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• Absorption


  The process by which a drug enters the bloodstream
• Passive Diffusion


  • Occurs down a concentration gradient without energy input
  • Drugs pass through the lipid bilayer of cell membranes
  • Drugs must be non-ionized and lipid-soluble to permeate membranes
• Factors Affecting Passive Drug Absorption
• Active Drug Absorption


  • Drugs are transported against a concentration gradient
  • ATP energy is needed for transportation of drugs
  • Drugs bind to carrier proteins in the cell membranes
• Examples of Drugs that Undergo Active Absorption

  • Antibiotics
  • Vitamins
  • Amino Acids
• Factors Affecting Active Drug Absorption
• Fick's law of diffusion


  Describes how substances passively move from an area of high concentration to low concentration
• Explanation of passive drug absorption

  • Cell Membrane Permeability
  • Concentration Gradient
  • Types of Molecules
• Fick's law equation


  Quantifies the rate of diffusion and is vital in understanding drug absorption in the body

  
• Factors affecting drug absorption
• Importance of understanding drug absorption kinetics

  • Therapeutic Efficacy
  • Pharmacokinetic Models
• Examples of drug absorption using Fick's law

  • Oral Drugs
  • Transdermal Medications
• Drug Ionization


  The process where a drug can exist in both ionized and non-ionized forms, affecting its solubility and permeability
• Weak Acid Drugs


  They only partially dissociate in solution, releasing fewer hydrogen ions
• Weak Base Drugs


  They partially accept hydrogen ions and become positively charged
• Henderson–Hasselbalch Equation


  • Describes the relationship between pH, pKa, and the ratio of the concentrations of the conjugate acid and base
  • Used to analyze and predict the behavior of weak acids and bases
• Step-by-Step Guide to Calculating Percent Ionization

  1. Calculate Concentrations

  2. Apply Henderson–Hasselbalch Equation

  3. Compute Percent Ionization
• Factors Affecting Drug Ionization
• Importance of Understanding Drug Ionization in Pharmacokinetics

  • Drug Absorption
  • Pharmacological Activity
• Examples of Calculating Percent Ionization for Weak Acid and Weak Base Drugs

  • Step 1
  • Step 2
  • Step 3
• Transcellular Drug Absorption

  Involves drug passage through cell membranes, which can be influenced by lipophilicity and molecular size
• Examples of Drugs Undergoing Transcellular Absorption

  • Diazepam
  • Atenolol
• Paracellular Drug Absorption


  Involves drug passage between cells, primarily influenced by the size of the intercellular clefts and tight junctions
• Examples of Drugs Undergoing Paracellular Absorption

  • Mannitol
  • Lithium
• Factors Influencing Transcellular and Paracellular Absorption
• Gastrointestinal (GI) tract


  A complex system responsible for the digestion and absorption of food, starting at the mouth and ending at the anus
• Anatomy of the GI tract

  • Main Organs
  • Tissue Layers
  • Blood Supply
• Physiology of the GI tract

  • Peristalsis
  • Enzymatic Action
  • Hormonal Regulation
• Stomach emptying time and its effect on digestion

  • Stomach Enzymatic Activity
  • Rate of Nutrient Release
  • Digestive Enzyme Activation
• GI transit time and its effect on nutrient absorption

  • Variation in Absorption
  • Nutrient Bioavailability
  • Impact on Water Absorption
• Factors affecting stomach emptying time and GI transit time
• Clinical implications of altered stomach emptying time and GI transit time

  • Gastrointestinal Disorders
  • Nutritional Deficiencies
  • Medication Effects
• The GI tract's function relies on intricate processes with multifaceted interconnections
• Multifactorial influences on stomach emptying and GI transit underscore individual variability
• Understanding and managing these processes are crucial for clinical and nutritional implications
• The Role of Food in Digestion and Absorption

  • Digestive Enzymes
  • Nutrient Absorption
  • Role in Drug Absorption
• The Impact of Food on Drug Absorption

  • Enhanced Absorption
  • Delayed Absorption
  • Nutrient Interactions
• Examples of Drugs Affected by Food Intake

  • Antibiotics
  • Thyroid Medication
  • Blood Thinners
• Clinical Implications and Considerations

  • Patient Compliance
  • Individual Variability
  • Monitoring and Education
• Exploring innovative drug formulations and dietary management strategies