solubility and pH

• What is the difference between strong and weak dissociation?

  Strong dissociation completely ionizes, weak does not
• How does pH relate to ionization?

  pH affects the ionization of drugs
• What role does pH play in drug solubility?

  pH influences the solubility of drugs
• How does physiological pH in the GIT influence solubility?

  Physiological pH affects drug solubility in GIT
• Where in the GI tract is drug solubility maximized?

  In the region with optimal pH for the drug
• How is pH and pKa useful in drug formulation?

  They predict ionization and solubility of drugs
• What is the formula for pH?

  pH = -Log [H⁺]
• What does a high pH indicate?

  Low hydrogen ion concentration
• What does a low pH indicate?

  High hydrogen ion concentration
• What is the concentration of H₃O⁺ at pH 7?

  $10^{-7} \text{ M}$
• What is the concentration of OH^- at pH 7?

  $10^{-7} \text{ M}$
• What happens when H⁺ concentration increases?

  H₃O⁺ concentration increases
• What is the Arrhenius definition of acids and bases?

  Acids produce H⁺, bases produce OH^-
• What is an example of a strong acid?

  HCl
• What is the Bronsted-Lowry definition of acids and bases?

  Acids are proton donors, bases are proton acceptors
• How do strong acids behave in solution?

  They completely dissociate in aqueous solution
• How do weak acids behave in water?

  They partially dissociate due to low proton donation
• What is an example of a strong base?

  NaOH
• What is the ionization behavior of weak bases in water?

  They partially dissociate due to low proton acceptance
• What is the acid dissociation constant (Ka)?

  Ka measures the degree of ionization of an acid
• What does a larger Ka value indicate?

  Greater degree of ionization
• How does increasing H⁺ affect Ka?

  It decreases Ka and increases un-dissociated form
• What is the relationship between pKa and Ka?

  pKa = -log(Ka)
• What does pKa represent for an acidic drug?

  pKa is the pH at which 50% is ionized
• How does increasing pH affect the ionization of acidic drugs?

  Increases ionization ratio significantly
• What is the effect of decreasing pH on acidic drugs?

  Decreases ionization ratio significantly
• What is the relationship of pKa for basic drugs?

  pKa is the pH at which 50% is ionized
• How does increasing pH affect the ionization of basic drugs?

  Decreases ionization ratio significantly
• What is the effect of decreasing pH on basic drugs?

  Increases ionization ratio significantly
• What is the relationship between pKa and solubility for acidic and basic drugs?

  • Acidic drugs: Solubility increases above pKa
  • Basic drugs: Solubility increases below pKa
• What is intrinsic solubility?

  Solubility of an ionizable drug in unionized form
• How does pH influence the solubility of drugs?

  pH affects the ionized and unionized forms
• What is the significance of pH in biological fluids?

  It influences drug ionization and permeability
• What is the pH of gastric juice when fasted?

  1-2.1
• What is the pH of pancreatic juice?

  7.9-8.4
• What is the pH of blood?

  7.4
• What is the pH of cerebrospinal fluid?

  7.35
• What is the pH of urine in males?

  5.7
• What is the pH of urine in females?

  5.8
• What is the pH of lachrymal fluid?

  7.4