Pharmacology Concepts Overview

Pharmacokinetics

• The study of how drugs are absorbed, distributed, metabolised, and cleared from the body.

Pharmacodynamics

• The study of how drugs affect the body.
• Includes understanding how drugs produce their effects, including their mechanism of action and interactions with receptors.

The stages of alcohol intoxication

• The stages of alcohol intoxication are based on blood alcohol content (BAC).
• Range from sobriety to death.

Key points about the stages of alcohol intoxication

• Emax: The maximal pharmacological response, representing the maximum effect of a drug.
• EC50: The concentration of a drug that produces 50% of the maximal effect, representing the drug's potency.
• Sigmoidal Curve: Shows the relationship between drug concentration and its effect, typically S-shaped.
• Logarithmic Scale: Used on the x-axis to display a wider range of concentrations.

Concentration effect relationship in pharmacodynamics

• Drug Potency: One drug is more potent than another if it achieves the same effect at lower concentrations.
• EC50: The concentration at which a drug achieves 50% of its maximum effect.
• Alternative medications: Switching to medications with a lower risk of adverse drug reactions (ADRs).

Concentration effect relationship in pharmacology

• The relationship between drug concentration and its effects on the body, including both beneficial and harmful effects.

Key points about concentration effect relationship in pharmacology

• Therapeutic Window: The range of drug concentrations where beneficial effects are achieved with minimal harmful effects.
• Benefit Curve: The blue solid line representing the therapeutic effect of the drug, which rises steeply in the middle and then levels off at higher concentrations.
• Pharmacodynamics: The study of the effects of a drug on the body.
• PK/PD: The relationship between pharmacokinetics and pharmacodynamics, showing how the effect of a drug changes over time.

PK-PD relationship of pentazocine

• The relationship between the plasma concentration of a drug and its therapeutic effect over time.
• Pentazocine: A drug used to relieve pain.
• Graph: Shows the relationship between plasma pentazocine concentration and analgesia score over time.
• Curves: Two curves are plotted on the graph: plasma concentration and analgesia score.

Pharmacokinetic parameters

• Graph shows a typical plasma concentration-time profile after oral administration of a drug.
• Other statins show lower overall reductions in LDL cholesterol.

Important notes about Pharmacokinetic parameters

• Statins lower LDL cholesterol and risk of heart disease.
• Increasing the dose may not help if a person is not responding adequately.

Factors affecting drug response variability

• Pharmacokinetics: The study of how a drug is absorbed, distributed, metabolised, and excreted by the body.
• Pharmacodynamics: The study of the effects of a drug on the body.

Mechanism of Action

• Medicines work by interacting with the body to create effects
• There are various mechanisms of action, including agonists, antagonists, modifiers, and modulators

Normal Cellular Activity

• Normal cellular activity is achieved when the body's natural chemicals interact with receptor sites on the cell membrane
• This leads to optimal cellular activity, crucial for bodily functions

Antagonists

• Antagonists block the body's natural chemicals from binding to receptor sites
• This leads to decreased cellular activity

Midazolam Clinical Pharmacology

• Midazolam is a lipophilic benzodiazepine, affecting its pharmacokinetics and pharmacodynamics
• It has a rapid onset of action, essential for its clinical use
• Midazolam is extensively metabolized by CYP3A4, potentially influencing its half-life and effectiveness
• It boasts a considerable volume of distribution (1-3 L/kg), affecting its pharmacokinetics and pharmacodynamics
• Midazolam's half-life ranges from 1.5 to 5 hours, but can significantly vary due to various factors

Drug Action and Disposition

• This concept illustrates the journey of a drug through the body, spanning from administration to excretion
• The free drug represents the active form
• Bound drug refers to the drug attached to plasma proteins
• Metabolism involves breaking down the drug into metabolites, ultimately leading to excretion
• Excretion is the final stage of drug elimination, where metabolites are removed from the body
• The relationship between free and bound drugs in tissues is depicted separately
• The harm curve signifies the potential adverse effects of the drug, rising later than the benefit curve
• The safety margin, represented by the blue area between the benefit and harm curves, indicates the drug concentration range where benefits are substantial while harm remains minimal

Concentration Effect Relationship

• This section focuses on the relationship between drug concentration and its effects on the body, including both beneficial and harmful outcomes
• Pharmacodynamics involves the study of a drug's effects on the body
• The PK/PD relationship highlights how a drug's effect changes over time

PK-PD Relationship of Pentazocine

• This exemplifies the connection between plasma drug concentration and its therapeutic effect over time
• Pentazocine is a pain-relieving medication
• The graph illustrates the relationship between plasma pentazocine concentration and analgesia score over time
• Two curves are plotted: plasma concentration and analgesia score

Pharmacokinetic Parameters

• The graph demonstrates a typical plasma concentration-time profile following oral administration of a drug

How Medicines Work

• Medicines interact with the body's natural chemicals and cellular receptors to either activate or hinder cell activity.
• There are two main types of medicines: stimulatory and inhibitory.

Stimulatory Medicines

• Stimulatory medicines enhance cellular activity by interacting with receptor sites on the cell membrane.
• These medicines work by mimicking the body's natural chemicals and binding to receptor sites leading to an increase in cellular activity.

Inhibitory Medicines

• Inhibitory medicines block cellular activity by interacting with receptor sites on the cell membrane.
• These medicines work by blocking the binding of natural chemicals to receptor sites, which leads to a decrease in cellular activity.

Medicine Actions

• Agonists: bind to a receptor and activate it, leading to a response.
• Antagonists: bind to a receptor and block its activation, leading to a decrease in response.
• Modifiers: alter the activity of a protein or enzyme, which leads to a change in response.
• Modulators: regulate the activity of a protein or enzyme, which leads to a change in response.

Molecular Targets

• Molecular targets are the specific proteins or molecules that medicines interact with to produce their effects.

Drug Action and Disposition

• The diagram illustrates a drug's journey through the body: from administration to excretion.
• Free Drug:: The central element in the diagram representing the drug in its free (unbound) form.
• Bound Drug: The drug bound to plasma proteins, shown in the "PLASMA" section.
• Metabolism: The process of breaking down the drug into metabolites, leading to eventual excretion.
• Excretion: The final stage of drug elimination. This is when metabolites are removed from the body.
• Tissue: Shows the relationship between free and bound drugs in tissues.

Adverse Drug Reactions

• Definition: Adverse drug reactions (ADRs) are unintended and harmful effects of a drug.
• Types:
  • Type A: Dose-related and predictable, related to the drug's pharmacological action.
  • Type B: Not dose-related, unpredictable, and not related to the drug's pharmacological action.
• Causes:
  • Pharmacological: Due to the drug's mechanism of action.
  • Pharmacokinetic: Due to drug absorption, distribution, metabolism, and excretion.
  • Pharmacodynamic: Due to the drug's interaction with the body.
• Influencing Factors: Factors that can influence both pharmacokinetics and pharmacodynamics include:
  • Renal disease
  • Hepatic disease
  • Pregnancy
  • Drug interactions
  • Obesity
  • Environmental factors
  • Age
  • Genetic differences
  • Other diseases
• Variability in Drug Response: The central concept influenced by these factors.
• Adherence: A factor that directly affects variability in drug response.

Explore key concepts in pharmacokinetics and pharmacodynamics through this quiz. Understand the stages of alcohol intoxication and important pharmacological parameters like Emax, EC50, and the concentration-effect relationship. Test your knowledge on how drugs function in the body and their effects on various systems.