Pharmacology

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Pharmacology

• by
• Stian Skogly

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• Objectives
• Define the principle of pharmacokinetics and
  pharmacodynamics
• Explain the general concepts of pharmacotherapy
• Describe formulations and routes of drug
  administration
• List indications, contraindications, side
  effects, precautions, in use and doses of iodine
  and barium containing radiopaque substances,
  muscle relaxants and sedations. Commonly used as
  premedications in radiological imaging.
• Describe the drug interactions involving
  radiopaque substances and radiation
• Describe emergency management of problem
  associated to the use of radiopaque contrast
  medium, sedatives and muscle relaxants

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Kinetics and dynamics

• Pharmacodynamics
• Describes the effects of drugs on the organism
• Pharmacokinetics
• Absorption, distribution, metabolism, and
  excretion of the drug

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Pharmacodynamics

• Most targets are proteins
• Agonists stimulates
• Antagonists blocks

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Stimulation
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A D M E
B S O R P T I O N
I S T R I B U T I O N
E T A B O L I S M
X C R E T I O N
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Absorption

• Drug ? blood
• Permeability
• Lipid solubility, aqueous solubility
• Routes of administration
• GI tract (oral, sublingual, rectal)
• Parenteral (i.v., i.a., i.m., s.c, intradermal,
  topical, intrathecal)
• Pulmonary (inhaled)
• First pass effect
• Portal circulation?Liver?Inactivation?Systemic
  circulation
• Bioavailability
• Percent of unchanged drug reaching the systemic
  circulation

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Distribution

• Blood ? body tissue
• Apparent volume of distribution
• Lipid soluble drugs have a great distribution
  volume
• Aqueous soluble drugs have a small distribution
  volume
• Greater distribution volume, slower elimination
  rate

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Metabolism

• Blood ? Liver
• Inactivation of drug to metabolite by enzymes
• Phase 1 reactions
• More hydrophillic ? urine
• Phase 2 reactions
• Bile ? Faeces or urine
• More hydrophilic ? urine

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Exretion

• Liver Metabolism ? blood or bile
• Kidney Water soluble metabolites
• GI tract Inactivated drugs or from bile
• Lungs Gaseous drugs (anaesthetics)
• Breast milk
• Sweat
• Saliva

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Elimination

• Two main types of eliminations
• 1. order kinetics (most common)
• 0. order kinetics

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First order kinetics

• Excretion is concentration dependent,
  proportional to the plasma concentration
• Exponential kinetics ? Half life
• Most drugs at therapeutic doses follows this type
  of kinetics

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Half life

• The time required for 50 of the drug to be
• eliminated

Amount of drug in placma
Time
t1/2
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Zero order kinetics

• When elimination process is saturated, a constant
  amount of the drug is eliminated over a given
  time period.
• Ethanol is a example

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Steady state

• Takes 3-5 half lifes to reach plateau
• Total amount of drug in body at steady state is
  roughly equal to one dose multiplied with 1.5
• Different dosage regimens for drugs with short
  and long half life

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Amount of drug in body
Time
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Therapeutic index

• The area between the lowest and the highest
  concentration giving effect
• Toxicity is most common outside the therapeutic
  window
• Adverse drug reactions are most common over the
  therapeutic window

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• Objectives
• Define the principle of pharmacokinetics and
  pharmacodynamics
• Explain the general concepts of pharmacotherapy
• Describe formulations and routes of drug
  administration
• List indications, contraindications, side
  effects, precautions, in use and doses of iodine
  and barium containing radiopaque substances,
  muscle relaxants and sedations. Commonly used as
  premedications in radiological imaging.
• Describe the drug interactions involving
  radiopaque substances and radiation
• Describe emergency management of problem
  associate the use of radiopaque contrast medium,
  sedatives and muscle relaxants

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General concepts of pharmacotherapy

• Treating
• Antibiotics
• Preventing
• Lipid lowering drugs
• Vaccinations
• Diagnosing
• Contrast media

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• Objectives
• Define the principle of pharmacokinetics and
  pharmacodynamics
• Explain the general concepts of pharmacotherapy
• Describe formulations and routes of drug
  administration
• List indications, contraindications, side
  effects, precautions, in use and doses of iodine
  and barium containing radiopaque substances,
  muscle relaxants and sedations. Commonly used as
  premedications in radiological imaging.
• Describe the drug interactions involving
  radiopaque substances and radiation
• Describe emergency management of problem
  associate the use of radiopaque contrast medium,
  sedatives and muscle relaxants

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Ways of administration

• Tablets
• Capsules
• Sublingual tablets
• Emulsions
• Suspensions
• Suppositories
• Clysters
• Injections i.v.
• Injections i.a.
• Injections i.m.
• Injections s.c
• Intrathecal

• Pads
• Implants
• Eye drops
• Ear drops
• Nose spray
• Inhalation aerosol
• Inhalation powder

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Common formulations

• Tablets.
• Easy to administrate. Patients can do this at
  home without problems.
• Not need to be sterile because of the acids in
  the stomach ? Easy to produce
• - Long time for absorption
• 1. pass metabolism
• Intra venous injections
• No absorption. Rapid effect
• Must be sterile and without pyrogens
• Hospital administration
• Oral solutions
• More rapid effect than tablets, since it is
  already a solution which could be absorbed from
  the stomach/intestine.
• No need to be sterile.
• Easy to administrate
• - Need time for absorption. No absorption for i.v
  injections.

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• Objectives
• Define the principle of pharmacokinetics and
  pharmacodynamics
• Explain the general concepts of pharmacotherapy
• Describe formulations and routes of drug
  administration
• List indications, contraindications, side
  effects, precautions, in use and doses of iodine
  and barium containing radiopaque substances,
  muscle relaxants and sedations. Commonly used as
  premedications in radiological imaging.
• Describe the drug interactions involving
  radiopaque substances and radiation
• Describe emergency management of problem
  associate the use of radiopaque contrast medium,
  sedatives and muscle relaxants

26
Check out this for more details

• www.neprad.com

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Glomerular filtration rate
(140 Age (years) x Body weight (kg)
ClKr (ml/min)
0,8 x serum creatinine (µmol/l)
The calculated value has to be reduced by 15 for
females
GFR 60-90 ml/min Mild reduced renal function GFR
30-59 ml/min Moderate reduced renal function GFR
15-29 ml/min Severe renal failure
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• Objectives
• Define the principle of pharmacokinetics and
  pharmacodynamics
• Explain the general concepts of pharmacotherapy
• Describe formulations and routes of drug
  administration
• List indications, contraindications, side
  effects, precautions, in use and doses of iodine
  and barium containing radiopaque substances,
  muscle relaxants and sedations. Commonly used as
  premedications in radiological imaging.
• Describe the drug interactions involving
  radiopaque substances and radiation
• Describe emergency management of problem
  associate the use of radiopaque contrast medium,
  sedatives and muscle relaxants

29
Check out this for more details

• www.neprad.com

30

• Objectives
• Define the principle of pharmacokinetics and
  pharmacodynamics
• Explain the general concepts of pharmacotherapy
• Describe formulations and routes of drug
  administration
• List indications, contraindications, side
  effects, precautions, in use and doses of iodine
  and barium containing radiopaque substances,
  muscle relaxants and sedations. Commonly used as
  premedications in radiological imaging.
• Describe the drug interactions involving
  radiopaque substances and radiation
• Describe emergency management of problem
  associate the use of radiopaque contrast medium,
  sedatives and muscle relaxants

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Emergency management

• The practiotioner will tell you about this point
• Adrenalin
• Emergency adrenaline
• Ephedrine
• Atropine

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