Absorption, distribution, metabolism, and excretion are sometimes referred to collectively as ADME processes. These processes determine when the drug appears in the blood stream and for how long it remains there.
3. Introduction-
Primary goals of clinical pharmacokinetics include
enhancing efficacy and decreasing toxicity of a
patient’s drug therapy.
The development of strong correlations between drug
concentrations and their pharmacologic responses has
enabled clinicians to apply pharmacokinetic principles
to actual patient situations
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5. Definition-
Pharmacokinetics is the study of movement of drug in
the body.
or
Pharmacokinetics is the study of drug absorption,
distribution, metabolism and excretion.
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6. Pharmacokinetics is involve the four main process-
• Absorption
• Distribution
• Metabolism
• Excretion
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7. Absorption-
Absorption is the transfer of a drug from its site of
administration to the bloodstream.
The rate and extent of absorption depends on the route
of administration, the formulation and chemical
properties of the drug, and physiologic factors that can
impact the site of absorption.
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9. When a drug is administered intravenously,
absorption is not required because the drug is
transferred from the administration device directly
into the bloodstream.
Administration by other routes may result in less
availability due to incomplete absorption.
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10. The drug molecules must pass through the selectively
permeable membranes of the cells lining the
gastrointestinal tract to reach the bloodstream.
Depending on their chemical and physical properties,
drugs will be absorbed either by passive diffusion or
carrier-mediated transport across these membranes.
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11. Factors that affect drug
Absorption-
(A) Pharmaceutical Factors-
Disintegration time
Dissolution time
Nature and types of dosage form
pKa of drug and pH
Salt form of drug
Drug solubility
Patients Related factors
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12. (B) Patients Related factors-
• Age
• Gastric emptying time
• Intestinal transit time
• GI pH
• Disease state
• Blood flow through GIT
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13. Distribution-
After absorption, drugs are simultaneously distributed
throughout the body and reaches into the every part of
the body.
In this process, the drug molecules interacting with
receptors on cell membranes or inside of cells, other
molecules may move back into the bloodstream.
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15. The drug distribution is mostly depend on the blood
flow of particular organ. Because the blood flow to
different organs of the body is not equal.
The most vitally important organs of the body receive
the greatest supply of blood. These organs include the
brain, liver, and kidneys.
Skeletal muscle and bone receive less blood, and
adipose tissue (fat) receives the least.
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16. Factors that affect Drug
Distribution-
Factors Related to Drug-
Lipid Solubility
Molecular size
Cellular binding
Duration of action
Therapeutics effect
Toxic effects
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17. Factors Related to body-
• Vascularity
• Blood barrier
• Plasma binding proteins
• Free and bound form of drug
• Drug intraction
• Disease state
• Drug reserviors
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18. Drug Metabolism-
The process of undergoing chemical changes is called
biotransformation, or metabolism.
As previously noted, anything absorbed through the GI
tract goes directly into the portal circulation that
feeds into the liver, and the liver is change the
chemical nature with the help of suitable enzyme.
Liver is the main site of metabolism for almost drugs.
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19. A specific group of cytochrome P-450 enzymes
involves in liver’s that metabolised the drugs
molecules.
Some important enzymes are-
• Cytochrome P-450 monoxigenase
• Estrase
• Amidase
• Estrase
• Methyltransferase
• N-acetyltransferase
• UDP- glocuronosyltransferase.
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20. Factors that Affect Drug
Metabolism-
Some important factors that affect the metabolism of
drugs-
Age
Sex
Genetics
Body Temperature
Stimulator (Drugs)
Inhibitors (Drugs)
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21. Excretion of Drug
The complete removal of the drug from the body is
referred to as elimination or Excretion.
Elimination of the drug encompasses both the
metabolism of the drug, and excretion of the drug
through the kidneys, and to a much lesser degree into
the bile.
Excretion into the urine is one of the most important
mechanisms of drug removal.
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22. The kidneys act as a filter for the blood and create
urine as a vehicle for removal of waste.
When a medication is given repeatedly, as most are in
real patients, the total amount of drug in the body will
increase up to a point and then stabilize.
At this point, the amount being taken in by the patient
is equal to the amount being removed by the liver and
kidneys.
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23. Factors that Affect Drug Excretion-
Polarity of Drugs
Size
pH
Blood Flow in Kidney
Disease of kidneys
Disease of Liver
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