Core Concepts in Pharmacology

1
Core Concepts in Pharmacology

• Chapter 5
• Pharmacokinetics

2
Therapeutic effect and target cells

• What is the relationship between therapeutic
  effect and target cells?
• What is the greatest barrier to achieving the
  therapeutic effect?
• What physiologic processes hinder the achievement
  of therapeutic effects?

3
Substance Passage Through Plasma Membranes

• What role does diffusion play in achieving the
  therapeutic effect?
• Compare and contrast the two processes involved
  in diffusion.

4
Four Components of Pharmacokinetics

• Absorption
• Distribution
• Metabolism
• Excretion
• What do you remember about these processes?

5
What do you think?

• What other organs are involved in excretion?
• What effect will liver or kidney impairment have
  on the pharmacokinetics of medication.
• What are the implications for the prescriber?
• What are the implications for the nurse
  administering the prescribed drugs?

6
First Pass Effect

• Figure 5.4
• What is the problem with the first pass effect?
• What can be done to bypass the first pass
  effect?

7
Plasma Proteins and Drug Distribution

• Drugs bind with plasma proteins
• Drug protein complexes
• Capillary membranes impermeable
• Drug does not reach target cells
• Drugs and other agents compete for plasma
  proteins
• Affinity
• Increasing blood levels
• Toxicity

8
Therapeutic response and plasma drug level

• Direct relationship
• What nursing responsibility is essential when
  administering drugs with low safety profiles?
• Define
• Minimum effective concentration
• Toxic concentration
• Therapeutic range

9
Achieving and Maintaining Therapeutic
Concentrations

• Repeated dose scheduling
• Drug accumulates in blood stream
• Plateau reached
• Amount administered amount excreted

10
Differentiate between Loading Dose and
Maintenance Dose

• Loading Dose
• Higher amount of given drug
• What is the benefit to administering a loading
  dose?

• Maintenance Dose
• Doses administered at intermittent (scheduled)
  times
• What is the purpose of maintenance doses?

11
Plasma half-life (t ½)

• Describes drugs duration of action
• Describe h0w the frequency of dosing differs
  depending upon the drugs half-life.
• How does renal or liver disease affect drug
  half-life?

12
Application problem

• ciprofloxacin hydrocholride (Cipro) has a
  half-life of 4 hours.
• You administer a 500 mg oral dose of
  ciprofloxacin. How long will it take to have
  less than 1o mg of that dose circulating?