Drug Actions and Potency Comparison

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Questions and Answers

What occurs when there is an abnormal response to a therapeutic dose of a drug due to a genetic defect?

Hyper-susceptibility

Idiosyncrasy (correct)

Hypersensitivity Reaction

Dependence

Which component is NOT part of the structure of nucleotides?

Phosphoric acid

Amino acid (correct)

Nitrogenous bases

5-carbon sugar

What is the primary biological function of nitrogenous bases in nucleotides?

To provide structural support

To store energy

To bond nucleic acids together (correct)

To facilitate cell division

Which statement accurately describes the characteristics of nucleic acids?

They encode and store information in the nucleus. (A) Signup and view all the answers

What leads to withdrawal manifestations when a drug is ceased after repeated use?

Dependence (A) Signup and view all the answers

In comparing the efficacy of drugs A, B, C, and D, which of the following is the correct ranking from highest to lowest efficacy?

B > A > D > C (A) Signup and view all the answers

What term is used when one drug increases the effect of another drug acting on a different receptor?

Synergism (C) Signup and view all the answers

What is the main distinction between potentiation and synergism in drug interactions?

Potentiation leads to increased potency; synergism leads to increased efficacy. (C) Signup and view all the answers

Which type of curve provides information about drug dose relative to therapeutic responses in a population?

Quantal Dose-Response-Curve (D) Signup and view all the answers

Why can the potency of drugs A, B, C, and D not be compared directly?

They act on different receptors. (C) Signup and view all the answers

What is indicated by a low Therapeutic Index (TI)?

The drug is not safe. (A) Signup and view all the answers

What does the Median-Effective-Dose (ED50) represent in a quantal dose-response curve?

The dose that induces a specific therapeutic response in 50% of the population. (B) Signup and view all the answers

Which of the following statements accurately describes tachyphylaxis?

It refers to an immediate decrease in responsiveness to a drug. (B) Signup and view all the answers

Therapeutic Drug Monitoring is particularly necessary for which category of medications?

Drugs with a narrow therapeutic window. (D) Signup and view all the answers

What is the primary cause of tolerance that develops gradually through repeated drug administration?

Downregulation of receptors. (A) Signup and view all the answers

Which of the following correctly describes the nitrogenous bases found in RNA?

Adenine, Cytosine, Uracil (A) Signup and view all the answers

What bonds link nucleotides in a DNA polymer?

Phosphodiester bonds (B) Signup and view all the answers

What structural feature of DNA protects the nitrogenous bases from degradation?

The sugar-phosphate backbone (B) Signup and view all the answers

How many phosphates can a nucleotide contain?

1, 2, or 3 (C) Signup and view all the answers

What distinguishes mitochondrial DNA from nuclear DNA?

Mitochondrial DNA is circular and found in the mitochondrial matrix. (B) Signup and view all the answers

Study Notes

Drug Actions

Efficacy versus potency are important in drug selection.
Comparing drugs' responses when acting on the same or different receptors is important.
Understanding potentiation and antagonism is crucial in therapy.
Predicting drug safety and toxicity through quantal dose-frequency curves is essential.
Graded dose-response curves are used in therapy.

Quantitative Comparison of Drug Effects (Same Receptor)

Comparing agonists (B, C, D, E, F) to a full agonist (A) shows potency differences (e.g., E > A).
Agonists B, C, and E may have the same efficacy as A.
Drugs D and F have less efficacy than A (D < F).

Effect of Adding Another Drug

Adding a drug that shifts the dose-response curve to the left increases potency.
Adding a drug that shifts the curve to the right decreases potency.
A drug shifting the curve parallel to the right, overcome by increasing agonist concentration, is a competitive reversible antagonist.
A drug shifting the curve to the right non-parallel and not overcome by increased agonist concentration is a competitive irreversible or non-competitive antagonist.

Quantitative Comparison of Drug Effects (Different Receptors)

Drugs acting on different receptors can vary in efficacy.
Drugs acting on different receptors cannot be compared in terms of potency.
If one drug increases the action of another drug acting on a different receptor, it's called synergy or potentiation.

Quantal Dose-Response Curve

Used to predict drug safety.
Median Effective Dose (ED50): drug dose for half the population to have a therapeutic response.
Median Toxic Dose (TD50): drug dose for half the population to show a specific toxic response.
Therapeutic Index (TI): TD50/ED50; a high TI indicates drug safety.

Drug Safety and Monitoring

Drugs with a narrow therapeutic window require monitoring of blood drug concentrations (therapeutic drug monitoring).
Drugs with wide therapeutic windows don't need monitoring.

Drug Response Variations

Drug responses can be reduced (tolerance), increased (hypersensitivity), or altered (idiosyncratic reactions).
Tolerance is often related to repeated drug administration.
Drug hypersensitivity can be due to genetic defects or immune responses.

Nucleotides & Nucleic Acids

Nucleic acids are vital biological molecules.
DNA and RNA comprise nucleic acids.
Nucleotides are monomers made of three parts:
- 5-carbon sugar (ribose or deoxyribose).
- Phosphoric acid.
- Nitrogenous bases (purines or pyrimidines).
Pyrimidines include cytosine, thymine, and uracil.
Purines include adenine and guanine.
DNA is a double helix with complementary base pairing (A-T, G-C).
DNA is located in the nucleus and mitochondria.

Functions of DNA

DNA carries genetic material.
DNA is responsible for protein synthesis.

Ribonucleic Acid (RNA)

A type of nucleic acid, with three main types.
Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes.
Transfer RNA (tRNA): Carries amino acids to ribosomes.
Ribosomal RNA (rRNA): Helps synthesize proteins in ribosomes.

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Description

Explore the intricacies of drug actions, focusing on the concepts of efficacy and potency in drug selection. Learn to compare different drugs acting on the same receptors and understand the importance of dose-response curves in predicting safety and efficacy. This quiz covers essential pharmacological principles relevant to therapeutic applications.