1. Pharmacokinetics and Pharmacodynamics
Chapter 2
Pharmacokinetics and Pharmacodynamics

2. Pharmacotherapeutics
The study of how drugs are used to treat, prevent, and diagnose disease and illness
Pharmacokinetics – how the body assimilates, incorporates, and eliminates a drug
Pharmacodynamics – how a drug affects the body

3. You will be able to explain to an athlete…
Why it is important to take medications as prescribed by a physician
How drugs work
Why drugs work
How long a drug remains active
What the potential drug adverse effects are
Other general questions they ask

4. What is a Drug?
A chemical that interacts with and affects living organisms to produce a biological response
A drug alters physiological functions by replacing, interrupting, or potentiating existing cellular functions
Primary or secondary effects

5. Pharmacodynamics
Receptor Sites – a component of a cell to which a drug binds to produce an effect
Most drugs act at specific locations in tissues or organs
“lock and key” analogy (pgs 18-19)
Affinity – the force that makes 2 agents bind or unite
Efficacy – the capacity to elicit a response

6. Dose Response
Threshold – lowest dose capable of producing a perceivable response
Potency – amount of a drug necessary to produce a desired effect
Figure 2-2 Pg 19

7. Determining the time response of a dose:
Latency – “onset of action”, time required to produce an observable effect
Maximal Effect – time required to reach peak efficacy
Duration of Action – time period over which a drug produces a response after a single dose

8. Time Response Influenced by: Route of administration
Solubility of the drug
How fast the drug is distributed to action site
Time it takes to be inactivated and excreted from the body

9. Therapeutic Index – the range in which desired effects are produced
Used to determine the safety parameters of doses

10. Half-Life – determined by the time required to reduce by one-half the amount of the drug present in the body
Drugs have different & distinct half-lives
Comparison for drug elimination rates
Determines frequency with which multiple doses of a drug can be safely administered
Half-life does not change with the drug dose

11. Pharmacokinetics
Absorption – speed, rate, and extent of absorption is dependant on its’ physical and chemical properties
Solubility of the drug
Surface area of intended site of action
Specific route of administration

12. Enteral
Oral ingestion - safest, most common, convenient, economical route of administration
Taken by mouth = onset of action within 1 hour
Oral mucosa – sublingual or buccal routes
Vast capillary blood supply = dissolve rapidly

13. Enteral
Preliminary passage or “first-pass metabolism” Figure 2-7 pg 24
Solutions
Liquid form, syrups, elixirs
Capsules and tablets
Sustained-release

14. Parenteral Non-oral route of administration
Drug delivered directly to target site
Not subjected to first-pass metabolism
Routes include
Subcutaneous
Intramuscular
Intravenous
Intrathecal
Intra-articular

15. Inhalation Form of gases or fine mists
Lungs: large surface area and rich blood supply = effective means of absorbing and transporting meds into blood supply rapidly
Special devices propel meds onto alveolar and bronchial tissues

16. Topical Applied to skin or mucous membranes
Difficult to reach systemic circulation
Used to treat skin problems
Routes
Ointments
Creams
Transdermal patches

17. Pharmacokinetics
Distribution – to act on a specific receptor site, the drug must pass through the different biological layers and then be transported to the site via the bloodstream
Cell membrane review

18. Modes of transportation across cell membrane
Filtration
Diffusion
Active transport

19. Pharmacokinetics
Metabolism – process of ridding the body of foreign substance (biotransformation)
Breakdown of original drug compound into metabolites, which are eliminated
Rate of metabolism
Liver is primary organ, specialized enzymes that metabolize drugs or foreign compounds

20. Pharmacokinetics Excretion Routes of drug elimination
Urine, bile, feces
Lungs, salivary, sweat, mammary glands
Kidney is major organ
Patient Health

21. Factors Affecting Drug Response
Age
Infants & older adults
Weight & Gender
Men vs. women
Dosing based on weight
Time of administration
With food vs. before meals

22. Barriers to Drug Distribution
Blood-brain barrier
Placental barrier
Barriers inhibit certain chemicals in the bloodstream that may be dangerous or toxic to the individual or fetus

23. Drug Safety Five Rights of Drug Administration Right drug
Right patient
Right dose
Right route
Right time

24. Other guidelines: Drug prescribed = Drug dispensed
Read Directions carefully
Missed dosing
Proper storage
Safe storage
Know medical history
Potentiation