma concentration of a drug?

Increased side effects. Signup and view all the answers

What role does the efflux transporter P-glycoprotein (P-gp) play in drug absorption?

It extrudes drugs back into the intestinal lumen. Signup and view all the answers

What is the effect of larger particle size on the rate of drug absorption?

It decreases the rate of dissolution, leading to slower absorption. Signup and view all the answers

What is the primary benefit of modified-release drug formulations?

Sustained drug levels with less frequent dosing. Signup and view all the answers

What does a large volume of distribution (Vd) imply about the drug's location in the body?

A larger quantity of drug is present in extravascular tissue. Signup and view all the answers

Which factor increases the speed of redistribution of a drug in the body?

Greater lipid solubility of the drug. Signup and view all the answers

What is the role of efflux transporters like P-glycoprotein at the blood-brain barrier?

Prevents nonlipid soluble drugs from entering the brain. Signup and view all the answers

Which of the following is true about plasma protein binding?

Free unbound drugs elicit biological responses. Signup and view all the answers

What could lead to a clinically significant increase in free drug concentration?

Saturation of binding sites due to increased drug concentration. Signup and view all the answers

How does the placental membrane affect drug passage?

It enables free passage for lipophilic drugs. Signup and view all the answers

What is a primary function of the blood-CSF barrier?

To limit entry of nonlipid soluble drugs. Signup and view all the answers

What is the significance of competitive binding in plasma protein binding?

It can lead to displacement of other drugs and increased toxicity. Signup and view all the answers

What happens when nonlipid-soluble drugs are present in high concentrations in maternal circulation?

They can gain access to the fetus over time. Signup and view all the answers

What determines the binding affinity of acidic drugs to plasma proteins?

Their charge and hydrophobicity. Signup and view all the answers

Study Notes

Drug Absorption

Definition: The process of a drug entering the body, often through the gastrointestinal tract, and crossing lipid barriers to reach its target.
Routes of Administration:
- Enteral routes: Oral, sublingual, buccal, rectal
- Parenteral routes: Subcutaneous, intramuscular, intravenous, intrathecal
Factors Influencing Oral Absorption:
- Dosage forms/Formulation: Capsules and coated tablets can provide controlled-release options.
- Lipid Solubility: Non-ionized, lipid-soluble drugs are readily absorbed from the stomach.
- Degree of Ionization: Basic drugs ionize in the stomach, leading to better absorption in the duodenum.
- First-Pass Metabolism: Drugs metabolized in the liver before reaching circulation can reduce bioavailability.
- Gastric Emptying Rate: Faster gastric emptying can accelerate absorption.
- Intestinal Motility: Increased motility can reduce absorption time.
- Complexation with Gut Contents: Interactions with food or other drugs can affect solubility and absorption.
- Disease State: Conditions like diarrhea or malabsorption can affect drug absorption.

Bioavailability

Definition: The fraction of an administered drug that reaches the systemic circulation unchanged.
Factors Affecting Bioavailability:
- First-Pass Metabolism: The extent of metabolism in the liver can significantly influence bioavailability.
- Drug Formulation: Different dosage forms can have different bioavailability profiles.
- Food Interactions: Food intake can delay absorption and alter metabolism.
Bioequivalence: When two versions of a drug have similar absorption and bioavailability.

Drug Distribution

Definition: The movement of a drug from the bloodstream to tissues and organs.
Factors Influencing Distribution:
- Lipid Solubility: Highly lipid-soluble drugs distribute quickly to high blood flow organs like the brain and heart.
- Ionization: Ionized drugs are less likely to cross lipid barriers.
- Plasma Protein Binding: Bound drugs are inactive; only free drugs are available to enter tissues.
- Transporters: Specific transporters can facilitate or limit entry into certain tissues.
- Blood Flow: Organs with high blood flow receive greater drug concentrations.

Volume of Distribution (Vd)

Definition: A hypothetical volume that represents the amount of drug in the body relative to its concentration in plasma.
Interpretation: A large Vd indicates that a significant portion of the drug is distributed outside the plasma.

Drug Redistribution

Process: Initially, highly lipid-soluble drugs distribute to well-perfused organs. As their concentration in plasma drops, they redistribute to less vascular tissues, such as fat and muscle.

Penetration into Brain and CSF

Blood-Brain Barrier (BBB): Tight junctions in brain capillaries limit the entry of non-lipid soluble drugs.
Blood-Cerebrospinal Fluid (CSF) Barrier: Similar to BBB, located at the choroid plexus.
Transporters: Efflux transporters (e.g., P-gp) and other specialized transporters can influence drug entry into the brain.

Passage Across the Placenta

Placental Membrane: Lipoidal membrane allows passive diffusion of lipophilic drugs.
Transporters: Placental efflux transporters (e.g., P-gp) can limit fetal exposure.
Metabolism: The placenta can also metabolize drugs, further influencing fetal exposure.

Plasma Protein Binding

Binding: Acidic drugs bind to albumin; basic drugs bind to α1-acid glycoprotein.
Pharmacological Activity: Bound drugs are inactive; only free drugs are pharmacologically active.
Competition for Binding: Drugs with high affinity for binding sites can displace other drugs, possibly leading to increased free drug concentrations and potential toxicity.

Tissue Storage

Accumulation: Drugs can accumulate in certain organs due to active transport or binding to specific tissue components.
Examples: Tetracycline in the liver, iodine in the thyroid, isoniazid in the brain, tetracycline in bone and teeth, thiopentone in adipose tissue.

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Description

Test your knowledge on drug absorption processes, including routes of administration and factors influencing oral absorption. This quiz will cover concepts such as dosage forms, lipid solubility, and first-pass metabolism. Ideal for students and professionals in pharmacology.