Pharmacokinetics

Pharmacokinetics

1. Routes of drug administration

   • Enteral (by mouth)
     • Oral
       • Solid
       • Liquid
     • Sublingual
       • Chewing gum
       • Lozenges
       • Sprays
       • Tablets
   • Parenteral (by injection)
     • Intravenous (IV)
     • Intramuscular (IM)
     • Intradermal (ID)
     • Subcutaneous (SC)
     • Intraperitoneal (IP)
     • Epidural
     • Intrathecal
     • Intracerebroventricular (ICV)
   • Others
     • Inhalational
       • Aerosol
       • Gases
     • Topical
       • Creams
       • Gels
       • Ointments
       • Sprays
     • Transdermal
       • Patches
       • Plasters
     • Rectal
       • Suppositories
       • Enemas
     • Intranasal

2. Drug absorption process

   • Mechanisms
     • Passive Diffusion
     • Active Transport
     • Endocytosis
     • Exocytosis
   • Factors affecting absorption
     • Drug Properties
       • Size
       • Hydrophilicity & Hydrophobicity
       • pKa of drug
       • Chemical stability of drug
     • Routes of Administration
       • Into circulation directly (Complete absorption)
         • IV
       • Into circulation indirectly (Incomplete absorption)
         • IM
         • SC
         • Intradermal
         • Topical
       • Oral
     • Blood flow to administration site
     • Surface area (SA) for absorption
     • Dosage forms of drugs
     • Drug-drug interactions

3. Drug distribution process

   • Major body compartments
     • Plasma
       • Movement from plasma to interstitium depends on
         • Drug Properties
         • Blood Flow
         • Capillary Permeability
         • Binding of drugs to proteins
     • Extracellular space (Interstitium)
     • Cells/tissues

4. Drug biotransformation process

   • Phase I
     • Unmasking polar functional group
     • Cytochrome P450 system (CYP)
       • Drug-Drug Interaction
   • Phase II
     • Highly polar conjugate to be eliminated by kidney
       • Enzymes
         • Glucuronyl transferase
         • Catalyze conjugation of glucuronic acid
   • Factors affecting
     • Genetic differences
     • Liver diseases
     • Age
     • CYP enzyme induction/inibition
   • First pass effect
     • Enterohepatic cycling

5. Pharmacokinetic parameters

   • Bioavailability (F)
   • Volume of distribution (Vd)
   • Clearance (Cl)
   • Half-life (t1/2)
   • Loading dose (DL)
   • Steady-state plasma concentration (Css)

6. Drug excretion

   • Routes
     • Milk
     • Lung
     • Fecal
     • Sweat, saliva and tears
     • Renal
       • 3 processes
         • Filtration
           • Glomerular Filtration Rate (GFR)
         • Secretion
           • Proximal convoluted tubule
         • Reabsorption
           • Distal convoluted tubule
       • Factors affecting renal excretion
         • Urine pH
         • Urine flow rate
         • Plasma protein binding
         • Competition for active tubular secretion
         • State of renal function

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