Introduction to Pharmacology

Questions and Answers

What affects a drug's action?

The quantity of drug that reaches the receptor and the degree of attraction (affinity) between the drug and its receptor.

What is disintegration in pharmacology?

The breakdown of a tablet into smaller particles.

What is dissolution?

Dissolving of smaller particles in the gastrointestinal fluid before absorption.

What determines how long it takes for a drug to take effect?

Absorption. Signup and view all the answers

What is absorption?

Movement of a drug from the site of administration into the bloodstream. Signup and view all the answers

What influences the bioavailability of a drug?

The drug's formulation, route of administration, and physiological conditions. Signup and view all the answers

What is the elimination half-life of a drug?

The time it takes for the concentration of the drug in the plasma or total amount in the body to be reduced by 50%. Signup and view all the answers

What can cause an Adverse Drug Reaction (ADR)?

An unwanted or harmful reaction experienced following the administration of a drug under normal conditions. Signup and view all the answers

What is drug toxicity?

Adverse effects of a drug that occur because the dose or plasma concentration has risen above the therapeutic range. Signup and view all the answers

What role does the placenta play in drug distribution?

It serves as a barrier and facilitator for the transfer of substances between the maternal blood circulation and the developing fetus. Signup and view all the answers

What is the process of metabolism in pharmacokinetics?

The process by which the body changes the chemical structure of a drug to a metabolite. Signup and view all the answers

Describe the process of absorption of the sedative-hypnotic medication taken by Mary.

The sedative-hypnotic medication is taken orally, disintegrates and dissolves in the GI fluid, allowing it to be absorbed into the bloodstream. Signup and view all the answers

Explain the process of distribution of the sedative-hypnotic medication within Mary's body.

The medication is transported through the bloodstream to the brain where it acts on GABA receptors. Signup and view all the answers

Describe the process of metabolism of the sedative-hypnotic medication in Mary's body.

The liver metabolizes the medication to facilitate its elimination from the body. Signup and view all the answers

Study Notes

Introduction to Pharmacology

Drug action depends on the amount reaching receptors and affinity to those receptors.
Intrinsic activity measures a drug's ability to produce effects once bound to its receptor.
Pharmacology investigates the biochemical and physiological effects of drugs and their mechanisms of action.

Key Processes in Drug Action

Disintegration: Breakdown of solid drug forms into smaller particles.
Dissolution: Dissolving of these particles in gastrointestinal fluids prior to absorption.
Rate Limiting: Time taken for a drug to disintegrate and dissolve for absorption into the body.

Pharmacokinetics

The branch of pharmacology that studies how the body processes drugs, crucial for determining proper dosages and maximizing therapeutic outcomes.
Involves four main components: absorption, distribution, metabolism, excretion.

Absorption

Movement of a drug from its site of administration into the bloodstream.
Absorption speed affects how quickly a drug takes effect; rapid absorption equates to faster action.
Passive Transport: Moves drugs without energy; Active Absorption requires energy.
Surface area, time in contact with absorptive surfaces, blood flow, solubility, and ionization influence absorption rates.
Bioavailability: Proportion of active drug reaching systemic circulation; influenced by formulation and route of administration.

Distribution

Transport process of drugs to their site of action, influenced by blood flow, permeability, plasma protein binding, and tissue affinity.
Volume of Distribution (Vd): Extent to which a drug disperses into body compartments.
Blood-brain barrier protects the CNS while allowing essential nutrients to pass.
The placenta acts as both a barrier and facilitator for drugs affecting fetal circulation during pregnancy.

Metabolism (Biotransformation)

The liver primarily metabolizes drugs into more water-soluble metabolites for easier excretion.
First-pass metabolism reduces the amount of active drug available post-liver processing.
Factors influencing metabolism include genetics, time of administration, and the patient's age.

Excretion

The process of drug removal from the body primarily via kidneys.
Renal Clearance and Hepatic Clearance are key in determining drug elimination rates.
Elimination half-life indicates the time taken for drug concentration to reduce by half; short half-lives require frequent dosing versus longer half-lives allowing for less frequent administration.

Drug Effects

Therapeutic Effect: Desired action that cures or supports a condition.
Adverse Drug Reaction (ADR): Harmful or unintended effects requiring dosage adjustments or discontinuation.
Adverse Event: Any harm occurring while on medication, irrespective of causal link.
Side-effects: Effects other than the intended therapeutic effect; may be less harmful and predictable than ADRs.
Drug Toxicity: Occurs when drug levels exceed the therapeutic range, often due to overdose.
Drug Abuse: Misuse of drugs leading to addiction or severe health risks.
Hypersensitivity/Allergy: Excessive immune responses can lead to tissue damage; anaphylaxis is a severe allergic reaction needing immediate care.

Case Scenario: Mary

Phase 1: Absorption - Sedative-hypnotic medication taken orally; absorbed in the gastrointestinal tract.
Phase 2: Distribution - Drug reaches the brain, binding to GABA receptors to promote sleep.
Phase 3: Metabolism - Liver metabolizes the drug for elimination after its effects.
Phase 4: Excretion - Kidneys filter drug metabolites into urine for excretion.

Conclusion

Understanding pharmacokinetics is vital for ensuring medications are used safely and effectively.
Each phase of drug action is intricately linked, influencing overall therapeutic efficacy and patient outcomes.

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Description

This quiz explores the foundational concepts of pharmacology, including drug actions, receptor interactions, and intrinsic activity. Understanding how drugs affect the body on a biochemical and physiological level is crucial for nursing and medical practice. Test your knowledge on the mechanisms of drug effects and the critical factors influencing drug action.