BIOL122 Lecture 1: BIOL122 notes weeks 1-10
NHPA’s
National Health Priorities Australia:
• Diseases and conditions that significantly contribute to the burden of illness and
injury in the Australian community
• Arthritis and musculoskeletal conditions
• Asthma
• Cancer control
• Cardiovascular health
• Diabetes mellitus
• Injury prevention and control
• Mental health
• Obesity
• Dementia
Pharmacokinetics:
Studies of movement of drugs within the body; i.e. drug absorption, distribution,
metabolism and excretion. How the body acts on drugs
Drug Absorption:
Passage of a drug from its site of administration into plasma: i.e., how does the drug get
into the blood?
Drugs must cross cell membranes: e.g. oral drugs cross mucosa and epithelial layers of the
GI tract.
How are drugs transported across the membrane?
- membrane openings (filtration): movement of particles distinguished by size of molecule
- passive diffusion: movement down gradient, no energy required
- active transport: movement against gradient, energy required
- carrier molecules: can be active or passive
Week 1:
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What determines drug absorption?
1 Nature of absorbing surface
• Number of cell membrane layers, many vs few. E.g. skin vs under the tounge
• Surface area. Large vs small/ e.g. lungs have huge surface area
• Blood supply. Good vs poor. E.g. connective tissues such as tendons and ligaments
are poorly vascularised
2 Chemical structure
• Lipid solubility
• Degree of ionisation
• Molecular weight
• Dissolution rate
• pH of aqueous phase
charged molecules are not allowed to get through a plasma membrane, but water molecules
can eause its so sall. Drugs that dissolve well will be absorbed fast
Drug
distribution:
The movement of a drug from site of administration to tissues (via blood)
Many drugs exist in circulatory system bound to plasma proteins
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Ol fee dugs a eet phaaologial effets
Determinants of drug distribution:
• concentration of free drug
• concentration of plasma proteins
• proportion of body fat and body water
• barriers: blood- brain and placenta
Drug bioavailability:
• proportion of administered dose that
reaches systemic circulation and is able to
exert its effects
• reported as percentage of administered dose
• Variable. (dependant on route of
administration, absorption, etc.)
Drug metabolism
Enzyme modification of drug molecules
Start of the elimination process
Hepatic biotransformation (liver)
• Beginning of drug metabolism by liver enzymes
• A process which converts lipid soluble drugs into water soluble products- can no
longer be absorbed- preparation for excretion
• Some drugs are activated after biotransformation. E.g. codeine, aspirin
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Document Summary
National health priorities australia: diseases and conditions that significantly contribute to the burden of illness and. Nhpa"s injury in the australian community: arthritis and musculoskeletal conditions, asthma, cancer control, cardiovascular health, diabetes mellitus, mental health, obesity, dementia. Studies of movement of drugs within the body; i. e. drug absorption, distribution, metabolism and excretion. Drugs must cross cell membranes: e. g. oral drugs cross mucosa and epithelial layers of the. Membrane openings (filtration): movement of particles distinguished by size of molecule. Passive diffusion: movement down gradient, no energy required. Active transport: movement against gradient, energy required. Carrier molecules: can be active or passive. 1 nature of absorbing surface: number of cell membrane layers, many vs few. E. g. skin vs under the tounge: surface area. Large vs small/ e. g. lungs have huge surface area: blood supply. E. g. connective tissues such as tendons and ligaments are poorly vascularised.
