Overview of Pharmacology

Overview of Pharmacology

• Definition: The study of drugs, their properties, effects, mechanisms, and uses in medicine.
• Divisions:
  • Pharmacodynamics: Effects of drugs on biological systems.
  • Pharmacokinetics: Movement of drugs within the body (absorption, distribution, metabolism, excretion).

Drug Classifications

• By Source:

  • Natural (plants, animals, minerals)
  • Synthetic (chemically produced)
  • Semi-synthetic (modified natural compounds)

• By Therapeutic Effect:

  • Analgesics (pain relief)
  • Antibiotics (infection control)
  • Antipyretics (fever reduction)
  • Antidepressants (mood regulation)

• By Mechanism of Action:

  • Agonists (activate receptors)
  • Antagonists (block receptors)

Routes of Administration

• Enteral: Oral, sublingual, rectal.
• Parenteral: Intravenous, intramuscular, subcutaneous.
• Topical: Skin applications, inhalation.

Absorption Factors

• Route of Administration: Affects speed and extent of absorption.
• Drug Formulation: Solubility, formulation type (tablet, liquid).
• Physiological Conditions: pH, gastrointestinal motility.

Distribution

• Volume of Distribution (Vd): Measure of drug distribution throughout the body.
• Plasma Protein Binding: Drugs can bind to proteins, affecting availability.
• Blood-Brain Barrier: Selectively allows certain drugs to pass into the brain.

Metabolism

• Liver Function: Major site for drug metabolism (biotransformation).
• Phase I Reactions: Oxidation, reduction, hydrolysis.
• Phase II Reactions: Conjugation (making substances more water-soluble).

Excretion

• Primary Route: Kidney (urine).
• Secondary Routes: Bile, sweat, saliva, exhalation.
• Half-Life: Time taken for drug concentration to reduce by half; influences dosing schedules.

Side Effects and Toxicity

• Adverse Drug Reactions (ADRs): Unintended effects ranging from mild to severe.
• Drug Interactions: Effects when two or more drugs are taken together, can enhance or reduce effectiveness.
• Toxicology: Study of the harmful effects of substances on the body.

Drug Development Process

• Preclinical Trials: Laboratory and animal studies.
• Clinical Trials: Phases I-IV involving human subjects.
• Regulatory Approval: Review by agencies (e.g., FDA) before market release.

Key Terminology

• Therapeutic Index: Ratio of toxic dose to therapeutic dose.
• Bioavailability: Percentage of drug that reaches systemic circulation.
• Loading Dose: Initial higher dose to quickly achieve therapeutic levels.
• Maintenance Dose: Regular dosing to maintain desired drug concentration.

Important Concepts

• Drug Receptor Interaction: Binding to specific receptors to elicit a response.
• Tolerance: Decrease in response to a drug over time.
• Withdrawal: Symptoms occurring when stopping a drug after prolonged use.

Overview of Pharmacology

• Pharmacology encompasses the study of drugs, including their properties, effects, mechanisms, and medicinal uses.
• Divided into two main fields:
  • Pharmacodynamics examines how drugs affect biological systems.
  • Pharmacokinetics focuses on how drugs move through the body, including absorption, distribution, metabolism, and excretion.

Drug Classifications

• By Source:

  • Natural drugs come from plants, animals, or minerals.
  • Synthetic drugs are chemically produced in laboratories.
  • Semi-synthetic drugs are derived from natural compounds with modifications.

• By Therapeutic Effect:

  • Analgesics relieve pain.
  • Antibiotics help control infections.
  • Antipyretics are used to reduce fever.
  • Antidepressants assist in mood regulation.

• By Mechanism of Action:

  • Agonists activate specific receptors.
  • Antagonists block receptor activation.

Routes of Administration

• Enteral Administration: Includes oral, sublingual, and rectal routes.
• Parenteral Administration: Involves intravenous, intramuscular, and subcutaneous methods.
• Topical Administration: Involves drug delivery through skin applications and inhalation.

Absorption Factors

• The route of administration significantly influences the speed and extent of drug absorption.
• The drug's formulation affects solubility and absorption; variations include tables and liquids.
• Physiological conditions such as pH and gastrointestinal motility can alter absorption rates.

Distribution

• Volume of Distribution (Vd) measures how extensively a drug disperses throughout the body.
• Plasma protein binding determines the availability of drugs in circulation, as many drugs adhere to plasma proteins.
• The Blood-Brain Barrier selectively permits certain drugs to enter the brain, protecting it from harmful substances.

Metabolism

• The liver is the principal site for drug metabolism, also referred to as biotransformation.
• Phase I reactions, including oxidation, reduction, and hydrolysis, prepare drugs for elimination.
• Phase II reactions, often involving conjugation, enhance water-solubility to facilitate excretion.

Excretion

• The primary route for drug elimination is the kidneys, resulting in excretion through urine.
• Secondary routes include the bile, sweat, saliva, and exhalation.
• Half-life defines the duration for the drug concentration in the body to decrease by half, crucial for determining dosing schedules.

Side Effects and Toxicity

• Adverse Drug Reactions (ADRs) can vary from mild to severe and are unintended effects of drugs.
• Drug interactions occur when multiple drugs are taken, potentially enhancing or diminishing effects.
• Toxicology studies the detrimental impacts substances may have on the body.

Drug Development Process

• Preclinical trials involve laboratory and animal studies before testing on humans.
• Clinical trials follow a phased approach (I-IV) to assess drug safety and efficacy among human subjects.
• Regulatory approval is necessary for a drug to enter the market, involving reviews by agencies like the FDA.

Key Terminology

• Therapeutic Index: Indicates the safety margin of a drug, derived from the ratio of toxic to therapeutic doses.
• Bioavailability: Represents the percentage of a drug that reaches the systemic circulation effectively.
• Loading Dose: The initial, higher dosage of a drug intended to quickly achieve therapeutic levels.
• Maintenance Dose: Regular doses administered to sustain desired drug levels in the body.

Important Concepts

• Drug-receptor interactions are essential for eliciting biological responses.
• Tolerance reflects a reduced response to a drug following prolonged use.
• Withdrawal refers to symptoms occurring when a drug is ceased after extended usage.

This quiz covers the fundamental concepts of pharmacology, including drug classifications, mechanisms of action, and routes of administration. Test your understanding of pharmacodynamics and pharmacokinetics, as well as the various types of drugs and their effects on the body.