Excretion

• excretion

  Removal of a drug from the body may occur via a number of routes, the most important being through the kidney into the urine. Other routes include the GIT, skin glands, lung.
• lungs

  Gases (C02) & Volatile Liquids (Halothane)
• alimentary tract

  1. Saliva (pH= 8): Morphine, Aspirin, Iodide & Mercury
  2. Stomach Morphine.
  3. Bile, Intestine : → Either:
  4. Excreted in large intestine
  5. Reabsorbed - Entero-Hepatic Circulation e.g Rifampicin .
  6. Some anti-microbials are excreted in bile in an active form e.g. Ampicillin → Useful in treatment of Cholecystitis & Typhoid carrier
  7. Larqe Intestine: Either via the bile or unabsorbed oral drugs
• Skin Glands

  1. Sweat Vit B1, Hg, As & Rifampicin → Red discoloration of sweat.
  2. Milk
  3. Most of drugs administered to lactating women are detectable in breast milk.
  4. pH of milk (7) is more acidic than plasma (7.4) → Ion trapping for basic drugs.
  5. Milk is rich in fat → Retention of lipid soluble drugs.
  6. May affect suckling baby e.g Purgatives